A Reconfigurable $2times/2.5times/3times/4times$ SC DC–DC Regulator With Fixed On-Time Control for Transcutaneous Power Transmission

摘要

A reconfigurable switched-capacitor dc–dc regulator for transcutaneous power transmission is presented in this paper. An area-efficient power stage that can be configured to four different conversion ratios under different input voltages, is proposed to maintain high power efficiencies and small output ripples of the regulator over a wide input voltage range caused by coupling variations. Instead of using a low-dropout regulator for post regulation, a fixed on-time regulation scheme is developed to provide output regulation and reduce the switching power loss under the light load condition. Implemented in a standard 0.35- n-well CMOS process, the proposed regulator delivers a maximum output current of 10 mA and achieves the peak power efficiency of 82%. When the input voltage varies by 1.6 V, the power efficiency of the proposed regulator can be improved by 40% compared with the regulator efficiency with a fixed-ratio power stage. The output ripple reaches 24 mV that is 0.5% of the output regulated voltage.