Hello everyone,
During my design of filter, I do not do monte carlo simulation, and the measurement results are ok.
Now I did monte carlo simulation by using statistical file provided by foundry. Because process variations can be corrected by tuning circuit of filter,for example, pll built by filter'gm and C. I only run monte carlo mismatch simulation.  I found gm mismatch changed the filter frequency response much,mismatch of C is much smaller than mismatch of gm.
The measured response of filter is much better than worst case of monte carlo simulation, I think the reasons can be followings:
1. gm cell is carefully placed during layout, so device mismatch is much smaller.
2. monte carlo simulation simulate circuit with distritution provided by foundry, perhaps it is two pessimistic.

My question are:
1. Between the two reasons I bring forward above, which is of the major importance?
2. During the design of circuit, need the designer do much work to decrease mismatch effects? like scale the width and length of mosfet, this may tradeoff with other circuit performance, such as speed, area,etc.

Best regards

Thank you very much.
I just test 3 chips, perhaps this is not enough.

Best regards
tulip