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How to make NMOS transistor more rectangular in layout?

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Cyrk

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Large NMOS

Hi.

Is there any way to make NMOS transistor (l=200u w=5u) more rectangular in layout?
 

elbadry

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Re: Large NMOS

You can make it fingered and adjust finger width to give the desired aspect ratio
 

    Cyrk

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elmolla

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Re: Large NMOS

Pardon me, What do you mean by fingered? You mean like the high frequency BJTs?
 

Hughes

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Large NMOS

You can use serpentine channel.

As shown in the figure. If you are sure L>>W, use a rectangle poly and a serpentine diff.
 

layout_designer

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Re: Large NMOS

Example:
U can take 40 fingers. And arrange them in two rows of twenty each. More than two rows increases parasitics.
 

YESH_23

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Large NMOS

fingered means breaking down the width of the transistor and then connecting them in parallel
 

paulux

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Re: Large NMOS

Is there any analysis on performance such as parasitic capacitors, parasitic resistance, effect of mismatch and etc....on Large L & Small W.....e.g.W/L=2/400? Any materials, books or papers about this topic? Any comments are highly welcomed...
 

shiva4u

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Re: Large NMOS

Sorry for diverting guys, The question asked is L=200 but you are all saying to finger it. Fingering the length is not possible right, If the width is 200u then you can go for the fingering. I think the question itself is wrong.
 

cicer

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Large NMOS

what is the process that the L of nmos can be 200u ?
 

avlsi

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Re: Large NMOS

I think the question woruld be for W=200 and L=5 ,if L=200,then even Moore would have not thought of a law. Because it all started around L=10 to 15 um.Today in 65 nm.
 

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