GaN-based Class J and Doherty Hybrid Power Amplifiers for C-band communications

Abstract

Gallium Nitride (GaN) is nowadays the leading semiconductor technology for the design of transmitters with high RF power at microwave and millimeter wave frequency bands. This paper describes the design, assembly and validation of Class J and Doherty Power Amplifiers (PA) for C-band communications using GaN HEMTs and hybrid technology. The RF performance of each fabricated prototype is assessed and compared to simulations. In simulation, the Class J PA provided at 5.8 GHz 37.3 dBm of RF output power, 14 dB of transducer power gain and 53% of PAE (Power Added Efficiency) at 2 dB compression. The measured RF performance achieved 36 dBm of output power, 12 dB of gain and 47 % of PAE at a slightly lower frequency in C band. On the other hand, the simulated Doherty PA (DPA) achieved at 5.8 GHz a drain efficiency (η) greater than 50% (from 34 to 40 dBm of output power) within the Doherty regime, while providing between 10 and 11.8 dB of gain in the same 6 dB range. The DPA prototype showed lower measured performance than in simulation, providing 9 dB of gain and 39 dBm of maximum output power in C band