A Highly Efficient Three-Stage Doherty Power Amplifier with Flat Gain for WCDMA Applications

Abstract

A three-stage Doherty power amplifier (DPA) with a flat gain is represented. The driving amplifier at an input of peaking cells is used to achieve high efficiency and flat gain to control the input power level of peaking cells. For the experimental validation, the proposed DPA is implemented using a GaN HEMT and Si LDMOSFETs. For a continuous wave signal, power-added efficiencies of 34.0% and 39.3% are obtained at 8.5-dB back-off power (BOP) and 4.0-dB BOP from the saturation output power, respectively. The measured one-carrier wideband code division multiple access results show high efficiency and flat gain characteristics above 10 dB over the entire output power range.