Analog layout automation has a couple of open source tools where your mileage may vary: 1) BAG3 (https://github.com/bluecheetah/bag3_analog) 2) Laygo2 (https://github.com/niftylab/laygo2) 3) ALIGN (https://github.com/ALIGN-analoglayout/ALIGN-public) But, it is ongoing research and there are a few different approaches, for instance in this survey article there are many techniques listed: https://www.mdpi.com/2079-9292/11/3/435 - these do include simulated annealing. FPAAs have been around since the 80s but never really achieved commercial viability and are still a work in progress (although you can buy a pretty simple ones). I know Hasler at Georgia Tech is pushing hard to have these adopted and has released some open-source tool to interact with her own SoC FPAA (https://woset-workshop.github.io/PDFs/2020/a18.pdf). Thread in Slack Conversation