Intrinsic Small-Signal Equivalent Circuit of GaAs MESFET’s

Finite Element Time Domain Method is used to determine the intrinsic elements of a broadband small-signal equivalent circuit (SSEC) of FET’s. The values of the differents elements are calculated from the Y parameters of the intrinsic MESFET, which are obtained from the Fourier analysis of the device transient reponse to voltage-step perturbations at the drain and gate electrodes. The success of this analysis depends crucially on the accuracy of the values calculated for the instantaneous currents at the electrodes during the transient. As application we have determined the SSEC for the case of a vertical drain and source contacts GaAs MESFET’s.