An Improved MESFETs Model Including Average Thermal Conditions, Breakdown, Sub-threshold and Gate Diode ON Operation

A large signal model for MESFETs is presented. It uses the Curtice model for the intrinsic MESFET, in order to be compatible with existing CAD programs. To increase the accuracy for high level driving conditions, the operation within drain breakdown region, the gate diode conduction, and the sub-threshold conduction for high VDS values are considered. For parameter extraction, the I(V) characteristics should be measured under the same thermal conditions that occur in experimental circuits. Accordingly, the MESFET is characterized under pulsed conditions, with high or low level equal to the DC bias. A good agreement between experimental and simulation results, not only for the parameter extraction conditions, but also for non-linear circuits such as mixers, were obtained.