Ultra high efficiency microwave power amplifier for wireless power transmission

Realizing ultra-high-efficiency power amplifiers operating at 5.8 GHz is a key issue for wireless power transmission such as space solar-power satellite systems and wireless smart-grid short-distance power supply systems. To achieve ultra-high efficiency, current and voltage waveform control is indispensable to eliminate power dissipations at the harmonic frequencies and to keep a balance between the supplied DC power and the 5.8-GHz output power. This paper reports optimized design techniques, including class-F, inverse class-F, and reactive harmonic load amplifiers. The developed GaN HEMT amplifier delivered a record-high drain efficiency of 90% and a power-added efficiency (PAE) of 79%.