Op amp analysis transfer function

Discussion in 'Homework Help' started by Jacl, Feb 15, 2013.

  1. Jacl

    Thread Starter New Member

    Feb 15, 2013
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    [​IMG]

    I need a little help here. This is an ideal op amp. I need to find the transfer function Vi/Vo.

    This is what I have so far (nodal analysis):

    [​IMG]

    Then I'm not sure about the op amp gain , Vb = A * Vo?

    I get confused when I try to proceed.
     
  2. The Electrician

    AAC Fanatic!

    Oct 9, 2007
    2,281
    326
    I think you really want to find the transfer function Vo/Vi, don't you?

    Also, the opamp gain is Vo=Vb*A, not Vb=Vo*A

    The two equations you have appear to be the KCL derived relationships at node a and node b.

    You need another equation.

    A = 1+R4/R3, so Vo=Vb*(1+R4/R3). This will serve as one more equation.

    Now you just eliminate Va and Vb; do you know how to do that?
     
    Jacl likes this.
  3. Jacl

    Thread Starter New Member

    Feb 15, 2013
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    Yes, I meant Vo/Vi. Thanks for your help! I understand it now.
     
  4. halfknot

    New Member

    Apr 21, 2013
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    Somewhat related question:

    If I have a a 1st order op-amp low-pass filter circuit that also gives signal inversion: How do I perform an ideal op-amp analysis to give the voltage transfer function of the circuit?
     
  5. The Electrician

    AAC Fanatic!

    Oct 9, 2007
    2,281
    326
    Start a new thread, post a schematic, ask your question.

    Show what progress you have already made in solving the problem.
     
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