A 60% efficient envelope tracking power amplifier for 40W, 2.6GHz LTE base station with in/output harmonic tuning

This paper presents the results of the development of a highly efficient GaN HEMT-based envelope tracking (ET) Class-E power amplifier (PA) for 2.6GHz LTE base stations. This PA incorporates a unique harmonic tuning technique at both input and output to perform a wide frequency range operation. The fabricated internally-matched PA module exhibited a saturation output power level of 200W with 74% drain efficiency and 15dB gain. In combination with an ET modulator and digital pre-distorter (DPD), it was confirmed that our ET PA can achieve an average efficiency of over 60% and an adjacent carrier leakage ratio of -49dBc, which is, to the best of author's knowledge, the best performance of 2.6GHz LTE base station with a 40W average output power level. In the measurements, two carriers with 10MHz band LTE signal across 2.62-2.69GHz were used, where the peak to average power ratio (PAPR) was 6.5dB.