how will i know which process corner is the best/worst case?
we made a layout for a cmos inverter. the input is just a pulse and the output waves for the three corners are shown and their rise/fall times are measured and compared. based on the data, how will i describe the 3 corners and how will i know which corner is the best or the worst case?
The first letter stands for all nmos transistors, the second for all pmos (or the other way round, don't remember).
T=typical
S=slow
F=fast
... concerning propagation delay and switching speed.
For best case, FF is used, together with highest voltage and lowest temperature
For worst case, SS, lowest voltage and highest temperature.
Typical case of course is TT, typical voltage and temperature (usually 25°C, but could be a different typ. application temp.)