I would really love to see how this goes connected to the gate circuit in a high side mosfet in a switching supply. If you can actually see the gate waveform fairly accurately, that would be impressive. Any specs on common mode rejection ratio at various frequencies?
The people here use these probes (Yokogawa brand labeled, 100MHz BW spec) to monitor gate drive signals on high side IGBTs, common mode is up to 800V and up to a some kV/us (well, it depends, can't go into details). And yes, they can see a gate drive signal.
There's also a downside: no one checks the probes for compensation and CMRR, not even when they get calibrated in a external cal lab :-(
It's perfectly possible to pull a probe out of the storage box with a fresh cal sticker on it and real bad compensation / CMRR. Some months ago, I volunteered an re-adjusted a bunch of them - again no one noticed the change.
The probe simply is used to measure and document the gate signals, no matter if they are misread by bad compensation or CMRR.
I really like these probes, even if I don't need the high safety ratings (other people here need that), but when it comes to real perfomance, it's better to have your own that has never been used by the power people and lab rats before - they simply do not take care of their equipment.
BTW, the probes I re-adjusted have standard SMT components (1206 planar resistors and caps) for the high voltage divider (several components in series). That's quite cheap ass style, yes it works as long as you don't treat them with high dV/dt rates and you don't have high voltage transients. The standard resistors and capacitors degrade slowly over time (and change their values) if you treat them this way (which is well within their safety ratings, no specs exceeded), leading to bad compensation and CMRR. Then one says, they are worth each dollar they cost - yes maybe in terms of safety they provide, but no, not in terms of performance and long time stability I do expect from such an expensive accessory.
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