An examination of several large signal capacitance models to predict GaAs HEMT linear power amplifier performance

This article examines several methods of modeling the charge/capacitance characteristics of GaAs HEMT devices for use in large signal models applied to the design and simulation of linear power amplifiers. Emphasis is placed on the effect these charge/capacitance models exhibit on the accuracy of the large signal model to predict linear power amplifier characteristics including gain, output power, efficiency, and linearity. Model predictions are contrasted to on-wafer load pull measurements made using a single-tone sinusoid, two-tone sinusoid, and a /spl pi//4 DQPSK stimuli compliant to the NADC standard. The results suggest the description of the device's charge/capacitance characteristics significantly effects large signal model accuracy.