Analysis and design of dual-input Doherty power amplifier with enhanced efficiency for broadband application

There is a large efficiency degradation between the two efficiency peaks in a broadband Doherty power amplifier (DPA) when the working frequency deviates from the center point. In this paper, dual-input technique is adopted to improve the conversion efficiency over the dynamic power range in broadband DPAs. The efficiency between the two efficiency peaks in the DPA is enhanced through dynamically control the input power levels of the carrier and peaking power amplifiers (PAs) as well as the phase difference between the two sub-amplifiers. As a proof of concept, a broadband dual-input DPA (DI-DPA) operating over 1.1-2.2 GHz is fabricated and measured in this paper. Experimental results show the fabricated DI-DPA delivers a saturation output power of 43.5-44.7 dBm with a gain of 9.6-11.5 dB and a drain efficiency of 50.5%-58.6% in the interested frequency band. Meanwhile, a 6 dB back-off drain efficiency of 40.4%-65.8% is also obtained by the DI-DPA over 1.1-2.2 GHz.