Extracting a polynomial ac FET model with thermal couplings from S-parameter measurements

To simulate the linearity properties of RF FET amplifiers operating at moderate signal levels, this paper extends small-signal FET modelling and characterization to include the effects of nonlinearities. Pulsed S-parameter measurements are employed to avoid the problem of self-heating and to characterise electro-thermal distortion mechanisms. The extracted nonlinear ac model can be used in Volterra analysis to gain an insight into distortion mechanisms.