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Affordable <200MHz PDN analysis / impedance measurement hardware?

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inevitableavoidance:

--- Quote from: joeqsmith on November 12, 2024, 07:23:13 pm ---
Without knowing if you solved the ground loop problem, its hard to say.   Also, our goals for making these measurements are not the same.  You may be better off with what you have for now.

--- End quote ---

Having a fully differential measurement I have no shared ground path and thus no ground loops - the same as when using a for example a J2113A (Semi-Floating Differential Amplifier) with a VNA. Just like a Four-Wire Kelvin measurement, where a VNA is more like a Three-wire measurement.

joeqsmith:

--- Quote from: inevitableavoidance on November 12, 2024, 08:25:09 pm ---
--- Quote from: joeqsmith on November 12, 2024, 07:23:13 pm ---
Without knowing if you solved the ground loop problem, its hard to say.   Also, our goals for making these measurements are not the same.  You may be better off with what you have for now.

--- End quote ---

Having a fully differential measurement I have no shared ground path and thus no ground loops - the same as when using a for example a J2113A (Semi-Floating Differential Amplifier) with a VNA. Just like a Four-Wire Kelvin measurement, where a VNA is more like a Three-wire measurement.

--- End quote ---

So your plan is to use that same basic circuit you are showing with your Analog Discovery with your H4?   I don't see a problem with breaking the VNA's ground this way.   

inevitableavoidance:

--- Quote from: joeqsmith on November 12, 2024, 08:50:37 pm ---So your plan is to use that same basic circuit you are showing with your Analog Discovery with your H4?   I don't see a problem with breaking the VNA's ground this way.

--- End quote ---

Sorry - I completely misunderstood what you said. It’s been a long day. Disregard what I said.

I haven’t solved it yet, but thought it might be accurate enough using it above 100mOhm to cover the range above 25Mhz.

I do still plan to make a differential amplifier for it with the IC nctnico used in his 1.4Ghz differential probe, but haven’t gotten to it yet.

Smokey:

--- Quote from: inevitableavoidance on October 28, 2024, 02:57:41 pm ---...
Here's the board measuring a low impedance capacitor array:

...

--- End quote ---

what is that capacitor board???  I gots to know!  purpose, total capacitance, how the hell did they place/solder all those caps when they are damn near touching??

joeqsmith:

--- Quote from: inevitableavoidance on November 12, 2024, 09:01:14 pm ---
--- Quote from: joeqsmith on November 12, 2024, 08:50:37 pm ---So your plan is to use that same basic circuit you are showing with your Analog Discovery with your H4?   I don't see a problem with breaking the VNA's ground this way.

--- End quote ---

Sorry - I completely misunderstood what you said. It’s been a long day. Disregard what I said.

I haven’t solved it yet, but thought it might be accurate enough using it above 100mOhm to cover the range above 25Mhz.

I do still plan to make a differential amplifier for it with the IC nctnico used in his 1.4Ghz differential probe, but haven’t gotten to it yet.

--- End quote ---

In the manual, I show measuring my standards using my old HP network analyzer at 2.5kHz.  The 0.1 ohm standard had 2.74% error without the common mode transformer.  With it, 0.54%.  I could repeat this at higher frequencies but it will only get worse.   I could also attempt it with my H4 with / without transformer.    I doubt it would meet your requirements with a direct connection.       

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