@Stefan Schippers I have assigned variable

width

to nmos

W

parameter. Defined it using

.param width=5

in ngspice and swept using

.dc width 2 5 1

but getting an error. Why this error is coming while sweeping parameter in dc statement and what is the solution ?

You can not do a dc sweep over a parameter. You need to do a loop and use the ngspice control language. See this example, in the sky130_tests/ directory.

@Stefan Schippers I tried building a testbench to sweep vdd supply of circuit. Simulation seems to be ending successfully but not able to get output waveforms. Can you please help finding issue here?

Add a

remzerovec

instruction before the write command. I have changed the timestep in the tran command for better precision, added

uic

in the tran command (Use initial conditions) and added a

.ic v(out)=1

to force oscillation.

Thanks very much @Stefan Schippers it is working now. I think main issue was absence of

remzerovec

but I could not get significance of this command as per ngspice manual to

removes vectors of length zero from the current plot.

Some variables (like transistor body currents) get no data (no current injection in substrate) so their data vectors are empty. Why the

write

command errors out instead of skipping these null vectors remains a mistery.