Highly Efficient and Multipaction-Free P-Band GaN High-Power Amplifiers for Space Applications

In this paper, the authors report upon the development of multipaction-free P-band (UHF) GaN high-power amplifiers (HPAs) with target RF output power values of 140 W and power-added efficiency beyond 70%. Initially, two different 80-W class single-ended power modules were designed, manufactured, and tested using GaN devices from two different manufacturers. Load–pull techniques were used in both designs to achieve the best tradeoff in terms of RF output power, efficiency, and stability. Secondly, two identical power modules have been combined in a balanced architecture in order to obtain the required level of RF output power. Multipaction analyses and tests have been carried out to guarantee reliable operation in space. The HPAs have been characterized over temperature from $-{\hbox{15}}\ ^{\circ}{\hbox{C}}$ to $+{\hbox{55}}\ ^{\circ}{\hbox{C}}$ in pulsed and constant-wave conditions, showing negligible drifts over temperature and multipaction-free operation. RF output power in excess of 180 W at 70% drain efficiency is also demonstrated.