A Fully-Integrated Biofuel-Cell-Based Energy Harvester with 86% Peak Efficiency and 0.25V Minimum Input Voltage Using Source-Adaptive MPPT

Abstract

This paper presents a cold-starting energy harvester in 65nm CMOS with source degradation tracking and automatic MPPT. A power-efficient architecture is proposed to keep the internal circuitry operating at 0.4V while regulating the output voltage at 1V using switched-capacitor DC-DC converters and a hysteresis controller. Peak efficiency of 86% is achieved at 0.39V input voltage and $1.34\mu\mathrm{W}$ of output power with 220nW of internal average power consumption. Integrated operation with lactate biofuel cells is demonstrated.