difference Interdigitization and Common Centroid layout
Both are used for matching of transistors
in interdigitised pattern all the transistors are in interleaved pattern like suppose there are two transistors with 2 fingers each.then
AB|BA
here the first half is exactly mirrored.here the variations for A and B are same.
in common centroid pattern we care for X and Y variations unlike in interdigitised we care only X variations.then
A|B
B|A
common centroid is more precision than interdigitised .ALL differential pairs are matched using this.
Re: what is the difference Interdigitization & Common Centroid layout ?
Typically, this form of layout is used for precise matching of only two
devices. The method can be extended to more devices; however, the routing for such a
compound device becomes very cumbersome.
Because each device finger is the same size, this structure provides a very symmetric and
compact layout. Again, the device fingers on the ends of each row are different than the
internal fingers with respect to their surrounding environment, potentially giving rise to
process dependent device variations. The option of using dummy devices will again
alleviate this problem.