High-Efficiency Transmission-Line Inverse Class F Power Amplifiers for 2-GHz WCDMA Systems

In this paper, a novel load-network solution to implement the transmission-line inverse Class F power amplifiers for base station WCDMA applications is presented. The theoretical analysis is based on an analytical derivation of the optimum load-network parameters to control the second and third harmonics at the device output, including the device output parasitic shunt capacitance and series inductance. The transmission-line inverse Class F LDMOSFET and GaN HEMT power amplifiers using NXP BLF6G22LS-75 and CREE CGH27060F devices, respectively, were designed and measured. The high-performance results with the drain efficiency of 70.2% and power gain of 18.0 dB for a 60-W LDMOSFET power amplifier and with the drain efficiency of 82.3% and power gain of 14.3 dB for a 50-W GaN HEMT power amplifier were achieved at an operating frequency of 2.14 GHz. Index Terms -- RF power amplifier, inverse Class F, transmission line, efficiency, resonant circuit, LDMOSFET, GaN HEMT.