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What is a FET's ohmic region used for?

  1. May 7, 2015 #1
    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
     
  2. jcsd
  3. May 8, 2015 #2

    meBigGuy

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    Gold Member

  4. May 8, 2015 #3

    LvW

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    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.
     
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