In IC Layout , what is the difference between transistor multipliers and fingers?

[bio_man]

Hi folks,

In IC Layout , what is the difference between transistor multipliers and fingers?
I want to layout bunch of transistors with W/L= 21/0.6 and some wider gates (63/0.6). To save area and decrease Rgate, I decided to do fingering. However, I got confused between the two, multipliers and fingers. I attached the ayout and extracted view of the two ways. I layout one transistor using 2 multipliers with W=10.5um and the other one with two fingers also W=10.5um. The extracted devices shows the same, So can I say multiplier and fingers are the same?



Thanks

 

[dick_freebird]

For "digital" and "mixed signal" kits there may be no
practical difference.

For "RF" where you care more about Cgd and Cdb than
almost other thing, you would be way worse off with
m=N nf=1 FETs than with m=1 nf=N FETs, because the
total Cdb will be nearly double (with linearity especially
a concern).

Extract "permute" rules govern how the equivalence of
different finger*multiplier arrangements are assessed.

 

[rangermad]

No, they are not the same. The transistor on the left has contacts in the middle which will allow you to parallel the two transistors. The transistor on the right has no contacts but a smaller gate to gate spacing. This may simply be due to an option on the transistor pcell.

What technology are you using?

Rob

 

[bio_man]

What technology are you using?

Rob

CN05 (0.5um CMOS from ON semiconductor)