A dual-band UMTS/LTE highly power-efficient class-ABJ Doherty GaN PA

This paper reports on the realization of a dual-band high power Class-ABJ GaN Doherty power amplifier (PA) for base-station transmitter system (BTS) applications. The designed Doherty PA module consists of two individual single-ended high power-efficient AlGaN/GaN PAs with multi-harmonic Class-ABJ termination operating in both UMTS 2.1-2.2 GHz and LTE 2.6-2.7 GHz communication bands. Measurements have been performed on both the single-ended and Doherty PA prototypes driving both modules with a 5 MHz WCDMA signal having different PAR. The measured single-ended PA block yields around 39.3 dBm average POUT as well as 40% and 37% average DE at the two center frequency bands F_C=2.15GHz and F_C=2.65 GHz when driving it with a WCDMA signal having 5.6 dB PAR. The Doherty PA prototype was tested by using a WCDMA input signal with higher PAR=7.7 dB. These measurement results demonstrate around 40% average drain efficiency and 44 dBm average P_OUT in the UMTS band at F_C=2.15 GHz and around 36% average DE and 42.9 dBm average P_OUT in the LTE band at F_C=2.65 GHz.