Reply-To: "Kevin Aylward"
From: "Kevin Aylward"
Subject: Re: what is the fastest W/L ratio for NMOS and PMOS transistor?
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Date: Thu, 19 Dec 2002 07:38:37 -0000
NNTP-Posting-Date: Thu, 19 Dec 2002 07:38:40 GMT
> When I increase size of NMOS/PMOS transistor, sometims get shorter
> raise time/ fall time, but sometimes get longer, is the parasitic
> capacitance problem ?
> Does there have a golden W/L ration for NMOS and PMOS transistor?
> (not ratio logic not any else, just think it is one NMOS transistor
> and one PMOS transistor independently :)
Length should always be the minimum if maximum sped is required. The
optimum width will depend on the loading capacitances and driving
device. A small device, although having smaller load capacitances wont
be able to drive a large load. If the device is too big for the load, it
can load the driver stage to result in a net slow down.
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