Design of Inverse Class-F High-Efficiency GaN Doherty RF Power Amplifier

Inverse class F power amplifier (IFPA) can obtain high efficiency when working close to the saturated state. By combining the IFPA with Doherty structure, a RF power amplifier characterized with high efficiency at huge power back-off region can be achieved. This paper presents the design and implementation of an inverse class F Doherty power amplifier using a GaN HEMT transistor, which is designed at the band of 910MHz-950MHz. From the measured results for a 930MHz single tone, the drain efficiency of 64.2% is achieved at a 7. 5 dB back-off point from its saturated output power. Taking three-carrier WCDMA signal as a test signal, the proposed power amplifier is linearized by using the DPD techniques.After linearization, the measured adjacent channel power ratio (ACPR) is -35.9dBc (lower) and -35.39dBc (upper).