A concurrent 2.15/3.4 GHz dual-band Doherty power amplifier with extended fractional bandwidth

Abstract

A novel output-combining network for a concurrent dual-band Doherty power amplifier (DPA) is proposed. The proposed output combiner employs a modified II-network, which enables the absorption of main and peaking transistors' output parasitics over an extended frequency range and eliminates the need for offset lines that compromise the achievable bandwidth. In addition to performing the impedance inversion, the proposed combiner incorporates the biasing feeds and presents small low-frequency impedances to both transistors in order to improve the DPA linearizability when driven with concurrent dual-band modulated signals. A 50-W dual-band DPA demonstrator was successfully designed to operate across two bands, 2.05-2.30GHz and 3.2-3.62GHz. It achieved greater than 49% and 47% drain efficiency at a 6-dB output back-off over the two bands, and was successfully linearized under single and dual-band modulated signal stimuli.