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I was measuring the high side command and low side command of a synchronous buck converter when I saw the following phenomenom when I was increasing the input voltage of the buck. The phenomenom appears on the red and green signals which are respectively the low and high side command.

Here is the expected behavior @ Vin = 300V

enter image description here

Here is what happens when Vin = 400V

enter image description here

The green signal is shifted by some amount. The phenomenom is not linked to the board as when I use two correct probes it does not appear. This a problem of instrumentation and the problem comes from this differential probe :

enter image description here

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https://www.francaise-instrumentation.fr/st1000-2-sonde-differentielle-2-voies-30-mhz.html

I am sorry as the user manual is in french...

I was wondering if someone was able to understand what was the problem of the probe ?

Jess
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