Broadband high-efficiency Doherty power amplifier based on novel phase and impedance transform structure

Abstract

Traditional Doherty power amplifiers (DPAs) have severely limited bandwidth due to the presence of a quarter wavelength (λ/4) compensation microwave line. This paper proposes a novel phase compensation and impedance transform structure that can maintain a 90-degree phase shift over a wide frequency range, which is a good alternative to traditional λ/4 microwave line. To verify the validity of the proposed structure, a DPA has been designed and fabricated based on the proposed structure. The saturated output power reaches 43 dBm, and the output efficiency of the drain stage is more than 65% from 2.6 GHz to 3.8 GHz. Meanwhile, over 43% drain efficiency is obtained at 6 dB back-off power.