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Design >> Analog Design >> Optimum number of fingers
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Message started by summi on Aug 6^th, 2013, 8:22am

Title: Optimum number of fingers
Post by summi on Aug 6^th, 2013, 8:22am

Dear Forum,
Can any one explain what is the basis of number of fingers for a mosfet either high frequency performance or mismatch point of view. I know many times layout decides number of fingers, but i would like to know is there any problem with higher number of fingers (exepct complicated routing) or is diffussion cap keep on decreses with numbr of fingers? Even gate resistance should keep on decrease with number of fingers but some where i heard verticle resistance dominates at some point and gare res keep on increase after words...

I am not finding much informtion in books and other resouces so any kind of hint will appriciated.

Br,
Summi.

Title: Re: Optimum number of fingers
Post by harpoon on Aug 7^th, 2013, 12:43am

A suggested answer is 4

Title: Re: Optimum number of fingers
Post by loose-electron on Aug 7^th, 2013, 4:56am

What is the resistance of your gate stripe vs. the frequency you drive it at, vs, the amount of capacitance present at the gate?

Title: Re: Optimum number of fingers
Post by boe on Aug 9^th, 2013, 1:46am

harpoon wrote on Aug 7^th, 2013, 12:43am:

A suggested answer is 4

harpoon,
it is said the answer is 42... ;-)
- B O E