GaN HEMT high efficiency amplifier for Microwave Wireless Power Transmission

In this paper, GaN HEMT high efficiency amplifier for Microwave Wireless Power Transmission (MWPT) is presented. The effects of harmonic of 0.7μm and 0.25μm gate length GaN HEMTs were measured by harmonic load-pull measurement. In the measurement, it was revealed that the 0.25μm gate device included higher harmonics than 0.7μm gate device. It is because cuf-off frequency of 0.25μm gate device is higher than 0.7μm gate device. 0.25μm short gate length GaN HEMT which has 25GHz high cut-off frequency was used for amplifier. The matching circuit was designed so that 2nd and 3rd harmonics are tuned to obtain maximum power added efficiency (PAE). PAE of 75% was successfully obtained with 7W output power at 5.8GHz.