I'm working with isolated NMOS devices right now with GF180 PDK, and it extraction is weird.
I have this self-oscillating voltage doubler here. It is made of a central ring oscillator, which powers a positive supply VHI and a negative supply VLO.
If I extract only the ring oscillator, it is ok. But when I extract the whole voltage doubler, the ring oscillator gets a new port which isn't connected anywhere. Why?