A Fully Integrated Nine-Ratio Switched-Capacitor Converter With Overlapped-Conversion-Ratio Modulation for IoT Applications

Abstract

This article presents a fully integrated step-down switched-capacitor (SC) converter with nine voltage conversion ratios (VCRs) that regulates an output load voltage ( VOUT) of 0.1–3.67 V with an input voltage of 2.5–5 V . The proposed con- verter employs 5-V metal–insulator–metal capacitors and 1.8-V native MOSFET capacitors to achieve both power density and conversion efficiency that are suitable for the Internet-of-Things (IoT) applications. In addition, the power stage is operated by the proposed overlapped-conversion-ratio modulation (OCRM), which prevents the severe closed-loop efficiency loss caused by conventional VCR control schemes. Thus, the proposed converter regulates VOUT through digitally controlled 15 nine-ratio SC cells, enabling the frequency-scalable power conversion operation. With a 180-nm CMOS process, the proposed converter achieves 87% peak efficiency and the maximum output power of 421 mW.