Symmetrical Doherty Power Amplifier With Extended Efficiency Range

A symmetrical Doherty power amplifier (PA) with an extended efficiency range is proposed. This paper proves the existence of a class of symmetrical Doherty PAs having efficiency peaks for back-off levels larger than 6 dB. A design technique is developed that maintains the full voltage and current swings of both the main and auxiliary transistors. The concept is experimentally verified in a 1.95-GHz 25-W circuit demonstrator fabricated using identical GaN HEMT devices. An average power-added efficiency of 50% and adjacent power leakage ratio of -49 dBc is obtained with 9-dB peak-to-average power-ratio 20-MHz long-term evolution test signals.