S-params can be result of nonlinear model of device, or it is used only ofr ac/dc?

In simulation packages, like ADS, MWO, HFSS, QUCS, SPICE,.... device can be represented with s-parameters or non-linear model. Does that mean that S-parameters not used in non-linear model, and are just result of all that transistor parameters and capacitance values?

S-parameter is a linear model which is derived at specific DC operation point of nonlinear model.

S-parameter is the electrical characteristics of the particulater device whcich was modeled across frequecny (ac) and with dc (in case of transistor)

Hi, you can use s2p model or nonlinear model in simulation softwares. If you use s2p model, software uses fixed s2p parameters defining component in all conditions such as bias, etc. , but if nonlinear model is used then software applies biasing condition to the component and calculates s-parameters at those conditions and therefore with nonlinear model you can change biasing conditions while s-parameters are valid.

S-parameters are not necessarily the "result" of the non-linear model. At least when presented in a manufacturers datasheet, they are moreoften empirical measurement results while the non-linear model is a theoretical consruct that has been fitted to a set of measurements. Hopefully, it's results conform to the given S-parameters, but not necessarily exactly and rarely in all possible operation points.