An 88%-Power-Efficiency Accuracy-Enhanced DC-DC Conversion System for Transcutaneous-Powered Cochlear Implants

This paper presents a dc-dc conversion system consisting of a switched-capacitor voltage tripler and a low-dropout regulator (LDO) for transcutaneous-powered cochlear implants. Break-before-make mechanism is developed in the tripler to improve the power efficiency and reduces the output glitch. The current-buffer compensated LDO as a post-regulator of the tripler not only removes the glitch from the tripler, but also maintains a constant and stable output voltage irrespective of the change in different load currents. The accuracy of the output voltage is thus significantly enhanced. In a standard 0.35-μm CMOS, results show that the proposed system can deliver up to 60mA load current and achieve the peak power efficiency of 88%. The maximum output voltage variation is only 0.6% of the nominal output of 4.84V under full load current change of 60mA.