I am designing some synthesizable analog modules using sky130. Here is the first draft of a design brief on a VCO: http://diychip.org/ringoscillator.html . The references might also be useful if you want to layout your own ring oscillators as they are recent and publicly available. The next brief will cover a synthesizable bipolar DAC.

Is there an index page you're building up as you publish these?

diychip.org for the moment. As soon I can get a Spice file to simulate the placed designs out of the OpenLane flow, I will put them into a github repo.