DIY sampling "scope"

PFC · 2012-12-14T09:35:10+00:00

Hi guys ! I'm looking for a solution to measure PCBs, power supply decoupling performance, input impedance of stuff that has inputs, etc... I've got a 60 MHz network analyzer, works great, but I'd like to go a bit higher in frequency, without spending megabucks. And suddenly, this post from 2008 : So, if someone here has interest in designing the fast stuff (or just throwing some schematics), I'd gladly volunteer for the rest (usb, micro, adc, software, gui, etc). Basically a board which : - outputs a fast pulse or edge - has an input with a sampler running synchronous to the output, with a delay sweep - ADC, usb, pc, display With a Cypress FX2 ez-usb chip, streaming USB2 at full bandwidth is simple, I've got a board with that running from a previous project. Anyone interested ?

J

John Larkin 13 years ago

I don't know if anybody still makes switching-type TDs. The manufacturing process was incredible. GPD bought the GE product line, and made TDs for some years, but they are now an electro-optics company.

The "slideback" concept doesn't need to be implemented with TDs. The basic idea is that each sample event delivers a single bit, a flag that is the sign of the (signal-feedback) voltage at the instant of sampling. There are lots of ways to do that. It's inefficient, but that wouldn't matter in many TDR applications... just take a lot of samples.

TDs were cool. Some would generate 25 ps steps, in 1964.

John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators

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Phil Hobbs 13 years ago

idea

the

to

applications...

Those were the 200 mA ones. They all seem to have had about 200 pF of capacitance.

Cheers

Phil Hobbs

Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 USA +1 845 480 2058 hobbs at electrooptical dot net http://electrooptical.net

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Tim Williams 13 years ago

Ah, found it. But this is self-triggered, so it can't be used for equivalent time sampling a waveform, only the highest point on the waveform.

You could add a pulse generator to it, but then you need the timing generation, and the pulse generator, which again necessitates an accurate trigger generator. I don't see how this helps.

Tim

Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms

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John Larkin 13 years ago

Not so.

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John Larkin Highland Technology Inc

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jlarkin at highlandtechnology dot com

Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators

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John Larkin 13 years ago

They can do nice eye diagrams on digital data streams.

John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators

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Fred Abse 13 years ago

I have a Tek TDR/sampler plugin that does exactly that.

Stated to be

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Phil Hobbs 13 years ago

Which model? The SD-24 does 17 ps, but uses SRDs.

Cheers

Phil Hobbs

Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 USA +1 845 480 2058 hobbs at electrooptical dot net http://electrooptical.net

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John Larkin 13 years ago

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Fred Abse 13 years ago

7S12. I don't have the manual for the pulser, only the main TDR, but the waveform looks very TD, and it's only 300mV.

"For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." (Richard Feynman)

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mike 13 years ago

Don't know which head you have. The S-50 is a 50mA TD. The S-52 is a TD, but couldn't find the spec in the time I was willing to spend. Probably 50 or 100mA.

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DIY sampling "scope"

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