OCV(On-chip Variations), caused by PVT variation.
set_timing_derate -early 0.8 (capture clock path for setup checks or launch clock path for hold checks, early < 1)
set_timing_derate -late 1.1 (launch clock path for setup or capture clock path for hold checks, late > 1)
默认cell_delay和net_delay都加上同一derate值，也可分别加。
set_timing_derate -cell_delay -early 0.9
set_timing_derate -cell_delay -late 1.0
- Cell check delays, such as setup and hold of cell, can be derated by using -cell_check option.
- -clock option applies derating only to clock paths.
- -data option applies derating only to data paths.
(1) No need to derate for late path when Worst PVT condition.
set_timing_derate -early 0.9
set_timing_derate -late 1.0
or
set_timing_derate -early 0.8 -clock
(2) No need to derate for early path when best-case fast PVT corner.
set_timing_derate -early 1.0
set_timing_derate -late 1.2