RF-DC conversion circuit using quadrature hybrid for complex maximum power point tracking

Abstract

This paper proposes the concept of a complex maximum power point tracking (MPPT) circuit for adaptive conjugate impedance matching of wireless power transfer. The proposed circuit consists of an orthogonal power distribution circuit using quadrature hybrid and two rectifier circuits and DC-DC converters. By controlling the input impedance of two DC-DC converters, the complex impedance of RF input can be varied to satisfy complex conjugate matching. This circuit enables high-power and high-frequency handling for matching circuits because no variable device is used in the RF region, and control is done in the DC region. Measurements at 433MHz confirm that complex impedance in the RF region can be controlled by adjusting the two real impedances.