Novel design of highly-efficient concurrent dual-band GaN Doherty power amplifier using direct-matching impedance transformers

摘要

A novel methodology for designing concurrent dual-band Doherty power amplifier (DPA) is presented in this paper. The required impedance conditions of the carrier amplifier to achieve high-efficiency performance at back-off region are discussed from a new perspective. A novel combine network with direct-matching impedance transformers is then presented to support the load modulation conditions for concurrent dual-band operations. A 1.8-2.6 GHz dual-band Doherty amplifier employing commercial GaN devices is then designed and implemented to validate the proposed method. The fabricated power amplifier (PA) achieves 72% and 60% efficiency for saturation operation at 1.8 and 2.6 GHz, respectively. For the 6 dB back-off region, the measured efficiencies are 63% and 51% in the two designed bands.