Author Topic: Yet another fast edge pulse generator  (Read 28822 times)

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Offline Leo Bodnar

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Yet another fast edge pulse generator
« on: July 08, 2017, 10:06:34 PM »
Executive summary: (updated 1st September 2017)
40-50 picosecond risetime (and even faster falltime) generator with 1V peak to peak 10MHz squarewave output.  Has trigger output.
Powered and configured from USB.  Ships ready to use.
BNC jack for direct connection to your test equipment.
Designed and hand-built in the UK.
Available in stock for £49.99



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Here is a simple pulse generator I have made for testing medium BW scopes' risetimes.  This explains BNC connector on the PCB.
It produces flat top signal with clean and fast rise and fall edges.

I had a few different designs built, using CML and LVPECL drivers, fast comparators and laser diode drivers. Some are good, some bad,  some with 400mVpp, some 2Vpp, some well 50R terminated, some not.  Not a grave issue for launching pulse directly into oscilloscope 50R input but it might be a problem for some applications I have.  Still working on them - my target is ~40ps trise/tfall in the most compact volume.

With 4 or 5 Jim Williams avalanche generators I made over the years I never felt satisfied with the result.  Jim's pulser design is infinitely tweakable (which is a blessing and a curse) and needs some work before it becomes a risetime testing device from slew rate limit testing device. I wish Jim wrote an app note on the distinction between slew rate and rise time and their practical limits. A lot of people I have talked to don't understand the difference.   I had an opamp design guy being unable to explain why ideal RC network has characteristic risetime but no slew rate limit. Avalanche design does not have clean fall edge either. Anyway, I did not want another avalanche pulser.

This one is the simplest, based on 572 comparator from AD. 

It shows 60ps rise and fall time on CSA803A with SD-26 head.  Unlike most scopes, CSA803A cannot trigger from observed signal itself (only from external trigger input) so I had to use an ugly contraption of BNC-N-type-SMA with a T-piece to pick up part of the signal and feed it into the trigger. This does not help signal integrity but I'm reasonably happy with 60ps in such a setup.

I have attached a few oscilloscope screenshots I had around.
Tek CSA 803A with SD-26 (20GHz) 62ps risetime / 59ps falltime
Agilent MSO-X 3024A (200MHz) 1.6ns
LeCroy DDA-125 (1.5GHz) 295ps
LeCroy WavePro 7300A (3GHz) 143ps

All risetimes are for 10%-90% levels into internally terminated 50R scope inputs.

UPDATE =============== UPDATE =================== UPDATE

Gentlemen,

I have finished the configuration software and I call the project ready to ship. 
You can adjust output level from 50mV to 1.2V peak-to-peak and flip the trigger/output phase in case you are using sampling scope.
Settings are non-volatile, stored in the device and survive power off. 

There is a user calibration multiplier if you want to fudge voltage levels to read reasonably accurate value.
Output matches indicated value to about 5-10%.  But above 1000mVpp actual and indicated output start diverging due to output current source saturation.

Rise and fall times stay reasonably low throughout the whole output range (50-1200mVpp) but to keep specified 50ps edge time keep the output level below 700mVpp.

Order yours here: USB Pulser

Many thanks for your custom!
Leo
« Last Edit: September 02, 2017, 04:45:55 AM by Leo Bodnar »
 
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Online fcb

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Re: Yet another fast edge pulse generator
« Reply #1 on: July 08, 2017, 10:14:47 PM »
Very smart Leo.

I like the USB connector for the 5v (I built a USB powered JWG earlier this year), and also the tag connect for the PIC!

Any plans to sell these?
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #2 on: July 08, 2017, 10:23:41 PM »
I like the USB connector for the 5v (I built a USB powered JWG earlier this year), and also the tag connect for the PIC!
Any plans to sell these?

I'll be happy to build a few for sale if this is something useful to others.

Leo

Online tggzzz

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Re: Yet another fast edge pulse generator
« Reply #3 on: July 08, 2017, 10:29:48 PM »
An alternative approach is:
  • one "section" consisting of a 74lvc1g14 + 143ohm series resistor to give an output of 0->1.5V to 0->5V depending on Vcc, with an output impedance of ~150ohms
  • three of those sections in parallel, to give an output impedance of ~50ohms
  • driven by whatever signal is available, including a simple RC relaxation oscillator at a suitable frequency
That certainly gives a clean signal with <1ns transition time into 50ohms. I can't directly measure any faster with my 350MHz scopes. However, indirect frequency-domain measurements indicate a transition times of ~650ps, and a quick test by someone else (i.e. not verified by me) indicated ~300ps rise/fall times.
There are lies, damned lies, statistics - and ADC/DAC specs.
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Offline smoothVTer

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Re: Yet another fast edge pulse generator
« Reply #4 on: July 09, 2017, 12:42:05 AM »
Very useful.  I am also interested in acquiring one of these if you'd be willing to sell one.  What would you charge for a completed assembly?
 

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Re: Yet another fast edge pulse generator
« Reply #5 on: July 09, 2017, 01:59:11 AM »
Very useful.  I am also interested in acquiring one of these if you'd be willing to sell one.  What would you charge for a completed assembly?

I'm not really interested in starting a cottage industry, thanks.

I can't guarantee those results since I can't measure them properly; I only have a Tek 485. So the price would be £1000, to enable me to buy a scope that could measure the output properly :)

They aren't that difficult to make on a double-sided pcb. The major issue is to get good power supply decoupling, which implies broad and short tracks to the Vcc and ground pins.

If you are prepared to do a bit of experimentation, then it might even be possible to make a tolerable one on a breakout board. I'd start by trying a single 74lvc1g* and a 43ohm series resistor, with an 0603 decoupling capacitor mounted diagonally on top of the 74lcv1g*; I used wirewrap wire to connect the capacitor to the pins. Edge launch SMA connectors would be the simplest connector option.
There are lies, damned lies, statistics - and ADC/DAC specs.
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Offline H.O

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Re: Yet another fast edge pulse generator
« Reply #6 on: July 09, 2017, 02:10:17 AM »
I'll be happy to build a few for sale if this is something useful to others.

Leo

I'd gladly purchase one if you decide to build a batch.
 
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Offline WastelandTek

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Re: Yet another fast edge pulse generator
« Reply #7 on: July 09, 2017, 02:22:26 AM »
That looks like just the ticket, especially as it seems Vincent is too busy at Tesla to make his Jim Williams implementation available.

What is the plateau duration on this?  I understand that is a problem with the Williams pulsers.
« Last Edit: July 09, 2017, 02:27:14 AM by WastelandTek »
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Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #8 on: July 09, 2017, 02:59:23 AM »
Thank you for the comments, guys.  I will make a batch and let you know - I have some PCBs and components left from prototyping.

This is essentially 50% duty ratio rectangular pulse so plateau duration depends on the frequency.  This particular design uses internal PIC oscillator which is slaved to the USB clock to keep it simple and compact.  Output frequency is 12MHz. This works fine for ordinary scopes that trigger off the same signal front they are capturing which is almost all the scopes out there apart from few sampling ones like CSA 803 / Tek 1180x / 8300. In that respect it's no different in operation than vanilla JW pulser.

Leo

edit: s/square/rectangular/
« Last Edit: July 09, 2017, 03:01:01 AM by Leo Bodnar »
 
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Offline rx8pilot

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Re: Yet another fast edge pulse generator
« Reply #9 on: July 09, 2017, 03:26:36 AM »
Love it.

I would love to have one if it somehow becomes available. If you prefer not to make a (small) business out of it - I bet a few forum members would be willing to do the assembly and sell them as a courtesy service. I could run a few panels through my pick and place line and have 100 in a few hours.......not to make any money but because these things are interesting.
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Online fcb

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Re: Yet another fast edge pulse generator
« Reply #10 on: July 09, 2017, 03:31:15 AM »
Thank you for the comments, guys.  I will make a batch and let you know - I have some PCBs and components left from prototyping.

This is essentially 50% duty ratio rectangular pulse so plateau duration depends on the frequency.  This particular design uses internal PIC oscillator which is slaved to the USB clock to keep it simple and compact.  Output frequency is 12MHz. This works fine for ordinary scopes that trigger off the same signal front they are capturing which is almost all the scopes out there apart from few sampling ones like CSA 803 / Tek 1180x / 8300. In that respect it's no different in operation than vanilla JW pulser.

Leo

edit: s/square/rectangular/

My JWG just used USB for power - be good if it didn't need a 'real' USB port to work, so it could run from everything including USB power-banks.
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #11 on: July 09, 2017, 03:40:26 AM »
My JWG just used USB for power - be good if it didn't need a 'real' USB port to work, so it could run from everything including USB power-banks.

Yep, this is how it works.  USB connectivity is there "for free" and not of much importance or necessary for operation.

rx8pilot, thank you for your offer, I have few dozen PCBs remaining and it's not a big deal to assemble them manually.  I'd be amazed if the world market is that huge.  But stranger things happened :)

Leo

Offline rx8pilot

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Re: Yet another fast edge pulse generator
« Reply #12 on: July 09, 2017, 04:17:16 AM »
I'd be amazed if the world market is that huge.  But stranger things happened :)

Leo

Me too - I would guess a low number which is probably why these things are not commercially made even by niche manufacturers. It is a fun and educational tool to learn about though. I have been diving into high-speed digital signal integrity over the past year and it is like drinking from a fire hose. This little circuit could be fun for TDR experiments, PCB structures, and other mysterious challenges related to high-speed design. Pretty much anything even close to those rise times is huge and expensive.
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Online MK

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Re: Yet another fast edge pulse generator
« Reply #13 on: July 09, 2017, 06:25:20 AM »
do you have a circuit diagram perhaps?

 

Offline edavid

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Re: Yet another fast edge pulse generator
« Reply #14 on: July 09, 2017, 07:45:24 AM »
rx8pilot, thank you for your offer, I have few dozen PCBs remaining and it's not a big deal to assemble them manually.

Did you hand solder the ADCMP572?

Also, have you thought about adding a pretrigger output?
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #15 on: July 09, 2017, 07:52:22 AM »
MK, formalising the schematic is not a priority at the moment.

Did you hand solder the ADCMP572?
Also, have you thought about adding a pretrigger output?

No, this has been reflowed.
Pre-trigger would need another connector.  I'd like to keep this simple for now until it's working well.
Leo

Offline lukier

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Re: Yet another fast edge pulse generator
« Reply #16 on: July 09, 2017, 07:56:17 AM »
I'd be amazed if the world market is that huge.  But stranger things happened :)

I would like to buy one unit (if possible). I was thinking about this pricey comparator before, but here you have well evaluated design, proven by equipment I don't have (sampling or > 1GHz oscilloscope) - that's a big plus.
 

Offline edavid

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Re: Yet another fast edge pulse generator
« Reply #17 on: July 09, 2017, 08:17:41 AM »
Pre-trigger would need another connector.

It could just be a couple of header pins.
 

Offline Neomys Sapiens

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Re: Yet another fast edge pulse generator
« Reply #18 on: July 09, 2017, 08:33:13 AM »
U would like to register too for such a device. Albeit I concur with edavid that a pretrigger output would come handy.
 

Offline richnormand

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Re: Yet another fast edge pulse generator
« Reply #19 on: July 09, 2017, 12:25:27 PM »
This looks great to check my S-6 sampling head on my trusted Tek scope.
Had to change a switching amp in it.
It does seem to function fine now but this would be the acid test as the risetime is supposed to be 30ps.
In theory the switching amp should not have affected the sampling diodes but who knows.
I would be interested in getting one too. External trig output is also a neat idea.
Cheers and thanks.
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #20 on: July 09, 2017, 05:28:02 PM »
I already have some PCBs here so I'd like to use them but I'll see what I can do with pre-trigger output for the next batch.

What time delay (if any) between the pulse and pre-trigger are you thinking of?

Leo
 
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Offline edavid

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Re: Yet another fast edge pulse generator
« Reply #21 on: July 10, 2017, 03:53:44 AM »
I already have some PCBs here so I'd like to use them but I'll see what I can do with pre-trigger output for the next batch.

What time delay (if any) between the pulse and pre-trigger are you thinking of?

The Tek 7T11 requires 75ns, so you could just make it one clock period.

I don't know if there are other samplers that require a greater delay.
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #22 on: July 10, 2017, 04:13:51 AM »
OK, for the next spin I am going to remove the MCU, use 10MHz TCXO as a frequency reference and break out LVCMOS buffered pre-trigger.

With 10MHz stable repetitive signal sampling scopes can trigger on the nearest edge which is 50ns away or next one at 100ns.

Buffered TCXO cycle-to-cycle jitter is probably going to be in the order of of few ps but this is not going to be a deal breaker - hopefully.

In a pinch this can also be used as a 10MHz reference oscillator or source of harmonics-rich signal.

Leo

Offline richnormand

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Re: Yet another fast edge pulse generator
« Reply #23 on: July 10, 2017, 11:32:27 AM »
As an example my S-53 trigger recognizer can take a trigger input up to 100 MHz so your present rep rate of 12 MHz should not be an issue at all.

Since this is a sampling scope the time delay is not that important (the main plugin is used as a TDR after all, so I can add a delay at will) but trig jitters are.

Often I have to amplitude divide the signal and go through an amp and divide by 100 Hittitte chip to generate the trigger. Not ideal as this can corrupt the signal.

In it's present form just a 12 MHz pulse in sync with either the rise or fall of the waveform would be OK since for a sampling scope the sync jitter will be the real issue.

It looks like I could use your present design directly. But just a test point on the board with a trigger output ( buffered from the test signal) would be very nice indeed.

Have fun!
« Last Edit: July 10, 2017, 11:40:14 AM by richnormand »
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #24 on: July 13, 2017, 03:48:30 AM »
Update: I have added an SMA with trigger output and re-spun the boards.
I should have them tuned and tested by early next week.
Thanks
Leo


Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #25 on: July 14, 2017, 12:50:24 AM »
I think I have the design ready.  I am very happy with its performance and form-factor.  I might continue tweaking it a little bit but it's necessary to declare any project ready to ship at some point.  So it is.

Here is the list of features it has ended up with.

  • Fixed 10MHz pulse train with fast rise and fall times.
  • Rise time and fall time around 50ps
  • Variable amplitude between 100mVpp and 1Vpp (via USB .)  AC coupled.
  • Trigger output ~1.5Vpp amplitude into 50R load.  AC (default) or DC (solder jumper) coupled
  • BNC jack for direct connection to oscilloscope input
  • USB powered. Power requirement is 200mA at 5V.  Can be powered from a USB charger.

I have about a dozen PCBs and can supply them starting from next week at £50 plus shipping for a fully assembled, tested and ready to go unit.  This will barely cover my design costs and if this becomes a commercial product will probably be revised (up or down.)
As a bonus I will print out individual rise/fall time screenshots for each unit on my CSA 803A + SD-26 test setup for this run and supply them with the device.

It would be helpful if you indicate your interest by posting here so that I know how many units to assemble.

Thanks
Leo

P.S. I hope this is not considered heavily commercial for this forum.  If you think it is please let me know.
« Last Edit: July 14, 2017, 01:01:39 AM by Leo Bodnar »
 
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Offline lukier

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Re: Yet another fast edge pulse generator
« Reply #26 on: July 14, 2017, 12:58:20 AM »
I have about a dozen PCBs and can supply them starting from next week at £50 plus shipping.  This will barely cover my design costs and if this becomes a commercial product will probably be revised (up or down.)
It would be helpful if you indicate your interest by posting here so that I know how many units to assemble.

I would be interested, but please clarify, £50 for the PCB, PCB + parts or assembled kit?
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #27 on: July 14, 2017, 01:02:31 AM »
I would be interested, but please clarify, £50 for the PCB, PCB + parts or assembled kit?
Fully assembled, tested and ready to go unit.
Thanks
Leo

Offline lukier

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Re: Yet another fast edge pulse generator
« Reply #28 on: July 14, 2017, 01:04:44 AM »
Then count me in :)
 

Offline rx8pilot

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Re: Yet another fast edge pulse generator
« Reply #29 on: July 14, 2017, 02:27:42 AM »
I would be interested, but please clarify, £50 for the PCB, PCB + parts or assembled kit?
Fully assembled, tested and ready to go unit.
Thanks
Leo

Totally. Want. One.  :-+ :-+
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Offline H.O

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Re: Yet another fast edge pulse generator
« Reply #30 on: July 14, 2017, 02:54:50 AM »
Definitely, I'd take one if I may, thank you!
 

Online chriswebb

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Re: Yet another fast edge pulse generator
« Reply #31 on: July 14, 2017, 03:10:19 AM »
I too would be interested in this device.
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Offline JPortici

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Re: Yet another fast edge pulse generator
« Reply #32 on: July 14, 2017, 04:06:22 AM »
I want one too! :D
 

Offline richnormand

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Re: Yet another fast edge pulse generator
« Reply #33 on: July 14, 2017, 04:26:52 AM »
Put me down for one also.
Cheers and thanks.
 

Offline tecman

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Re: Yet another fast edge pulse generator
« Reply #34 on: July 14, 2017, 04:58:32 AM »
I'm good for one as well

paul
 

Offline steverino

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Re: Yet another fast edge pulse generator
« Reply #35 on: July 14, 2017, 05:01:52 AM »
+1 please and thank you
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #36 on: July 14, 2017, 05:07:18 AM »
Thank you, gentlemen.  I'm on it.

Offline JPortici

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Re: Yet another fast edge pulse generator
« Reply #37 on: July 14, 2017, 06:06:18 AM »
let us know if you put up a preorder/page list :-+

i WANT one when they'll be ready, but would you consider in the future a new version, powered by let's say 2 coin cells? instead of having to connect a usb cable...

where did you get your pcb made? i like them very much, simillar to the boards from one of our assemply houses (they're quite expensive to set up though, for hobby projects)
« Last Edit: July 14, 2017, 06:12:06 AM by JPortici »
 

Offline tatus1969

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Re: Yet another fast edge pulse generator
« Reply #38 on: July 14, 2017, 07:28:54 AM »
Great job!

If your batch isn't sold out, I would also love to buy one.
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Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #39 on: July 14, 2017, 07:42:55 AM »
I will try to accommodate everyone :)  Thanks, guys.

Offline orin

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Re: Yet another fast edge pulse generator
« Reply #40 on: July 14, 2017, 07:52:38 AM »
Add me to the list too please.
 

Offline electrolust

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Re: Yet another fast edge pulse generator
« Reply #41 on: July 14, 2017, 11:03:33 AM »
One for me, if you can ship to US.  I'm happy to take a single US shipment as remail them to final destination.
 
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Offline marshallh

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Re: Yet another fast edge pulse generator
« Reply #42 on: July 14, 2017, 12:25:11 PM »
You can set up a public Google Docs spreadsheet and link it, people can add their names to the list. Worked well for me, no need to trawl through posts to see who wanted one  :-+
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Offline all_repair

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Re: Yet another fast edge pulse generator
« Reply #43 on: July 14, 2017, 02:03:25 PM »
May I order one.  Thank you.
 

Offline Berni

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Re: Yet another fast edge pulse generator
« Reply #44 on: July 14, 2017, 03:18:15 PM »
I would like to buy one too
 

Offline ivaylo

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Re: Yet another fast edge pulse generator
« Reply #45 on: July 14, 2017, 03:39:56 PM »
one more please...
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #46 on: July 14, 2017, 05:31:48 PM »
Thanks, all.  The purpose of having people expressing interest is so that I can estimate suitable batch size and purchase components in correct quantities. This has worked great so far, I see that I need to run another batch of PCBs early next week.

Thank for your offer electrolust, I can ship with FedEx or Airmail around the world from our small office so this is not a problem.  We get good rates.

Online capt bullshot

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Re: Yet another fast edge pulse generator
« Reply #47 on: July 14, 2017, 08:41:16 PM »
Count one in for me too ...
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Offline Andie

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Re: Yet another fast edge pulse generator
« Reply #48 on: July 14, 2017, 09:29:54 PM »
Leo,

awesome! I would like to buy one, too!

Regards,
Andreas
 

Offline The Electrician

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Re: Yet another fast edge pulse generator
« Reply #49 on: July 15, 2017, 01:34:38 AM »
Put me on the list.  Another great forum project showing up on a great forum.
« Last Edit: July 15, 2017, 01:36:36 AM by The Electrician »
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #50 on: July 15, 2017, 02:12:42 AM »
I have assembled and tested all the last revision boards I had. 
They all have identical rise/fall time and profiles to within +-2ps.  Therefore, I won't be printing individual screenshots like I planned before - they all look the same within my measurement capabilities.  I have attached representative screen captures for the whole batch.

I am planning to finish output level configuration software this weekend and start shipping immediately and reorder more PCBs and parts.
I did not expect that level of interest - for which I am grateful :)

Thanks
Leo



 
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Online BravoV

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Re: Yet another fast edge pulse generator
« Reply #51 on: July 15, 2017, 02:38:18 AM »
I'm in for one, thank you.  :-+

Offline TheAmmoniacal

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Re: Yet another fast edge pulse generator
« Reply #52 on: July 15, 2017, 02:39:03 AM »
I would also be interested in one? Just PM me with details.
« Last Edit: July 15, 2017, 02:51:16 AM by TheAmmoniacal »
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Offline mk_

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Re: Yet another fast edge pulse generator
« Reply #53 on: July 15, 2017, 03:50:42 AM »
I'm in for two boards

thanks

Michael
 

Offline metrologist

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Re: Yet another fast edge pulse generator
« Reply #54 on: July 15, 2017, 05:27:21 AM »
I have assembled and tested all the last revision boards I had. 
They all have identical rise/fall time and profiles to within +-2ps.  Therefore, I won't be printing individual screenshots like I planned before - they all look the same within my measurement capabilities.  I have attached representative screen captures for the whole batch.

I am planning to finish output level configuration software this weekend and start shipping immediately and reorder more PCBs and parts.
I did not expect that level of interest - for which I am grateful :)

Thanks
Leo

Very impressive! Let me ask a question.

One for me, if you can ship to US.  I'm happy to take a single US shipment as remail them to final destination.

electrolust, you are a confirmed US distributor?

Are all of the assembled units already spoken for?

I might have to join the TEA party here soon...
 

Offline jpb

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Re: Yet another fast edge pulse generator
« Reply #55 on: July 15, 2017, 05:32:04 AM »
If they are still available then I would like to register my interest, thank you.
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #56 on: July 15, 2017, 05:38:05 AM »
I intend to keep making them until there is interest so don't panic, everyone who wants one will have a chance to get one.
Leo
 
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Offline barry14

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Re: Yet another fast edge pulse generator
« Reply #57 on: July 15, 2017, 09:10:14 AM »
You can put me down for one unit also.  I appreciate the effort you put into this project.  Thanks from everyone.
 

Offline WastelandTek

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Re: Yet another fast edge pulse generator
« Reply #58 on: July 15, 2017, 02:24:09 PM »
I intend to keep making them until there is interest so don't panic, everyone who wants one will have a chance to get one.
Leo

sweet!
I'm new here, but I tend to be pretty gregarious, so if I'm out of my lane please call me out.
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #59 on: July 16, 2017, 03:19:17 AM »
Gentlemen,

I have finished the configuration software and I call the project ready to ship. 
You can adjust output level from 50mV to about 1.2V peak-to-peak and flip the trigger/output phase in case you are using sampling scope.  Not much of exciting science.  Settings are non-volatile, stored in the device and survive power off. 

There is a user calibration multiplier if you want to fudge voltage levels to read reasonably accurate value.  Output matches indicated value to about 5-10%.  Rise and fall times seems to stay the same throughout the whole output range (50-1200mVpp.)

I have 12 units in stock available here for shipping on Monday July the 17th: USB Pulser

The next batch is coming on Wednesday so I am going to continue taking orders after the first 12 are gone.  If you order does not ship on Monday, don't panic it's being assembled, tested, calibrated and shipped this week.

Many thanks for this fun!
Leo
« Last Edit: July 16, 2017, 03:21:41 AM by Leo Bodnar »
 

Offline TheAmmoniacal

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Re: Yet another fast edge pulse generator
« Reply #60 on: July 16, 2017, 03:28:38 AM »
Looks good!

Quote
Thank You! We Appreciate your Business!
Your Order Number is: 20498

Thanks.
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Offline JPortici

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Re: Yet another fast edge pulse generator
« Reply #61 on: July 16, 2017, 03:34:26 AM »
excellent :-+ will order this week
 
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Offline Berni

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Re: Yet another fast edge pulse generator
« Reply #62 on: July 16, 2017, 04:00:35 AM »
Nice, already went ahed and ordered mine.

Im curious how will it look like on my 4GHz scope.
 
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Offline H.O

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Re: Yet another fast edge pulse generator
« Reply #63 on: July 16, 2017, 04:19:48 AM »
Placed my order as well, thank you for making this available, much appreciated!
 
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Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #64 on: July 16, 2017, 04:34:51 AM »
Cheers, guys.  This is probably an ultimate case of impulse buying.

Offline richnormand

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Re: Yet another fast edge pulse generator
« Reply #65 on: July 16, 2017, 04:50:47 AM »
In response to my previous posting indicating my interest I just placed an order on your website a few minutes ago :)

Will be interesting how my sampling scope signal looks with your unit.
Software is a very nice touch too.

Cheers.

 
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Offline macboy

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Re: Yet another fast edge pulse generator
« Reply #66 on: July 16, 2017, 05:08:04 AM »
Count me in for one unit.
Ordered one unit. Looking forward to playing with this on my Lecroy WavePro 960 and Tek 2465A.
« Last Edit: July 16, 2017, 05:18:24 AM by macboy »
 

Offline HighVoltage

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Re: Yet another fast edge pulse generator
« Reply #67 on: July 16, 2017, 05:19:33 AM »

I'll be happy to build a few for sale if this is something useful to others.

Leo
If you build some, I am interested in buying one.
Thanks
Really good work!
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Offline macboy

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Re: Yet another fast edge pulse generator
« Reply #68 on: July 16, 2017, 05:21:59 AM »
Cheers, guys.  This is probably an ultimate case of impulse buying.
Impulse buying? Never! you can't measure risetime with an impulse  :P
 

Offline HighVoltage

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Re: Yet another fast edge pulse generator
« Reply #69 on: July 16, 2017, 05:40:56 AM »
Code: [Select]
Thank You! We Appreciate your Business!
Your Order Number is: 20505

Thanks, I just ordered one on your website
There are 3 kinds of people in this world, those who can count and those who can not.
 
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Offline Berni

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Re: Yet another fast edge pulse generator
« Reply #70 on: July 16, 2017, 05:56:24 AM »
Also it would be nice if the frequency was adjustable from a range of choices. For example this is useful for TDR measurements of cables and if you have a long cable then you need a lower frequency than 10MHz in order for all the reflections to make it back before the next pulse. Perhaps make it a choice of 10MHz 1MHz 100KHz 10KHz 1KHz.
 

Offline jpb

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Re: Yet another fast edge pulse generator
« Reply #71 on: July 16, 2017, 06:01:51 AM »
Your Order Number is: 20506 (Just placed order on website)
Thanks
 
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Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #72 on: July 16, 2017, 07:24:46 AM »
Also it would be nice if the frequency was adjustable from a range of choices. For example this is useful for TDR measurements of cables and if you have a long cable then you need a lower frequency than 10MHz in order for all the reflections to make it back before the next pulse. Perhaps make it a choice of 10MHz 1MHz 100KHz 10KHz 1KHz.
Yes, I have considered TDR use for long cables.  This would need quite a redesign as opposed to just a tweak.  For example, current version has AC coupled output and 10MHz pulse droop on 50R load is only a few percent across the pulse span.
With 1kHz the output would have to be DC coupled which will need a redesign and re-qualification of the frontend.  The tradeoff will probably include losing crisp pulse fronts and going back to 100+ps risetimes.  Isn't spread spectrum TDR all the rage now for new designs anyway?

Offline rx8pilot

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Re: Yet another fast edge pulse generator
« Reply #73 on: July 16, 2017, 07:46:15 AM »
Just placed the order. Look forward to pulsing. Thanks Leo - looks like a nice clean design
Thank you EEVBlog for all the support in the Keysight Test to Impress Giveaway voting!
 
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Offline Berni

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Re: Yet another fast edge pulse generator
« Reply #74 on: July 16, 2017, 08:26:20 AM »
Also it would be nice if the frequency was adjustable from a range of choices. For example this is useful for TDR measurements of cables and if you have a long cable then you need a lower frequency than 10MHz in order for all the reflections to make it back before the next pulse. Perhaps make it a choice of 10MHz 1MHz 100KHz 10KHz 1KHz.
Yes, I have considered TDR use for long cables.  This would need quite a redesign as opposed to just a tweak.  For example, current version has AC coupled output and 10MHz pulse droop on 50R load is only a few percent across the pulse span.
With 1kHz the output would have to be DC coupled which will need a redesign and re-qualification of the frontend.  The tradeoff will probably include losing crisp pulse fronts and going back to 100+ps risetimes.  Isn't spread spectrum TDR all the rage now for new designs anyway?

Ah right i didn't know there was an AC coupling limitation with it. Makes sense to have a fixed frequency then. The 10MHz is enough for about 10m of cable anyway.
 

Offline JacquesBBB

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Re: Yet another fast edge pulse generator
« Reply #75 on: July 16, 2017, 09:01:04 PM »
Hi Leo,

Just ordered one on your website.
Could you provide the schematics ?

Thanks

Jacques
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #76 on: July 16, 2017, 10:19:20 PM »
Hi Leo,

Just ordered one on your website.
Could you provide the schematics ?

Thanks

Jacques

Hi Jacques,
Thank you.  I don't have ready to go schematics at the moment.  There is just a PIC and the driver.  I am still tweaking and changing it between revisions.
Leo

Offline lukier

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Re: Yet another fast edge pulse generator
« Reply #77 on: July 17, 2017, 07:34:02 AM »
Order placed. Thanks!
 

Offline Gixy

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Re: Yet another fast edge pulse generator
« Reply #78 on: July 17, 2017, 06:12:50 PM »
Order 20535 placed. Thks!
 

Offline sdouble

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Re: Yet another fast edge pulse generator
« Reply #79 on: July 18, 2017, 06:22:18 AM »
hi and congrats,
any chance to have a version with adjustable frequency.
I'm personnally interested in a low frequency version.
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #80 on: July 18, 2017, 07:19:35 AM »
any chance to have a version with adjustable frequency. I'm personnally interested in a low frequency version.
Low/adjustable frequency needs substantial redesign.  Maybe something for v.3
Leo

Offline sdouble

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Re: Yet another fast edge pulse generator
« Reply #81 on: July 18, 2017, 11:56:19 PM »
good to know, thanx
 

Offline Mark

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Re: Yet another fast edge pulse generator
« Reply #82 on: July 19, 2017, 01:24:03 AM »
Order 20515 received with thanks! 
 

Offline tecman

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Re: Yet another fast edge pulse generator
« Reply #83 on: July 19, 2017, 02:56:44 AM »
Where do I find the website ?

paul
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #84 on: July 19, 2017, 03:18:38 AM »
Hi Paul,
http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295
I have shipped all the boards that I had. All outstanding orders will ship by the end of this week.
Cheers
Leo
Where do I find the website ?

Offline lukier

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Re: Yet another fast edge pulse generator
« Reply #85 on: July 19, 2017, 05:43:43 AM »
The pulser arrived today - neat little gadget, need to buy a box for it.

I didn't try the trigger out or USB connectivity yet, just a simple test with my WaveRunner 6100A. 50 Ohm termination, RIS mode (i.e. equivalent sampling, in real time it is 10-15 ps worse), the rise time is around 240 ps, well under the datasheet specification of 300 ps.
 
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Offline jpb

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Re: Yet another fast edge pulse generator
« Reply #86 on: July 20, 2017, 03:36:41 AM »
Mine too arrived yesterday, but sadly it came during a brief period when no one was home so it is now gone to the sorting office :(
My wife went to the sorting office today with the little card, but they wouldn't give it to her because it was addressed to me and she didn't have any id for me. |O

Tomorrow, my wife has kindly agreed to have another go, taking my ID with her - so perhaps I'll get it tomorrow evening when I return from work.
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #87 on: July 20, 2017, 05:16:18 AM »
Update: I have sent out all orders received over the weekend.  Thank you!
There are three remaining units ordered yesterday and day before yesterday awaiting new PCB batch.  They will be shipped on Friday or Monday.
Cheers
Leo
« Last Edit: July 20, 2017, 05:24:59 AM by Leo Bodnar »
 

Offline rx8pilot

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Re: Yet another fast edge pulse generator
« Reply #88 on: July 20, 2017, 05:53:25 AM »
This device will add a few entries into the 'Show us your square wave' thread.

I think that mine has arrived - my wife is checking. Looking forward to a quick check on the 6Ghz Keysight scope!

Looking forward to various TDR experiments. It will be a nice tool to learn a little about high-speed design which is consuming my efforts at the moment.

EDIT:
Arrived in the USA - 70ps rise - 20% overshoot. Curious about the overshoot, was more than expected based on the test report that Leo included.
« Last Edit: July 20, 2017, 07:12:39 AM by rx8pilot »
Thank you EEVBlog for all the support in the Keysight Test to Impress Giveaway voting!
 

Offline The Electrician

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Re: Yet another fast edge pulse generator
« Reply #89 on: July 20, 2017, 03:26:53 PM »
I got mine here in USA Tuesday.  Here's the rise on my R&S RTO1014 1 GHz scope, 295 picoseconds.

 

Offline jpb

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Re: Yet another fast edge pulse generator
« Reply #90 on: July 21, 2017, 03:55:42 AM »
Got mine today after one missed delivery and two trips to the post office.
About 750 psecs on my 350MHz scope which is nearer the 500MHz BW rather than 1 ns specified rise time.
I can't remember what rise time I got with my Jim Williams pulser - I need to check for a comparison.
 

Offline JPortici

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Re: Yet another fast edge pulse generator
« Reply #91 on: July 21, 2017, 04:03:16 AM »
This device will add a few entries into the 'Show us your square wave' thread.

most definetly.

about the overshoot, are you positive that the scope frontend has a gaussian responce? or maybe there is some parasitics? same for the wavejet screenshot...

@Leo, i haven't placed an order yet, do you still have one of them on stock? i have both keysight and a lecroy's reps coming over next week with loaners :)
« Last Edit: July 21, 2017, 04:06:01 AM by JPortici »
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #92 on: July 21, 2017, 04:40:33 AM »
about the overshoot, are you positive that the scope frontend has a gaussian responce? or maybe there is some parasitics? same for the wavejet screenshot...

@Leo, i haven't placed an order yet, do you still have one of them on stock? i have both keysight and a lecroy's reps coming over next week with loaners :)
I will make as many as needed, there is a new batch of PCBs coming tomorrow (Friday.) I will try to assemble, test and ship everything tomorrow or in the worst case - on Monday.

Regarding overshoot - I am not sure about exact dynamics of the total system, the PCB itself seems to be reasonably well damped - I have about 10% overshoot that dies down after 50ps on 20GHz SD-26.  Both of my LeCroys show higher and longer overshoot - this makes me think that it is coming from either frontend response or DSP processing rather than the pulser.

When it comes to really fast risetimes you typically have to choose between fastest risetime possible or minimum aberrations.  Jim Williams touched on that subject in his AN94.

There is an interesting series of appnotes from Picosecond Pulse Labs written by James Andrews that contain risetime results of numerous scopes and discussion of pulsers used:
https://kh6htv.files.wordpress.com/2015/11/an-02a-oscopes.pdf
https://kh6htv.files.wordpress.com/2015/11/an-02b-oscopes.pdf
https://kh6htv.files.wordpress.com/2015/11/an-02c-oscopes.pdf
https://kh6htv.files.wordpress.com/2015/11/an-02d-oscopes.pdf
https://kh6htv.files.wordpress.com/2015/11/an-02e-oscopes.pdf
It looks like PSPL uses two different pulsers - one for risetime measurements and the other for ringing, flatness and settling time measurements.

Leo
 
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Offline jpb

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Re: Yet another fast edge pulse generator
« Reply #93 on: July 21, 2017, 04:58:58 AM »
The overshoot is quite small - 79.1mV out of 1.363V which is only 6%.
 

Offline JPortici

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Re: Yet another fast edge pulse generator
« Reply #94 on: July 21, 2017, 05:04:21 AM »
Regarding overshoot - I am not sure about exact dynamics of the total system, the PCB itself seems to be reasonably well damped - I have about 10% overshoot that dies down after 50ps on 20GHz SD-26.  Both of my LeCroys show higher and longer overshoot - this makes me think that it is coming from either frontend response or DSP processing rather than the pulser.

yes, which i why i have asked :)
I tested my 500 MHz lecroy 7242B with a 1ns-rise/fall time pulse (trigger output from another scope, the fastest i could generate here at home) and it showed a nice and clean edge, i'm sure i'm not pushing it enough ;)

I am aware of the bandwidth/risetime tradeoff, which is of course pretty obvious if one thinks of the relationship between frequency responce and the need of sufficient attenuation to not incur in aliasing at a given real-time samplerate
I remember reading somewhere here in the forum that higher bandwidth keysight and/or lecroy had not a gaussian response, which is why i asked it in the first place
 

Offline jpb

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Re: Yet another fast edge pulse generator
« Reply #95 on: July 21, 2017, 05:20:10 AM »
I think that scopes below about 1GHz BW (I'm not certain of this dividing line though) are Gaussian while "high end" ones are not:
http://www.tek.com/support/faqs/how-bandwidth-related-rise-time-oscilloscopes

I'm pretty sure that my WaveJet is Gaussian.
 

Offline The Electrician

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Re: Yet another fast edge pulse generator
« Reply #96 on: July 21, 2017, 05:33:46 AM »
Have a look at the image in reply ##89.  The R&S RTO1000 series scopes are specifically designed to have a gaussian response.  The result I got is dead flat on the rising edge, but has some pre-undershoot.  The RTO1014 1 GHz scope is spec'd to have a 350 ps rise, and Leo's pulser gives me a 295 ps rise time.

I also have read that Tek and Keysight digital scopes don't have a gaussian frequency response.
 

Offline lukier

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Re: Yet another fast edge pulse generator
« Reply #97 on: July 21, 2017, 05:55:47 AM »
Not all scopes have an USB port :) I've powered up the old Tek 2467 and well 1.3 ns sounds a bit slow for a 350 MHz scope.
But I bought it "for parts or repair" so maybe there is something more to fix.

Edit: My bad, wrong graticule for the right cursor. So 1ns which seems OK for 350 MHz.
 

Offline becoolnike

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Re: Yet another fast edge pulse generator
« Reply #98 on: July 21, 2017, 08:53:38 AM »
I love it but it will be nice to have to have differential output instead of just single ended output for TDR Applications like measuring
twisted pair cable.

adcmp572 has already that capability.
 

Offline tatus1969

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Re: Yet another fast edge pulse generator
« Reply #99 on: July 21, 2017, 03:59:07 PM »
I got mine here in USA Tuesday.  Here's the rise on my R&S RTO1014 1 GHz scope, 295 picoseconds.
It looks like there is maybe some sin(x)/x post processing here, causing that pre-ringing, and obscuring the real waveform.
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Online capt bullshot

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Re: Yet another fast edge pulse generator
« Reply #100 on: July 22, 2017, 09:39:13 PM »
Today mine arrived. I guess my TDS580 wins the prize for the most ringing display
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Offline HighVoltage

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Re: Yet another fast edge pulse generator
« Reply #101 on: July 23, 2017, 05:24:24 AM »
Your pulse generator arrived today in Germany, thanks for the fast shipment.

One question.
When I run your software on my PC, (Win7), I get weird selection numbers for the voltage selection.
Is it the software or anything I am missing?
See attachments
There are 3 kinds of people in this world, those who can count and those who can not.
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #102 on: July 23, 2017, 05:28:34 AM »
Your pulse generator arrived today in Germany, thanks for the fast shipment.

One question.
When I run your software on my PC, (Win7), I get weird selection numbers for the voltage selection.
Is it the software or anything I am missing?
See attachments
It looks like a decimal dot/comma confusion. 
Temporary bugfix: for now assume it is in microvolts :D
I will try to change my locale and see if I can replicate and fix this.
Leo

Offline Berni

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Re: Yet another fast edge pulse generator
« Reply #103 on: July 23, 2017, 05:44:34 AM »
Aww so it doesn't have a secret 2kV output range in select European places? Would be pretty impressive with that rise time. ;D

I'm on vacation so Il know if I got mine once I get back home.
 

Offline rx8pilot

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Re: Yet another fast edge pulse generator
« Reply #104 on: July 23, 2017, 06:50:38 AM »
Today mine arrived. I guess my TDS580 wins the prize for the most ringing display

It will be interesting to learn what contributes to the different responses seen on various scopes.
Thank you EEVBlog for all the support in the Keysight Test to Impress Giveaway voting!
 

Offline HighVoltage

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Re: Yet another fast edge pulse generator
« Reply #105 on: July 23, 2017, 07:21:02 AM »
OK, I will wait for you to figure out the decimal point.

Here are my measurements on my slowest scope.
This is an Agilent branded DSO-X-2002A, 70 MHz

« Last Edit: July 23, 2017, 10:07:15 PM by HighVoltage »
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Offline HighVoltage

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Re: Yet another fast edge pulse generator
« Reply #106 on: July 23, 2017, 09:50:17 PM »
OK, tested on my Agilent MSO-X-3104A, 1 GHz scope

Rise time 440 ps

The software is running on an older XP
This time I get good numbers like 1000 but if I select a different number, like 1400, the signal is not changing at all.
« Last Edit: July 23, 2017, 10:09:50 PM by HighVoltage »
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Offline HighVoltage

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Re: Yet another fast edge pulse generator
« Reply #107 on: July 23, 2017, 10:06:06 PM »
Now tested on my Agilent MSO 7045B 500 MHz scope

Rise Time 1.03 ns
No overshoot, may be the scope is too slow!

This time Software running on a Lenovo Laptop with Win7 Pro and all works as expected
« Last Edit: July 23, 2017, 10:07:52 PM by HighVoltage »
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Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #108 on: July 23, 2017, 10:08:34 PM »
Now tested on my Agilent MSO 7045B 500 MHz scope
Rise Time 1.03 ns
No overshoot, may be the scope is too slow!
Don't forget to terminate input to 50R if you want fastest and cleanest risetime.
Leo

Offline HighVoltage

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Re: Yet another fast edge pulse generator
« Reply #109 on: July 23, 2017, 10:21:24 PM »
Now my last scope for this test, a Keysight MSO-X-6004A, 6 GHz, 50 Ohm
Rise time is 88 ps
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Offline HighVoltage

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Re: Yet another fast edge pulse generator
« Reply #110 on: July 23, 2017, 10:43:57 PM »
Now tested on my Agilent MSO 7045B 500 MHz scope
Rise Time 1.03 ns
No overshoot, may be the scope is too slow!
Don't forget to terminate input to 50R if you want fastest and cleanest risetime.
Leo

You are right, I forgot the 50 Ohm setting.
Here again the same scope, 50 Ohm turned ON
Rise time 630 ps
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Offline HighVoltage

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Re: Yet another fast edge pulse generator
« Reply #111 on: July 23, 2017, 10:52:31 PM »
Just for fun I tested your pulse generator on a 20 year old Fluke PM3394B, 200 MHz
50 Ohm input
1.84 ns rise time


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Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #112 on: July 23, 2017, 11:07:19 PM »
Now my last scope for this test, a Keysight MSO-X-6004A, 6 GHz, 50 Ohm
Rise time is 88 ps
Assuming total system risetime Tsystem2 = Tscope2 + Tpulser2
It checks out reasonably well:
Tsystem = 88ps, Tpulser = 50ps
From there Tscope = 72ps
MSO-X-6004A specification lists 75ps risetime.

Pleasant UI on that Fluke.
« Last Edit: July 23, 2017, 11:14:20 PM by Leo Bodnar »
 

Offline Berni

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Re: Yet another fast edge pulse generator
« Reply #113 on: July 24, 2017, 02:45:32 AM »
Neat to see some CROs join in even if they are hybrids.

Oh and do all your scopes have names like that?
 

Online capt bullshot

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Re: Yet another fast edge pulse generator
« Reply #114 on: July 24, 2017, 10:59:54 PM »
Found some time and tried the Wavewhatever MX104 @work
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Offline HighVoltage

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Re: Yet another fast edge pulse generator
« Reply #115 on: July 25, 2017, 02:30:26 AM »
Neat to see some CROs join in even if they are hybrids.

Oh and do all your scopes have names like that?

Only on my high voltage bench, Scope-1 to Scope-6 because I am switching the RS232 connection manually to one PC input for data acquisition.
 
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Offline WastelandTek

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Re: Yet another fast edge pulse generator
« Reply #116 on: July 25, 2017, 02:48:12 AM »
Found some time and tried the Wavewhatever MX104 @work

now that is pretty
I'm new here, but I tend to be pretty gregarious, so if I'm out of my lane please call me out.
 

Offline H.O

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Re: Yet another fast edge pulse generator
« Reply #117 on: July 25, 2017, 04:23:48 AM »
Received mine today, thank you Leo!
Here's my Rigol DS4000 series:
 

Offline Gixy

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Re: Yet another fast edge pulse generator
« Reply #118 on: July 25, 2017, 08:18:01 PM »
Hi Leo,
News from order 20535?
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #119 on: July 25, 2017, 09:06:46 PM »
Hi Leo,
News from order 20535?
Hi Denis,
Shipped on the 20th of July with Airmail.
Thanks
Leo

Offline TheAmmoniacal

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Re: Yet another fast edge pulse generator
« Reply #120 on: July 25, 2017, 09:22:28 PM »
Mine has arrived, all good. Thanks.

Will have a look at the output on my scopes when I get home from vacation.
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Offline Gixy

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Re: Yet another fast edge pulse generator
« Reply #121 on: July 25, 2017, 09:53:45 PM »
Should be there today hopefully. Thks Leo
 

Online capt bullshot

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Re: Yet another fast edge pulse generator
« Reply #122 on: July 25, 2017, 11:38:58 PM »
Today we had a demo of some Tek stuff here.
I managed to get screenshots from the new MSO58 2GHz flagship. This has a frickin large screen - with lots of space for ringing. I believe my TDS580 (see somewhere above) isn't that bad in terms of Tek-ringing. I do still like more the clean edge of the LeCroy.
(first two pictures)

Then there was the fabulous fiber optic isolated probe with 500MHz bandwith - the signal looks a bit different (third picture)
Fforgot to adjust the timebase for the rise time display to work, too many people around distracting me.
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Offline HighVoltage

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Re: Yet another fast edge pulse generator
« Reply #123 on: July 26, 2017, 12:40:39 AM »
Do I see this right, the Tektronix 2GHz MSO58 has 213 ps rise time with this 50ps pulse generator ?

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Online capt bullshot

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Re: Yet another fast edge pulse generator
« Reply #124 on: July 26, 2017, 02:18:11 AM »
Do I see this right, the Tektronix 2GHz MSO58 has 213 ps rise time with this 50ps pulse generator ?

Thtat's what I've seen. The specification (taken from Tek website) is:
Bandwidth (calculated rise time)   350 MHz (1,15 ns), 500 MHz (800 ps), 1 GHz (400 ps), 2 GHz (225 ps)

They must have different frontends for the 2GHz models, since many specs are different between 2GHz and less than 2GHz models.
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Offline Gixy

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Re: Yet another fast edge pulse generator
« Reply #125 on: July 26, 2017, 06:02:31 AM »
Hi Leo,
Received mine today as hoped.
Tested on Rigol MSO2302A (300MHz, upgraded...) and Tektronix 2445A (150 MHz). Results as awaited, perfect!
Rigol MSO2302A (300MHz): 1.050ns (rise), 1.090ns (fall)
Tektronix 2445A (150 MHz): 2,00ns (rise), 2,10ns (fall)

The software rose an error when launched: Error '13' uncompatible type (Windows 10).
Thanks again.

 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #126 on: July 27, 2017, 04:39:23 AM »
Received mine today as hoped.
Tested on Rigol MSO2302A (300MHz, upgraded...) and Tektronix 2445A (150 MHz). Results as awaited, perfect!
The software rose an error when launched: Error '13' uncompatible type (Windows 10).
Cheers,
I am looking into the problem - looks like a decimal comma/point issue.
Leo

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #127 on: July 29, 2017, 10:19:29 PM »
I have modified the configuration software to fix the decimal comma/point issue for locales that use decimal comma.

Please try downloading new version again: http://leobodnar.com/files/pulser_configuration.exe

Thanks
Leo

Offline Gixy

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Re: Yet another fast edge pulse generator
« Reply #128 on: July 30, 2017, 01:33:58 AM »
Hi Leo,
Works perfectly well now, including calibration. Thanks a lot  :-+
 

Offline maukka

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Re: Yet another fast edge pulse generator
« Reply #129 on: July 30, 2017, 05:34:25 PM »
I have modified the configuration software to fix the decimal comma/point issue for locales that use decimal comma.

You should tell Rigol how to do that...

They say it's impossible to fix their PSU control software.

Quote
we can't change it. All of our test devices needs point separator for communication
 

Offline hs3

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Re: Yet another fast edge pulse generator
« Reply #130 on: July 31, 2017, 05:55:09 AM »
I tested a few Rigol scopes with the pulse generator.

DS1102E





DS1074Z 100 MHz





DS2072 300 MHz with 1M input





DS2072 with 50R through terminator





DS4014 500 MHz





One thing that could be noticed when testing several Rigol scopes one after another was that as the series number gets higher the user experience can be quite different and feels much snappier. Well the hardware under the hood is quite different too.
« Last Edit: July 31, 2017, 06:02:46 AM by hs3 »
 

Offline hs3

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Re: Yet another fast edge pulse generator
« Reply #131 on: July 31, 2017, 06:06:11 AM »
And then a few other scopes too

Keysight DSOX3014T





LeCroy WavePro 7300A


« Last Edit: July 31, 2017, 06:07:55 AM by hs3 »
 

Offline awallin

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Re: Yet another fast edge pulse generator
« Reply #132 on: July 31, 2017, 05:57:32 PM »
I think it would be nice to collect the results into an online spreadsheet and a chart similar to this one - any volunteers  ???

with an estimated Tpulser ~50ps the rise-times should be accurate to 10% up to 3 or 3.5 GHz - if my chart is roughly right..
 

Offline H.O

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Re: Yet another fast edge pulse generator
« Reply #133 on: July 31, 2017, 07:29:23 PM »
I just started a Google spreadsheet and added what's been posted in this thread so far. See attached screenshot.
Any suggested changes before I try to make it public (never made a shared one before)? What should we call it?


 
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Online grumpydoc

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Re: Yet another fast edge pulse generator
« Reply #134 on: July 31, 2017, 07:33:23 PM »
I just started a Google spreadsheet and added what's been posted in this thread so far. See attached screenshot.
Any suggested changes before I try to make it public (never made a shared one before)? What should we call it?
I'd make the default sort order manufacturer and then model.
 

Offline awallin

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Re: Yet another fast edge pulse generator
« Reply #135 on: July 31, 2017, 11:52:37 PM »
I just started a Google spreadsheet and added what's been posted in this thread so far. See attached screenshot.
Any suggested changes before I try to make it public (never made a shared one before)? What should we call it?

awesome  :-+
I'd make the X-axis the manufacturer specified BW of the scope.
maybe there's a way to make a shaded background between say 0.35/BW and 0.45/BW - where we'd expect the measurements to fall.
 

Offline Tom45

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Re: Yet another fast edge pulse generator
« Reply #136 on: August 01, 2017, 01:54:39 AM »
Here are some of my scopes:

Tek 2246                  100MHz   Analog     50 ohm*   2070  2280
Tek 2465                  300MHz   Analog     50 ohm     1080  1260
Tek 7904/7A26          200MHz   Analog     50 ohm*   1650  1700
Tek 7904/7A24          400MHz   Analog     50 ohm      700   800

Rigol 1074Z                 70MHz   1GS/sec   50 ohm*   3940  4570
Rigol 1074Z                 20MHz   1GS/sec   50 ohm*  14630  15910  (20MHz bandwidth limit)

Siglent SDS1202X      200MHz   1GS/sec   50 ohm    1750 1790

OWon PDS8102T        100MHz   1GS/sec   50 ohm*   2040  1960

*= 1Meg input with external 50 ohm pass through terminator
 

Offline HighVoltage

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Re: Yet another fast edge pulse generator
« Reply #137 on: August 01, 2017, 02:10:21 AM »
Any suggested changes before I try to make it public (never made a shared one before)? What should we call it?

Yes, add a column with Leo's calculation for the scope's rise time
see below..






Now my last scope for this test, a Keysight MSO-X-6004A, 6 GHz, 50 Ohm
Rise time is 88 ps
Assuming total system risetime Tsystem2 = Tscope2 + Tpulser2
It checks out reasonably well:
Tsystem = 88ps, Tpulser = 50ps
From there Tscope = 72ps
MSO-X-6004A specification lists 75ps risetime.

Pleasant UI on that Fluke.
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Offline Gixy

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Re: Yet another fast edge pulse generator
« Reply #138 on: August 01, 2017, 03:21:27 PM »
Good idea for the spreadsheet and good suggestions to improve.
Two remarks for my lines :
- first scope is in fact Rigol MSO2072A upgraded in MSO2302A (that's what appears in the system info after upgrade)
- second one is Tek 2445A, not 2445
Gixy
« Last Edit: August 01, 2017, 03:29:05 PM by Gixy »
 

Offline metrologist

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Re: Yet another fast edge pulse generator
« Reply #139 on: August 01, 2017, 03:49:27 PM »
The DS1074Z seems slower than it should. How I could get ~2ns with a mercury switch?
 

Offline H.O

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Re: Yet another fast edge pulse generator
« Reply #140 on: August 01, 2017, 09:12:53 PM »
Hi,
I've fixed the mistakes pointed out by Gixy, added the datapoints provided by Tom45 and added a column with the calculated scope risetime taking the risetime of the pulser into consideration. The calculated bandwidth numbers are then based on the calculated risetime.

I've opened the spreadsheet up for viewing (at least I think I have):
https://docs.google.com/spreadsheets/d/1uknvUdL4gNuTyuK7MNAkCj95GFSsDtfgr7nObVppFiE/edit?usp=sharing

I've yet to figure out the sorting stuff and I don't quite understand what graphing we should do. If anyone wants to help out just drop me a PM and I'll try to set you up with editing rights (or should I just allow full editing rights?)
 

Offline mk_

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Re: Yet another fast edge pulse generator
« Reply #141 on: August 01, 2017, 11:08:00 PM »
MDO3054 from TEK @ 50 Ohm.



 

Offline awallin

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Re: Yet another fast edge pulse generator
« Reply #142 on: August 01, 2017, 11:17:27 PM »

I've opened the spreadsheet up for viewing (at least I think I have):
https://docs.google.com/spreadsheets/d/1uknvUdL4gNuTyuK7MNAkCj95GFSsDtfgr7nObVppFiE/edit?usp=sharing

now we really need someone with a >10gig scope to confirm the intrinsic pulser rise-time  ;D
https://docs.google.com/spreadsheets/d/1W7VlSqhM8XUgPErtco0ETyDvSDprG7elEpLsuc_W-FA/edit?usp=sharing
(I wanted a solid line for the Tscope+Tpulser prediction, but not sure how to do it in googledocs..)
 

Offline lukier

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Re: Yet another fast edge pulse generator
« Reply #143 on: August 01, 2017, 11:29:34 PM »
I've requested the edit access, can update the details on my entries.

Also, please bring back the 0.45 factor. 0.35 is useless nowadays except the analog or low-end scopes, i.e. not most scopes on the list.
 

Offline Tom45

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Re: Yet another fast edge pulse generator
« Reply #144 on: August 01, 2017, 11:50:07 PM »
I've requested the edit access, can update the details on my entries.

Also, please bring back the 0.45 factor. 0.35 is useless nowadays except the analog or low-end scopes, i.e. not most scopes on the list.

The last three columns are 0.45/risetime, user, and comment. Perhaps you need to scroll over to see them?
 

Offline lukier

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Re: Yet another fast edge pulse generator
« Reply #145 on: August 01, 2017, 11:56:25 PM »
The last three columns are 0.45/risetime, user, and comment. Perhaps you need to scroll over to see them?

I was replying to awallin and in reference to his copy of the sheet.
 

Offline mk_

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Re: Yet another fast edge pulse generator
« Reply #146 on: August 02, 2017, 12:48:19 AM »
and here from an Agilent DL6104 @ internal 50Ohm

 

Offline Howardlong

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Re: Yet another fast edge pulse generator
« Reply #147 on: August 02, 2017, 03:43:55 AM »
57.6ps on a 20GHz HP 54120B/54121A setup, but as this uses 3.5mm/SMA connectors, I very strongly suspect the limitation is my professionally terminated BNC-SMA cable. The best I could get out of the cable from the internal <33ps rise time TDR output of the 54121A test set with that cable (and a further BNC/SMA transition) was about the same. I tried a number of BNC/SMA interseries connectors of assorted qualities (none that I'd call professional) as well as the 12" RG223 SMA-M/BNC-F cable, and the cable gave the best results.



 

Offline H.O

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Re: Yet another fast edge pulse generator
« Reply #148 on: August 02, 2017, 04:47:39 AM »
Hi,
Data from mk_ and Howardlong has been added, so has my own 2465B:



It does not quite live up to it's specification or I'm doing something wrong with it using the 10x mag

 

Offline Tom45

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Re: Yet another fast edge pulse generator
« Reply #149 on: August 02, 2017, 05:12:30 AM »
Hi,
Data from mk_ and Howardlong has been added, so has my own 2465B:

It does not quite live up to it's specification or I'm doing something wrong with it using the 10x mag

It looks like your 500ps timebase is OK.

You need to adjust the vertical gain so that the square wave top is at the solid line above the top dotted line, and the square wave bottom is at the solid line below the lower dotted line. Then the two dotted lines will be at 10% and 90%. Set the two cursors where the trace crosses the 10% and 90% dotted lines.

That should give a better result.

Also, I've noticed on my analog scopes, the shape of the trace varies some between channels. Is that because the analog scopes are old and need some TLC? Or was there that much variation when they were new? I don't know.

You might want to try 1 and 2 to see if there is a noticeable difference.
 

Offline lukier

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Re: Yet another fast edge pulse generator
« Reply #150 on: August 02, 2017, 05:19:09 AM »
You need to adjust the vertical gain so that the square wave top is at the solid line above the top dotted line, and the square wave bottom is at the solid line below the lower dotted line. Then the two dotted lines will be at 10% and 90%. Set the two cursors where the trace crosses the 10% and 90% dotted lines.

His measurement is correct. Waveform's top and bottom should be on the dotted lines(!) and then the next solid line is the 10% and 90%. This is even marked on the overlay in the photo.
 
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Offline Tom45

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Re: Yet another fast edge pulse generator
« Reply #151 on: August 02, 2017, 06:36:35 AM »
You need to adjust the vertical gain so that the square wave top is at the solid line above the top dotted line, and the square wave bottom is at the solid line below the lower dotted line. Then the two dotted lines will be at 10% and 90%. Set the two cursors where the trace crosses the 10% and 90% dotted lines.

His measurement is correct. Waveform's top and bottom should be on the dotted lines(!) and then the next solid line is the 10% and 90%. This is even marked on the overlay in the photo.

You are right!  The few times I've ever needed to measure rise time I never bothered to look at the scale. I just went with my faulty memory of what I once knew.   Thanks for setting me straight.

Now I need to go back and redo my Tek analog scope measurements.

Tom
 

Offline WastelandTek

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Re: Yet another fast edge pulse generator
« Reply #152 on: August 02, 2017, 07:12:27 AM »

You are right!  The few times I've ever needed to measure rise time I never bothered to look at the scale. I just went with my faulty memory of what I once knew.   Thanks for setting me straight.

Now I need to go back and redo my Tek analog scope measurements.

Tom

This....is what I absolutely love about this forum.  I have seen it several times in the short period I have been a member; someone say, in essence "oh god, you're right, I was mistaken"  this is a rare thing on the internet and to be applauded IMO.

Leo seems to have done an outstanding job on this pulser, looking forward to getting one.
I'm new here, but I tend to be pretty gregarious, so if I'm out of my lane please call me out.
 

Offline bson

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Re: Yet another fast edge pulse generator
« Reply #153 on: August 02, 2017, 07:47:19 AM »
Still making these?  I missed the thread initially but would love to buy one!
<This space intentionally left blank>
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #154 on: August 02, 2017, 07:55:25 AM »
Still making these?  I missed the thread initially but would love to buy one!
Sure, I have them in stock.

Get yours here.

Thanks
Leo

Offline Tom45

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Re: Yet another fast edge pulse generator
« Reply #155 on: August 02, 2017, 08:03:44 AM »
Still making these?  I missed the thread initially but would love to buy one!

Leo has a business designing and selling items such as this pulse generator. So it should be available long term which benefits all of us.

http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295
 

Offline Gixy

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Re: Yet another fast edge pulse generator
« Reply #156 on: August 02, 2017, 09:17:14 AM »
Another good old analog scope: HP 1742A, 100MHz, 50 Ohm. Rise & Fall times: 3.5ns.

It is generally admitted to use 0.35 (0.356 indeed) for scopes with BW lower than 1GHz and 0,45 for the others.
 

Offline alank2

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Re: Yet another fast edge pulse generator
« Reply #157 on: August 02, 2017, 09:40:00 AM »
I ordered one - really looking forward to it!
 

Offline electrolust

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Re: Yet another fast edge pulse generator
« Reply #158 on: August 03, 2017, 12:24:31 AM »
Received mine via the slow boat ... works great.  I won't bother to post results, they are like everyone else's here.  But I do want to comment on how professionally made and packed the device was.  Wow!
 

Offline rx8pilot

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Re: Yet another fast edge pulse generator
« Reply #159 on: August 03, 2017, 03:11:07 AM »
But I do want to comment on how professionally made and packed the device was.  Wow!

Totally. Super sharp.
Thank you EEVBlog for all the support in the Keysight Test to Impress Giveaway voting!
 

Offline orin

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Re: Yet another fast edge pulse generator
« Reply #160 on: August 03, 2017, 03:11:43 AM »
Mine arrived last week after a really good attempt by some postal service or other to squash it...

Here is what my HP 54542A sees.  I have no way of taking screenshots over GPIB from this scope (and don't feel like spending $59 for software that claims to be able to do it*) so it's a cellphone picture.  The scope is set to repetitive with 8 averages.

*no, 7470.exe doesn't work with it.
 

Offline electrolust

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Re: Yet another fast edge pulse generator
« Reply #161 on: August 03, 2017, 04:43:49 AM »
Question: Is the overshoot actually there, or it is an artifact of sin(x)/x interpolation?  If it's actually there, is it part of the output or is that a byproduct of the [short] transmission line / PCB trace / etc.
 

Offline branadic

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Re: Yet another fast edge pulse generator
« Reply #162 on: August 03, 2017, 04:49:16 AM »
Quote
Here is what my HP 54542A sees.  I have no way of taking screenshots over GPIB from this scope (and don't feel like spending $59 for software that claims to be able to do it*) so it's a cellphone picture.  The scope is set to repetitive with 8 averages.

If your unit has RS232 interface available you can simply read data via RS232-USB-adapter using any terminal program such as hterm. I would recommand using gnu octave, it just takes a few commands to aquire data and plot them also live.

-branadic-
Prema 5000 | Prema 5017 SC | Keithley 181 | Tek 2465A | VNWA2.x with TCXO upgrade and access to: Keysight 3458A, Keithley 2002, Prema 5017 SC, 34401A, 34410A, HDO6054, Keysight 53230A and other goodies at work
 

Offline HighVoltage

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Re: Yet another fast edge pulse generator
« Reply #163 on: August 03, 2017, 05:08:53 AM »
I was surprised that the measured rise time of the Keysight MSO-X-6104A from rx8pilot was significantly faster than mine.
He measured 70 ps and my instrument had measured 88 ps

So, I measured all my 4 channels again:

Scope-Channel, t-rise, Overshoot
CH 1,  88.6,   6.3%
CH 2,  87.9,   6.8%
CH 3,  82.7,   9.8%
CH 4,  83.2,   8.6%

Still about 12 to 18 ps slower than the rx8pilot data.
May be it is related to the overshoot.

Leo Bodnar:
I would like to buy another pulser from you but I would like you to make sure it has the smallest possible overshoot, like in the picture from rx8pilot or even less.
Is that possible that you pre-select one?

Or what do you think is the difference between the measurements of these two scopes?




« Last Edit: August 03, 2017, 05:13:28 AM by HighVoltage »
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Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #164 on: August 03, 2017, 05:21:18 AM »
I would like to buy another pulser from you but I would like you to make sure it has the smallest possible overshoot, like in the picture from rx8pilot or even less.
Is that possible that you pre-select one?
All units are quite consistent in their parameters - within 1-2% overshoot and &plusmn;4ps risetime.
I can try critically damping the output to have no overshoot - it will increase the risetime by ~10ps.
I am going to make another batch tomorrow or on Friday and will try tweaking one unit.
At the moment I only have 20GHz SD-26, 12.5GHz SD-22 and 3GHz WavePro 7300A to go by.
Leo

Offline lukier

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Re: Yet another fast edge pulse generator
« Reply #165 on: August 03, 2017, 05:33:21 AM »
Question: Is the overshoot actually there, or it is an artifact of sin(x)/x interpolation?  If it's actually there, is it part of the output or is that a byproduct of the [short] transmission line / PCB trace / etc.

My LeCroy WaveRunner 6100A (1 GHz) screenshot was without sin(x)/x. I can redo the measurement with sin(x)/x turned on and we'll see the difference.
 

Offline HighVoltage

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Re: Yet another fast edge pulse generator
« Reply #166 on: August 03, 2017, 06:10:43 AM »
I would like to buy another pulser from you but I would like you to make sure it has the smallest possible overshoot, like in the picture from rx8pilot or even less.
Is that possible that you pre-select one?
All units are quite consistent in their parameters - within 1-2% overshoot and &plusmn;4ps risetime.
I can try critically damping the output to have no overshoot - it will increase the risetime by ~10ps.
I am going to make another batch tomorrow or on Friday and will try tweaking one unit.
At the moment I only have 20GHz SD-26, 12.5GHz SD-22 and 3GHz WavePro 7300A to go by.
Leo

Then it seems I was wrong and want the opposite.
I want the fastest possible rise time, so I need a larger overshoot?
Can you tweak that too?

In a way to match the one from rx8pilot
Here is his picture again:

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Offline WastelandTek

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Re: Yet another fast edge pulse generator
« Reply #167 on: August 03, 2017, 06:28:42 AM »

At the moment I only have 20GHz SD-26, 12.5GHz SD-22 and 3GHz WavePro 7300A to go by.
Leo

"only"   ;D
I'm new here, but I tend to be pretty gregarious, so if I'm out of my lane please call me out.
 
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Offline Howardlong

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Re: Yet another fast edge pulse generator
« Reply #168 on: August 03, 2017, 07:17:23 AM »
I don't have an msox6000 series, but I'd assume there's a way to change to equivalent time sampling as there is on the mso7000 where it's in the Acquire menu. Switching to equivalent time on my mso7104b and 54831d (masquerading as a 54832d) significantly improves rise time figures, I assume because of sampling aliasing errors in real time mode, but I wouldn't be surprised if the filtering may be changed somewhat too.

This ties into the overshoot that brick wall filters typically create, employed in real time sampling especially at higher speeds closer to the sampling rate, in an effort to avoiding aliasing problems. More gentle Gaussian filters avoid the overshoot but are more prone to aliasing: it's good old fashioned engineering compromise at work. It's also why the rise time/bandwidth calculation fudge factor changes.

There are a number of Keysight docs on the phenomenon, for example http://literature.cdn.keysight.com/litweb/pdf/5988-8008EN.pdf

« Last Edit: August 03, 2017, 07:56:59 AM by Howardlong »
 

Offline HighVoltage

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Re: Yet another fast edge pulse generator
« Reply #169 on: August 03, 2017, 08:06:52 AM »
I don't have an msox6000 series, but I'd assume there's a way to change to equivalent time sampling as there is on the mso7000 where it's in the Acquire menu. Switching to equivalent time on my mso7104b and 54831d (masquerading as a 54832d) significantly improves rise time figures, I assume because of sampling aliasing errors in real time mode, but I wouldn't be surprised if the filtering may be changed somewhat too.

This ties into the overshoot that brick wall filters typically create, employed in real time sampling especially at higher speeds closer to the sampling rate, in an effort to avoiding aliasing problems. More gentle Gaussian filters avoid the overshoot but are more prone to aliasing: it's good old fashioned engineering compromise at work. It's also why the rise time/bandwidth calculation fudge factor changes.

There are a number of Keysight docs on the phenomenon, for example http://literature.cdn.keysight.com/litweb/pdf/5988-8008EN.pdf

Yes, there is a similar menu in the 6000X scope

I tried following Data Acquisition Modes:
- Realtime = 88,5 ps
- Realtime (Max Update Rate) = 88,5 ps
- Equivalent time = 89.4 ps

I also tried the different acquisition modes:
- Normal
- Peak detect
- Averaging
- High Resolution
But the rise time will always be around 88ps, compared to rx8pilot's 70 ps.

Thanks for the link to the Keysight doc, I will study it.





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Offline Cerebus

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Re: Yet another fast edge pulse generator
« Reply #170 on: August 03, 2017, 09:57:20 AM »
Anybody got a syringe I can use to squeeze the magic smoke back into this?
 

Offline orin

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Re: Yet another fast edge pulse generator
« Reply #171 on: August 03, 2017, 12:09:59 PM »
Quote
Here is what my HP 54542A sees.  I have no way of taking screenshots over GPIB from this scope (and don't feel like spending $59 for software that claims to be able to do it*) so it's a cellphone picture.  The scope is set to repetitive with 8 averages.

If your unit has RS232 interface available you can simply read data via RS232-USB-adapter using any terminal program such as hterm. I would recommand using gnu octave, it just takes a few commands to aquire data and plot them also live.

-branadic-


Thanks for the hint.

I had totally forgotten that this puppy has a floppy drive.  If the drive is working...

So, I found a suitable floppy, found the disk menu, saved the image in TIFF format, read it in using an external USB drive on the Mac, converted it to PNG and uploaded it.

This image is while the scope is still building up the trace in repetitive mode.  No connecting of the dots at this point.  It sure shows that the overshoot is real on this scope.

I found the scope's spec and rise time is spec'd at 700ps.  I guess 475ps is quite acceptable!

Edit: The 1.333ns max rise time isn't real - it's an artifact of how the repetitive sampling works.
« Last Edit: August 03, 2017, 12:17:17 PM by orin »
 

Offline alank2

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Re: Yet another fast edge pulse generator
« Reply #172 on: August 03, 2017, 12:36:16 PM »
What is the calibration adjustment for?  The peak to peak voltage output?
 

Offline KE5FX

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Re: Yet another fast edge pulse generator
« Reply #173 on: August 03, 2017, 02:51:56 PM »
Mine arrived last week after a really good attempt by some postal service or other to squash it...

Here is what my HP 54542A sees.  I have no way of taking screenshots over GPIB from this scope (and don't feel like spending $59 for software that claims to be able to do it*) so it's a cellphone picture.  The scope is set to repetitive with 8 averages.

*no, 7470.exe doesn't work with it.

It should.  I don't have one of those but I've had success reports from at least one other user.  I have a note from another user with a 54502A that says that the listen-only option needs to be selected in 7470.exe's GPIB menu.  Give that a try, maybe, and hit 'w' to make it wait for a plot.  What happens if you press the plot button on the 54542A? 
 

Offline orin

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Re: Yet another fast edge pulse generator
« Reply #174 on: August 03, 2017, 05:16:26 PM »
Mine arrived last week after a really good attempt by some postal service or other to squash it...

Here is what my HP 54542A sees.  I have no way of taking screenshots over GPIB from this scope (and don't feel like spending $59 for software that claims to be able to do it*) so it's a cellphone picture.  The scope is set to repetitive with 8 averages.

*no, 7470.exe doesn't work with it.

It should.  I don't have one of those but I've had success reports from at least one other user.  I have a note from another user with a 54502A that says that the listen-only option needs to be selected in 7470.exe's GPIB menu.  Give that a try, maybe, and hit 'w' to make it wait for a plot.  What happens if you press the plot button on the 54542A?


Probably not 7470.exe's fault.  It's probably some 64bit OS/probably fake 82357B/Keysight libraries 488.2 support problem.  'w' gave an immediate error.  I should take the Prologix ethernet adapter home and try it instead.

I think the plot button displayed some message as if it was in progress, then the message went away quietly.  I'd set the GPIB settings on the scope to print to a 7470A at that point.  Even in this state, 'w' in 7470.exe gave an immediate error.

I have had 7470.exe work before on the same PC with the 8568A SA, but I don't recall which adapter I used.

For now, sneaker-net with the floppy drive is working.
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #175 on: August 03, 2017, 05:22:51 PM »
What is the calibration adjustment for?  The peak to peak voltage output?
It tweaks reported voltage span in the top dropdown selection.  If you want Vpp reported by the application to match accurately measured actual value, adjust the calibration factor.  This is not a calibration grade equipment so use it "for indication use only."
Leo

Offline bson

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Re: Yet another fast edge pulse generator
« Reply #176 on: August 03, 2017, 05:30:02 PM »
Try setting the scope to "talk only" if possible to drive a plotter.
<This space intentionally left blank>
 

Offline Leo Bodnar

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Offline Howardlong

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Re: Yet another fast edge pulse generator
« Reply #178 on: August 03, 2017, 06:59:24 PM »
Try setting the scope to "talk only" if possible to drive a plotter.

FWIW, that's the way I made it work on an HP 54120B using a Prologix USB GPIB adapter.

As a one-off, I run the GPIB Configurator tool and select the correct COM port, Update the CONFIG.INI, and exit the configurator.

Each time I need to get some screen prints, I run the 7470A emulator (as administrator), select Display->1280x960, select View->Overlay all sources, File->Close all visible plots, and from the Plot menu on the scope I select each of the three plots, one at a time. Once I have the plots, I need I press the space bar to exit the "Listen" mode and I usually use Windows' snipping tool rather than the application to save the bitmap, no particular reason other than that's my workflow.

So in view of the above, more often than not, I just use a camera ;-)

This is Leo's 50ps generator which for some reason performed better today at 54.8ps, but I am sure a lot of that is due to my crappy BNC->SMA transition:


This is the 54121A's TDR pulse viewed on Ch1, the same channel it's generated on, note timebase is now 20ps/div:


The is the same internal TDR pulse viewed on a different channel to where it's generated, i.e. Ch3:
« Last Edit: August 03, 2017, 08:39:30 PM by Howardlong »
 

Online grumpydoc

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Re: Yet another fast edge pulse generator
« Reply #179 on: August 03, 2017, 07:27:36 PM »
I took the plunge and ordered one on Monday - having finally realised that having the time to build something similar was fantasy  :)

Hope that it arrives soon.
 

Offline Howardlong

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Re: Yet another fast edge pulse generator
« Reply #180 on: August 03, 2017, 08:37:35 PM »
I took the plunge and ordered one on Monday - having finally realised that having the time to build something similar was fantasy  :)

Hope that it arrives soon.

FWIW, I ordered mine on Saturday and it arrived on Tuesday (UK).
 

Offline marshallh

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Re: Yet another fast edge pulse generator
« Reply #181 on: August 04, 2017, 08:06:59 AM »
Working great. Very high quality construction and packaging as well. Pushes the LeCry to 330ps

Verilog tips
BGA soldering intro

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Offline orin

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Re: Yet another fast edge pulse generator
« Reply #182 on: August 04, 2017, 02:26:34 PM »
Mine arrived last week after a really good attempt by some postal service or other to squash it...

Here is what my HP 54542A sees.  I have no way of taking screenshots over GPIB from this scope (and don't feel like spending $59 for software that claims to be able to do it*) so it's a cellphone picture.  The scope is set to repetitive with 8 averages.

*no, 7470.exe doesn't work with it.

It should.  I don't have one of those but I've had success reports from at least one other user.  I have a note from another user with a 54502A that says that the listen-only option needs to be selected in 7470.exe's GPIB menu.  Give that a try, maybe, and hit 'w' to make it wait for a plot.  What happens if you press the plot button on the 54542A?


Probably not 7470.exe's fault.  It's probably some 64bit OS/probably fake 82357B/Keysight libraries 488.2 support problem.  'w' gave an immediate error.  I should take the Prologix ethernet adapter home and try it instead.

I think the plot button displayed some message as if it was in progress, then the message went away quietly.  I'd set the GPIB settings on the scope to print to a 7470A at that point.  Even in this state, 'w' in 7470.exe gave an immediate error.

I have had 7470.exe work before on the same PC with the 8568A SA, but I don't recall which adapter I used.

For now, sneaker-net with the floppy drive is working.


It works with the Prologix Ethernet adapter.

Set "No assigned plotter address" on 7470.exe's GPIB menu.
Set the 54542A to talk and select HP 7470.  Disable saving images to disk.
Use the 'w' command on 7470.exe.

Now the Print button on the 54542A does what it should.
 

Offline rx8pilot

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Re: Yet another fast edge pulse generator
« Reply #183 on: August 04, 2017, 02:52:54 PM »
I took the plunge and ordered one on Monday - having finally realised that having the time to build something similar was fantasy  :)

Hope that it arrives soon.

I spent hours researching an approach to build one - probably would have taken another few days to design it, a few days for prototype, another few days for REV B, ........ about a few weeks later, I may or may not have something that worked.

Then I saw this. Lovely. Can't wait to have a play day.
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Offline orin

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Re: Yet another fast edge pulse generator
« Reply #184 on: August 04, 2017, 03:03:49 PM »
Mine arrived last week after a really good attempt by some postal service or other to squash it...

Here is what my HP 54542A sees.  I have no way of taking screenshots over GPIB from this scope (and don't feel like spending $59 for software that claims to be able to do it*) so it's a cellphone picture.  The scope is set to repetitive with 8 averages.

*no, 7470.exe doesn't work with it.

It should.  I don't have one of those but I've had success reports from at least one other user.  I have a note from another user with a 54502A that says that the listen-only option needs to be selected in 7470.exe's GPIB menu.  Give that a try, maybe, and hit 'w' to make it wait for a plot.  What happens if you press the plot button on the 54542A?


For the record, a screenshot of the error I get immediately when using the w command and 82357B/Keysight IO libraries is attached.  I'd have sent it as a PM, but the forum doesn't seem to allow attachments to PMs.


 

Offline KE5FX

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Re: Yet another fast edge pulse generator
« Reply #185 on: August 04, 2017, 04:15:41 PM »
Looks good. 

That's a (very) old version of 7470.exe, but given the density and layout of the label text, it might actually look better than the higher-fidelity vector text renderer in the current build.
 

Offline orin

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Re: Yet another fast edge pulse generator
« Reply #186 on: August 04, 2017, 04:55:23 PM »
Looks good. 

That's a (very) old version of 7470.exe, but given the density and layout of the label text, it might actually look better than the higher-fidelity vector text renderer in the current build.


It was an old version - I hadn't updated that computer.  I think the file dates were sometime in 2012!

I have now updated that computer and would have to say I prefer the old label text.
 

Online grumpydoc

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Re: Yet another fast edge pulse generator
« Reply #187 on: August 05, 2017, 07:28:32 AM »
Finally arrived  :)  :-+

Very neat gadget.

Some timings to add
LeCroy 9354T (500MHz) - 10Gs/s RIS 660-670ps
Lecroy WavePro 950 (1GHz) - 50Gs/s RIS - 270ps; 16Gs/s single-shot 280ps (no photo for the latter)
Philips/Fluke PM3394A (200MHz) analogue mode 1.72ns
Philips/Fluke PM3394A dgital mode 1.66ns

The Philips needs calibrating as there is a lot of overshoot and ringing.







« Last Edit: August 09, 2017, 11:00:15 PM by grumpydoc »
 

Offline alank2

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Re: Yet another fast edge pulse generator
« Reply #188 on: August 05, 2017, 09:44:02 AM »
A question - is it better to look at an equivalent time sample mode or single shot mode for the rise time/fall time measurements?
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #189 on: August 05, 2017, 09:19:42 PM »
A question - is it better to look at an equivalent time sample mode or single shot mode for the rise time/fall time measurements?
From what I have seen, it looks like different scopes use different strategies and reconstruction filters in both modes.  Single shot mode is typically much more challenging and usually enables sharper roll-off filters that produce more ringing.  On LeCroys equivalent sampling usually shows slightly better risetime results.


I have been playing with various settings and component selection (RF 0201 and 0306 caps) for the pulser and it looks like the best risetime setting is achieved when the output level is set at around 820mV (with 1.000 calibration.)  Actual amplitude as reported  by the scope is 920mV and peak-peak is 976mVpp.  This is including 6% overshoot.  You can match them up by setting calibration adjustment to 1.118 if you want - this does not affect the signal in any way.

Also the pulser fall time is slightly (4-5ps) faster than the rise time.  I can't explain why, probably output stage is marginally better at turning off.

I can't help posting a screenshot from CSA803A - only because standard deviation of risetime measurement is 800 femtoseconds.  Nice, woody word :)

And yes, 11800/CSA803 user interface is not elegant.

Leo
« Last Edit: August 05, 2017, 09:24:34 PM by Leo Bodnar »
 

Offline Lukas

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Re: Yet another fast edge pulse generator
« Reply #190 on: August 07, 2017, 09:19:05 AM »
Maybe I missed it, but which output driver (the one branded AJK BAA) are you using in the latest revision?
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #191 on: August 07, 2017, 09:29:32 AM »
Maybe I missed it, but which output driver (the one branded AJK BAA) are you using in the latest revision?
MAX3949

Offline awallin

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Re: Yet another fast edge pulse generator
« Reply #192 on: August 09, 2017, 08:14:02 PM »
Lecroy WaveSurfer 62MXs-B, 600 MHz, 5GS/s, 50R DC
average rise-time 551.6 ps - no surprises there  8)
the fall-time was jumping around a lot - may try this again later with more time/care.
more scopes at work to follow - cheerio  :-+
 

Offline mweymarn

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Re: Yet another fast edge pulse generator
« Reply #193 on: August 09, 2017, 10:23:16 PM »
Hi,

Received my pulser some time ago. Thanks Leo. Two screenshots attached, using the default settings of the pulser.

First is a Tek TDS7254 (2.5 GHz 20 GS/s), connected via a TCA-BNC adapter.
The second one is a R&S (Hameg) HMO3052 (500 MHz 4 GS/s).
 

Offline TheAmmoniacal

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Re: Yet another fast edge pulse generator
« Reply #194 on: August 10, 2017, 05:19:52 AM »
Keysight DSOX1102G, 70 MHz, 1G

4.4 ns rise time.

Micsig MS220T, 200 MHz

1.7 ns rise time.

Tell me if anyone want screenshots.
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MTBF ~ 700.000 h
 

Offline alank2

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Re: Yet another fast edge pulse generator
« Reply #195 on: August 10, 2017, 05:39:03 AM »
I received mine today!

Are all the measurements being done here 10%/90% or 20%/80% ?
 

Offline TheAmmoniacal

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Re: Yet another fast edge pulse generator
« Reply #196 on: August 10, 2017, 05:43:56 AM »
I received mine today!

Are all the measurements being done here 10%/90% or 20%/80% ?

10%/90% surely?
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Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #197 on: August 10, 2017, 06:18:30 AM »
Are all the measurements being done here 10%/90% or 20%/80% ?
There is a long tradition of using 10%-90% when measuring rise time of analogue (asynchronous) signals.

Digital is all messy:
USB 2.0 specify rise time for 10%-90% levels.
PCI Express, HDMI and most logic level specs use 20%-80%.
Maybe it's low voltage swing, maybe improved receivers and reclockers tolerance, maybe it just looks better.

Conversion factor between them for a gaussian response system is about x1.6 which is substantial, so when in doubt - spell it out.

Offline alank2

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Re: Yet another fast edge pulse generator
« Reply #198 on: August 10, 2017, 09:40:38 AM »
Thanks Leo - pulser works great!!

Rise/fall averaged across all channels.

Pico 2207B (70 MHz): rise=2512, fall=2421 (50 ohm passthrough)
Pico 2407B (70 MHz): rise=2686, fall=2564 (50 ohm passthrough)
HP 54645D (100 MHz): rise=2375, fall=2375 (50 ohm passthrough)
BK 2120 (20 Mhz): rise=20000 (50 ohm passthrough, it was 2/5 of a graduation where the graduation was 50nS)
Rigol DS2072 (300 MHz): rise=980, fall=994 (50 ohm passthrough)
Rigol DS4014 (500 MHz): rise=653, fall=647 (50 ohm built-in)
 

Offline richnormand

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Re: Yet another fast edge pulse generator
« Reply #199 on: August 17, 2017, 07:16:53 AM »
Got mine today. Nice packing job, perfect. Thanks Leo.  Love the trig output. :)

As stated in my earlier post here I wanted to check my old Tek S6 sampling head after changing a sampling-and-hold Tek opamp with a generic one. I am using a 7s12 TDR plugin with a s-53 trigger recogniser for this measurement.

Using the 10-90% I got about 58ps rise-time. As 100% I used the high level after the ringing stopped. I also assumed the pulser supplied trace showing a rise-time of 49.2ps for the unit as correct as I do not know the specs of the measuring instrument. I assume it is much better than my old stuff ::) If true, that gives me 30.7ps for the S-6 unit using the usual the t^2 sum equation. It's specifications are 30ps rise-time.

Not bad considering how old it is! ;D

Next step will be to test my R7912 transient digitizer for its single shot 1GHz bandwidth.
« Last Edit: August 17, 2017, 07:54:13 AM by richnormand »
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #200 on: August 18, 2017, 10:36:03 PM »
I also assumed the pulser supplied trace showing a rise-time of 49.2ps for the unit as correct as I do not know the specs of the measuring instrument. I assume it is much better than my old stuff ::)
I have two CSA803A in very good condition, looking almost brand new inside and a variety of sampling heads, one SD-30 (40GHz) and a number of SD-26(20GHz) and SD-22(12.5GHz.)
They are all from different sources and I have cross-checked them against each other - they all agree within noise floor limits. 
This is old equipment from 1990's so it hardly makes any sense to get calibrated, especially for the fun project like this.

I use CSA803A with SD-26 head (17.5ps nominal risetime) installed to print the slips I include with each pulser I send away.
I have tested few units on SD-30 (8.8ps risetime) and there is only 2-3ps difference in the total result - as expected.

Overall I am quite happy with the pulser design performance so will leave it as it is for now.

Leo
« Last Edit: August 18, 2017, 10:37:45 PM by Leo Bodnar »
 

Offline richnormand

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Re: Yet another fast edge pulse generator
« Reply #201 on: August 19, 2017, 05:03:50 AM »
Thanks for the trace information Leo.  :)

The risetime numbers do make sense then, even if I shave a few ps to deconvolve your trace.... well within experimental error.

""Overall I am quite happy with the pulser design performance so will leave it as it is for now.""
Agreed! The unit is a very nice piece of work, don't mess with greatness. :)

I believe my S-6 sampling head with about 10GHz bandwidth is circa 1970s vintage so your equipment is positively modern by my standards :-+

Can't wait to see what you come up with as an encore.

Cheers and thanks.

rich

 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #202 on: September 02, 2017, 05:07:29 AM »
Gentlemen,

Thanks to all of you who supported me by buying one of the pulsers!

To date,  the feedback was very good, performance was excellent and very stable. 
All current devices show risetime between 40 and 50ps and falltime around 40 ps.

I have received new PCB batch and keep assembling the pulsers to maintain stock levels.  They ship same/next working day.

If you wanted to get one - get it now, there is no guarantee that it will be available forever.

Cheers
Leo

http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295
« Last Edit: September 12, 2017, 06:02:25 AM by Leo Bodnar »
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #203 on: September 22, 2017, 12:01:59 AM »
Update 21 September 2017.

I have been slightly tweaking the design between the batches to milk a bit more performance out of it.

Latest batch of the pulsers that I have assembled today all show risetime and falltime below 40ps.

I use two CSA803As with two cross-checked SD-30 40GHz sampling heads to individually test each and every unit.

Here are the rising and falling edge screenshots from a typical fully assembled pulser.

If you still want one - get it while you can.

Thank you for your interest, gentlemen.

Leo

« Last Edit: September 22, 2017, 12:16:09 AM by Leo Bodnar »
 
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Offline modmix

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Re: Yet another fast edge pulse generator
« Reply #204 on: September 30, 2017, 08:05:55 PM »
Would like to tell you about my 40psec device received recently.

it comes with printed measurements: Pulser_40psec_Leo_Bodnar_Measurement_web.jpg - awesome  ;)

Unfortunately, my Tektronics 2465B appears to be a bit slow: Pulser_40psec_Leo_Bodnar_2465B_50R_rise_web.jpg
RiseTime => 284 MHz
FallTime =>  320 MHz

My Hameg HM407 is better than spec: Pulser_40psec_Leo_Bodnar_HM407_rise_web.jpg
RiseTime => 41 MHz
FallTime => 45 MHz

Out of curiosity I connected the device to my GPS synced counter:  Pulser_40psec_Leo_Bodnar_52320A_web.jpg
< 32 mHz Allan Deviation is quite good...
Looks like I've got an easily transportable 10 MHz reference in addition  ;)

Cheers
Ulli
« Last Edit: September 30, 2017, 08:07:54 PM by modmix »
 

Offline Howardlong

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Re: Yet another fast edge pulse generator
« Reply #205 on: October 02, 2017, 08:33:06 AM »
There’s a limitation on the 2465B and 2467B auto measurement system which aflicts fast signals.

You’ll have to do it manually with your #1 eyeball and the graticule & cursors, with a vertical vernier and x10 timebase setting I’m afraid to get a decent response.
« Last Edit: October 02, 2017, 08:39:48 AM by Howardlong »
 

Offline Howardlong

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Re: Yet another fast edge pulse generator
« Reply #206 on: October 02, 2017, 08:38:07 AM »
Here's my 2467b

 

Offline EV

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Re: Yet another fast edge pulse generator
« Reply #207 on: October 12, 2017, 12:19:38 AM »
I got my generator today.

Here are measured rise times from my Tektronix scopes 2465B and 7904.
Tek 7904 has 7T11 and 7S11 (with S-4) plug-ins installed. I used internal triggering.
 

Online capt bullshot

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Re: Yet another fast edge pulse generator
« Reply #208 on: October 12, 2017, 05:29:42 AM »
More pictures made with my pulser (first batch):

S4 sampling head / 7S12 in 7603 Mainframe


S2 sampling head / 7S12 in 7603 Mainframe

« Last Edit: October 12, 2017, 06:03:21 AM by capt bullshot »
Safety devices hinder evolution
 

Online capt bullshot

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Re: Yet another fast edge pulse generator
« Reply #209 on: October 12, 2017, 06:00:39 AM »
Two more

Tek 468 in non-store (analog 100MHz BW) mode, 5ns/div


Tek TDS420

« Last Edit: October 12, 2017, 06:02:24 AM by capt bullshot »
Safety devices hinder evolution
 

Offline EV

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Re: Yet another fast edge pulse generator
« Reply #210 on: October 12, 2017, 06:59:59 PM »
Here are rise and fall time pictures from Tektronix TDS3032:
 

Offline macboy

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Re: Yet another fast edge pulse generator
« Reply #211 on: October 13, 2017, 01:59:38 AM »
Tek 2465A  (refer to Buy/Sell forum if you want it!).
 

Offline MrW0lf

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Re: Yet another fast edge pulse generator
« Reply #212 on: October 13, 2017, 07:59:46 AM »
50ps pulser + PicoScope 2408B with 50ohm passthru.



...and first experiment. Tried to get actual pulses instead of square. At the end of tower is short:




« Last Edit: October 13, 2017, 08:01:24 AM by MrW0lf »
 

Offline EV

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Re: Yet another fast edge pulse generator
« Reply #213 on: October 13, 2017, 08:37:02 AM »
Tektronix 7103R with 7A29 and 7B15 plug ins. Rise time is about 310 ps.
 
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Offline macboy

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Re: Yet another fast edge pulse generator
« Reply #214 on: October 13, 2017, 09:39:07 AM »
[/img]

...and first experiment. Tried to get actual pulses instead of square. At the end of tower is short:


Impulse response can be mathematically determined from the step response, just differentiate. Then you can get the system frequency response from that impulse response by taking FFT.
 

Offline MrW0lf

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Re: Yet another fast edge pulse generator
« Reply #215 on: October 13, 2017, 09:47:12 AM »
Impulse response can be mathematically determined from the step response, just differentiate. Then you can get the system frequency response from that impulse response by taking FFT.

That's another story :) In this case was specifically interested in creating physical pulse, not characterize scope etc. In fact I could not characterize scope in original software with this method anyway because:
It will do derivative just fine. Even agrees to do FFT on it. But due to some bug wont render trace :-BROKE And even if it would no use. FFT trace is hard-limited to 100MHz. Because it is officially 100MHz scope. Actually it is ~140MHz scope of course. I hate when excellent hardware is crippled by "almost there" programming + politics.



Edit: MatLab seems to do the supposed thing, 3.2dB diff 10MHz vs 150MHz:

« Last Edit: October 13, 2017, 09:54:55 PM by MrW0lf »
 

Offline EV

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Re: Yet another fast edge pulse generator
« Reply #216 on: October 13, 2017, 05:50:01 PM »
Here is rise time for Tektronix 2247A:
 

Offline macboy

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Re: Yet another fast edge pulse generator
« Reply #217 on: October 14, 2017, 12:58:50 AM »
Here are a couple of screenshots from my Lecroy WavePro 960 (2 GHz, 16 GS/s).
Trace "A" is an average of the channel under test (for noise reduction).
Trace "B" is the derivative d/dt of A. Note the vertical scale of 1 GV/s per div!
Trace "C" is the FFT of B.
Trace C gives the frequency response of the oscilloscope and pulser (and any cable connecting them, none in this case).

Trace A shows rise time of 268 ps. Using the relation 0.45/Tr=BW, it estimates 1.68 GHz. Obviously such rules of thumb are not universally applicable. The actual -3 dB point in Trace C is 2.03 Ghz.

It can be shown mathematically that an impulse has equal energy at all frequencies. So, if you pass an impulse through a system, you can measure the frequency response by looking at what went through. Generating an actual impulse is impractical, largely because generating one with enough energy to measure practically presents difficulties. For example, an impulse that delivering the same energy to the system as does a 50 ps 1 V rising edge, would require a 50 ps wide, 20 000 000 000 volt pulse. I can't generate 20 GV in my lab, and my scope input wouldn't like it if I could  :scared:  Actually, we don't quite need that much energy but it is still difficult to generate a well-behaved impulse. Fortunately, we can use math trickery instead. We know that the d/dt of a step is an impulse. The "d/dt of the response to a step" is the same as the "response to the d/dt of a step" (response to an impulse). So we apply a fast rise step to the system, measure system step response, then take d/dt of the step response to get the system impulse response. Then convert to frequency domain (take FFT) to get frequency response. That is exactly what is shown in Trace C.

In this case, the frequency response can be seen varying about +/- 1 dB from zero to 2 GHz, and dropping extremely rapidly after 2 GHz. The -3 dB point relative to DC is 2.03 GHz.

I have a variable filter (Krohn Hite 3202r), which can do high pass, low pass, bandpass, and notch modes with a continuously variable corner/center frequency. It can be entertaining to set up the scope to display the frequency response in real time while playing with the filters.

p.s. MrW0lf, confine your FFT to a single period and you'll get the nice flat-top result. In this case, you want the DC imbalance that is present in the impulse response.



« Last Edit: November 01, 2017, 02:00:26 AM by macboy »
 
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Offline MrW0lf

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Re: Yet another fast edge pulse generator
« Reply #218 on: October 14, 2017, 02:15:39 AM »
macboy, thanks for clarifications. I will play with pulser later and try to reproduce by-the-book result. Have not tried this before because of software issues. Only recently got MatLab because stuff not doable in original software started to pile up.

BTW I had to use multiple periods because just extracted raw data - 1GSa/s non averaged is not sufficent - small number of periods will just show garbage.

As for my original physical impulse shot - I have interest in solitons, but no fancy indoor waveguide:


So have to do it small and with electricity much like this:
https://youtu.be/I9m2w4DgeVk?t=11m46s
 

Offline zucca

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Re: Yet another fast edge pulse generator
« Reply #219 on: October 14, 2017, 02:33:21 AM »
TEA got me again, I just ordered one.

Very interesting  results. Since I am pretty virgin on this topic:

https://www.edn.com/electronics-blogs/bogatin-s-rules-of-thumb/4424573/Rule-of-Thumb--1--The-bandwidth-of-a-signal-from-its-rise-time

http://literature.cdn.keysight.com/litweb/pdf/5988-8008EN.pdf

Sorry if was already posted somewhere here...

EDIT:
of course was already there:
http://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/msg1271710/?topicseen#msg1271710

EDIT2:
@Leo Bodnar, Did you post it in the Buy/sell section? I coudn't find it, such a nice product deserves more customers...
« Last Edit: October 14, 2017, 03:59:15 AM by zucca »
Can't know what you don't love. St. Augustine
Can't love what you don't know. Zucca
 

Offline MrW0lf

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Re: Yet another fast edge pulse generator
« Reply #220 on: October 14, 2017, 06:23:08 AM »
Ok, tried hard to get it right:

ETS monster style: 20GSa/s, single wfm (zoomed), averaged, 1kpts:

Get nice smooth graph but overly optimistic.

RTS style: 1GSa/s, many wfms (zoomed on single), averaged, 1Mpts:

Detailed FFT, quite realistic result.

Possibly there are issues with approach MatLab Signal Analyzer uses:
https://se.mathworks.com/help/signal/ug/spectrum-computation-in-signal-analyzer.html

Interesting which low end scopes could actually pull this off in native GUI? GW Instek possibly? It's a shame Picos cant do it - its not by design but by some stupid bug :(
« Last Edit: October 14, 2017, 06:45:05 AM by MrW0lf »
 

Offline EV

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Re: Yet another fast edge pulse generator
« Reply #221 on: October 15, 2017, 03:42:57 AM »
Here is rise time from Tektronix 7904 with plug ins 7A29 and 7B92A. It is about 600 ps.
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #222 on: October 19, 2017, 07:42:57 AM »
I have been to the Electronics Design Show in Coventry (UK) earlier today and dropped by our friends from Tektronix and Pico Technology.

Thanks to James from Tek and Kieran and Trevor from Pico Tech for testing the pulser.  It is not easy to demo your complicated top line equipment live when everybody is watching - especially to test a surprise customer device.  When I have showed up both scopes were set up to run demos for eye pattern tests and TDR but engineers were more than happy to rip the setup apart and connect my unknown DUT - both scopes worked flawlessly and we had great fun.

Tektronix had 33GHz BW, 100Gsps realtime DPO73304SX scope on their stand and the pulser edge speed result was 31ps.

Pico Technology demoed 20GHz BW sampling scope with TDR capability which measured the pulser risetime at 34ps.

Leo

Offline HighVoltage

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Re: Yet another fast edge pulse generator
« Reply #223 on: October 19, 2017, 08:47:41 AM »
What a nice opportunity top test your pulse generator.
And great pictures, thanks for sharing.

There are 3 kinds of people in this world, those who can count and those who can not.
 

Offline MrW0lf

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Re: Yet another fast edge pulse generator
« Reply #224 on: October 19, 2017, 09:11:08 AM »
BTW, later I managed to partially work around fft(derivative(signal)) issue on Pico RTS range software also, described here. Hope in future some wizardry gone into ETS software can be channeled down the range so could do fun stuff with less effort.
 

Offline Tom45

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Re: Yet another fast edge pulse generator
« Reply #225 on: October 19, 2017, 09:21:31 AM »
Wow! The Tek scope reports 30.851912 psec rise time.   :-DD
 

Offline WastelandTek

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Re: Yet another fast edge pulse generator
« Reply #226 on: October 21, 2017, 05:18:34 AM »
I have been to the Electronics Design Show in Coventry (UK) earlier today and dropped by our friends from Tektronix and Pico Technology.

Thanks to James from Tek and Kieran and Trevor from Pico Tech for testing the pulser.  It is not easy to demo your complicated top line equipment live when everybody is watching - especially to test a surprise customer device.  When I have showed up both scopes were set up to run demos for eye pattern tests and TDR but engineers were more than happy to rip the setup apart and connect my unknown DUT - both scopes worked flawlessly and we had great fun.

Tektronix had 33GHz BW, 100Gsps realtime DPO73304SX scope on their stand and the pulser edge speed result was 31ps.

Pico Technology demoed 20GHz BW sampling scope with TDR capability which measured the pulser risetime at 34ps.

Leo

That is really cool!
I'm new here, but I tend to be pretty gregarious, so if I'm out of my lane please call me out.
 

Offline Howardlong

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Re: Yet another fast edge pulse generator
« Reply #227 on: October 21, 2017, 06:29:18 AM »
I realise it might be a bit niche, but a native SMA or 3.5mm version might perform even better!
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #228 on: October 21, 2017, 06:37:46 AM »
I realise it might be a bit niche, but a native SMA or 3.5mm version might perform even better!
It would need total redesign to show appreciable improvement.
I have tested SMA version today and apart from subtle changes it did not have much advantage over BNC.
Also consider the fact that BNC version test result includes SMA-BNC interseries connector.
Leo
 
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Offline Howardlong

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Re: Yet another fast edge pulse generator
« Reply #229 on: October 21, 2017, 07:14:50 AM »
I realise it might be a bit niche, but a native SMA or 3.5mm version might perform even better!
It would need total redesign to show appreciable improvement.
I have tested SMA version today and apart from subtle changes it did not have much advantage over BNC.
Also consider the fact that BNC version test result includes SMA-BNC interseries connector.
Leo

Understood, but... you’re assuming I am in the ownership of a kickass bnc-f to sma-m interseries adapter. I have a couple decent amphenol ones going the other way. A decent interseries adapter would cost significantly more than your generator ;-)

I realise t’internet can obscure wry smiles, which is how I wrote my last message and write this one too: I know it’s not a simple part replacement, it’s a board respin and test, and there’s unlikely to be much of a market, but I live in hope, until I can find a decent reasonably priced interseries adapter of course!

In the meantime, thanks for your product, it’s certainly appreciated here.
 

Offline Howardlong

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Re: Yet another fast edge pulse generator
« Reply #230 on: October 21, 2017, 07:20:07 AM »
Hmmm, did you take your existing board and simply replace the BNC with an appropriately dimensioned SMA? I migt be interested in doing that mod, if it’s that simple and I can find the SMA male with the right mount. It might mean I’ll have to buy another pulse generator, of course.
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #231 on: October 21, 2017, 07:39:07 AM »
Hmmm, did you take your existing board and simply replace the BNC with an appropriately dimensioned SMA? I migt be interested in doing that mod, if it’s that simple and I can find the SMA male with the right mount. It might mean I’ll have to buy another pulse generator, of course.
Howard, I can do this for you (or anyone else) if you want.  This is, perhaps, slightly ugly looking but mechanically and performance-wise very solid.  There are 0201 components near the central pin solder joint so if you are doing it yourself make sure you don't sweep them off.  You know your components are small when they fall down through the vias.
I can put male or female SMA and set it at 90 degrees, not skewed like below.  SMA female was quite expensive so I'd need to charge an extra £10 for this version.

In fact, you are welcome to this one that you see on the pictures and risetime plot. Photos are of the actual item. :D

Leo

Offline KE5FX

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Re: Yet another fast edge pulse generator
« Reply #232 on: October 21, 2017, 07:40:31 AM »
I have tested SMA version today and apart from subtle changes it did not have much advantage over BNC.
Also consider the fact that BNC version test result includes SMA-BNC interseries connector.
Leo

It's not that the performance of the BNC connector is unacceptable in itself, it's that the whole idea behind a fast pulser is to test fast hardware.  Having to use a BNC-to-SMA adapter with a fast DUT is certainly worse than having to use an SMA-to-BNC adapter with a slower DUT.
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #233 on: October 21, 2017, 07:46:39 AM »
It's not that the performance of the BNC connector is unacceptable in itself, it's that the whole idea behind a fast pulser is to test fast hardware.  Having to use a BNC-to-SMA adapter with a fast DUT is certainly worse than having to use an SMA-to-BNC adapter with a slower DUT.
I accept your reasoning but I had problems with people not being able to find suitable USB cable locally.
Looks like I'd have to make and stock SMA version as well at some point.
Leo

Offline KE5FX

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Re: Yet another fast edge pulse generator
« Reply #234 on: October 21, 2017, 08:18:19 AM »
It's not that the performance of the BNC connector is unacceptable in itself, it's that the whole idea behind a fast pulser is to test fast hardware.  Having to use a BNC-to-SMA adapter with a fast DUT is certainly worse than having to use an SMA-to-BNC adapter with a slower DUT.
I accept your reasoning but I had problems with people not being able to find suitable USB cable locally.
Looks like I'd have to make and stock SMA version as well at some point.
Leo

Would it make sense to go with SMA on the next spin, and sell an optional BNC adapter to go with it?
 

Offline Howardlong

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Re: Yet another fast edge pulse generator
« Reply #235 on: October 21, 2017, 09:37:44 AM »
Hmmm, did you take your existing board and simply replace the BNC with an appropriately dimensioned SMA? I migt be interested in doing that mod, if it’s that simple and I can find the SMA male with the right mount. It might mean I’ll have to buy another pulse generator, of course.
Howard, I can do this for you (or anyone else) if you want.  This is, perhaps, slightly ugly looking but mechanically and performance-wise very solid.  There are 0201 components near the central pin solder joint so if you are doing it yourself make sure you don't sweep them off.  You know your components are small when they fall down through the vias.
I can put male or female SMA and set it at 90 degrees, not skewed like below.  SMA female was quite expensive so I'd need to charge an extra £10 for this version.

In fact, you are welcome to this one that you see on the pictures and risetime plot. Photos are of the actual item. :D

Leo

You’re on: PM me the total inc P&P with your Paypal details.

FWIW, 0201 not a problem here. Sometimes I go down to 01005 if I have to. 008004 not yet encountered, probably just a matter of time though the way things are going. Meh, 0201 passives going down vias, I had a 3x2 ball CSP do that on me recently. Losing a $0.001 passive is one thing, a $3 chip feels much less of a write off, especially if you’re down to your last 2 or 3 contingency parts on a prototype.
 

Offline borjam

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Re: Yet another fast edge pulse generator
« Reply #236 on: October 23, 2017, 06:34:15 PM »
I ordered one last week, should arrive today :)

One suggestion: could you please share the protocol specs to configure it? A Windows program is very inconvenient for someone not using Windows. It should be very easy to implement in Python, at least for simple command-line usage.

 

Offline HighVoltage

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Re: Yet another fast edge pulse generator
« Reply #237 on: October 23, 2017, 08:05:11 PM »
Looks like I'd have to make and stock SMA version as well at some point.
Leo

Leo,
If you ever release a SMA version, I am interested in getting a 3rd pulse generator from you.
Thanks!
 
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Offline Berni

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Re: Yet another fast edge pulse generator
« Reply #238 on: October 23, 2017, 10:12:19 PM »
Seeing that most people are using these to test scopes i think a BNC is pretty welcome.

That being said i do tend to use SMA for everything and since test equipment usually does not have SMA i have a bunch of SMA to BNC and to N cables.

Is it possible to give it a dual footprint that takes both? Then have the BNC one be the standard version while the special version having no connector soldered and provide one SMA in the kit (Some other non SMA connectors also fit)

That being said is this thing actually useful for RF stuff? Like maybe being a comb generator or something. I never tried mine on a spectrum analyzer.
 

Offline borjam

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Re: Yet another fast edge pulse generator
« Reply #239 on: October 23, 2017, 10:17:48 PM »
That being said is this thing actually useful for RF stuff? Like maybe being a comb generator or something. I never tried mine on a spectrum analyzer.
As a TDR to examine coaxial cable runs?
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #240 on: October 23, 2017, 11:06:47 PM »
That being said is this thing actually useful for RF stuff? Like maybe being a comb generator or something. I never tried mine on a spectrum analyzer.
I have tried it on 8595E just now.
Green trace is SA noise floor.
Leo

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #241 on: October 23, 2017, 11:11:20 PM »
One suggestion: could you please share the protocol specs to configure it? A Windows program is very inconvenient for someone not using Windows. It should be very easy to implement in Python, at least for simple command-line usage.
I'll try putting something together. You can only adjust output level and inversion, so it's not very exciting.
Leo

Offline borjam

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Re: Yet another fast edge pulse generator
« Reply #242 on: October 23, 2017, 11:54:19 PM »
One suggestion: could you please share the protocol specs to configure it? A Windows program is very inconvenient for someone not using Windows. It should be very easy to implement in Python, at least for simple command-line usage.
I'll try putting something together. You can only adjust output level and inversion, so it's not very exciting.
Thanks! If you have a simple description I can try to implement it in Python myself. Needless to say I'll share the program.
 

Offline HighVoltage

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Re: Yet another fast edge pulse generator
« Reply #243 on: October 24, 2017, 12:13:06 AM »
I have tried it on 8595E just now.
Green trace is SA noise floor.
Leo

How did you capture that trace from the HP 8595E so clearly?
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Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #244 on: October 24, 2017, 12:22:01 AM »
How did you capture that trace from the HP 8595E so clearly?
Thanks to KE5FX and his software - I did not have a proper chance to say how good and useful his stuff is! 
http://www.ke5fx.com/gpib/readme.htm

I'd wish for the font to line-up slightly better but I believe it is vectorised and compiled into the code. 
I have spent exactly 30 seconds on this issue because it is not a problem at all, just nit-picking.

Leo

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #245 on: October 24, 2017, 01:15:47 AM »
Here is measured spectrum (blue) against theoretical spectrum of ideal square wave (red) - only odd harmonics are shown for clarity.
My SA has not been calibrated for ages but it does not look too bad.
Leo

Offline KE5FX

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Re: Yet another fast edge pulse generator
« Reply #246 on: October 24, 2017, 05:22:28 AM »
How did you capture that trace from the HP 8595E so clearly?
Thanks to KE5FX and his software - I did not have a proper chance to say how good and useful his stuff is! 
http://www.ke5fx.com/gpib/readme.htm

I'd wish for the font to line-up slightly better but I believe it is vectorised and compiled into the code. 
I have spent exactly 30 seconds on this issue because it is not a problem at all, just nit-picking.

Leo

You're welcome -- credit goes to texaspyro for his work on the renderer.  :-+  You can try displaying the plot with 7470_legacy.exe to use the old fixed-width font, but for everything that looks better, something else will tend to look worse.  HP-GL is hard to get right.
 

Offline borjam

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Re: Yet another fast edge pulse generator
« Reply #247 on: October 24, 2017, 06:07:17 PM »
Received yesterday, nice piece of kit!

I didn't have much time but I tried it on a Siglent SDS1202X-E and a "grown up" Rigol DS1074Z (using a T BNC adapter and a SMA 50 ohm terminator from the miniVNA Tiny calibration kit) and it works very well. I even did a quick and dirty TDR with a piece of coax.

Hoping to have more time this week, I'll post the screenshots.
 

Offline texaspyro

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Re: Yet another fast edge pulse generator
« Reply #248 on: October 25, 2017, 12:19:12 PM »
How did you capture that trace from the HP 8595E so clearly?
Thanks to KE5FX and his software - I did not have a proper chance to say how good and useful his stuff is! 
http://www.ke5fx.com/gpib/readme.htm

I'd wish for the font to line-up slightly better but I believe it is vectorised and compiled into the code. 
I have spent exactly 30 seconds on this issue because it is not a problem at all, just nit-picking.

Leo

You're welcome -- credit goes to texaspyro for his work on the renderer.  :-+  You can try displaying the plot with 7470_legacy.exe to use the old fixed-width font, but for everything that looks better, something else will tend to look worse.  HP-GL is hard to get right.

Yep,  HP-GL rendering is a royal pain... there is basically no way to "get it right".   There are a LOT of interpretations of what HP-GL should do and it seems that everything that spews HP-GL somewhere does it wrong / different.   It was a lot of work getting the HP-GL2 renderer to handle all the example files in the gpibkit install.   You tweak it for one oddball, fubar'd instrument and it borks another one.  Anyway, 7470.exe has one of the most capable HP-GL renderers out there... at least for instrument dumps   ;)   The CERN viewer is also very good:  http://service-hpglview.web.cern.ch/service-hpglview/hpglviewer.html

I originally wrote the HP-GL renderer to use with my Atmel 2561 based GPIB controller that emulates a Prologix serial GPIB interface.  It was done as sort of a joke, but turned out to be rather useful.  It could display instrument screen dumps (HP-GL or PCL) on a 160x80 monochrome LCD touchscreen.  The fonts used are vector fonts that were generated from a VGA dot matrix font (and are the same fonts used in Lady Heather and my gcode processor program). 

 

Offline HighVoltage

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Re: Yet another fast edge pulse generator
« Reply #249 on: October 25, 2017, 08:28:34 PM »
Hello KE5FX and texaspyro
Many years ago, I tried to find a software to collect a screen shot from my old HP spectrum analyzer, until I gave up. Now I am surprise to hear that there is something.
Thank you so much !

I am traveling right now, but I will test this on the weekend, when I am back.
You should start a separate thread on this, I think lots of people would be interested.

In the olden days, when I had a HP plotter, I was always curious why the plotting sequence was sometimes very odd. And every plot that was made, was different in sequence. May be that was also a problem in programming a capture software for HP/GL?

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Offline 1Ghz

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Re: Yet another fast edge pulse generator
« Reply #250 on: October 31, 2017, 12:57:54 AM »
Agilent 54622D 100MHz 200MS/s: Avg rise time 7.47 ns, Real-time average acquisition, 5 ns timebase
Agilent 54622D 100MHz 200MS/s: Avg rise time 2.77 ns, Average acquisition, 5 ns timebase
Agilent 54642D 500MHz 2GS/s: Avg rise time 0.7 ns, Real-time average acquisition, 1 ns timebase
Agilent 54642D 500MHz 2GS/s: Avg rise time 0.63 ns, Average acquisition, 1 ns timebase
LeCroy LC534AM 1GHz 10GS/s: Avg rise time 0.31 ns, RIS (Random Interleaved Sampling) acquisition, 1 ns timebase
LeCroy J-250 1GHz 16GS/s (WavePro 950): Avg rise time 0.246 ns, Single-shot acquisition, 0.5 ns timebase

Works great! Thank you, Leo!  :-+
« Last Edit: November 01, 2017, 09:45:41 PM by 1Ghz »
 

Online grumpydoc

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Re: Yet another fast edge pulse generator
« Reply #251 on: October 31, 2017, 05:53:59 AM »
Agilent 54622D 100MHz 200MS/s: Avg rise time 7.47 ns

Works great! Thank you, Leo!  :-+
That seems slow for a 100MHz 'scope - should be around 3.5ns?
 

Offline H.O

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Re: Yet another fast edge pulse generator
« Reply #252 on: October 31, 2017, 07:50:13 AM »
I've updated the spreadsheet with all the entries so far.
In the spreadsheet all calculated bandwidths are based on a pulser risetime of 50ps which we now know is quite concervative, especially with Leo's 2nd generation units. As is, the spreadsheet doesn't even handle the 31ps to 34ps figures properly.

The spreadsheet is here:
https://docs.google.com/spreadsheets/d/1uknvUdL4gNuTyuK7MNAkCj95GFSsDtfgr7nObVppFiE/edit?usp=sharing

If anyone want access to it just PM me your email adress and I'll add you to the list.
 

Offline Gixy

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Re: Yet another fast edge pulse generator
« Reply #253 on: October 31, 2017, 05:23:36 PM »
@H.O
Hi,
You forgot my post #156 for the HP 1742A in the table.
Cheers,
Denis
 

Offline EV

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Re: Yet another fast edge pulse generator
« Reply #254 on: October 31, 2017, 06:45:27 PM »
@H.O

In my post 207 the rise time of Tek 7904 with 7T11 and 7S11 (with S-4) is less than 60 ps (not 80 ps).
« Last Edit: October 31, 2017, 08:54:35 PM by EV »
 

Offline EV

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Re: Yet another fast edge pulse generator
« Reply #255 on: October 31, 2017, 06:53:22 PM »
Here is an other picture with 50 ps time base.
 

Offline 1Ghz

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Re: Yet another fast edge pulse generator
« Reply #256 on: October 31, 2017, 10:06:33 PM »
That seems slow for a 100MHz 'scope - should be around 3.5ns?

It's because the real-time sampling rate is low.
I've updated my reply.
 

Offline Howardlong

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Re: Yet another fast edge pulse generator
« Reply #257 on: October 31, 2017, 10:15:04 PM »
That seems slow for a 100MHz 'scope - should be around 3.5ns?

It's because the real-time sampling rate is low.
I've updated my reply.

Running the 54642D in equivalent time might improve its rise time performance a little too, certainly I've found that on other Agilent/Keysight scopes that support it (e.g. MSO7104B, 54832D).
 

Offline 1Ghz

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Re: Yet another fast edge pulse generator
« Reply #258 on: October 31, 2017, 11:11:05 PM »
Running the 54642D in equivalent time might improve its rise time performance a little too, certainly I've found that on other Agilent/Keysight scopes that support it (e.g. MSO7104B, 54832D).

I've updated my reply once again.
 

Offline macboy

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Re: Yet another fast edge pulse generator
« Reply #259 on: November 01, 2017, 01:35:43 AM »
..
LeCroy J-250 1GHz 16GS/s (WavePro 950): Avg rise time 0.246 ns, Single-shot acquisition
..
Works great! Thank you, Leo!  :-+
I hate that your 1 GHz J-250 (WavePro 950 ish) is faster than my 2 GHz WavePro 960. But I've confirmed a -3dB point just above 2 GHz on the 960 so it does live up to spec. And my overshoot and ringing looks very different than yours. Curious.

Can you try the same bandwidth measurement technique that I used in my post? This will show you not only the -3 dB point but also the passband ripple of the scope. It's nice to know those things. You may or may not have deep FFT support on your unit depending on options (look for WAVA or WAVAPRO or WPRO in options list).
 

Offline 1Ghz

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Re: Yet another fast edge pulse generator
« Reply #260 on: November 01, 2017, 02:36:59 AM »
Can you try the same bandwidth measurement technique that I used in my post?

Yes, here's pictures.

LeCroy J-250 1GHz 50GS/s (WavePro 950): Avg rise time 0.251 ns, RIS (Random Interleaved Sampling) acquisition, 5 ns timebase
« Last Edit: November 01, 2017, 09:47:03 PM by 1Ghz »
 

Online grumpydoc

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Re: Yet another fast edge pulse generator
« Reply #261 on: November 01, 2017, 02:59:42 AM »
Can you try the same bandwidth measurement technique that I used in my post?

Yes, here's pictures.
I must try this with the 950, though I know it only has the "vanilla" FFT
 

Offline macboy

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Re: Yet another fast edge pulse generator
« Reply #262 on: November 01, 2017, 05:59:03 AM »
Can you try the same bandwidth measurement technique that I used in my post?

Yes, here's pictures.
Nice, way beyond spec. And a nice rolloff, not the brick wall that the 960 has.
I guess you could change your name to 1.8GHz now.  :-DD
 
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Offline richnormand

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Re: Yet another fast edge pulse generator
« Reply #263 on: November 01, 2017, 07:02:04 AM »
Said in my previous post that I would try it on my Tek R7912AD.

This is a single shot transient digitizer with a 500MHz bandwidth (about 1GHz direct access).
The 10 to 90% risetime looks to be around 700ps.
Using the risetime ~ 0.35/bandwidth guide I get 500MHz...... 8)





 

Offline richnormand

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Re: Yet another fast edge pulse generator
« Reply #264 on: November 01, 2017, 07:15:49 AM »
Update 21 September 2017.

I have been slightly tweaking the design between the batches to milk a bit more performance out of it.

Latest batch of the pulsers that I have assembled today all show risetime and falltime below 40ps.


You mentioned a few revisions to get a better performance. I have your Rev E batch rated as 50ps. From the photo I can see a few modifications in the upper right.
Is this something that I can retrofit on the old board or would that be too tricky?

 :)
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #265 on: November 01, 2017, 07:32:14 AM »
You mentioned a few revisions to get a better performance. I have your Rev E batch rated as 50ps. From the photo I can see a few modifications in the upper right.
Is this something that I can retrofit on the old board or would that be too tricky?
 :)
Current revision is Rev.G and I have modified power bypass quite a lot. So the short answer is "tricky" :)
The best I can offer you is another one from current Rev.G with a discount.  But 50ps is pretty darn fast as it is.
Leo

Offline richnormand

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Re: Yet another fast edge pulse generator
« Reply #266 on: November 01, 2017, 08:02:26 AM »
Thanks Leo.
Since 50ps is already much faster than anything I own right now I'll be OK for the next while!
I was just intrigued on how you did it and if it was easily transferable to the previous version when I saw your posting.
Cheers.
 

Offline Berni

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Re: Yet another fast edge pulse generator
« Reply #267 on: November 01, 2017, 07:52:45 PM »
Said in my previous post that I would try it on my Tek R7912AD.

This is a single shot transient digitizer with a 500MHz bandwidth (about 1GHz direct access).
The 10 to 90% risetime looks to be around 700ps.
Using the risetime ~ 0.35/bandwidth guide I get 500MHz...... 8)

Now that is quite a beast. I had to look it up and its pretty interesting.

http://w140.com/tekwiki/wiki/7912

Turns out back in 1973 they made this work using a CRT tube with a plate of detectors on the end(That are also read with a electron beam like a vidicon tube) to create a high speed AD converter.
« Last Edit: November 01, 2017, 08:11:27 PM by Berni »
 

Offline 1Ghz

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Re: Yet another fast edge pulse generator
« Reply #268 on: November 01, 2017, 10:38:07 PM »
HP 16530A 100MHz 400MS/s: Avg rise time 3.4 ns, Average acquisition, 5 ns timebase
 

Offline H.O

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Re: Yet another fast edge pulse generator
« Reply #269 on: November 02, 2017, 02:48:45 AM »
Thank you to those who pointed out some mistakes and omissions in the spreadsheet (on and off list).
I believe I've fixed those now and I've added the last day(s) entries.
 

Online grumpydoc

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Re: Yet another fast edge pulse generator
« Reply #270 on: November 02, 2017, 10:41:34 AM »
Can you try the same bandwidth measurement technique that I used in my post?

Yes, here's pictures.
I must try this with the 950......

And the result is:



Not quite as good as 1GHz's machine, but not too shabby.

Out of interest the Lecroy is good for this analysis as it makes it easy to use the output of one maths function as the input to another - that does not seem to be the case for a Keysight DSO1024A or Tenma 72-8725 that I have recently had to play with - it could simply be that I've not figured out how to get them to play ball but both of these 'scopes seem to have fairly shallow memories and only do FFT based on what is on screen.

What other 'scopes can do this analysis to show the impulse power spectrum?
 

Offline macboy

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Re: Yet another fast edge pulse generator
« Reply #271 on: November 02, 2017, 11:14:28 AM »
I was able to convince my Phillips PM3320A (ca. 1987) to do it, but it wouldn't the horizontal of the FFT result as frequency, only as points. I guess the firmware designers didn't anticipate users doing FFT of a d/dr of a waveform. Anyway the resulting FFT just wasn't as convincing as the WavePro result. I manually measured the -3dB bandwidth as 375 MHz, not bad for a 200 MHz scope.

Is your WavePro actually as grey as it looks in the photo? My 960 is a distinctive blue-grey that is actually quite ugly.
 

Online grumpydoc

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Re: Yet another fast edge pulse generator
« Reply #272 on: November 02, 2017, 09:09:31 PM »
Is your WavePro actually as grey as it looks in the photo? My 960 is a distinctive blue-grey that is actually quite ugly.
Blue-grey is about right, no attempt was made for accurate colour balance in the above shot so the camera has almost certainly interpreted the front panel as mid grey and adjusted accordingly.
 

Offline Berni

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Re: Yet another fast edge pulse generator
« Reply #273 on: November 03, 2017, 06:11:37 AM »
Here i tried the pulsar on a Agilent MSO9204H.



Doing a FFT of a derivative is easy here since it has 16 math channels to choose from and each can feed in to the next.

About what is to be expected with a rise time of 147ps and the FFT showing a -3dB bandwith at 3.1GHz.
 

Offline Howardlong

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Re: Yet another fast edge pulse generator
« Reply #274 on: November 03, 2017, 09:24:40 AM »
With a Leo SMA modded version on an HP 54120B & 54121A combo, 35.6ps. (I was getting about 55ps on the BNC version with a rather generic BNC-SMA interseries adapter of indeterminate provenance).

I feel sure I may be able to do better with some experimentation: still it's almost as good as the scope's internal pulse generator (~33ps).

 

Offline rx8pilot

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Re: Yet another fast edge pulse generator
« Reply #275 on: November 03, 2017, 12:09:22 PM »
That is pretty cool.....especially for a tiny $75 device.

Glad I got one.
Thank you EEVBlog for all the support in the Keysight Test to Impress Giveaway voting!
 

Offline texaspyro

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Re: Yet another fast edge pulse generator
« Reply #276 on: November 23, 2017, 01:45:24 PM »
I got in my pulser a couple of days ago.  A couple of new measurements for the table:

Tek TDS3034 (non-A) up-hacked to TDS3054:  560 ps / 715 MHz
Tek THS730A: 1.4 ns /  285 Mhz

Used 0.4 / rise time for the calculation.
 

Online Jwalling

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Re: Yet another fast edge pulse generator
« Reply #277 on: November 27, 2017, 11:30:55 PM »
Got mine a week or so ago. Build quality is excellent and it works great!

Results:
Agilent   54832D   1000         331   
Tektronix   TDS784A   1000         270   
Tektronix   TDS3052     500           620   
Tektronix   TDS694C   3000         106   
Agilent   54855A   6000         68
Jay

System error. Strike any user to continue.
 

Offline HighVoltage

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Re: Yet another fast edge pulse generator
« Reply #278 on: November 28, 2017, 02:59:45 AM »
Got mine a week or so ago. Build quality is excellent and it works great!

Results:
Agilent   54832D   1000         331   
Tektronix   TDS784A   1000         270   
Tektronix   TDS3052     500           620   
Tektronix   TDS694C   3000         106   
Agilent   54855A   6000         68

I had to look up the Agilent model number 54855A.
It is a real-time scope with a bandwidth of  7 GHz?
Nice result of 68 ps!


There are 3 kinds of people in this world, those who can count and those who can not.
 

Online grumpydoc

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Re: Yet another fast edge pulse generator
« Reply #279 on: November 29, 2017, 12:12:46 AM »
Keysight DSO1024A



2.48ns seems borderline slow for a 200MHz 'scope - I guess it comes in as 0.5/BW and the DSO1024A drops to 500Ms/s when all channels are in use so it probably has a pretty tight filter on the front end.
 

Offline Howardlong

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Re: Yet another fast edge pulse generator
« Reply #280 on: November 29, 2017, 12:19:45 AM »
Keysight DSO1024A



2.48ns seems borderline slow for a 200MHz 'scope - I guess it comes in as 0.5/BW and the DSO1024A drops to 500Ms/s when all channels are in use so it probably has a pretty tight filter on the front end.

Is the scope 50-ohm terminated?
 

Online grumpydoc

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Re: Yet another fast edge pulse generator
« Reply #281 on: November 29, 2017, 12:33:31 AM »
Keysight DSO1024A

2.48ns seems borderline slow for a 200MHz 'scope - I guess it comes in as 0.5/BW and the DSO1024A drops to 500Ms/s when all channels are in use so it probably has a pretty tight filter on the front end.

Is the scope 50-ohm terminated?
No and I suspect that might have something to do with the response.

Disappointingly though for a 200MHz 'scope the DSO1024A has no built in 50 ohm termination.

However the path from Leo's pulser to the front end is so short that I suspect putting any external termination in will make things worse, not better.

I have a home made 50 ohm pass-through somewhere - I might dig it out and see if my suspicion is correct.
 

Online grumpydoc

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Re: Yet another fast edge pulse generator
« Reply #282 on: November 29, 2017, 08:43:40 AM »
I have a home made 50 ohm pass-through somewhere - I might dig it out.....

OK, so, makes a huge difference! 1.24ns

Trying to get my head around the interaction of the termination resistance and the input capacitance of the 'scope (18pf, so about 8.8 ohms at a GHz).



Fair bit of ringing though, similar with a T piece and the usual crappy 50 ohm terminator.



The data sheet gives 1.8ns but that is just a calculated figure (using 0.35/BW)
 

Offline WastelandTek

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Re: Yet another fast edge pulse generator
« Reply #283 on: December 02, 2017, 03:52:22 PM »
hey Leo

Are you thinking the design iterations are pretty much done now?
I'm new here, but I tend to be pretty gregarious, so if I'm out of my lane please call me out.
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #284 on: December 02, 2017, 08:44:54 PM »
hey Leo
Are you thinking the design iterations are pretty much done now?
Hiya,
Pretty much so. 
Pulser performance went beyond what I originally wanted it to do. It even has an LED now.
Cheers
Leo

Offline WastelandTek

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Re: Yet another fast edge pulse generator
« Reply #285 on: December 03, 2017, 04:33:59 AM »
hey Leo
Are you thinking the design iterations are pretty much done now?
Hiya,
Pretty much so. 
Pulser performance went beyond what I originally wanted it to do. It even has an LED now.
Cheers
Leo

right on, I think I am deserving a Christmas present  ;)
I'm new here, but I tend to be pretty gregarious, so if I'm out of my lane please call me out.
 

Online FriedLogic

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Re: Yet another fast edge pulse generator
« Reply #286 on: December 03, 2017, 09:53:32 AM »
It's not that the performance of the BNC connector is unacceptable in itself, it's that the whole idea behind a fast pulser is to test fast hardware.  Having to use a BNC-to-SMA adapter with a fast DUT is certainly worse than having to use an SMA-to-BNC adapter with a slower DUT.
I accept your reasoning but I had problems with people not being able to find suitable USB cable locally.
Looks like I'd have to make and stock SMA version as well at some point.
Leo

Has anyone come across any readily available good and cheap SMA(f) - BNC(m) adaptors? (not surplus expensive ones, but cheap when bought new)

The main problem with most of the cheap BNC adaptors and plugs that I've seen is that they are missing the raised flange around the end of the ground connection on the plug, so don't connect well with the socket. The plating on a lot of them does not help much either.

I've sometimes bent the contacts out a little so that they connect better, but that's certainly not ideal.
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #287 on: December 03, 2017, 10:00:07 AM »
Has anyone come across any readily available good and cheap SMA(f) - BNC(m) adaptors? (not surplus expensive ones, but cheap when bought new)

The main problem with most of the cheap BNC adaptors and plugs that I've seen is that they are missing the raised flange around the end of the ground connection on the plug, so don't connect well with the socket. The plating on a lot of them does not help much either.

I've sometimes bent the contacts out a little so that they connect better, but that's certainly not ideal.
I use these https://www.digikey.co.uk/products/en?keywords=314-1184-ND when testing the pulsers.
« Last Edit: December 03, 2017, 10:02:13 AM by Leo Bodnar »
 

Offline Berni

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Re: Yet another fast edge pulse generator
« Reply #288 on: December 04, 2017, 05:26:28 PM »
I would buy another one of these if a SMA version becomes available.

I would guess that most people would still prefer it to be BNC since that makes it a great scope speed testing tool. But with the sort of speeds this thing is going at makes the rated few GHz frequency on a BNC seam a bit lacking. While SMA on the other hand goes in to the low 10s of GHz and is pretty widespread so i'm sure anyone that dabbled with RF has some SMA cables and adapters laying around.

You can probably make the PCB compatible with both SMA and BNC, then just solder BNCs on most of them while leaving a few without connectors. That way you can make small quick runs of the SMA version, but if there is not enough interest you can still go ahead and put BNCs on those too. Guess it would make sense to make the SMA version a few dollars more expensive for the extra trouble.
 

Offline HighVoltage

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Re: Yet another fast edge pulse generator
« Reply #289 on: December 04, 2017, 09:22:22 PM »
I would buy another one of these if a SMA version becomes available.

Same here.
if you make the SMA version available, I will take one too.
There are 3 kinds of people in this world, those who can count and those who can not.
 

Offline WastelandTek

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Re: Yet another fast edge pulse generator
« Reply #290 on: December 05, 2017, 12:44:05 PM »
OK Leo, order 23042 in

Thank you and have a good holiday!
I'm new here, but I tend to be pretty gregarious, so if I'm out of my lane please call me out.
 

Offline EEngo

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Re: Yet another fast edge pulse generator
« Reply #291 on: December 06, 2017, 07:55:03 AM »
Leo, thank you very much, my order arrived today. :-+ :box:

the Lecroy DDA125 (aka LC684, 1.5GHz analog bandwith) was mentioned in your very first post with 295ps  :-//, here are some additional measurements (see attachments):

Channel A: 248 ps
Channel B: 245 ps
Channel C: 249 ps
Channel D: 241 ps

perhaps someone with access could update the list, some more scopes will hopefully follow tomorrow (HP54616B, HM2008,Rigol MSO2202)
 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #292 on: December 06, 2017, 08:15:48 AM »
OK Leo, order 23042 in
Thank you and have a good holiday!
Thank you for your order, it has shipped today.

Leo, thank you very much, my order arrived today.

the Lecroy DDA125 (aka LC684, 1.5GHz analog bandwith) was mentioned in your very first post with 295ps  :-//, here are some additional measurements (see attachments):

Channel A: 248ps
...
My pleasure!  That was the older pulser model based on ADCMP***, its design has changed since then.  Amplitude increased too.
Leo

Offline Converter

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Re: Yet another fast edge pulse generator
« Reply #293 on: December 07, 2017, 03:29:27 AM »
Hello, Leo,
Order Number is: 23079
Please send the latest version of the design.

Sergey.
 

Offline EEngo

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Re: Yet another fast edge pulse generator
« Reply #294 on: December 07, 2017, 09:13:59 AM »
another measurements (see attachments):

HP 54616B (500 MHz): 540 ps  :-+
Hameg HM2008 (200 MHz): 1,5 ns  :palm:
Rigol MSO2202 (200 MHz): 1,3 ns  ;)

cool project, thanks leo!  :-+

 

Offline Leo Bodnar

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Re: Yet another fast edge pulse generator
« Reply #295 on: December 08, 2017, 05:46:42 AM »
cool project, thanks leo!  :-+
You are welcome!
Thanks to everyone who ordered one.
All the orders have been shipped - usually within one working day from placing them.
Leo

Offline H.O

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Re: Yet another fast edge pulse generator
« Reply #296 on: December 08, 2017, 06:27:52 AM »
The list has been updated, 94 entries this far.
 

Online grumpydoc

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Re: Yet another fast edge pulse generator
« Reply #297 on: December 08, 2017, 07:52:36 PM »
The list has been updated, 94 entries this far.

The DSO1024A entry needs correcting to 1240ps. It turns out that termination does matter after all** :)


** In other news: Pope is Catholic etc.
 

Offline richnormand

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Re: Yet another fast edge pulse generator
« Reply #298 on: December 09, 2017, 03:43:42 AM »
Nice work H.O.
For the very fast systems (sampling scopes et al) you might have to note if the pulser is the early or the late version.
I would think that 40ps compared to 50ps  Tr will make a difference on a system with a 20ps risetime and such...

 

Offline H.O

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Re: Yet another fast edge pulse generator
« Reply #299 on: December 09, 2017, 04:08:15 AM »
I'm sure it does but I can only put in the list what the user reports here, I unfortunately don't know which user has which version.

I usually have to Google scope sample rate and look at the attached photos/screenshots to figure out if internal/external/no termination has been used. When I don't know I leave that entry blank.

And, as you can see, for the very fast system the formula fails so the list is far from perfect.

I'll fix the DS1204A entry on the next round.
 

Offline texaspyro

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Re: Yet another fast edge pulse generator
« Reply #300 on: December 09, 2017, 04:54:56 AM »
My TDS3034->3054 hack and THS730A measurements were done terminated at 50 ohms.
 

Offline EEngo

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Re: Yet another fast edge pulse generator
« Reply #301 on: December 09, 2017, 08:31:41 PM »
thank you H.O.  :-+

all my measurements (DDA125, HP54616B, HM2008 and MSO2202) were done with internal 50 Ohm termination.
 

Offline Orange

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Re: Yet another fast edge pulse generator
« Reply #302 on: December 12, 2017, 06:58:23 AM »
The 100MHz Siglent SDS1104X-E and an upgraded 500MHz Agilent MSO7054A

Very nice compact pulser, as compared to my good old Tektronix 284.
Excelent piece of work Leo !
 

Online FriedLogic

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Re: Yet another fast edge pulse generator
« Reply #303 on: December 12, 2017, 11:25:40 AM »
Has anyone come across any readily available good and cheap SMA(f) - BNC(m) adaptors? (not surplus expensive ones, but cheap when bought new)

The main problem with most of the cheap BNC adaptors and plugs that I've seen is that they are missing the raised flange around the end of the ground connection on the plug, so don't connect well with the socket. The plating on a lot of them does not help much either.

I've sometimes bent the contacts out a little so that they connect better, but that's certainly not ideal.
I use these https://www.digikey.co.uk/products/en?keywords=314-1184-ND when testing the pulsers.



Thanks, but it was more the ones to allow an SMA based pulser to be used on a BNC scope that I was wondering about, and those are the ones that seem harder to do right - however the “You may also be interested in....” bit on the page that you linked to actually led to fairly cheap ones that at least looked OK. I'll need to try some sometime.
I've had so much trouble with cheap connectors that I tend to buy surplus good ones, which are often not too expensive.

One of the good things about the BNC version of the pulser is that it avoids most folk having to mess with these adaptors.
 

Online FriedLogic

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Re: Yet another fast edge pulse generator
« Reply #304 on: December 12, 2017, 07:24:09 PM »
The discussion about the potential effects of BNC to SMA adaptors got me to wondering if I could see any difference with the IBZ DS800C 4GHz scope that I have.
I hadn't used it much before, and don't normally deal with anything this fast, so it was a bit of a learning curve...  With the pulser I was finally able to give it a proper workout.


These are connectors that I used and some prices:

An old surplus Huber+Suhner. No idea of the model, but it looks like RS 716-4779, which is £61.69+VAT.

Emerson VA506. It was from ebay, but is £5.43+VAT from CPC

Cinch 29-3855. It was £2.95+VAT from RS

Also from ebay: “Handy Utility Adapter BNC Female Jack To SMA Male Plug RF Connector Straight EW” #401116160491.  £0.99 including post from China.


There are probably a few more (or at least larger) variables involved when using this scope than something like a CSA803, so the rise times are a bit of an estimate. I also only tested one sample of each.

Anyway, the numbers that I came up with for now are:
52ps      H+S   
53-54ps   Cinch  29-3855
54-55ps   Emerson VA506   
58-60ps   ebay 99p

The sheet I got with this pulser gave the measured rise time as 31.8ps

Has anyone tried this with something more stable? This is rather pushing the limits of a scope that is $300 new!
Deliberately moving/loosening the connectors did suggest that there was not really much instability caused by this adaptor - although I would still like to get hold of an SMA version, and something a bit better to test it on.


 
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Offline macboy

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Re: Yet another fast edge pulse generator
« Reply #305 on: December 13, 2017, 03:59:42 AM »
The discussion about the potential effects of BNC to SMA adaptors got me to wondering if I could see any difference with the IBZ DS800C 4GHz scope that I have.
I hadn't used it much before, and don't normally deal with anything this fast, so it was a bit of a learning curve...  With the pulser I was finally able to give it a proper workout.
...
...
The sheet I got with this pulser gave the measured rise time as 31.8ps

Has anyone tried this with something more stable? This is rather pushing the limits of a scope that is $300 new!
Deliberately moving/loosening the connectors did suggest that there was not really much instability caused by this adaptor - although I would still like to get hold of an SMA version, and something a bit better to test it on.
Thanks for the comparison. It seems even the cheapies are not too shabby.

Screenshots please!   As it is a USB scope it should be easier to do than most of us.

The risetimes indicate much better than 4 GHz bandwidth, probably >10 GHz. If the pulser itself really is 31.8 ps, then your scope manages approximately 41 ps. (rise times of source and scope add as root-sum-of-squares). Even using the more conservative conversion factor of 0.45/Tr, you get ~ 11 GHz estimated bandwidth.

I'd be very interested in seeing the shape of the pulse (overshoot, ringing, etc.).

I had never heard of this USB scope before, but I am very interested now.

 

Offline rx8pilot

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Re: Yet another fast edge pulse generator
« Reply #306 on: December 13, 2017, 06:43:07 AM »
Has anyone tried any experiments using this device as a step source for TDR impedance measurements.
Thank you EEVBlog for all the support in the Keysight Test to Impress Giveaway voting!
 

Offline WastelandTek

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Re: Yet another fast edge pulse generator
« Reply #307 on: December 14, 2017, 09:33:14 AM »
I hope I'm doing this right...Tek 2445

I'm new here, but I tend to be pretty gregarious, so if I'm out of my lane please call me out.
 

Offline Berni

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Re: Yet another fast edge pulse generator
« Reply #308 on: December 14, 2017, 05:40:42 PM »
Has anyone tried any experiments using this device as a step source for TDR impedance measurements.

For fun i did try sticking on a SMA T adapter and put it on my scope. Worked reasonably well. It could tell if a short 15cm coax was close to 50 Ohm. I could also tell the difference between sticking a SMA terminator on the end of a coax directly versus using adapters to go to BNC to N to SMA before going in a terminator. (I think i just wanted to go to BNC and back but didn't find the correct gender BNC to SMA adapter in a hurry but has some N ones laying on the bench)
 
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Offline Gerhard_dk4xp

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Re: Yet another fast edge pulse generator
« Reply #309 on: December 15, 2017, 05:49:02 AM »
from PSPL app note  AN3045C:

They use their pulse sharpener to mod the 18 GHz 54754A TDR
to 50 GHz, using a non-TDR 50 GHz 54752A  scope plugin. That
means that they must re-implement the coupling to the DUT.

Picosecond Pulse Labs has been bought by TEK, but the app note
is still on the net. The app note is about comparing different TDRs.

The 54750 can use convolution to calculate away its own risetime.

regards, Gerhard

« Last Edit: December 15, 2017, 05:52:21 AM by Gerhard_dk4xp »
 

Online FriedLogic

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Re: Yet another fast edge pulse generator
« Reply #310 on: December 15, 2017, 07:10:02 PM »
Thanks for the comparison. It seems even the cheapies are not too shabby.

Screenshots please!   As it is a USB scope it should be easier to do than most of us.

The risetimes indicate much better than 4 GHz bandwidth, probably >10 GHz. If the pulser itself really is 31.8 ps, then your scope manages approximately 41 ps. (rise times of source and scope add as root-sum-of-squares). Even using the more conservative conversion factor of 0.45/Tr, you get ~ 11 GHz estimated bandwidth.

I'd be very interested in seeing the shape of the pulse (overshoot, ringing, etc.).

I had never heard of this USB scope before, but I am very interested now.

It was interesting how much the speed went with price, but I suppose that shows the effort that went into getting the performance right. Law of diminishing returns there too!

I've attached a couple of plots. I should start another topic sometime for more plots from it, but too many other things I should be doing at the moment...

There have been some threads related to the DS800, like:
http://www.eevblog.com/forum/testgear/10-ghz-usb-oscilloscope-by-darwin-sabanovic/
but there's not really that much out there on it.

 


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