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    deep triode subthreshold

    Hi,

    Is it true that a NMOS is easier kept in the triode region if its W/L ratio it larger?

    Thanks.

    •   Alt20th February 2004, 03:09

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    Re: Triode region of NMOS transistor

    easier kept on subthreshold region......current density will be very low...

    Amit



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    Re: Triode region of NMOS transistor

    To keep any trnaistor in triode region, Vds must be smaller than the saturation voltage defined as Vdssat=2/(n*gm/Id), where n is the inverse of the subthreshold slope.

    For a given Id, as W/L increrases, gm/Id does it too and then Vdssat decreases. In the limit (very deep) of subthreshold conduction, Vdssat saturates to about 3-4Vt, where Vt is kT/q.



    •   Alt20th February 2004, 09:06

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    Re: Triode region of NMOS transistor

    you can use the triode region of the MOS as controllable conductance. Works great for transconductance stages with ground refered input voltage. If L get longer the linearity improves. For most techs 4*Lmin works.



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    Re: Triode region of NMOS transistor

    Quote Originally Posted by rfsystem
    you can use the triode region of the MOS as controllable conductance. Works great for transconductance stages with ground refered input voltage. If L get longer the linearity improves. For most techs 4*Lmin works.
    why L get large, the linearity improves? Thank you!



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    Re: Triode region of NMOS transistor

    Quote Originally Posted by shanmei
    Quote Originally Posted by rfsystem
    you can use the triode region of the MOS as controllable conductance. Works great for transconductance stages with ground refered input voltage. If L get longer the linearity improves. For most techs 4*Lmin works.
    why L get large, the linearity improves? Thank you!
    channel length modulation has less impact?



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    Re: Triode region of NMOS transistor

    HI
    Vds<Vgs-Vt to maintain a transistor in linear region.W/L also effect current flow .



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