Analysis of two BJTs

Discussion in 'Homework Help' started by stn0091, Jan 12, 2013.

  1. stn0091

    Thread Starter New Member

    Jan 11, 2013
    3
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    [​IMG]

    The problem statement says to determine all node and branch currents. I've done so in my work attached, but that's not what I'm interested in.

    What kind of circuit is this? How's it work? What change in the input signal (+5V on the left) would cause Q1 to turn off and Q2 to turn on?
     
  2. WBahn

    Moderator

    Mar 31, 2012
    17,737
    4,789
    Assume that the top transistor is just barely starting to turn on - so there is a tiny, tiny (i.e., basically zero) current flowing. What will the emitter voltage be? What will the base voltage be? What will the input voltage be? Now do the same assuming that the lower transistor is just barely starting to turn on.
     
  3. Veracohr

    Well-Known Member

    Jan 3, 2011
    550
    75
    It's a push-pull output stage.
     
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