2014 Volume 11 Issue 17 Pages 20140682
Practical class-E power amplifier circuits with shunt capacitance have been increasingly exploited in wireless power transmission systems for efficiency enhancement. Most designs, however, have often assumed that the shunt capacitance is linear and the maintainable efficiency in the low power supply has received little attention simultaneously. In this paper, we propose a class-E design with a shunt capacitance composed of nonlinear and linear capacitances, which was implemented and measured with 92.5% Power-Added Efficiency (PAE) at 13.56 MHz operating frequency and 4 W output power level. In addition, an adaptive bias control circuit that drives the drain voltage of power amplifier was realized to up-hold high PAE at a lower input power range.