The-OpenROAD-Project
Dumping estimated parasitics as SPEF
Description
You can run estimate_parasitics prior to RCX extraction with OpenROAD, however, there isn't a way to dump this data to a SPEF file as far as we can tell. We're trying to bring up a PDK internally and it would be helpful for calibrating the RC values.
Suggested Solution
A way to dump the estimated parasitics would be ideal.
Additional Context
No response
There isn't a method currently. How would you use the spef? If you just need something like total C that's simpler.
There isn't a method currently. How would you use the spef? If you just need something like total C that's simpler.
We're trying to compare the values pre and post-routing (and RCX) to try and calibrate the RC values to try to get the pre-routed values a bit closer to post-route extracted parasitics.
If total C (presuming you meant per-net) can also be dumped the same format pre and post routing and RCX, that would also be helpful as a starting point.
@donn take a look in ORFS where we have a script that does linear correlation between GPL, GRT, and RCX parasitics on both total cap and total res.
write_net_rc.tcl contains a bunch of procs for extracting cap and res for each net.
write_net_rc_script.tcl uses those procs to get the GPL, GRT, and RCX cap and res into CSV files.
correlateRC.py does a simple linear regression on the estimated cap and the extracted cap to generate a correlated setRC.tcl
make correlate_rc will run these scripts on a specific design
make correlate_rc_platform will run the correlation on all designs in an entire platform, rather than just on a single design. Although for some reason Make always wants to rebuild a design from scratch even if it exists.
