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Design >> Analog Design >> Fingering a transistor ...
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Message started by somisetty on Jun 11^th, 2009, 4:33am

Title: Fingering a transistor ...
Post by somisetty on Jun 11^th, 2009, 4:33am

Hi all,

what are the advantages of fingering a transistor in terms of circuit design?

I have transistors M1 and M2 with widths/lengths as W1/L1 and W2/L2 respectively.If there are connected in series together as shown in the figure.what would be the value of widths/lengths (W3/L3) of M3 transistor which is equivalent to M1 and M2?

Thanks

Title: Re: Fingering a transistor ...
Post by raja.cedt on Jun 11^th, 2009, 5:23am

hi,
very simple you will get less diffusion cap... roughly i remember it will be half of the original cap provided if your fingers are very high
there i assumed that gates of both m1 and m2 are connected, in that case m2 will be in triode and if both w1 and w2 are equal then m3 size will be w1/(l1+l2), if they are not equal then i guess very big equation will come.

thanks,
rajasekhar.