MOSFET analysis

Discussion in 'General Electronics Chat' started by ispymalik, Dec 21, 2009.

  1. ispymalik

    Thread Starter Member

    Apr 7, 2008
    18
    0
    Just a few question on analyzing an analog circuit.
    the attached photo is all variable, values at this moment dont matter.

    I was attempting to find the voltage gain of this amplifier circuit.

    I am confused as to why our TA said that the resistance of Rin is approx. 1/gm2... (i found it to be 1/Ro2)

    he found this by using the small signal analysis method and only find the input impedance seen by the NMOS transistor as it leaves the drain.

    So, ultimately two questions.
    1) how would you go about analyizing this circuit.
    2) any ideas how he derived 1/gm2 as the Rin resistance

    The answer i got from the TA was
    Votlage gain = vsig/vout = Gm1(Ro1 // 1/gm2)

    P.S. School's out.. thus, its not homework.
     
    Last edited: Dec 21, 2009
  2. ispymalik

    Thread Starter Member

    Apr 7, 2008
    18
    0
    bump for hope =)
     
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