Design of highly efficient, high output power, L-band class D.1 RF power amplifiers using GaN MESFET devices

In this article, two class D^-1 amplifiers is presented, both implemented with GaN MESFETs and working around 900 MHz, delivering 20.7/51.1 W output power with 75/78 % peak drain-efficiency. A simple nonlinear model optimized for switched mode operation is developed from basic device data, and is used to predict intrinsic current and voltage waveforms during the design process. In general, very good agreement between modeled and simulated data is obtained considering the limited amount of parasitic parameters covered by the device model.