A 33W GaN HEMT Doherty amplifier with 55% drain efficiency for 2.6GHz base stations

A 33 W average output power Doherty power amplifier (PA) for 2.6 GHz band was developed using compact package advanced GaN HEMTs which have Cds reduced 20%. A small-footprint Doherty network was successfully designed with plain small signal analysis, and the method was very practical. The Doherty PA exhibited a saturation output power of 52.5 dBm (178 W) and a saturated drain efficiency of 65.6%. The Doherty PA also achieved a drain efficiency of 55%, an ACLR of -52.8 dBc and a power gain of 13.8 dB at the average output power of 45.2 dBm (33 W) with 4-carrier W-CDMA signal at 2.6 GHz using commercially available digital pre-distortion system. These excellent performances show good suitability for 2.6 GHz band base stations (BTS), for example, W-CDMA, LTE and WiMAX, and small-sized circuit structure contributes to realize compact remote radio head type of BTS.