Doherty Power Amplifiers for Ka-Band Satellite Downlink

This paper describes the design, realization and tests of different Doherty power amplifiers (DPAs) specifically conceived for Ka-band satellite downlink applications, i.e., 17.3 - 20.3 G Hz. In particular, different design strategies have been explored by accounting for the possibility to combine power on-chip at either device or PA level, also exploring the parallel (current summing) and “series” (voltage summing) interconnection of elementary devices. As a result, three DPAs have been implemented on a commercial GaN HEMT process with 100 nm gate length grown on Silicon substrate. Pros and cons of these different solutions will be highlighted by presenting the main design steps and the preliminary experimental results.