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The-OpenROAD-Project / OpenLane

OpenLane is an automated RTL to GDSII flow based on several components including OpenROAD, Yosys, Magic, Netgen and custom methodology scripts for design exploration and optimization.
https://openlane.readthedocs.io/
Apache License 2.0
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SKY130 DECAP12 is too dense on LI1. Proposed solution. #1014

Closed armleo closed 2 years ago

armleo commented 2 years ago

Prompt

I have very not dense design. DECAP12 has 80% coverage of the area, and since all spare locations have DECAP12, it means that I will always be above 40% maximal area for LI1.

Proposal

My proposal would be to modify the filler insertion to limit how much of the area can be covered by DECAP12/DECAPS/Fillers.

Alternative: Use DECAP12 from efabless to workaround. It has sligtly less capacitance, but does not suffer from this problem.

Up to OpenLane to decide what to do.

vijayank88 commented 2 years ago

@armleo A testcase will help to debug and analyse what best can be done.

armleo commented 2 years ago

The current Magic check does not validate the li1 density rule. Any design with low density and big die area (1mmx1mm) are enough to reproduce. Do you want me to create a design for openlane to test?

vijayank88 commented 2 years ago

yes. If you've fix for the issue, PR will be great help for community.

antonblanchard commented 2 years ago

FYI https://github.com/RTimothyEdwards/open_pdks/pull/212 adds the EF decap 12 to open_pdks