A Power-Efficient Resonant Current Mode Receiver With Wide Input Range Over Breakdown Voltages Using Automated Maximum Efficiency Control

This article proposes a series-
LC
resonant current mode receiver (RCM R
_X
) for wirelessly powered battery chargers. With a series-
LC
scheme, the RCM R
_X
can operate at higher resonant voltages than transistor breakdown voltages, enabling robust near-field wireless power transfer. In the series-
LC
RCM R
_X
, a dual automated maximum efficiency control (AMEC) and a passive zero-current detector (ZCD) adaptively adjust operation states, ensuring nonresidual energy in the R
_X

LC
tank at the end of the charging mode. Moreover, the passive ZCD operation algorithm increases the power delivered to the load or battery by minimizing the idle period between charging and resonant modes. The 180-nm standard CMOS chip, which used only 1.8-V transistors, can operate with 6.84× higher resonant voltage up to 12.32 V than the transistor breakdown voltage, 1.8 V, while receiving an input power up to 169 mW, enabling a wide input range over variable coil distances. The proposed system achieves the measured power conversion efficiency up to 84.9% at the input power of 16.8 mW.