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

This article presents a fully integrated step-down switched-capacitor (SC) converter with nine voltage conversion ratios (VCRs) that regulates an output load voltage ( $V_{\text{OUT}}$ ) of 0.1-3.67 V with an input voltage of 2.5-5 V. The proposed converter 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 $V_{\text{OUT}}$ 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.