evilguy said:
So, if we want to assure our design is robust, how many corner we have to consider? is this corner analysis represent process variation in ic fabrication?
If you are doing purely digital design you can do the following as minimum number of corners:
TTT
SSS (-20% or process dependent)
FFF (+20% or process dependent)
TFS
TSF
For mixed signal stuff you need to add the I/O nMOS and pMOS to the list so it would look like:
TTTTT
SSSSS
FFFFF
TFSFS
TSFSF
TTTSS
TTTFF
Hope that helps.