Symmetrical Doherty Power Amplifier with High Efficiency and Extended Bandwidth

This paper introduces a load modulation network for the Doherty power amplifier (PA). The proposed combiner network demonstrates inherent wideband characteristics and effectively addresses the impact of output parasitics resulting from the transistors, thereby achieving exceptional bandwidth performance. To validate the concept, a wideband prototype Doherty PA is designed and measured, employing GaN HEMT transistors. The experimental results exhibit a drain efficiency of 51-63 % at the peak output power and 41-53 % at 6-dB output power back-off across 1.6-2.7 GHz. Furthermore, the measured peak output power of 43.8±0.5 dBm within the same frequency range confirms the theoretical framework and demonstrates the promising potential of the proposed wideband Doherty PA for future applications in wireless transmitters.