Pass Transistor

Discussion in 'Homework Help' started by sunshine27, Mar 14, 2011.

  1. sunshine27

    Thread Starter New Member

    Feb 24, 2011
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    0
    Calculate the output impedance of the emitter-follower circuit called the pass transistor: assume that beta=200

    **see attached diagram**

    I don't know how to do this, I thought that it would just be the 1k resistor, because that is the resistor that we are measuring vout across, but I don't think that is it.... any help would be great!!
     
  2. USMCJames

    New Member

    Mar 14, 2011
    1
    0
    If memory serves correct, I believe the formula you are looking for is Zin = Beta * Emitter Resistor (200 * 1k)
     
  3. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    5,448
    782
    The question actually relates to the output resistance rather than input resistance.
     
  4. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    5,448
    782
    Rout is approximately Re|| (re+Rbase/β)

    re=26/Ie(mA)

    Assume a β of say 200.

    Rbase= 6k8||10k

    Re=1K

    Then you have it.
     
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