Open Flow Improvements

[threonyl]

Hi!

Do you welcome contributions to make the substrate more usable with open tools? I am exploring substrate in a similar way to how SRAM22 used it with the old codebase.

The old substrate is quite coupled to closed tools for simulation, parasitics, DRC, and LVS.

I have a few improvements in my local branch. Specifically:

• Adding ngspice AC/DC op analysis
• A very crude start of ngspice Monte Carlo analysis (provided that you have OPEN_PDKS point to a suitable library with AGAUSS expressions)

It is not my aim to provide the same level of support for all tools, but to make the 'hackable' path available. Such that I can test out ideas more freely without being coupled to a server. Does this sound like something you would want to upstream?

Thanks!