Reasons for driving voltage deviation caused by high voltage differential probe

The switching characteristic is determined by the driving voltage of the device in the switching process 、 terminal voltage 、 Terminal current represents one of the most important characteristics of power semiconductor switching devices .

Generally speaking , Double pulse test can be used for equipment evaluation , In the circuit design, directly measure the equipment waveform on the running converter .

In order to draw the right conclusion , Accurate switching process waveform is very important .

The high-voltage differential probe has differential input and high input impedance , In the process of power development, it is generally selected to measure the driving waveform .

Sometimes the driving waveform obtained when using the high-voltage differential probe appears very coarse , This is often caused by the excessive attenuation multiple of the high-pressure differential probe . Large attenuation factor , The range of high-pressure differential probe is large , The resolution is greatly reduced , At the same time, the oscilloscope will amplify the noise when restoring the signal . At this time, it is necessary to select the high-pressure differential probe with small attenuation multiple or the gear with small attenuation of the high-pressure differential probe . We use the high-voltage differential probe in the figure below to measure the driving voltage , The attenuation times are selected respectively 50 Times and 500 times , It is obvious in the figure below 500 The driving waveform is very thick at times of attenuation .

50 Times and 500 Multiple attenuation waveform comparison

Schematic diagram shows Tektronix high pressure differential probe

The above high-voltage differential probe causes the driving voltage to be out of range

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