Broadband Doherty Power Amplifier Based on Coupled Phase Compensation Network

Abstract

In this article, a new technique is presented to dramatically enhance the bandwidth of a postmatching Doherty power amplifier (PM-DPA). This technique is based on a coupled-line phase compensation network (PCN). Theoretical analysis shows this coupled-line PCN results in wideband impedance matching by reducing the external Q-factor in the peaking branch. Finally, when augmented with suitably selected peaking amplifier impedances, the proposed technique gave improved peak efficiency and output power over an extended bandwidth. For experimental verification, a DPA based on commercially available GaN HEMT devices (Cree CGH 40010F) was designed and fabricated. Measured results of the proposed DPA show 6-dB back-off operation between 1.3 and 2.3 GHz (55% fractional bandwidth) with efficiency in excess of 41%.