Hello all. I tried performing process variations for polyresistor by changing the tt in the following command to other processes (say fs , sf etc..) but the simulation results are identical. Is the command right or any other command has to be included? Thank you in advance. .lib ~/open_pdks/sky130/sky130A/libs.tech/ngspice/sky130.lib.spice tt .

Corners "tt", "ss", etc., refer to transistors and are the process corners where changes in doping levels change the behavior of the transistor. Resistors and capacitors are handled separately by corners "ll", "hh", etc., for low valued resistor/capacitor and high valued resistor/capacitor. Note that the "sky130.lib.spice" file only has these backend corners combined with the nominal transistor corner. If you want to simulate, e.g., "ss" + "ll", you would need to create your own .lib file with the appropriate .include statements for the corner you want.

Thank you.