EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: leftek on August 08, 2021, 12:37:27 pm
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Hello, i would like to measuring the bias signal of IGBT with oscilloscope in MATH functions (-).
The problem is that i take a dirty signal o the screen of oscilloscope due the effect of the emmiter-ground voltage (that is high). How can ι isolate the bias signal to be clear? Who is the right way?
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If you are going to have any possibility of success using subtraction to make a differential measurement, then first you have to adjust the gain and frequency response (probe compensation) of each channel so they match. This means connecting both probes to the same test source and adjusting the gain and probe compensation of one or both probes for maximum common mode rejection ratio at all frequencies.
The better solution is to use either a high voltage differential probe or an isolated probe, but these are not inexpensive.
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I can't take right waveform. I think that i must purchase differential probes.
Thank you.
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I can't take right waveform. I think that i must purchase differential probes.
The calibration waveform just needs to be a rough square wave with an amplitude of the same order as the common mode voltage that you want to measure. The calibration is to minimize the output signal.
The waveform at the source of the IGBT should meet these requirements if you do not have anything better.
Any high voltage differential probe should be tested with the same signal to get an idea of its performance before relying on it.