Author Topic: Yet another fast edge pulse generator  (Read 27750 times)

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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

Online 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!
 

Online 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

Online 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
 

Online 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 ?

Online 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.
 

Online 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%.
 

Online 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.
 

Online 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.
Your living is determined not so much by what life brings to you as by the attitude you bring to life; not so much by what happens to you as by the way your mind looks at what happens.

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