Thanks for the help yesterday, now that I have got my schematics and simulations set up, but now I think I have a different problem: When I extracted my circuit from the MAGIC layout, the extracted spice netlist contains subcircuits with the exact name used by the standard cells. Since my testbench simulation includes both the standard cells, and the extracted netlist, there are multiple subcircuits with the same name in my simulation. Do you know how NGSPICE resolves the collision of names? Hopefully the picture below will help to explain the problem. (I am not even certain this is the reason why my circuit misbehaves, maybe this is not even the issue.)