A 13.56 MHz Wireless Power Transfer System With Reconfigurable Resonant Regulating Rectifier and Wireless Power Control for Implantable Medical Devices Xing Li

Abstract

A 13.56 MHz wireless power transfer system with a 1X/2X reconfigurable resonant regulating (R )r e c t i fi e ra n d wireless power control for biomedical implants is presented. Output voltage regulation is achieved through two mecha- nisms: 1) a local PWM loop at the secondary side controls the duty cycle of mode-switching of the rectifier between the 1X and 2X modes; and 2) a global control loop obtains the mode-switching in- formation from the secondary sid e and send it back to the primary side through the wireless channe l and adjusts the transmitter power of the primary coil to adapt to load and coupling variations. Two novel backscattering uplink tec hniques are proposed for fast and energy-efficient data feedback. The first is for general data transmission using Manchester c ode; and the second is for fast duty cycle feedback to cater for f ast load-transien t responses. Stability analysis of the entire system with the two control loops is also presented. The primary transmitter and the secondary R r e c t i fi e ra r ef a b r i c a t e di n0 . 3 5µ mC M O Sp r o c e s sw i t ht h e digital control circuits implemented using FPGA. The measured maximum received power and receiver efficiency are 102 mW and 92.6%, respectively. For load tr ansients, the overshoot and the undershoot are approximately 11 0 mV and the settling times are less than 130 µs.