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Homework Help: Transfer function with noise?

  1. Oct 28, 2007 #1

    Is it possible to calculate the gain of a closed loop system with Noise? Here's a diagram describing what i mean:

    http://img206.imageshack.us/img206/8955/cltfmh8.png [Broken]

    I've got the following so far:

    [tex]Vout = \frac{A1A2Vin}{1 + A1A2B} + [/tex] [tex]\frac{AVn}{1 + A1A2B} [/tex]

    But the question is asking for the closed loop gain. Would that just be:

    [tex]Vout / Vin = \frac{A1A2}{1 + A1A2B} +[/tex] [tex]\frac{AVn}{Vin(1 + A1A2B)} [/tex]

    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Oct 28, 2007 #2


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    if the question is well posed, it needs to still specify the gain (closed loop or not) from some specified input to a specified output. your first equation (i prettied it up a little) actually shows two different transfer functions.
    Last edited by a moderator: May 3, 2017
  4. Oct 29, 2007 #3
    What if i do this:

    [tex]A' = A2 (A1 + Vn) [/tex]

    and then...

    [tex]Vout / Vin = \frac{A'}{1 + A'B}[/tex]

    Is this logically correct?
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