Project questions w.r.t SKY 130 tapeout

[c-93]

• As we consider SRAM22 for an asic design: Was SRAM22 already taped-out in SKY130 before?

• Would it be possible for external users, who have access to corresponding licenses (or open source tools) to verify their sram22 macros? One could try magic, netgen, and klayout.

• Offtopic: How do the PDK patches conflict with the upstream SKY130 PDK? Would it be possible / a good idea to use the patched PDK just for a SRAM22 macro, and the upstream PDK for the remaining design? Or should the patched PDK be used globally?

Thanks for this great project. :)

edit: Typo

[rahulk29]

Thanks for checking out SRAM22!

• I'm afraid SRAM22 isn't quite ready for general use -- we are working to fix a few bugs found on test chips, and will publish updates when they are ready (likely a few months).
• I am not sure the open source tools understand SRAM DRC rules, so DRC/LVS would likely be challenging with open source tools. SRAM22 macros are DRC/LVS clean in Calibre, if you have access to that.
• The patched PDK have a few minor modifications, such as connecting VPB to VPWR in tap cells. I would recommend using the regular PDK for your design, and our patched PDK just for SRAM22.

[c-93]

Thanks for your response. I wish you all the best. You may close the issue or leave it open for documentation.

[RTimothyEdwards]

@rahulk29 : The sram22_sky130_macros repository latest commits are from only a few months ago. Does that mean that for those layouts, the issues mentioned above (one year ago) have been resolved?

[rahulk29]

The most recent macros have fixes that we believe address issues with older versions, but we do not yet have silicon measurement results to demonstrate that they work. We had a test chip on one of the eFabless ChipIgnite runs, though it's not clear if/when we might get that chip back. We're tentatively planning to resubmit the test chip on Cadence's MPW service.

In short, I wouldn't yet consider the latest macros production ready.

[smunaut]

Any updates ? Did you ever get any chips back ?

[rohanku]

We got the chips back and the SRAMs seem to be working. We plan to publish detailed measurement results in the near future.