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    Impedance calculation in CMOS circuit

    hi
    what is the impedance from x point to ground?(answer:1/g_mn).
    how does it calculated?
    thanks.
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    Re: Impedance calculation in CMOS circuit

    Impedance is the reciprocal of transconductance.



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    Re: Impedance calculation in CMOS circuit

    connection to v is not important?
    if i am doubt about your answer, how can i calculate it?
    i connection to v is replaced with connection to constant voltage, then what's the impedance?



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    Re: Impedance calculation in CMOS circuit

    Incomplete problem description results in ambiguous or useless answer. At least one unclear point is floating substrate nodes.

    Transconductance is a small signal quantity, respectively it's valid for a specific operation point only. Surely v must be connected to a constant voltage, also node I. You'll calculate the device currents and voltages for this operation point, get small signal conductances/impedances and know the answer.

    As far as I see, M1 will be in ohmic mode and thus contribute to x node impedance.



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