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Homework Help: JFETS/MOSFETS and applied potential

  1. Mar 19, 2013 #1
    Explain how and why the weak signal (potential) applied to the gate G modifies (or modulates) the strong (current) between the source S and the drain D in the JFET . In particular you must indicate what happens to the depletion layer and the conducting channel when
    a. (10) Positive potential is applied to the gate
    b. (10) Negative potential is applied to the gate

    1. This is a p-channel JFET.
    2. It may be useful to draw a comparison to the vacuum tube amplifier.

    I understand that applying positive potential causes a reduction in the drain current and that the gate voltage (VGG) becomes more positive till all current is cutoff. How does that relate to the vacuum tube amplifier ? And does that mean that the depletion layer decreases in size? I'm not sure i have a good grasp of this concept.
  2. jcsd
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