Analysis and Design of an Asymmetric Doherty Power Amplifier at 2.6 GHz using GaAs pHEMTs

Abstract

This work presents an analytical guideline for the design of N-way Doherty power amplifiers operating at an output back-off (OBO) larger than 6 dB. Using this concept, an asymmetric Doherty power amplifier (ADPA) is designed for efficient transmission of signals with a high peak to average power ratio (PAPR) of 8.5 dB. Both the main and peak amplifier consist of the discrete GaAs pHEMT TGF2025 from Qorvo. The ADPA achieves an output power of 28.5 dBm with a power added efficiency (PAE) of 56.0 % at 2.6 GHz. At the back-off power (BOP) of 20. 0dBm, the PAE reaches its first local maximum which is equal to 50.0 %. The bandwidth of the circuit corresponding to a power gain reduction of 1dB is 200MHz.