High voltage MOSFET bias

[EricKnabe]

So this may be my dumbest question yet, but bear with me.
If I have a MOSFET that can take up to 600V on the drain and I'm running 250V to it, but the max Vgs is like 30, then wouldn't that technically make it impossible to center bias without destroying it?

[antonis]

Only in case of DC grounded Sourse..

In case of Source resistor existence, you can use whatever Vgs is proper to have desirable Drain current..

edit: I might didn't get you right, so more data plz..
(like Mosfet configuration (CS, CD, CG) Drain current, desirable gain In case of CS) etc..

[PRR]

> technically make it impossible to center bias

No. You are confusing yourself somehow.

[antonis]

I think I got you now..
(Paul's "confusing yourself" worked as a catalyst..)

"Center bias" term is refered on Drain (for CS amp) or Source (for CD amp) voltage, resulted by V_CC - (I_DQ X R_D(S)) and NOT on Gate voltage absolute value..!!

e.g. For V_CC = 250V, center bias is 125V and can be set by a 125Ω resistor and 1A current or 125k resistor & 1mA current or any other R X I combination resulting into 125..

To get the appropriate Drain current you have to choose respectively proper V_GS voltage, which voltage is (ideally) independed of V_CC value..

So, Gate voltage value could be 10V say, for Drain current of 10mA so you can center bias Drain with a resistor of 12k5..

https://www.electronics-tutorials.ws/amplifier/mosfet-amplifier.html

[EricKnabe]

Thanks guys. I've since realized that yes, I was confusing myself.

[PRR]

Gate is control. Drain is load. They need not be related any more than a crane's cab and hook.