Why set hold uncertainy value in Signoff timing run

[owen_li]

Hi .

When I run the find timing signoff, I found there are hold uncertainty set in SDC.
As we know, jitter will not affect hold check.
So why add such hold uncertainty ? what does it account for ?
Thanks !

 

[vamsi1255]

Hold uncertainty is added in STA to account for modelling inaccuracies, STA signoff tool vs modelling tool miscorrelations, STA Signoff tool interpolations, Uncovered corner cases etc.

Hold uncertainty is always less than Setup uncertainty.

Hope it is clear.

Regards,
Vamsi