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> 1 GHz DIY differential probes
nctnico:
Does it need to be DIY from scratch? Tektronix P6860 logic analyser probes can be found cheap (say $50) and they have a differential amplifier for the clock / qualifier inputs and regular FET probe inputs for the other signals. All in all one probe gives you 2 differential and 16 regular fet probes with >2GHz (probably 3Ghz) bandwidth.
lukier:
--- Quote from: nctnico on August 14, 2016, 11:16:54 pm ---Does it need to be DIY from scratch? Tektronix P6860 logic analyser probes can be found cheap (say $50) and they have a differential amplifier for the clock / qualifier inputs and regular FET probe inputs for the other signals. All in all one probe gives you 2 differential and 16 regular fet probes with >2GHz (probably 3Ghz) bandwidth.
--- End quote ---
Interesting. Tektronix doesn't share much detail on the inner workings of their probes (but some companies seem to know more - e.g. http://www.movingpixel.com/SQUIRE.html). How do you power this probe (without TLA card/mainframe I assume in this thread) and terminate it for the scope (50 Ohm). Did you build an adapter from the probe high density connector (the side that goes to the TLA7AA4) to BNCs?
Cerebus:
Please ignore this, just marking thus to come back to.
Someone:
--- Quote from: JohnG on August 13, 2016, 03:37:19 pm ---I'm wondering if anyone has a working design or knows of one for a DIY wideband (DC to > 1 GHz) DIY differential probe. I've search for this on and off, and found some attempts, but have not found a successful design. I have come across references to a 2 GHz design published in Elektor July/Aug 2015, but I don't have the article so I don't know if this is a working design or not. I'd buy the issue if I had some indication that this was indeed a working design.
I've used these types of probes before, so I understand the voltage and impedance limitations they present.
There are a few reasons I'd like to have a DIY design. First, to learn from. Second, to have a design that is not tied to a particular brand scope >:(. Third, to extend or modify for different applications. In theory, one could have a few different probes for different voltage ranges, or similar.
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You'll have challenges simply driving the cable and scope input capacitance at 1GHz, you could start with a simple implementation of the THS3217 to get a feel for the project but it won't hit 1GHz. Cheap probes without manufacturer dependence are possible: https://www.eevblog.com/forum/projects/diy-100mhz-differential-probe/
joeqsmith:
--- Quote from: tggzzz on August 14, 2016, 10:36:26 pm ---A novel very simple and robust differential probe: http://emcesd.com/pdf/cd94scr.pdf
Not DC, the article measures refers to 500MHz.
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Interesting idea. Looks like the Mini-circuits 1-500MHz w/SMA cost about $65. Isolation is worse on their surface mount parts. I wonder why he did not have a resistive probe in his comparison.
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