How to make NMOS transistor more rectangular in layout?

[Cyrk]

Large NMOS

Hi.

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

 

[elbadry]

Re: Large NMOS

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

 

[elmolla]

Re: Large NMOS

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

 

[Hughes]

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]

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]

Large NMOS

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

 

[paulux]

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]

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.

 

[layout_designer]

Re: Large NMOS

So do u want to take L=200 or W=200?

 

[AhmedRaafat]

Re: Large NMOS

make it L=275.5 & w=600

 

[cicer]

Large NMOS

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

 

[avlsi]

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.