amplifiers: how can i sum two amplifiers with diferent properties

Discussion in 'Homework Help' started by naoficoemcasa, Oct 11, 2018.

  1. naoficoemcasa

    Thread Starter New Member

    Oct 6, 2018
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    0
    heelo,
    i have this exercise where i'm supost to sum 2 amplifiers with diferent characteristics, but i'm having a dificult time on how to. amp.PNG
     
  2. danadak

    Well-Known Member

    Mar 10, 2018
    1,565
    323
    Are you supposed to do a discrete design inside dashed amp block, or
    use opamps or.....a little more description would help.

    Homework I gather ?

    Regards, Dana.
     
  3. naoficoemcasa

    Thread Starter New Member

    Oct 6, 2018
    4
    0
    thanks for replying , this exercise has 3 questions. The first one is : Determine the values for Avo, Ais, Rmo and Gms of the equivalent amplifier (shown in broken lines, in the figure).
     
  4. danadak

    Well-Known Member

    Mar 10, 2018
    1,565
    323
    If you look at what you know

    1) You are given Vin, Vout, so you know composite Av
    2) Therefore you know Av of first stage
    3) You know output load and current, so calc Gm second stage
    4) Knowing that you can calc composite Gm

    I do not know what Ais or Rmo terms mean ?

    Regards, Dana.
     
  5. The Electrician

    AAC Fanatic!

    Oct 9, 2007
    2,576
    461
    There's another thread with similar parameters: https://forum.allaboutcircuits.com/threads/help-for-gain-parameters-for-quadrupoles.152778/

    I think that the second subscripts ("s" and "o") may stand for "short" and "open". That is, Avo means "open circuit voltage gain" and Ais means "short circuit current gain". Could Gms be "short circuit transconductance"? Rmo may be an output resistance, but I don't know what the "m" represents.

    naoficoemcasa, can you provide an explanation of these terms?
     
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