Hi, I am trying to perform post-layout simulations for a multi-loop ring oscillator, but could not achieve startup even after modifying the schematic and layout several times. How do I solve this?

I have no idea what the problem is unless you provide more meaningful detail about the problem.

@Tim Edwards I am extracting a netlist from Magic including parasitic capacitances, then including the extracted

.spice

file in the Xschem netlist. Ngspice doesn't throw any error, but the circuit doesn't start. I have also tried removing parasitics from the netlist.

Yes, but is ngspice throwing an error?

It does whenever I try to instantiate the subcircuit with an x in the front. Otherwise, it doesn't.