What is a FET's ohmic region used for?

[jaydnul]

The majority of FET applications are in the active region, right? (including amplification)

So what is the ohmic/linear region used for. Is it a reliable variable resistor?

Also, one quick off topic question: Do BJTs come in enhancement and depletion modes? Or is that just a FET feature?

Thanks

 

[meBigGuy]

You are correct that generally one stays out of the linear region.

Here is something about FETs as variable resistors
http://www.vishay.com/docs/70598/70598.pdf

BJTs do not use enhancement/depletion effects like FETs do, although there are depletion regions in BJTs which are critical to their operation.

http://ecee.colorado.edu/~bart/book/book/chapter5/ch5_2.htm

 

[LvW]

Yes - FET`s can be (and are) used as variable voltage-controlled resistors. As an example, they are used in linear (harmonic) oscillators for stabilizing the signal amplitude.
In this application, a dc voltage is derived from the output signal (rectification) which is used to control the gate voltage of a FET - thereby reducing the loop gain before the amplitude will be clipped by the finite power supply. But keep in mind that for quasi-linear operation of the FET the voltage between drain and source must not exceed some hundreds of millivolts.