svcvs is powerful in enabling time domain filter simulation with defined polynomial or pole/zeros. If my filter's transfer function doesn't easily fit to polynomial or pole/zero format, instead, I have the transfer function exported in text (gain vs. freq), is there a way to take in such info. and enable time domain filtering simulation?
The trouble is that arbitrary frequency-domain transfer functions might be non-physical and lead to causality problems in the simulator (this is one of the challenges with s-parameters that are non-physical - they can end up describing non-causal behaviour and lead to convergence difficulties in the time-domain). It would probably be better to do some kind of fit (maybe rationalfit in MATLAB?) to convert to a form that can be represented with svcvs.
There is also "fracpole" available in Spectre which was an implementation many years ago to help model fractional poles (e.g. for modelling empirical fits of skin-effect). See "spectre -h fracpole". Not necessarily what you want, but just some thoughts on related topics.