A 40W GaN HEMT Doherty Power Amplifier with 48% Efficiency for WiMAX Applications

A 40W GaN HEMT Doherty power amplifier (PA) for 2.5GHz band was developed. The Doherty PA was designed using large signal GaN HEMT models, and demonstrated a saturation output power of 54dBm (250W) and a drain efficiency of more than 60%. The measurement result shows good agreement with the large signal simulation result. We also investigated the Doherty PA linearity with digital pre-distortion (DPD) system, and obtained a drain efficiency of 48%, an ACLR of -53dBc and a power gain of 13.4dB at the average output power of 46dBm (40W) with 64QAM modulation signal. These superior performances show good suitability for 2.5GHz band WiMAX base stations.