A 6.78-MHz 100-W Class E Power Amplifier Module with an Adaptive Power Combiner

The class-E power amplifier module using an adaptive power combiner is proposed for 6.78-MHz wireless power transfer system for medium power transmission. Two class-E power amplifiers are designed to obtain more than 50-W output power at the load impedance which maximize the power-added efficiency of the amplifiers. The input impedances of the proposed power combiner are matched to the load impedances of the amplifiers, and the output signals of the amplifiers are combined and transmitted to a $50-{\Omega}$ reference impedance. The output characteristics of the proposed module are obtained using EM circuit co-simulation including the parasitic effects on a FR4 PCB. In the simulation results, the proposed module shows an output power of 50.2 dBm, a power-added efficiency of 88.5%, and a power gain of 29.2 dB at a 6.78-MHz operating frequency. The power-added efficiency of the proposed module is improved by 5% compared with a single 100-W class E power amplifier using the same power transistor.