Common Centroid for odd numbers

[DS1988]

Hi....i wanted to know what is the best way to layout in common centroid configuration when you have odd number of transistors to match ? Eg I have one transistor of width 3 and the other of width 6. i will first break the other one into 2 segments of 3 each ...now i have A and BB ......how do v lay it out in common centroid ?

 

[keith1200rs]

Split it into 6 transistors.

Keith.

 

[love_analog]

some interdigitizing is sufficient BAB. Splitting it further and doing common-centriod leads to many more metal wiring.

 

[DS1988]

Thanks both of you..... i would appreciate a little more help......How can v do matching of more than 4 transistors each having different widths .....?

 

[keith1200rs]

You need to make sure they are multiples of the same width. So, if you have 3um & 6um then you could use multiples of 3um and simply arrange them BAB as suggested. "Common centroid" isn't really applicable to strange multiples. You could split them further into 1.5um or 1um multiples, but I am not sure it will help matching much.

Keith.

 

[protonixs]

some interdigitizing is sufficient BAB. Splitting it further and doing common-centriod leads to many more metal wiring.

yeah, BAB is sufficient...