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  1. #1
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    [Moved]: constant-gm current reference

    Hi everyone,

    I would like to know why the constant gm is important, how it is translated physically into a circuit, what's the benefits of it.

    I read ken martin's book, and he shows the constant gm derivation being only a function of the transistors ratios. But what that means? Having a constant gm?


    Regards.

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    Re: constant-gm current reference

    A constant gm is an important block in gm-C filters. For maintaining the filter response across PVT, gm of the OTA needs to track a fixed gm. There are other circuits also available where one needs gm tracking.



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  3. #3
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    Re: [Moved]: constant-gm current reference

    Thanks for your response.

    I was reading prof. Martin book where he talks about the circuit that allows us to have a constant gm in the 2 stage opamp and I read somewhere (page 246 - 251) that the vds of Q7 would be equal to the vds of Q13. How is that possible? I have seen the equation and I can't understand how that's possible.

    CAn you or someone else explain me in an intuitive way how this is possible? They are different circuits and one transistor has nothing to do with the other.

    Regards.



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