I have a design routed using NDRs for all metal layers and each net is assigned to one of these NDRs. The NDRs for widths and spacings of metal layers are defined in a separate LEF, different from the technology LEF which defines rest of the other information.
I route using NanoRouter (routeDesign -globalDetail, perform extraction (extractRC), propagate a switching activity on all PIs, do a timing analysis (buildTimingGraph), perform EM analysis using verifyACLimit and then save the design and quit encounter.
Thereafter, I change some of the widths and spacings in the LEF that describes the NDR (the name of the rules are not changed) and relaunch encounter to restore the saved desig, load the LEF with NDRs (loadLeffile), perform extraction (extractRC), propagate a switching activity on all
PIs, do a timing analysis (buildTimingGraph) and perform EM analysis using
verifyACLimit. However, in the detailed report, I notice that none of the metal layer widths have changed. They are exactly the same as how it was routed before. I was expecting the widths to be updated from the LEF.
Please let me know how I can make it possible that verifyACLimit reports the updated wire widths without me having to re-route the design.
In reply to Kari:
Thanks for your response.
I added the option -incremental to loadLefFile and now I am able to see the change in width in the verifyACLimit report when I perform rest of the steps the same. However, now I see the the Irms has increased for wire segments routed in the layers for which I widened the width. I thought it should decrease. Can you please let me know why am I observing this?
In reply to SiddharthaUCSD:
I would not recommend this flow. The -incremental switch is really only for appending antenna information. Really, the NDRs should be in the tech lef and I would reload your session from scratch.
You're right, widening the wires should reduce the ACLimit violations. You say you see the width change in the aclimit report, but did the wires actually change? I think something is getting confused here. Try reloading from scratch, verify the wires are the right width and reroute them if they're not, then rerun verifyACLimit.