10 GHz USB Oscilloscope by Darwin Sabanovic

[branadic]

Hi,

I'm not sure if anyone knows about the sampling scopes developed by Darwin Sabanovic?

http://www.fastsampling.com/

Beside the DS800 8GHz Sampling Oscilloscope USB there is also the DS800E 11 GHz sampling oscilloscope available. The 11 GHz version is also sold by IC-Haus:

http://www.ichaus.de/product/iC227

Darwin Sabanovic has developed a more cost efficient version DS100 and is know trying to build up a bigger batch. That is why he's trying to collect money via kickstarter. The campaign ends today but the project is far away from the goal...

https://www.kickstarter.com/projects/1855991221/10-ghz-usb-oscilloscope

[Marco]

It's a shame about the kickstarter, I think the problem is that in the US (and Israel and to a lesser extent Asia) you can just too cheaply pick up old Tek sampling scopes.

[Marco]

Many DSO on the market do exactly the same, even my cheapo Siglent 1000CML does the same at '5GHz'.

Their bandwidth is limited by their probes, front end and ADC, they can use equivalent time sampling but it's futile ... the information is gone. At best they can use repeated sampling to increase the vertical resolution.

At these frequencies you need to use SMA connected directly to the DUT, you need to have nothing on the front end except maybe an attenuator (unless you're Tek or Agilent and can afford integrated MEMS relays) and you need a 10s of ps range sampling gate (or in this case latched comparator). Many DSOs do not have this.

[branadic]

The DS800 doesn't really sample at 8GHz, it needs a repetitive waveform to allow it to gather enough samples to simulate an 8GHz sample rate.

Many DSO on the market do exactly the same, even my cheapo Siglent 1000CML does the same at '50GHz'.

Wow, your cheap Siglent DSO is capable to display a 1 GHz signal without attenuation? 

Maybe you train yourself about the difference of a sampler and a DSO

[Bored@Work]

Hi,

I'm not sure if anyone knows about the sampling scopes developed by Darwin Sabanovic?

Yes, we know, because
https://www.eevblog.com/forum/crowd-funded-projects/10-ghz-usb-oscilloscope/

[mrflibble]

Yeah, it's a pity this one didn't go through. The plan was to chip in at about 80% complete (don't have that much random cash lying around to get in at the start ). It looked pretty damn interesting for the money, even if it meant having to do the software side of it yourself.

I hope he tries it again in the not-too-distant future after working a bit on his kickstarter marketing skills. I think he may have gotten more backers if he showed some example uses + screenshots of working software + direct links to noob-proof datasheets.

Or maybe not, but one can always hope. 

What did amuse me though was his other succesfully backed project. So on the one hand we have a pretty awesome (affordable!) sampler that doesn't even make it to 10% backed. And on the other hand we have Yet Another Whatever With Silver Ink, reaching $674k. What is this world coming to?

[Bored@Work]

I hope he tries it again in the not-too-distant future after working a bit on his kickstarter marketing skills. I think he may have gotten more backers if he showed some example uses + screenshots of working software + direct links to noob-proof datasheets.

Or maybe not, but one can always hope. 

What did amuse me though was his other succesfully backed project. So on the one hand we have a pretty awesome (affordable!) sampler that doesn't even make it to 10% backed. And on the other hand we have Yet Another Whatever With Silver Ink, reaching $674k. What is this world coming to?

He didn't mention words like Arduino, iPhone, Raspberry Pi, Android, smart phone and/or tablet.

[Marco]

Hey ... an android interface would be handy :p

[mrflibble]

I think we just worked out his next angle.

"Android / IPhone 10 GHz OMGWTFBBQ Sampler. Sample your arduino blinky leds like you never sampled them before! Also works with an RPi!". Should get him started at $674k easily.

[lpc32]

It's a shame about the kickstarter, I think the problem is that in the US (and Israel and to a lesser extent Asia) you can just too cheaply pick up old Tek sampling scopes.

Why the US, Israel, and Asia?

[SeanB]

Military Industrial Complex and Equipment scrapping.

[Lukas]

I'm currently working on a rather similar sampling oscilloscope. The frontend is practically identical (ADCMP582 as 'sampler', ADCMP567 as trigger comparator). The trigger-to-sample-delay is generated by a ring oscillator (the majority of the delay comes from a long pcb trace) and a LVPECL delay line. The bandwidth is about 5GHz, the step response looks acceptable.
It'll be finished in a year or two and released as open source hardware/software, since another hardware revision is to come (the frontend will be detachable) and the software on the PC side has grown in complexity because this shouldn't be another USB oscilloscope with crappy software. Seriously, I haven't come across a reasonably-priced oscilloscope with great software, that doesn't look like it has been slapped together using Visual Basic or even Labview. The best oscilloscope software I know is the FlexDCA (aside from the ability to choose from ~10 ugly themes and ~5 mode transition animations...) software from Agilent. Unfortunately, it's only compatible with oscilloscopes that cost >10.000$.

[free_electron]

And what is the bloody point of a sampling oscilloscope ? They are only useful on repetitive signals and you can look at eye diagrams ...

They are useless for day to day work , debugging work , signal analysis (analog or digital).

Walk in a bog circle around those things. If you are really in need of a sampling machine look for a used one on ebay.
None of the scope makers build em anymore.

[BravoV]

So its merely a trap for those who are not aware what a sampling scope is, and that shouting ... "LOOK !!! GHz scope under for just few hundreds dollar !! I'm buying one !!" ... is that it ?

[mrflibble]

And what is the bloody point of a sampling oscilloscope ? They are only useful on repetitive signals and you can look at eye diagrams ...

They are useless for day to day work , debugging work , signal analysis (analog or digital).

Walk in a bog circle around those things. If you are really in need of a sampling machine look for a used one on ebay.
None of the scope makers build em anymore.

Just because you happen to have access to an awesome scope with 10 GHz analog bandwidth, doesn't mean everyone has. This sort of sampler for $300 would enable several classes of measurement which otherwise are a wee bit out of reach. And yes, as you point out, all of them on repetitive boring repetitive signals that are repetitive.

[branadic]

And what is the bloody point of a sampling oscilloscope ? They are only useful on repetitive signals and you can look at eye diagrams ...

They are useless for day to day work , debugging work , signal analysis (analog or digital).

Walk in a bog circle around those things. If you are really in need of a sampling machine look for a used one on ebay.
None of the scope makers build em anymore.

That you are not working in RF/VHF/UHF-projects doesn't mean that noone does

[Marco]

None of the scope makers build em anymore.

Not in this low frequency range, but they still do make em.

[amiq]

They are useless for day to day work , debugging work , signal analysis (analog or digital).

Absolute nonsense.  Anyone working on picosecond electronics will need a sampling scope to verify their designs.  Just because it's a design area you have no knowledge of doesn't mean it doesn't exist.

[nctnico]

They are useless for day to day work , debugging work , signal analysis (analog or digital).

Absolute nonsense.  Anyone working on picosecond electronics will need a sampling scope to verify their designs.  Just because it's a design area you have no knowledge of doesn't mean it doesn't exist.

I strongly agree. A cheap sampling scope is very usefull if you work on HF circuits. Because the sampling rate of the ADCs is quite low (10k to 500k) you can easely use 10 to 16 bit ADCs which make is very accurate. I've been doing some experiments myself with a diode sampler front-end. These are not very hard. The biggest problem when desigining these kind of scopes is a trigger system with ultra low jitter .

[Lukas]

Interesting, which sampling diodes did you use, how did you drive them?

[mrflibble]

I've been doing some experiments myself with a diode sampler front-end. These are not very hard. The biggest problem when desigining these kind of scopes is a trigger system with ultra low jitter .

Interesting indeed. Wondering pretty much the same thing as Lukas. Which diodes did you use, and how did you hook things up?

[nctnico]

I've been doing some experiments myself with a diode sampler front-end. These are not very hard. The biggest problem when desigining these kind of scopes is a trigger system with ultra low jitter .

Interesting indeed. Wondering pretty much the same thing as Lukas. Which diodes did you use, and how did you hook things up?

So far mostly only simulation with BAS70 dual diodes. The trick is to feed a pulse into a shorted piece of stripline which makes the diodes conduct for a short period charging or discharging 2 capacitors (the voltage across is the sampled valued minus the previous sample).  The rise time of the pulse is driving the sampling window. I did some tests with a 2N2904 transistor in an avelanche pulse generator. The only time I needed 10V/div in 50 Ohm mode  on my scope Still I didn't like the risetime. So far it all looked good mostly on paper but I never experimented further due to lack of time and ideas about the triggering.

Anyway, yhis appnote from Linear covers some of the basics of a diode sampler:
http://cds.linear.com/docs/en/application-note/an79.pdf

[marshallh]

Bummer, I wanted one to check my serdes channels

[Lukas]

[...] ideas about the triggering.

What about random sampling? Continoulsy run the sampling clock and determine the time of the trigger event using a TDC.

[mrflibble]

[...] ideas about the triggering.

What about random sampling? Continoulsy run the sampling clock and determine the time of the trigger event using a TDC.

Heh, you beat me to it. Either use a TDC from Acam or roll your own with an fpga.

@Lukas: what would you use for the dithered clock? A regular clock that you "dirtied up" with added noise to get your dithering? Or a noise generator + gated clock? I have used the latter for testing my fpga based TDC, but never played with the former.

Then again, if the resolution of those delay lines is good AND they can be adjusted fast enough then that could be better. It would really depend on the linearity of the delay line and the settling time (and resolution ).

Mmmh, I see Acam added a new one since last I looked.

[fcb]

I was one of the few backers of Darwin's project on Kickstarter.

It would have been great to give it bench space here, and it would have been useful for something I've been working on.

[Lukas]

[...] ideas about the triggering.

What about random sampling? Continoulsy run the sampling clock and determine the time of the trigger event using a TDC.

Heh, you beat me to it. Either use a TDC from Acam or roll your own with an fpga.

@Lukas: what would you use for the dithered clock? A regular clock that you "dirtied up" with added noise to get your dithering? Or a noise generator + gated clock? I have used the latter for testing my fpga based TDC, but never played with the former.

Then again, if the resolution of those delay lines is good AND they can be adjusted fast enough then that could be better. It would really depend on the linearity of the delay line and the settling time (and resolution ).

Concerning the TDC: Acam and FPGAs aren't your only options. This guy has a really nice overview of available TDC technologies: http://www.ko4bb.com/~bruce/TDC.html Also see HP Journals from the 80s ... 90s. They described the TDCs they used in their random sampling digital oscilloscopes. They used multislope TDCs and achieved 1ps resolution IIRC. In some article, they also described how they dealt with clock dithering. My first try would be to alter the phase between acquisitions by using a slightly tunable VCXO.

In my sampling oscilloscope i'm using the 100EP196 LVPECL delay line. It allows digital coarse delay setting in steps of 10ps using a digital input and fine tuning by an analog control voltage. It drifts a lot over time/temperature, but the nonlinearity seems to stay somehow stable. The delay line can be configured as a ring oscillator to calibrate it. Once you've measured the nonlinearity it suffices to obtain the delays at zero and full delay. According to the datasheet, jitter is ~3ps.

[mrflibble]

Concerning the TDC: Acam and FPGAs aren't your only options. This guy has a really nice overview of available TDC technologies: http://www.ko4bb.com/~bruce/TDC.html Also see HP Journals from the 80s ... 90s. They described the TDCs they used in their random sampling digital oscilloscopes. They used multislope TDCs and achieved 1ps resolution IIRC. In some article, they also described how they dealt with clock dithering. My first try would be to alter the phase between acquisitions by using a slightly tunable VCXO.

Yeah, I know that list from Bruce. It's been a while since I went over the various options, but I seem to recall that the dual slope approach would mean a relatively low repetition rate. Maybe I misunderstood it at the time, but I didn't see how to reasonably get a 200 MHz repetition rate. And multislope was one bridge too far for me at that time.

Do you happen to know the HP Journal issue that deals with clock dithering?

In my sampling oscilloscope i'm using the 100EP196 LVPECL delay line. It allows digital coarse delay setting in steps of 10ps using a digital input and fine tuning by an analog control voltage. It drifts a lot over time/temperature, but the nonlinearity seems to stay somehow stable. The delay line can be configured as a ring oscillator to calibrate it. Once you've measured the nonlinearity it suffices to obtain the delays at zero and full delay. According to the datasheet, jitter is ~3ps.

Delay line configured as ring osc? As in have the CARRY4 chain (or whatever you use as delay element)  inline with the ring oscillator? So CARRY4 chain + bunch of inverters followed by a counter. And then run that for a fixed amount of time, as determined by at counter clocked with your regular sampling clock? I suppose that would work too. Another approach is a seperate ring osc. And yet another is to have an external noise source and then run a full calibration (count the bins). The last approach with external noise source is what I currently do. There might be some merit in having the delay line as part of a ring osc too though, mmmh.

[free_electron]

They are useless for day to day work , debugging work , signal analysis (analog or digital).

Absolute nonsense.  Anyone working on picosecond electronics will need a sampling scope to verify their designs.  Just because it's a design area you have no knowledge of doesn't mean it doesn't exist.

Like i said, except for some extreme things these machines are useless.
How many on the forum here do that kind of picocesond stuff ?

People in the 'industry' that actually do that stuff have access to proper machines. they wouldn;t be caught dead using this contraption.

I'm not downplaying the art involved in creating this machine. i couldn't do it so kudos to the project starter.
The danger is a bunch of hobbyist will flock to this thing "10Ghz for a nickel and a dime" and be VERY disappointed.

[branadic]

Concerning the TDC: Acam and FPGAs aren't your only options.

Sure, but they are for sure the cheapest on, for example GP22 <10,-€/pc.
TI also offers a TDC:

http://www.ti.com/product/ths788

but for a barefaced price of 121,78 € (Farnell).

[mrflibble]

Do they also sell the GP22 for < EUR 10 at single quantities to non-commercial entities aka private persons? Or lets say 3. Might be interesting for a little experiment.

[branadic]

The distributor for the integrated circuits made by ACAM is IS-Line GmbH. I bet they also sell to privat persons. I have an offer for 5pc. at a price of 13,02 € plus (Angelo Merte) taxes, which is still affordable for such a beast.

[pinkysbrein]

Is it really so difficult to make an integration + ADC TDC? You can just calibrate in between every measurement to get rid of temperature dependence.

[nctnico]

Another option is to use a programmable delay line. If you have 10ps steps then you could get an equivalent sampling rate of 100GHz. The TDS5xx/6xx/7xx can reach equivalent sampling times of 50GHz. There is a 'TDS520B component service manual' with all the diagrams. Maybe it tells or shows a bit of how Tek does that.

[mrflibble]

Another option is to use a programmable delay line.

Of course. I think the approach of a random trigger & use TDC to measure the delay of that trigger was just mentioned as another alternative.

There is a 'TDS520B component service manual' with all the diagrams. Maybe it tells or shows a bit of how Tek does that.

See for example: http://bee.mif.pg.gda.pl/ciasteczkowypotwor/Tek/ds520b-cm.pdf

[branadic]

Does anyone now how Darwin Sabanovic will proceed? I tryed to get in contact with him, but as before without success.
That reminds me of what someone else stated somewhere before, he's a poor sales and business man.

[David Hess]

And what is the bloody point of a sampling oscilloscope ? They are only useful on repetitive signals and you can look at eye diagrams ...

They do not suffer from overload recovery times and are uniquely useful for calibrating the transient response on reference flat pulse generators and therefor other instruments like real time oscilloscopes.  Their predictable frequency response allows them to be used as an alternative to thermal based instruments for accurate RF power measurement.

They are useless for day to day work , debugging work , signal analysis (analog or digital).

They certainly have their limitations and are not general purpose instruments but the same could be said for oscilloscopes faster than about 300 MHz where 50 ohm probe inputs are used.

None of the scope makers build em anymore.

They do still make them but only at the highest end where the highest bandwidth is needed although there are several USB based lower end commercial instruments available with Picoscope being the primary example.  Compare how much this project would have cost (since it failed to meet its funding requirements) for an 8 GHz sampling oscilloscope versus an 8 GHz digital storage oscilloscope.  Assuming you can live with its limitations, it will be much more economical for a given bandwidth.

[fcb]

Does anyone now how Darwin Sabanovic will proceed? I tryed to get in contact with him, but as before without success.
That reminds me of what someone else stated somewhere before, he's a poor sales and business man.

I'm not sure you can draw the conclusion that Darwin is a poor sales/business man, in-fact you could argue that walking away from this project makes business sense - it clearly failed to come close to the MVP threshold on KS.

Still, it's a pity. As a backer of the KS, I would have liked to own such a unit...

[eurofox]

I just bought the 11GHz version , delivery in 2-3 weeks 

I just build a ultra fast pulse generator, should be 50ps rising time (10-90%) but cannot measure it with my 1Ghz Agilent MSO-X scope (Rising time 450ps)

I will post the results of test the BS800E.

eurofox

[David Hess]

Interesting indeed. Wondering pretty much the same thing as Lukas. Which diodes did you use, and how did you hook things up?

So far mostly only simulation with BAS70 dual diodes. The trick is to feed a pulse into a shorted piece of stripline which makes the diodes conduct for a short period charging or discharging 2 capacitors (the voltage across is the sampled valued minus the previous sample).  The rise time of the pulse is driving the sampling window. I did some tests with a 2N2904 transistor in an avelanche pulse generator. The only time I needed 10V/div in 50 Ohm mode  on my scope

Trapped charge sampling bridges use the transition time of the trailing edge of the strobe to generate the sampling gate width.  Other sampling bridges use the width of the strobe which makes it more difficult to achieve very narrow sampling gate widths.

Trapped charge sampling bridges sometimes have problems because they generate a kick-out pulse much earlier than the sampling point so if your avalanche or tunnel diode pulse generator is too close to the sampling head, the kick-out may trigger it before the normal trigger occurs.  Anecdotally they also seem to have more blow-by problems but that may just be an implementation issue.

I am happy that suitable diodes for building sampling bridges are available from Avago (old HP) at inexpensive prices.  I wish there was a similar source for step recovery diodes.

[Lukas]

I just build a ultra fast pulse generator, should be 50ps rising time (10-90%)

Interesting, can you tell us more about it? Did you use a fast logic gate (OnSemi NBSG series) oder something more advanced?

[eurofox]

I just build a ultra fast pulse generator, should be 50ps rising time (10-90%)

Interesting, can you tell us more about it? Did you use a fast logic gate (OnSemi NBSG series) oder something more advanced?

It is based on a ultra fast comparator (SiGe) with basic rise time of 35ps (20-80%), output 200mV (50 ohm).
Very small board and housing including power supply from TRACO POWER (very small).
Triggered from any generator able to deliver square or pulse from ?? tested to 50Mhz with 0,4-2,5VPP (50 ohm)
Testing show it is very stable, no noise problems.
The output connections are very short to the SMA connector.

I need a "fast" oscilloscope for further testing and fine tuning. It is a first version prototype.

eurofox

[David Hess]

I just build a ultra fast pulse generator, should be 50ps rising time (10-90%)

Interesting, can you tell us more about it? Did you use a fast logic gate (OnSemi NBSG series) oder something more advanced?

It is based on a ultra fast comparator (SiGe) with basic rise time of 35ps (20-80%), output 200mV (50 ohm).
Very small board and housing including power supply from TRACO POWER (very small).
Triggered from any generator able to deliver square or pulse from ?? tested to 50Mhz with 0,4-2,5VPP (50 ohm)
Testing show it is very stable, no noise problems.
The output connections are very short to the SMA connector.

I need a "fast" oscilloscope for further testing and fine tuning. It is a first version prototype.

eurofox

Would that comparator be the Analog Devices ADCMP580 or one of its cousins?

The other integrated solution I have seen recommended for this sort of thing is the Micrel SY88922 laser driver which is slower but generates a larger output voltage swing.

[TerraHertz]

And what is the bloody point of a sampling oscilloscope ? They are only useful on repetitive signals and you can look at eye diagrams ...

Because most physical processes, physics, even electronic circuit behavior, are easily made to run repetitively. So for that old, cheap sampling scopes are fine. And thanks very much to everyone who avoids them, thus making them cheaper for the rest of us.

Chasing obscure rare data-stream related errors in communications protocols gives me the shudders. I'm very happy to leave that shit to others. And watch them pay King's Ransom amounts for real-time GHz scopes.

[madshaman]

For a sampling scope, I'm happy with my "ancient" HP 54120B sampling scope with 20Ghz test set, it's got nice 3.5mm inputs (which would add a lot to the cost of ANY scope input, and one also needs to take into account the need for sacrificial connectors, which also won't be cheap) and if I ever needed it, I could throw money away to get a 50Ghz test set.

That being said, old equipment is big, bulky, and not everyone appreciates its aesthetic beauty.  There's also only so much of it.

I can see many reasons why someone would want to own a new sampling scope, as long as it's useful to them.

[eurofox]

I just build a ultra fast pulse generator, should be 50ps rising time (10-90%)

Interesting, can you tell us more about it? Did you use a fast logic gate (OnSemi NBSG series) oder something more advanced?

It is based on a ultra fast comparator (SiGe) with basic rise time of 35ps (20-80%), output 200mV (50 ohm).
Very small board and housing including power supply from TRACO POWER (very small).
Triggered from any generator able to deliver square or pulse from ?? tested to 50Mhz with 0,4-2,5VPP (50 ohm)
Testing show it is very stable, no noise problems.
The output connections are very short to the SMA connector.

I need a "fast" oscilloscope for further testing and fine tuning. It is a first version prototype.

eurofox

Would that comparator be the Analog Devices ADCMP580 or one of its cousins?

The other integrated solution I have seen recommended for this sort of thing is the Micrel SY88922 laser driver which is slower but generates a larger output voltage swing.

Yep 

1/ In this ultra fast rising edge not many components are available
2/ It is cheap and easy aivalable
3/ Soldering this 16-LFCSP with a solder iron is  but I manage to do it, I try with hot air  , I have an oven but for one prototype with a few components 

eurofox

[eurofox]

And what is the bloody point of a sampling oscilloscope ? They are only useful on repetitive signals and you can look at eye diagrams ...

Because most physical processes, physics, even electronic circuit behavior, are easily made to run repetitively. So for that old, cheap sampling scopes are fine. And thanks very much to everyone who avoids them, thus making them cheaper for the rest of us.

Chasing obscure rare data-stream related errors in communications protocols gives me the shudders. I'm very happy to leave that shit to others. And watch them pay King's Ransom amounts for real-time GHz scopes.

Fully agree, apart from some specific datacom related problems in this very high speed most signals are repetitive and can be measured with a sampling scope.

With respect to remarks about probes, I think that on picosecond level probes are not really useful.
I solder an SMA connector on the place where I want to measure with very short wires, the enemy of picosecond pulses is capacity from PCB, wiring, cables.

eurofox

[David Hess]

Would that comparator be the Analog Devices ADCMP580 or one of its cousins?

The other integrated solution I have seen recommended for this sort of thing is the Micrel SY88922 laser driver which is slower but generates a larger output voltage swing.

Yep 

1/ In this ultra fast rising edge not many components are available
2/ It is cheap and easy available
3/ Soldering this 16-LFCSP with a solder iron is  but I manage to do it, I try with hot air  , I have an oven but for one prototype with a few components 

What I would like to try is using a differential output comparator or logic gate to emitter switch an RF transistor so the output pulse can be at a much higher level.  ECL does not have quite the output drive level to do this easily but a slower TTL/CMOS output comparator like an ADCMP603 could do it and the gain of the output transistor would restore some of the transition time performance.  That essentially duplicates how the Micrel SY88922 output stage works.

[Marco]

Since there is no current amplification in a common base amplifier I don't see how it could sharpen the edges much.

[eurofox]

Would that comparator be the Analog Devices ADCMP580 or one of its cousins?

The other integrated solution I have seen recommended for this sort of thing is the Micrel SY88922 laser driver which is slower but generates a larger output voltage swing.

Yep 

1/ In this ultra fast rising edge not many components are available
2/ It is cheap and easy available
3/ Soldering this 16-LFCSP with a solder iron is  but I manage to do it, I try with hot air  , I have an oven but for one prototype with a few components 

What I would like to try is using a differential output comparator or logic gate to emitter switch an RF transistor so the output pulse can be at a much higher level.  ECL does not have quite the output drive level to do this easily but a slower TTL/CMOS output comparator like an ADCMP603 could do it and the gain of the output transistor would restore some of the transition time performance.  That essentially duplicates how the Micrel SY88922 output stage works.

No problem with RF transistor to reach 5 or 10V but I think you will be in the nanosecond range and not on the picosecond range.

[David Hess]

Would that comparator be the Analog Devices ADCMP580 or one of its cousins?

The other integrated solution I have seen recommended for this sort of thing is the Micrel SY88922 laser driver which is slower but generates a larger output voltage swing.

Yep 

1/ In this ultra fast rising edge not many components are available
2/ It is cheap and easy available
3/ Soldering this 16-LFCSP with a solder iron is  but I manage to do it, I try with hot air  , I have an oven but for one prototype with a few components 

What I would like to try is using a differential output comparator or logic gate to emitter switch an RF transistor so the output pulse can be at a much higher level.  ECL does not have quite the output drive level to do this easily but a slower TTL/CMOS output comparator like an ADCMP603 could do it and the gain of the output transistor would restore some of the transition time performance.  That essentially duplicates how the Micrel SY88922 output stage works.

No problem with RF transistor to reach 5 or 10V but I think you will be in the nanosecond range and not on the picosecond range.

Since I already know 500 picosecond performance is possible this way with 2 GHz transistors, I hope to do better than that.

[eurofox]

500 picosecond/2Ghz is right for a sinus signal but I have some doubts you will make with this a fast rising edge pulse.
 

[David Hess]

500 picosecond/2Ghz is right for a sinus signal but I have some doubts you will make with this a fast rising edge pulse.

I know at least this level of performance is possible because that is about what my Tektronix PG506 achieves.  I would hope to do better with surface mount construction and faster transistors.

The alternative is the often discussed charge line avalanche pulse generator.  I have considered a step recovery or non-linear transmission line design but I know less about them and I suspect step recovery diodes would need to be qualified from existing and available varactor or PIN diodes.

[Marco]

Why not just put a MMIC wideband amplifier behind the fast comparator?

[eurofox]

500 picosecond/2Ghz is right for a sinus signal but I have some doubts you will make with this a fast rising edge pulse.

I know at least this level of performance is possible because that is about what my Tektronix PG506 achieves.  I would hope to do better with surface mount construction and faster transistors.

The alternative is the often discussed charge line avalanche pulse generator.  I have considered a step recovery or non-linear transmission line design but I know less about them and I suspect step recovery diodes would need to be qualified from existing and available varactor or PIN diodes.

I have a Tek PG506 (I have several module from Tek 500) and just did some test, 600ps and 200mV up to 2.7ns on 1V, maybe there something wrong with my unit but rising time change with amplitude. I order one week ago extension cables to check/calibrate all my Tek 500 modules.

[David Hess]

Why not just put a MMIC wideband amplifier behind the fast comparator?

You mean just to improve the output level without changing the transition time?

There has been a discussion going on (not here) about how to do something like this with DC to X frequency response and better than 5 volt peak-to-peak levels.  AC coupling cannot be used without a parallel low frequency path and DC coupling cannot be used without a similar DC servo controlling a floating output stage and bias.  Given that extra complexity, I am not sure it is worthwhile over the alternative open-loop designs and I suspect transient response if important would suffer.

[David Hess]

500 picosecond/2Ghz is right for a sinus signal but I have some doubts you will make with this a fast rising edge pulse.

I know at least this level of performance is possible because that is about what my Tektronix PG506 achieves.  I would hope to do better with surface mount construction and faster transistors.

The alternative is the often discussed charge line avalanche pulse generator.  I have considered a step recovery or non-linear transmission line design but I know less about them and I suspect step recovery diodes would need to be qualified from existing and available varactor or PIN diodes.

I have a Tek PG506 (I have several module from Tek 500) and just did some test, 600ps and 200mV up to 2.7ns on 1V, maybe there something wrong with my unit but rising time change with amplitude. I order one week ago extension cables to check/calibrate all my Tek 500 modules.

I think you have something wrong.  The transition time on mine does not change significantly with level and 2.7 nanoseconds is way outside of the maximum specification.  Maybe you were looking at the wrong edge on that particular fast transition output?  There are two outputs with one having a fast rise and the other having a fast fall.

[eurofox]

Below a table with the different technology and rise time of the pulse:

[David Hess]

20 volts is high enough to require compromising the RF performance of the transistor.  Besides the PG506 which easily beats that with discrete transistors albeit with only a 1 volt output, the various Tektronix 7000 standardizers do much better than 2.5 nanoseconds with discrete designs and again are lower voltage.

Even the Picosecond Pulse Labs 6110 and the NTSB design that it is based on are faster than that.

Step recovery diodes sure look good.  Anybody know where to buy them?

[eurofox]

20 volts is high enough to require compromising the RF performance of the transistor.  Besides the PG506 which easily beats that with discrete transistors albeit with only a 1 volt output, the various Tektronix 7000 standardizers do much better than 2.5 nanoseconds with discrete designs and again are lower voltage.

Even the Picosecond Pulse Labs 6110 and the NTSB design that it is based on are faster than that.

Step recovery diodes sure look good.  Anybody know where to buy them?

http://www.benl.ebay.be/itm/201069462442?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649

[David Hess]

Step recovery diodes sure look good.  Anybody know where to buy them?

http://www.benl.ebay.be/itm/201069462442?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649

Hehe.  That is like those Russian tunnel diodes.  I was thinking someone like Avago with full documentation and surface mount packaging.

[mathias]

Check out this supplier: http://www.rf-microwave.com/eng/shop/0/449-step-recovery-snap-off-comb-generators.html

I've bought from them before and am very happy with their service.

[David Hess]

Check out this supplier: http://www.rf-microwave.com/eng/shop/0/449-step-recovery-snap-off-comb-generators.html

I've bought from them before and am very happy with their service.

Thank you.

I suspect I am going to end up qualifying my own but that will make a good place to start from.

[eurofox]

Check out this supplier: http://www.rf-microwave.com/eng/shop/0/449-step-recovery-snap-off-comb-generators.html

I've bought from them before and am very happy with their service.

Thank you.

I suspect I am going to end up qualifying my own but that will make a good place to start from.

I bought a noise diode from them, very correct and very fast delivery 

[mathias]

BTW, I'm also working on a sampling head, however if I get up to 1GHz I will be very happy.

The sampling strobe is generated with an avalanche transistor for the moment. Trigger detection and everything else up to the puls generation is done with ECL logic.

[David Hess]

I would want to at least duplicate the performance of the Tektronix S-2 sampling head at about 4 GHz.  Apparently it was limited by the diodes it used and changing them can improve it significantly.

Has anybody tried using a transmission line (25 ohms?) to replace the sampling capacitance at the output of the bridge?  It seems like that would give better sampling efficiency.

[Marco]

So you would keep it open ended and turn the bridge off before the reflection hits and then let it bounce around for a bit to equalize?

[David Hess]

So you would keep it open ended and turn the bridge off before the reflection hits and then let it bounce around for a bit to equalize?

If the sampling gate width is adjusted to be the same as the transit time, then ideally it will not bounce at all.  One of my sampling books discusses this implementation but I know of no real world examples.

[mathias]

Isn't this close to what they are doing in the Tek S-4?

[David Hess]

Isn't this close to what they are doing in the Tek S-4?

I do not think so.  The Tektronix S-4 and S-6 (others?) use a traveling wave gate design where a segment of the transmission line carrying the signal is disconnected by the bridge diodes.  The sampling gate width depends on the transmission line length and the trailing edge transition time of the strobe but not the strobe width which is an advantage for fast operation.  Tektronix published detailed articles about how this works and I may not be describing it well.

The open transmission line design replaces the sampling capacitance with a transmission line.  Maybe it has no advantage over just using capacitance.  When I get around to it, I will certainly try it.  It is described in "Circuits for Electronic Instrumentation" by T. H. O'Dell which is also a reference for strobe generation and sampling circuits in general although not the traveling wave gate type.

[Marco]

The biggest problem when desigining these kind of scopes is a trigger system with ultra low jitter .

Is it really so hard? Obviously the expensive comparators Darwin uses can do it ... but couldn't you do something with discrete transistors and regenerative feedback like this as well  :



BTW, I found a really nice article describing the LLNL sampler (starts on page 36).

PS. hmm the amount of negative current which that circuit tries to push through Q3's emitter can't be healthy, but you could probably find someone familiar with time domain RF circuits to get a better circuit ... but these kind of Schmitt trigger like circuits can work at ~ 200 picosecond rise/fall times, described in papers, with a decent rise time on the input signal jitter shouldn't be a real problem at that point  (in simulation noise has nearly no effect).

[David Hess]

I think at least HP had some sampling oscilloscopes that worked like that as well.  I know I have read about that type of design before.

I think the jitter problem comes down to the lack of power supply rejection from the single ended logic which both processes the trigger and generates the strobe.  Differential comparators have natural power supply rejection and use an external reference for their switching threshold.    Some ECL has an external signal reference that can be used to add power supply rejection but I think discrete designs still seem to have an advantage over ECL because their ground and power supply returns can be controlled.  ECL differential input line receivers may useful however.

[LeoUCDavis]

http://ams.aeroflex.com/metelics/micro-metelics-prods-SRDs-beamlead.cfm

We've built some 50ps rise time pulse generators with these SRDs

Step recovery diodes sure look good.  Anybody know where to buy them?

[David Hess]

http://ams.aeroflex.com/metelics/micro-metelics-prods-SRDs-beamlead.cfm

We've built some 50ps rise time pulse generators with these SRDs

Who do you order the parts from though?  What is the pricing and availability?

[LeoUCDavis]

The SRDs are purchased from here:
http://www.rfmw.com/paw.aspx?type=710&manf=1036

Who do you order the parts from though?  What is the pricing and availability?

[DanielS]

And what is the bloody point of a sampling oscilloscope ? They are only useful on repetitive signals and you can look at eye diagrams ...

They are useless for day to day work , debugging work , signal analysis (analog or digital).

If you are doing debugging and signal analysis for one of your own designs, you can simply have a test mode from which to make your design generate repetitive patterns for signal testing purposes or add provisions to accept an external reference test signal.

For dealing with systems over which you have no control or visibility into, I agree that ETS becomes far less useful.

[nctnico]

A sampling scope is very usefull for TDR (time domain reflectometry) in order to look at how well a trace or cable connection is impedance matched and whether there are impedance changes along the trace or cable (for example a via or connector).

[Richard Crowley]

I work with HD digital video signals (HD-SDI) and I would love to have a USB device to simply monitor the eye pattern.  It would be very handy out in the field when debugging wiring problems with my mobile video production unit gear.

[eurofox]

Screen shots 6Ghz, 11Ghz signal and 67ps pulse

Not bad for this little scope.

[nctnico]

I'm still wondering where I can order this oscilloscope and where I can find some kind of datasheet.

[eurofox]

I'm still wondering where I can order this oscilloscope and where I can find some kind of datasheet.

You can order on the link below.

Time base range in 1-2-5 sequence 25ps to 100µs
Time base accuracy 0.5%FS +/-10 ps
Vertical resolution 12 Bit
Vertical divisions in 1-2-5 sequence 10 to 1000 mV
Maximum input voltage Sampler 2 Vpp
Enclosure size 102 x 56 x 123 mm

http://www.fastsampling.com/

The website and documentation is not the strongest point of Darwin but by own experience he is a very professional engineer and answer all emails with a minimum of delay.

My own experience is that it work well but you have to learn how to use it, it is not like another sampling scope but with some experience it become easy to use and it is low cost and take very little place.

It is extremely important in the Ghz en ps to use only 1st quality cable, connectors, DC blocker, attenuators, splitter with a minimum of 18Ghz bandwidth.
I reach a point now where I make my cables myself because the Suhner Sucoflex or similar are extremely expensive.


I should write a kind of new user manual but since I'm the only user here ....

The only alternative is an old Tek monster that cost a few K$ on the second hand market with spare parts getting difficult to find ....

[David Hess]

The only alternative is an old Tek monster that cost a few K$ on the second hand market with spare parts getting difficult to find ....

If you can live with analog sampling, then an even older Tektronix monster can be had for $100s and they include full service documentation.  A couple of them even include random sampling so a delay line or pretrigger is not required to show the trigger edge.

[eurofox]

The only alternative is an old Tek monster that cost a few K$ on the second hand market with spare parts getting difficult to find ....

If you can live with analog sampling, then an even older Tektronix monster can be had for $100s and they include full service documentation.  A couple of them even include random sampling so a delay line or pretrigger is not required to show the trigger edge.

David,

I suppose that you mean the Tek 7000 serie ....
I check it, the frames are not expensive but the head and the other dedicated plugin you need are still very expensive.
The 7000 frame is huge, I have no place on my bench to put is unit.

Maybe you mean another type of analog sampling scope?

[David Hess]

The only alternative is an old Tek monster that cost a few K$ on the second hand market with spare parts getting difficult to find ....

If you can live with analog sampling, then an even older Tektronix monster can be had for $100s and they include full service documentation.  A couple of them even include random sampling so a delay line or pretrigger is not required to show the trigger edge.

David,

I suppose that you mean the Tek 7000 series ....
I check it, the frames are not expensive but the head and the other dedicated plugin you need are still very expensive.
The 7000 frame is huge, I have no place on my bench to put is unit.

Maybe you mean another type of analog sampling scope?

I was thinking of the 7000 series and the older 3S series and 4S2 (3.9 GHz) sampler but 11k series sampling oscilloscopes which use SD series sampling heads are occasionally available at reasonable prices.  Jim Williams used the 1S1 with a 556 mainframe, 1S2 with a 547 mainframe, and 4S2 with a 661 mainframe.  The 3T2 might be worth considering because it supports random sampling but I have read that it is very difficult to maintain and work with.

The big problem as I see it is that the fastest sampling heads, above 4 GHz, are basically unrepairable because of hybrid construction and fragile like all sampling heads.  The 11k series and SD series sampling heads lack detailed service documentation.

I picked up a late 7854 with two 7S11/S-4 samplers and 7T11A timebase for about $300 a couple years ago but no doubt lucked out.  The 7854 had an obscure but easy to diagnose and repair problem (to me anyway) in the vertical CRT amplifier which I suspect lead to it being put into long term storage in lieu of being sent in for expensive diagnostics and repair.  There was evidence that someone had adjusted the readout calibration to try and make up for the vertical CRT amplifier problem which affected vertical gain.  The sampling system needed recalibration because of age and S-4s are known to have blow-by issues but within their limitations, they work well.  I am considering replacing them with a pair of slower S-2 sampling heads when lower bandwidth is acceptable.

As you point out, none of these solutions are small.  I currently see the sampling oscilloscope I have as a path to designing a modern replacement but that is a long term project.

[Alex Eisenhut]

The only alternative is an old Tek monster that cost a few K$ on the second hand market with spare parts getting difficult to find ....

If you can live with analog sampling, then an even older Tektronix monster can be had for $100s and they include full service documentation.  A couple of them even include random sampling so a delay line or pretrigger is not required to show the trigger edge.

Like the 567? Yeah, it's a monster but an entertaining one.

[nctnico]

At $700 the price is bit steep. I recall seeing a price around $300. I think I'd rather get a Tektronix TDS820 (6GHz) from a good year.

[eurofox]

At $700 the price is bit steep. I recall seeing a price around $300. I think I'd rather get a Tektronix TDS820 (6GHz) from a good year.

For $300 you just got a second hand current probe.

I got a recent TDS820 and was very disappointed when I start extensive testing.
It was one of the lasted (I sold it), trigger stopped at 1,7Ghz, according specification it was suppose to be at 2Ghz, a little sad for a 6Ghz instrument.
It was OK to measure pulses, it was a "big box" on my shelf if I compare to this little scope that I can hold on my hand.

I think a similar model with better software from Pico price tag is 10K$ or more.

It is not my scope for every day work, I like to play with ultra fast pulses and with this tool I can measure it.
In the beginning it was frustrating because lack of a decent documentation and it is not really like an usual scope, you have sometimes to use a DC blocker, a delay line (just very good coax cable), a power splitter and a prescaler to measure frequency above 4 Ghz and very good cables and connectors.

I just remind that a real time oscilloscope capable of working with such frequency cost second hand 70K$

http://www.ebay.com/itm/Agilent-DSA91304A-Infiniium-Oscilloscope-13GHz-w-4x-1169A-Probes-/351091960228?pt=BI_Oscilloscopes&hash=item51beb629a4

[David Hess]

I got a recent TDS820 and was very disappointed when I start extensive testing.
It was one of the lasted (I sold it), trigger stopped at 1,7Ghz, according specification it was suppose to be at 2Ghz, a little sad for a 6Ghz instrument.

It is unusual to need a slope/level trigger bandwidth equal to the vertical bandwidth.  Tektronix made an external countdown trigger but I do not know if they had one intended for the TDS820.  The 11k sampling oscilloscopes had a countdown trigger plug-in.  Some of their earlier analog timebases included a countdown trigger as well but that is not what they called it.

In the beginning it was frustrating because lack of a decent documentation and it is not really like an usual scope, you have sometimes to use a DC blocker, a delay line (just very good coax cable), a power splitter and a prescaler to measure frequency above 4 Ghz and very good cables and connectors.

Sampling oscilloscopes are a little weird and prone to mislead.  Tektronix had the 7S14 which is a 7000 series 1 GHz dual channel sampling oscilloscope plug-in with built in delay line that operates like a delayed sweep oscilloscope.

Some delay lines intended for sampling oscilloscopes include a pretrigger pickoff so no extraneous splitter is needed.

I had to pick up a DC block as well for my 7T11A because the external trigger is always DC coupled which occasionally caused problems with TTL level triggers that had a high DC offset.  The 7T11A trigger level range is tiny.

[Marco]

The trigger-to-sample-delay is generated by a ring oscillator (the majority of the delay comes from a long pcb trace)

So you just have some sort of monostable multivibrator with one end of the line at it's input and the other at it's output?

How is it affected by temperature? (External and internal as it heats itself up in the first few cycles after it's triggered.) What's the drift after a couple 10s of ns?

[Lukas]

The trigger-to-sample-delay is generated by a ring oscillator (the majority of the delay comes from a long pcb trace)

So you just have some sort of monostable multivibrator with one end of the line at it's input and the other at it's output?

How is it affected by temperature? (External and internal as it heats itself up in the first few cycles after it's triggered.) What's the drift after a couple 10s of ns?

You may call it such, basically it's just an AND gate with the output connected inverted to one input and the trigger (stays high) connected to the other. It provides the 'coarse' delay, fine delay is provided by an 100LVEP196 delay line. I'll have to see how the startup performance is like, since it requires a fast realtime scope to measure. I expect it not to drift that much since ECL power consumption doesn't depend very much on switching frequency.
I'm happy to hear about your suggestions about generating the variable delay. One other option I've been thinking of is to use some analog ramp kind of thing, i.e. charge a capacitor using a constant current source in the time between the trigger event and the second clock edge following the trigger and then continue to charge the capactitor up to a set limit after a certain number of clock cycles. Charging the capacitor linearily enough and holding its voltage constant during the clock cylces delay appear to be not that easy problems to solve.

[eurofox]

Last pulse test 

[Rionet]

Does anyone know how to contact with Darvin Sabanovic?
Email on http://www.fastsampling.com not works..

[Rionet]

Email on http://www.fastsampling.com/ not works, but clicking on "order" button jumps to make checkout via paypal.
So, can i pay without any worry about money if i not recieve working device? due to paypal protection system?

[Safar]

Email on http://www.fastsampling.com/ not works, but clicking on "order" button jumps to make checkout via paypal.
So, can i pay without any worry about money if i not recieve working device? due to paypal protection system?

It seems like web pages do not updates in last two years. I think that ask first in info@ibzelectronics.com would be clever.

[Mechatrommer]

So, can i pay without any worry about money if i not recieve working device? due to paypal protection system?

dont pay. you can get paypal protection but is it worth the hassle? contact the seller and make sure he's around, otherwise you pay or not pay, you wont get your item...

[Rionet]

Email messages to info@ibzelectronics.com rejected because email address is deleted.
So, no way to get contact..
Is it possible to get contact via paypal system?

[BravoV]

Email messages to info@ibzelectronics.com rejected because email address is deleted.
So, no way to get contact..
Is it possible to get contact via paypal system?

As you're so desperately to get it, also you can claim back your money if something wrong, why don't you just purchase now and report back to us how this ends up ?

[Rionet]

Yes, i really need scope with BW > 4Ghz to measure rise/fall time for periodical pulses with 50-100ps edges.

I was contacted to ICHaus
http://ichaus.de/product/iC227
http://ichaus.de/iC227_datasheet_en
They have device in stock and can sell it for 2500euro.
They say only differences with fastsampling.com is more accessories included and improved software.
They say nothing about relationships with Darvin, possible resellers.

If i click order on IBZ site, i forwarded to Paypal with payment to "IBZ Electronics".
I want try to make dummy payment for 1$ with message, but Paypal wants user email from me. How to get an email of Paypal user?

[Gerhard_dk4xp]

This is my take on the ADCMP580.

Board is home-etched on 0.5mm pre-sensitized Bungard FR4
from Altium - pdf - laser printer to foil - contact copy.

The scope to measure the result is a 54750A with 54751A 20 GHz
sampler. I solved my pulse problem by buying a 54754A 18 GHz
differential TDR plugin.

regards, Gerhard

AARgh! one pic too large and you can retype here everything.

[GerryBags]

Yes, i really need scope with BW > 4Ghz to measure rise/fall time for periodical pulses with 50-100ps edges.

Is something like this any use, Rionet: 54120B http://www.radwell.co.uk/en-GB/Buy/KEYSIGHT%20AGILENT%20HP/54120B