Products > Test Equipment
Affordable <200MHz PDN analysis / impedance measurement hardware?
joeqsmith:
--- Quote from: 2N3055 on October 08, 2024, 07:34:35 pm ---
--- Quote from: inevitableavoidance on October 08, 2024, 05:46:32 pm ---
--- Quote from: 2N3055 on October 08, 2024, 08:35:49 am ---Look up DG8SAQ VNWA 3.
--- End quote ---
That seems to have the perfect range for PDN applications, affordable too. Do you have direct experience with them? How's the software / user interface side of things?
--- End quote ---
I have it. Software is very powerful but acquired taste and needs some time to learn.
There is great community support and it has decent dynamic range in it's limited BW.
Software and manual can be downloaded. Take a peek.
--- End quote ---
--- Quote --- I’d be happy to get up to 200MHz / down to 5mOhm
--- End quote ---
Good enough to measure the 0.005 ohms? The original NanoVNA, with homemade transformer and blocks could measure down that low but I was really pushing its limits.
Do they support modes specific for PDN?
Someone:
--- Quote from: inevitableavoidance on October 08, 2024, 05:46:32 pm ---
--- Quote from: Someone on October 08, 2024, 07:39:23 am ---Do you already have a modern oscilloscope? A signal generator and some amplification will get you into milliohms.
--- End quote ---
Our messages just crossed! As mentioned above I've indeed been using a scope for the purpose. How would you go about implementing 'some amplification'? Purchase a fancy premade preamp? Breadboarding something with a random op amp? Something in between?
--- End quote ---
No problem.
--- Quote from: inevitableavoidance on October 08, 2024, 07:27:23 am ---Now I use my scope with its generator, a voltage + current channel, and a math channel, but it doesn't have the resolution / current capacity to measure low impedances, and doesn't have the bandwidth for the high frequencies. I might be able to wing a combination of the two to still measure DC to 50kHz it the impedance is high enough to measure on the scope.
--- End quote ---
Amplification can be on either (or both) sides of the DUT depends which is easier/cheaper for you or what you already have. You might only need a higher output signal generator or a simple LNA depending on how accurate/fast/noisy you need the measurements to be.
Some other things which can help you:
Use a transformer from the output of the signal generator, it breaks the ground loops and can be selected/wound with an appropriate turns ratio to better match the impedances (50ohm generator vs 0.1ohm PDN).
Measure the current being fed into the PDN either with a floating/isolated shunt or a clip on current probe.
inevitableavoidance:
@nctnico I've seen your DC to daylight differential amplifier on here - would it be possible to somehow spin that circuit to have a 50 ohm input impedance, and make the ground loop breaker that way?
@joeqsmith I've seen the coaxes on the breadboard - how'd you do it for an actual circuit board? Solder two together, run the through calibration, and then solder both to a pin pair you'd like to measure? How'd you do the other calibrations?
@Someone amplification on the current side could be done with something like this? https://www.ti.com/lit/ds/symlink/buf634a.pdf
Do you have any suggestions for parts on the other side?
ch_scr:
--- Quote from: inevitableavoidance on October 10, 2024, 08:26:36 am ---@joeqsmith I've seen the coaxes on the breadboard - how'd you do it for an actual circuit board? Solder two together, run the through calibration, and then solder both to a pin pair you'd like to measure? How'd you do the other calibrations?
--- End quote ---
The trick I've learned is to have a box of (semi-rigid) coaxes, terminated to e.g. SMA on one side, cut to precisely the same length on the other.
Then you can e.g. solder two together as a cal rig, solder the other two to the circuit, have a few spare for other stuff - but still share the cal rig...
nctnico:
--- Quote from: inevitableavoidance on October 10, 2024, 08:26:36 am ---@nctnico I've seen your DC to daylight differential amplifier on here - would it be possible to somehow spin that circuit to have a 50 ohm input impedance, and make the ground loop breaker that way?
--- End quote ---
For PDN measurement purposes, the 26dB dampening of my DIP1400 probe is not what you want. Using a transformer is a better option.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version