title: A Power-Efficient Wireless Capacitor Charging System Through an Inductive Link.
abstract: A power-efficient wireless capacitor charging system for inductively powered applications has been presented. A bank of capacitors can be directly charged from an ac source by generating a current through a series charge injection capacitor and a capacitor charger circuit. The fixed charging current reduces energy loss in switches, while maximizing the charging efficiency. An adaptive capacitor tuner compensates for the resonant capacitance variations during charging to keep the amplitude of the ac input voltage at its peak. We have fabricated the capacitor charging system prototype in a 0.35-μm 4-metal 2-poly standard CMOS process in 2.1 mm2of chip area. It can charge four pairs of capacitors sequentially. While receiving 2.7-V peak ac input through a 2-MHz inductive link, the capacitor charging system can charge each pair of 1μF capacitors up to ±2 V in 420μs, achieving a high measured charging efficiency of 82%.
authors.affiliation: GT-Bionics Laboratory, School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30308 USA.
authors.forename: Hyung-Min
authors.initials: HM
authors.lastname: Lee
authors.affiliation: GT-Bionics Laboratory, School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30308 USA.
authors.forename: Maysam
authors.initials: M
authors.lastname: Ghovanloo
keywords: Adaptive capacitor tuning; capacitor charger; charging efficiency; inductive power transmission