A 20 W GaN HEMT VHF/UHF Class-D power amplifier

Abstract

A 50 to 550 MHz wideband gallium nitride (GaN) HEMT power amplifier with over 20 W output power and 63% drain efficiency has been successfully developed. The demonstrated wideband power amplifier utilizes two GaN HEMTs and operates in a push-pull voltage mode Class D (VMCD). The design is based on a large signal simulation to optimize the power amplifier's output power and efficiency. To assure a wideband operation, a coaxial line impedance transformer has been used as part of the input matching network; meanwhile, a wideband a 1∶1 ferrite loaded balun and low pass filters are utilized on the amplifier's output side instead of the conventional serial harmonic termination.