Hello,
Has anyone tried to create a spectrum analyser using NGspice? Note I am not trying to do AC sweep. It’s basically to analyze noise from a switching node.
Regards,
Sam
Simulators usually do a FFT calculation for his.
I would be very dubious of the accuracy of modeling switching noise
Switching noise is very dependent on PCB layout. Both capacitive and inductive coupling and resistance of the copper tracks. FFT would mainly show the switching frequency and it’s harmonics, and those can be estimated from an AC sweep. “Spurious oscillations” are probably due to parasitics, and without being able to model those, simulating them would not make much sense.