A Calibration-Free Energy-Efficient IC for Link-Adaptive Real-Time Energy Storage Optimization of CM Inductive Power Receivers

Abstract

The design, development, and experimental characterization of an integrated circuit (IC) for maximizing the energy storage efficiency in resonant inductive current-mode (CM) power receivers are presented. The IC is designed to moni- tor the receiver’s incident energy and to determine and employ an optimal timing scheme for controlling its operation to maximize energy storage for a given period of time. Thanks to continuous monitoring of incident waveform dynamics, the IC automatically adapts its optimal solution on-the-fly to any change in the inductive link’s physical or electrical parameters (e.g., Q-factor variations and coils movement). To minimize the IC’s power consumption, all the high-speed blocks for monitoring, optimiza- tion point computation, and system control are implemented using analog circuits, making the solution needless of a high- speed analog-to-digital converter (ADC)/digital-to-analog con- verter (DAC). The IC is fabricated in a standard 0.18 µmC M O S process with an active area of 0.45 mm 2. Its efficacy in real-time optimization of energy storage efficiency is experimentally vali- dated for two different inductive links, showing perfect agreement with empirical measured data and theoretical predictions. Our measurement results show that by using the presented IC, the energy storage efficiency is improved by 53% and 67% for the two tested links, compared to the conservative schemes used for the receiver’s operation control. It has also been shown that the