A broadband three-device Doherty power amplifier based on a modified load modulation network

This paper proposes a broadband three-device Doherty power amplifier design. A new load modulation network with a shunt quarter-wavelength (λ/4) short stub is introduced for bandwidth extension. Comprehensive analysis of the proposed configuration is given to illustrate the operational principle. For demonstration purpose, a twin-peaking single-carrier Doherty amplifier prototype is devised based on three identical 10W GaN HEMTs. Measurement results show that at least 40% drain efficiency is achieved at 8-dB back-off power, from 2.0 to 2.6 GHz.