I am getting LVS errors when trying to build sky130 sram 1rw

Question

I am getting LVS errors when trying to build sky130 sram 1rw tiny right out of the box sequence of commands is git clone gt cd into openram folder gt set env vars gt make pdk gt make install gt cd into macros gt make sky130 sram 1rw tiny Am I doing something wrong Both stable and dev branches give me the same result

Mitch Bailey · Answer

< alex d> Getting the openram macros to pass LVS with magic and netgen can be tricky because 1 some layout cells do not have bulk well contacts 2 some layout cells have multiple unconnected power rails with the same text 3 netgen creates proxy pins for unmatched ports in otherwise matching circuits This works if the ports are not connected but may cause problems if the nets are merged at a higher hierarchy There are work arounds for all of these issues Can you post your gds and spice I ll take a look and may be able to suggest something

alex d · Answer

Here you go and just to clarify this is right out of the box with no modifications made of any sort fresh repo clone running the sky130 sram 1rw tiny example through docker If it was failing after I made some changes to it I would understand that I messed something up and it would be on me but LVS issues right out of the box seems odd

Matthew Guthaus · Answer

< alex d> I ve found that it is very dependent on which version of Magic and netgen There were many changes over a year or so that kept adding issues with the items < Mitch Bailey> mentions You are using the docker so that was the last known version to work for us

Matthew Guthaus · Answer

I have never seen this magic warning before openram verify magic run lvs Warning Equate pins cell sky130 fd pr special pfet pass is a placeholder treated as a black box openram verify magic run lvs Warning Equate pins cell sky130 fd pr special pfet pass is a placeholder treated as a black box

Matthew Guthaus · Answer

Looking through the mismatches most of them are from must connect supply pins that are later connected In particular it looks like the colend colenda cells are not connected to vssd1 vccd1 This is likely an extraction issue

alex d · Answer

So I m not doing anything wrong per se right

Matthew Guthaus · Answer

No nothing at all wrong

Matthew Guthaus · Answer

This has been my biggest frustration in the whole project to be honest

Mitch Bailey · Answer

gt I have never seen this magic warning before gt openram verify magic run lvs Warning Equate pins cell sky130 fd pr special pfet pass is a placeholder treated as a black box gt openram verify magic run lvs Warning Equate pins cell sky130 fd pr special pfet pass is a placeholder treated as a black box I believe all device models that are extracted as subcircuits have this message It is not generally a problem gt This has been my biggest frustration in the whole project to be honest I sort of chuckled when I read that From the tool side one of the biggest frustrations has been dealing with layout and schematics that only match at higher levels Hopefully there s some relatively simple solution