Add SG13G2 130nm PDK support

[trabdelbasset]

Changes

pdk.py — add PDK_SG13G2() with cell names and file paths from
the ihp-sg13g2 config. PDK root can be passed directly or set
via env var.

parameter.py — add SG13G2_PARAMETERS_TEMPLATE with track pitches
from sg13g2_tech.lef and placement settings from the ihp-sg13g2
platform config.

ecc_service.py — allow sg13g2 as a valid PDK name in set_pdk_root.

[Emin017]

Thank you for your contribution! Could you add some tests for the newly introduced PDK functionality to ensure that the new PDK works correctly?

[trabdelbasset]

Thank you for your contribution! Could you add some tests for the newly introduced PDK functionality to ensure that the new PDK works correctly?

I've added some tests for the SG13G2 PDK (path resolution, parameter isolation, and workspace integration).

I also want to suggest a more convenient approach for adding external pdks, rather than hardcoding external PDK parameters into pdk.py and parameter.py which could get difficult to maintain as we add more PDKs, I've refactored the architecture in dev so that external PDKs are dynamically loaded from an ecc_pdk.json file located at the PDK's root directory (--pdk-root). The internal ics55 PDK remains hardcoded as the default.

I've also updated the CLI to support this:

--pdk sg13g2 --pdk-root /path/to/ihp-sg13g2

what you think of this approach?

[Emin017]

I also want to suggest a more convenient approach for adding external pdks, rather than hardcoding external PDK parameters into pdk.py and parameter.py which could get difficult to maintain as we add more PDKs, I've refactored the architecture in dev so that external PDKs are dynamically loaded from an ecc_pdk.json file located at the PDK's root directory (--pdk-root). The internal ics55 PDK remains hardcoded as the default.

We may indeed need support for multiple PDKs, but we haven’t yet figured out the best way to integrate and support them, as this would increase the overall complexity of the software.