Design of a broadband L-band 160 W GaN power amplifier using SMT packaged transistors

This paper details the design of a broadband power amplifier using a state-of-the-art Qorvo transistor in a cost-effective SMT plastic package. The realised amplifier has 160W of output power between 1.2 and 1.8 GHz and is ideally suited to L-band radar and wideband communications applications. The QPD1013 transistor utilises Qorvo's 0.50 μm GaN-on-SiC technology which enables operation at 65 V, leading to improved efficiency and wide bandwidths. The design of the PA is described, including load-pull measurements and EM simulation of input and output matching networks. Particular consideration is given to the thermal challenges involved in using high-power GaN transistors in SMT packages. Two approaches to optimizing the thermal performance of the PCB have been assessed, the first using an array of copper-filled vias beneath the ground paddle of the transistor and the second using a copper coin embedded into the PCB. The results of both approaches are compared. Small-and large-signal measurements demonstrate the broadband performance of the realised amplifier.