resistor matching in layout

[saha.123]

Hi all.......
Why interdigitization is preferred over common-centroid in resistor matching layout???Is it routing complexity of latter one???? Any other reasons???

Thanks in advance

 

[erikl]

Yes, simpler routing is an important reason. Interdigitation can minimize wafer mismatch in one direction (vertical to the fingers) and - to some degree - also in the direction parallel to the fingers. Common centroid can achieve still a better symmetry, but for the cost of more routing complexity and - by this - area consumption - and larger parasitics.

Sometimes a mix of both methods makes sense, for a bit simpler routing.