Matching considerations

[RodrigoSP]

Hi everyone,

I would like to ask your opinion on a layout matching topic, since I hear different comments about it from time to time, and also change my mind about it all the time.
Consider you have the following two possibilities for a matching array:

Version 1:
A B A B
B A B A

Version 2:
A B B A
B A A B

What are your opinions on which array is the best, in general? Not looking into specific cases here.
What would be, in your understanding, the advantages and disavantages of each version? Is one better than the other?


Thanks in advance and best regards

 

[t4_v]

In my opinion, they are equal. Make distortion on Y-axis and X-axis and see that both matchings compensate the distortion in the same way. For example distortion on X-axis (rises in the right direction by 1):
1 2 3 4
1 2 3 4

and the distortion on Y-axis (rises down by 1):
0 0 0 0
1 1 1 1

Sometimes one pattern is "better" than other, because it is easier to lay down (make a layout).

 

[lazybear]

for what so call "perfectly matching", version 1 is considered the best for all non-ideal effects. i did meet this pattern once in sub-threshold design.
however, for common practice, we usually refer version 2 for simpler routing -> less time consumption, less extract wire coupling.