A 6.78 MHz Wireless Power Transfer System Enabling Perpendicular Wireless Powering with Efficiency Increase from 0.02% to 48.2% by Adaptive Magnetic Field Adder IC Integrating Shared Coupling Coefficient Sensor

To achieve a misalignment-free wireless power transfer (WPT), an IC for an adaptive magnetic field adder (AMFA), where the magnetic fields from multiple transmitter (TX) coils are adaptively added based on the coupling coefficient (k) between each TX coil and the receiver (RX) coil, is realized for the first time. A 6.78 MHz AMFA IC fabricated in 1.8 V, 180 nm CMOS integrating four power amplifiers (PAs) and shared k sensor increases the perpendicular WPT efficiency from 0.02 % to 48.2 % with the load power of 458 mW.