Derivation for Vin for my differential pair amplifer

Discussion in 'Homework Help' started by KaiL, Oct 11, 2016.

  1. KaiL

    Thread Starter Member

    Aug 30, 2014
    57
    0
    upload_2016-10-11_21-20-39.png
    I am trying to find Vin
    Is my derivation correct for Vin?
    Vin = Vg1
    --> Vg1 = Vs1 - Vsg1 = Vs1 - (Vthp + Vod)
    --> Vs1 = vd5
     
  2. Jony130

    AAC Fanatic!

    Feb 17, 2009
    3,957
    1,097
    |Vin| = |Vgs1| + |Vgs2|
     
  3. KaiL

    Thread Starter Member

    Aug 30, 2014
    57
    0
    Hmm why is |Vin| = |Vgs1| + |Vgs2|? why add 2 gs together = Vin?
     
  4. anhnha

    Active Member

    Apr 19, 2012
    773
    47
    From the picture, Vin is the voltage between two inputs of the differential pair. However, what you wrote is the voltage at the gate of M1 in reference to ground.
    What is the purpose in doing this? Are you calculating input common mode range?
     
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