370-W Output Power GaN-FET Amplifier with Low Distortion for W-CDMA Base Stations

Abstract

High output power and low intermodulation distortion (IMD) GaN-FET amplifiers are highly sought after for W-CDMA base stations. In order to obtain high output power, we have developed a field-modulating plate GaN-FET with a high maximum drain current and a high gate-to-drain breakdown voltage. Also, in order to suppress the memory effects that obstruct digital predistortion (DPD) linearization in W-CDMA power amplifiers, we have newly developed the bias network, in which frequency-dependent impedance at the base band of multi-carrier W-CDMA signals is reduced. As a result, the GaN-FET amplifier developed for W-CDMA base stations achieves a record 370-W W-CDMA peak output power, and a low DPD linearized IMD of less than -50 dBc at the highest W-CDMA average output power of over 60 W, resulting in a significant improvement of DPD linearization not only in IM3 but also in IMS and IM7