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Homework Help: Electronics Transistors

  1. Jun 5, 2010 #1
    Firstly, sorry if this is in the wrong section. I'll happily move it if it should be somewhere else.
    1. The problem statement, all variables and given/known data
    What is the impedence between the base of the BJT and ground of the common emitter amplifier circuit.

    2. Relevant equations
    Ic = IE

    3. The attempt at a solution
    So I started by saying that [tex]\Delta[/tex]Vb = [tex]\Delta[/tex]IE RE and that [tex]\Delta[/tex]IE = [tex]\Delta[/tex]IB hfe where hfe is the gain of the circuit. By then equating the two using [tex]\Delta[/tex]IE I find that [tex]\Delta[/tex]IB = [tex]\frac{\Delta V_{B}}{R_{E}h_{fe}}[/tex] so impedence is REhfe but this seems very simple considering the circuit. Am I missing anything?

    Attached Files:

  2. jcsd
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