Synopsys Pocv Setup Commands

Location coordinates are required to calculate path distance but are not required to calculate the path depth. Set the read_parasitics_load_locations variable to true, and then use the read_parasitics command

pt_shell> set_app_var read_parasitics_load_locations true
pt_shell> read_parasitics

Enable POCV Analysis – To enable graph-based POCV analysis, set the timing_pocvm_enable_analysis variable to true

pt_shell> set_app_var timing_pocvm_enable_analysis true

Set Standard Variation Sigma

pt_shell> set_app_var timing_pocvm_corner_sigma 3

Load POCV Information:

pt_shell> read_ocvm pocv_coefficient_file_name
pt_shell> read_ocvm pocv_distance_based_derating_file_name

Set Derating in POCV, The following command applies a 10% guard-band POCV derating on both early and late edge

pt_shell> set_timing_derate –cell_delay -pocvm_guardband -early 0.90
pt_shell> set_timing_derate –cell_delay -pocvm_guardband -late 1.10

Report derating factors

pt_shell> report_timing_derate -pocvm_guardband 

Reset derating factors

pt_shell> reset_timing_derate -pocvm_guardband 

Scale POCV Coefficient by 5%

pt_shell> set_timing_derate –cell_delay -pocvm_coefficient_scale_factor -early 1.05
pt_shell> set_timing_derate –cell_delay -pocvm_coefficient -late 1.05

Running PBA Analysis with Derate-Only Mode:
By default, PrimeTime performs both regular path-based analysis (path-specific slew propagation) and path-based POCV analysis during a path-based analysis (report_timing or get_timing_paths using the -pba_mode option), which removes the maximum amount of pessimism from the design, but the runtime can be large.
You can set the pba_derate_only_mode variable to true to perform path-based POCV analysis only. The analysis runtime is significantly improved at the cost of some pessimism removal.


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