Author Topic: Yet another fast edge pulse generator  (Read 112744 times)

0 Members and 3 Guests are viewing this topic.

Offline Tom45

  • Frequent Contributor
  • **
  • Posts: 511
  • Country: us
Re: Yet another fast edge pulse generator
« Reply #575 on: February 22, 2021, 03:26:33 am »
Set the timebase to the fastest setting that still shows the full rise time. At least some scopes use the displayed trace to compute the rise time. So if the total rise takes place in less than one major division the accuracy of the reported rise time won't be all that good.
 

Offline Kibabalu

  • Regular Contributor
  • *
  • Posts: 98
  • Country: de
Re: Yet another fast edge pulse generator
« Reply #576 on: February 22, 2021, 06:58:52 am »
And here the result from a Tektronix 2465B. Measurements made by using the SMA version of Leo's pulser with a rise time of approx. 28ps and a SMA to BNC adapter:

Measured Rise times inbetween 620ps and 660ps

The device clearly outreach its spec regarding the analog bandwidth.  :-+
« Last Edit: February 22, 2021, 07:04:18 am by Kibabalu »
 

Offline Tantratron

  • Frequent Contributor
  • **
  • Posts: 280
  • Country: fr
  • Radio DSP Plasma
    • Tantratron
Re: Yet another fast edge pulse generator
« Reply #577 on: February 22, 2021, 07:09:34 am »
And here the result from a Tektronix 2465B. Measurements made by using the SMA version of Leo's pulser with a rise time of approx. 28ps and a SMA to BNC adapter
Could you share the reference or model of where you purchased the specific SMA to BNC to match the SMA gender of Leo's pulser ?
 

Offline Kibabalu

  • Regular Contributor
  • *
  • Posts: 98
  • Country: de
Re: Yet another fast edge pulse generator
« Reply #578 on: February 22, 2021, 07:19:33 am »
I bought those quite cheap ones:

High Quality 4PCS SMA to BNC Kit RF Coaxial Adapter Male Female Coax Connectors

https://www.ebay.de/itm/143598904411
« Last Edit: February 22, 2021, 07:22:02 am by Kibabalu »
 

Online Berni

  • Super Contributor
  • ***
  • Posts: 3491
  • Country: si
Re: Yet another fast edge pulse generator
« Reply #579 on: February 22, 2021, 08:03:58 am »
Another way to demonstrate the impact of a adapter is to add extra unnecessary adapters in between and see what it does to the rise time. If the extra adapters don't do much then that one adapter probably doesn't either.

I usually find that a cheap coax cable does more distortion to a signal than a cheep adapter. At in the high GHz digits a piece of cheep generic coax becomes a 20dB attenuator.
 

Offline Kibabalu

  • Regular Contributor
  • *
  • Posts: 98
  • Country: de
Re: Yet another fast edge pulse generator
« Reply #580 on: February 22, 2021, 09:45:15 am »
The adapter usually gives an additional time delay of 20ps to 40ps, but it should not influence the rise time or give a significant attenuation.

When I find some time I'll measure it with my VNA.


« Last Edit: February 22, 2021, 05:33:37 pm by Kibabalu »
 

Offline Tantratron

  • Frequent Contributor
  • **
  • Posts: 280
  • Country: fr
  • Radio DSP Plasma
    • Tantratron
Re: Yet another fast edge pulse generator
« Reply #581 on: April 15, 2021, 06:09:19 am »
Finally the BNC version was available again from stock so I've ordered one unit to Leo Bodnar from France.
Attached picture with 1st test ob my TDS784D, really amazing quality product which confirms the 1GHz bandwidth.
Will try later on my TDS794D and the strange TDS784C which I believe to rather be TDS754C (eBay seller left the 4 attenuators capacitors and modified the 4 resistors).
 
The following users thanked this post: 2N3055

Offline artag

  • Frequent Contributor
  • **
  • Posts: 628
  • Country: gb
Re: Yet another fast edge pulse generator
« Reply #582 on: April 15, 2021, 09:42:00 pm »
I also just received one from the new stock.

I wanted it to check my DSO7000 scope out after modifying the input circuits so the BNC one was plenty fast enough (in fact, Leo's calibration showed this sample to be well beyond spec).

The first thing I tried it on was my HP53310A - I'd heard theat it could be used to make fast risetime measurements. But I got very strange results, with triggers failing  and time measurements that were for the period rather than the risetime.

I eventually realised that it's just too damn fast for the 53310A which can only resolve about 70ps - the risetime is shorter than the uncertainty in the trigger propagation.
 

Offline tggzzz

  • Super Contributor
  • ***
  • Posts: 13513
  • Country: gb
    • Having fun doing more, with less
Re: Yet another fast edge pulse generator
« Reply #583 on: April 15, 2021, 10:28:59 pm »
The first thing I tried it on was my HP53310A - I'd heard theat it could be used to make fast risetime measurements. But I got very strange results, with triggers failing  and time measurements that were for the period rather than the risetime.

Setting the threshold levels is critical, and without that you measure the period. Have a look at this thread https://www.eevblog.com/forum/testgear/hpagilent-53310a-modulation-domain-analyser-frequency-time-interval-analyser/msg3196908/#msg3196908
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Offline artag

  • Frequent Contributor
  • **
  • Posts: 628
  • Country: gb
Re: Yet another fast edge pulse generator
« Reply #584 on: April 15, 2021, 10:32:00 pm »

Albert,

Shariar did :



That is pure scope porn.
 

Offline Tantratron

  • Frequent Contributor
  • **
  • Posts: 280
  • Country: fr
  • Radio DSP Plasma
    • Tantratron
Re: Yet another fast edge pulse generator
« Reply #585 on: April 22, 2021, 05:26:18 pm »
Now tested with my reconditioned TDS794D...
 

Offline cncjerry

  • Supporter
  • ****
  • Posts: 1048
Re: Yet another fast edge pulse generator
« Reply #586 on: April 29, 2021, 01:27:31 am »
I don't remember if the contest here is 80/20 proximal/distal or 90/10?  Might have them reversed.  With Leo's at 80/20 I'm getting less than 30ps at 80/20.

See that's the problem with this thread, you end up with a scope (or two if I get my 8000 running) that has almost no practical purpose for verifying anything other than oc192 comm lines.  Note I said verifying because the carrier will fix it. Or you can play around looking for little bumps in coax lines... :-DD
 

Online Alex Eisenhut

  • Super Contributor
  • ***
  • Posts: 2691
  • Country: ca
  • If you can buy it for 4$ on eBay, why design it?*
Re: Yet another fast edge pulse generator
« Reply #587 on: April 29, 2021, 03:48:56 am »
I don't remember if the contest here is 80/20 proximal/distal or 90/10?  Might have them reversed.  With Leo's at 80/20 I'm getting less than 30ps at 80/20.

See that's the problem with this thread, you end up with a scope (or two if I get my 8000 running) that has almost no practical purpose for verifying anything other than oc192 comm lines.  Note I said verifying because the carrier will fix it. Or you can play around looking for little bumps in coax lines... :-DD

Doesn't the "o" stand for "optical"? I have an optical sampling head somewhere...
*Except AC/DC adapters on eBay. Avoid them all!
 
The following users thanked this post: robson2017


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf