A Dual-Mode Continuously Scalable-Conversion-Ratio SC Energy Harvesting Interface With SC-Based PFM MPPT and Flying Capacitor Sharing Scheme

This article proposes a continuously scalable-conversion-ratio (CSCR) switched-capacitor (SC) energy harvesting interface that extracts power from a thermoelectric generator (TEG), regulates a 0.75-V output load, and manages a 1.2-1.45-V battery. The structure employs the proposed CSCR SC converter to improve the power conversion efficiency up to 7.9% higher than that of the conventional converter. Moreover, the structure utilizes a proposed SC-based pulse frequency modulation (PFM) maximum power point tracking (MPPT) method to extract power from a TEG with an MPPT efficiency above 98.15%. In addition, the proposed interface adopts a flying capacitor sharing scheme for the dual-mode operation of the SC interface to increase both the peak end-to-end efficiency and maximum output power. With a 180-nm CMOS process, the proposed interface achieves a peak end-to-end efficiency of 85.4% and maximum output power of 20.8 mW.