MOSFETs do conduct in reverse with proper bias !

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hanspelmo

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In this application note:

https://ww1.microchip.com/downloads/en/AppNotes/01149c.pdf


You can find a reversed biased P channel MOSFET:

I tried it out and it works !
I placed a fixed 5V instead of battery and slowly increased voltage at gate of MOSFET (from 0 to 6V).
Voltage at load goes from 4.99V (Mosfet on) and decreases as FET turns OFF to aprox 4.3V (in my case) then went back up up again since diode nows conducts.

Anyways this principle is also used for analog bilateral switches (4066, DG211, etc...)

Try it out for yourself. It's worth it.

Conclusion: MOSFETs do conduct in reverse with proper bias !

Have a nice day.
 

Conclusion: MOSFETs do conduct in reverse with proper bias !
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Shouldn't be surprizing because it's just in concordance with datasheets and MOSFET theory.

In contrast to MOSFET used for analog switches, power MOSFET have a substrate diode, so they conduct also without "proper bias", but with one diode voltage drop, e.g. 0.7 V. To make a bipolar switch, that can disconnect both voltage polarities, you need two "anti-serial" connected power MOSFETs.
 


Plz describe what voltages you applied to what terminals (D,B,G,S) with the lowest voltage being 0V.
By reverse you mean that U_Drain < U_Source for an n-type FET ?
I guess for an n-Type the Gate usually has to be as positive as the most positive D, S Terminal, a more negative Bulk (perhaps connected to Drain) helps. The MOSFET is symmetric in nature, but like the BJT the real device is not. The function "resistance of gate voltage" can be moved by bulk bias as well as various manufacturing variables.
The only thing that will not happen is a n-Type getting more conductive with a lower voltage.
There is a good post here: https://www.edaboard.com/threads/258134/#post1105301
 
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