A 2.5–2.7GHz broadband 40W GaN HEMT Doherty amplifier with higher than 45% drain efficiency for multi-band application

A 40W average output power asymmetric Doherty power amplifier (PA) for 2.6GHz band was developed using broadband inverse class F GaN HEMTs. The Doherty PA was successfully designed for 2.5GHz-2.7GHz using simple small signal analysis with optimum load impedance obtained by load-pull measurement. To the main and peak amplifiers the saturated power of 105W and 160W GaN HEMTs were applied, respectively. The Doherty PA exhibited more than 54.3dBm(269W) saturated power and more than 45% drain efficiency with -52.5dBc ALCR at 8dB back-off point with 2-carrier W-CDMA signal over the wide frequency range of 2.5GHz-2.7GHz corrected by the digital predistortion (DPD) system. These excellent performances promise to be a good solution for 2.6GHz multi-band/multi-standard base-station transmitter system (BTS) such as FDD-LTE, TDD-LTE and WiMAX.