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  1. #1
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    small signal-model Promblem. why does the dependent Current source dissappear?

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    I saw this circuit in Razavi's book ——"Design of Analog CMOS integrated Circuits"
    I don't understand his analysis.
    the book says
    the gain is:

    It seems when considering the Small signal model
    the Dependent Current Sourse is gone.

    I think it should be like this:

    Say , a quarter of the book's answer.


    Could anyone help me with this puzzle?
    Why is the dependent Source gone?
    Or I made a mistake?
    Thank all of you in advance!

    best wishes to all guys here.
    sincerly,
    alex.

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  2. #2
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    Re: small signal-model Promblem. why does the dependent Current source dissappear?

    That is not the Current controlled current source. It is just a DC current ( iac=0)which its value is a fraction of M1's current to increase the gain.


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  3. #3
    Newbie level 6
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    Re: small signal-model Promblem. why does the dependent Current source dissappear?

    I got it!
    thank you very mUch.Milad-D.
    bEST WISHES TO you and your loves



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