Why worst case delay reports Setup violations and best case reports Hold violations.

[arjun2145]

Hi All,

i've a confusion why worst case report is considered as the Max delay violation(Setup violation) and Best case report as Min delay(hold violations).


And why we always calculate the hold violations at the launching flop.


thanks in advance,
Arjun

 

[rca]

worst case, means the lowest speed for the element, so if you reach your target frequency in this corner your design will reach at least the same frequency in the best corner (fastest speed).

For the hold time, below 130nm, it is better to check the hold time in best and worst corners.
In 65nm we saw hold time issue when we cross, the RC best/worst/typical with the corner worst/best, I means we have multiple corners, like worst-RC worst, worst-rc best, worst-rc typical...., and we check the hold time in all of this mode.