A high-efficiency 100-W four-stage Doherty GaN HEMT power amplifier module for WCDMA systems

In this paper, a novel high-efficiency four-stage Doherty power amplifier architecture convenient for practical implementation in base station applications for modern communication standards has been proposed and fabricated. In practical verification, each power amplifier is based on a 25-W Cree GaN HEMT device with the transmission-line load network corresponding to an inverse Class F mode approximation. In a CW operation mode with the same bias voltage for each transistor, an output power of 50 dBm with a drain efficiency of 77% was achieved at a supply voltage of 34 V. In a single-carrier WCDMA operation mode with PAR of 6.5 dB, a high drain efficiency of 61% was achieved at an average output power of 43 dBm, with ACLR₁ measured at -31 dBc level.