Design of continuous mode Doherty power amplifiers using generalized output combiner

Abstract

In this paper, a continuous mode Doherty power amplifier (DPA) working over an octave bandwidth is constructed using a generalized combiner. The generalized combiner provides the PA designers with more freedoms for realizing broadband DPAs. Theoretically, the generalized combiner could expand the working bandwidth of continuous mode DPA. A continuous mode DPA working over 1.2–2.7 GHz (a relative bandwidth of 76.9%) is implemented in this contribution for demonstrating the universality of the generalized combiner. As a demonstrator circuit, the fabricated DPA achieves drain effciencies of 40–54% and 44–75% at 6 dB back-off and saturation power levels, respectively. The maximum output power of the fabricated DPA is 42.1–44.2 dBm with a saturation gain of 7.2–11.3 dB over 1.2–2.7 GHz. When the designed DPA is excited by a 20 MHz LTE signal with a peak to average power ratio of 7.04 dB, the fabricated DPA achieves adjacent channel leakage ratios (ACLRs) of −29.5 dBc and −49.5 dBc at 2.4 GHz before and after DPD technique, respectively.