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Amplifier questions

  1. Jan 20, 2014 #1
    1. The problem statement, all variables and given/known data

    We have an amplificator of low frequences like in the figure.The transistor has these h parameters:
    hie=1.1k Ohm,hfe=50 Ohm
    In the entrance we have Vs and Rs=10 kOhm.
    Find A1,Ais,Av,Avs,Ri,Ri',R0 and R0'


    2. Relevant equations

    There are many.

    3. The attempt at a solution
    I ,myself did the pi model like in the figure.Is it correct?
    Please,check if I have put Rb in the right place in the pi equivalent
    http://i.imgur.com/ClGTLdd.jpg

    ALSO,can you please help me find what is asked?
    I think that
    V0=i0*Rc=-gm*vpi*Rc
    Vi=ib*(Rb|| rpi)=Vpi*(Rb/(Rb+rpi)
    Av=V0/Vi
    Avs=[Ri/(Ri+Rs)]*Av
     
  2. jcsd
  3. Jan 20, 2014 #2

    rude man

    User Avatar
    Homework Helper
    Gold Member

    hfe is dimensionless. Your value of 50 looks too low anyway.

    Your model looks OK. Did you compute Rpi?

    You are nasking for a lot of parameters and need to define each of them for us.
     
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