Optimum drain terminations for improving the linearity and efficiency of a microwave FET amplifier

This paper presents a novel design technique which improves the 2-tone Power Added Efficiency (PAE) and 3/sup rd/ order Intermodulation Distortion (IM3) product simultaneously by the provision of appropriate drain terminations at specific frequencies. This design technique is applied to a 1 W GaAs FET power amplifier operating at 2 GHz and the behaviour of 2-tone PAE and IM3/C are simulated under large-signal conditions. Results indicate that simultaneous improvements of 2-tone PAE (31% from 24%) and IM3/C (-46 dBc from -20 dBc) performance can be achieved under appropriate drain terminations.