Author Topic: Nchan Mosfet with AC on the Drain?  (Read 784 times)

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Offline TheBaconWizardTopic starter

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Nchan Mosfet with AC on the Drain?
« on: September 05, 2018, 03:24:11 pm »
Hi there,

I am working with an AC waveform that has DC offset and never goes negative. It is a 500khz waveform going from 0v-1kv and I would like to attenuate it (from anywhere between peak and o) using a PWM signal to determine by how much and when. It is being generated in the first-place by a mosfet and gate-driver and then goes to an output (where a load will be placed) and finally, ground.


Is there any way I could use a mosfet operated in its saturation region to sink that signal to ground before the load, to greater/lesser extent as desired, or is the AC nature of the current going into the drain always going to be a problem? Or could I maybe use the a fet as a variable resistor instead? Either way, we have AC at the drain (and therefore the source) and I don't know if there's a way to have that work.
« Last Edit: September 05, 2018, 03:35:16 pm by TheBaconWizard »
 

Offline thm_w

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Re: Nchan Mosfet with AC on the Drain?
« Reply #1 on: September 05, 2018, 11:19:11 pm »
Should be OK.
I assume the capacitance of the FET won't be a significant load on the output waveform.
If I'm understanding correctly a typical constant current load design will work, with some consideration for the bandwidth required.
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