A 2-20 GHz Distributed GaN Power Amplifier Using a Novel Biasing Technique

This paper presents the design and measurement of a 2 - 20 GHz GaN MMIC power amplifier fabricated on 100 μm silicon carbide using Qorvo's QGaN15 released process. A 2-stage, non-uniform distributed power amplifier architecture is selected to achieve high performance over a decade of bandwidth. The MMIC power amplifier is fully integrated, having on-chip DC blocking capacitors at the RF terminals and on-chip RF bias inductors while only requiring low-cost bypass capacitors at the power supply terminals. A novel technique for biasing the first stage is presented which prevents bandwidth reduction due to the cascade of multiple amplifier stages. The technique allows the output DC blocking capacitor on the first stage to be eliminated while also relaxing the requirement on the first stage drain bias inductor size. The measured PA produces 2.4 - 3.5 W of output power over the 2 - 20 GHz band with 18.4 - 36.5 % PAE. The large signal gain varies between 15.8 and 17.5 dB. This combination of output power, PAE and gain over the 2 - 20 GHz bandwidth will enable development of future high performance broadband systems.