MOSFET amplifier..... ?

[waleed101]

why are we bias MOSFET amplifier in the saturation region?

 

[crutschow]

Where would you bias it?

 

[waleed101]

for example in common source amplifier.....

 

[crutschow]

That didn't answer my question.

If you didn't bias it in the saturation region, then were would you bias it? :-?

 

[godfreyl]

why are we bias MOSFET amplifier in the saturation region?

IMHO, MOSFET terminology deserves to be dragged out and shot.

• In the "saturation region", you get linear amplification, so the output of the amplifier will have low distortion.
• In the "linear region", the amplification is very non-linear, so the output will be badly distorted.

Also, operating in the "saturation region" allows a large output voltage swing.



p.s. Question of my own:
For bipolar transistors, "saturation" means the device is switched hard on, with very small Vce. Now when a MOSFET is switched hard on, is that also called "saturation" (even though it's nowhere near the "saturation region"), or is there some other word for it.
:-?

 

[crutschow]

I agree that using the same term (saturation) to mean two different things for BJTs and MOSFETs is very confusing. It would have been nice if those who initially developed FETs had thought of that when they labeled the various operating points. Or perhaps they intentionally made it different to see if the user is paying attention. :-?

 

[waleed101]

ok ..... thanks for all.