The validation of nonlinear FET modelling and circuit simulation

摘要

There are strong economic arguments for a `right first time'ndesign method for nonlinear GaAs FET based MMICs and MICs. With this aimnthe authors have successfully implemented a lookup table method ofnMESFET representation in conjunction with the time domain simulatornASTEC3. This has been used to model the gate and drain currentngenerators and can also be applied to the voltage dependence of thenequivalent circuit reactances. It removes inaccuracy which can occurnwith algebraic functional forms and allows a clearer assessment of thenunderlying modelling and simulation processes. It also allowsnalternative device types to be examined without the often difficult andntime consuming development of functional forms to adequately representneach type. Circuit measurement at 100 MHz has been used to verify thenaccuracy of current generators based on DC characteristics. There arendiscrepancies between measured and simulated power saturation plots ofn0.5 and 2.5 db. Since this can occur in both linear and nonlinearnregions it is likely that dispersion due to surface and interface statesnis having an effect