Analysis of a fully matched saturated Doherty amplifier with excellent efficiency

Abstract

A saturated Doherty amplifier based on class-F amplifiers is analyzed in terms of its load modulation behavior, efficiency, and linearity. Simulations included the amplitude ratio and phase difference between the fundamental and third harmonic voltages, the current/voltage waveforms, load lines, and the third-order intermodulation amplitudes/phases of the carrier and peaking amplifiers. The saturated Doherty power amplifier was implemented using two Eudyna EGN010MK GaN HEMTs with a 10-W peak envelope power. For a 2.14-GHz forward-link wideband code-division multiple-access signal, the Doherty amplifier delivers an excellent efficiency of 52.4% with an acceptable linearity of - 28.3 dBc at an average output power of 36 dBm. Moreover, the amplifier can provide the high linearity performance of - 50 dBc using the digital feedback predistortion technique.