Nonlinear MOSFET model for the design of RF power amplifiers

A nonlinear equivalent circuit model for RF power MOSFETs is given. The model extraction uses cold S-parameter measurements. Pulsed drain current measurements are taken with the junction at the RF operating temperature. A method of thermally characterising the MOSFET is described. An equation is developed to represent accurately the drain current characteristics. The methods given are easily applied to devices which operate at up to 400 MHz with power ratings in the 1 W to 100 W range. The accuracy of the modelling procedure is verified by large-signal RF and DC measurements.