A Ka-Band Power Amplifier with Reconfigurable Impedance Matching Network

A tunable matching network integrated with the power amplifier (PA) is described that can adapt to potential impedance variations presented by the antenna. The matching network is designed to match loads within half-gamma around nominal 50-$\Omega$ impedance. The tunability is achieved by modifying the length of transmission line segments within the matching network by using reverse saturated SiGe switches. S-parameters and load-pull measurements have been obtained and demonstrate that the PA is able to adapt to different load impedances, therefore is able provide constant PAE and output power at a significantly extended range of impedance variations. In this paper, the design approach is explained that leads to significantly improved performance of the presented PA compared to previously published reconfigurable PAs.