A Dual-Mode 2:1 Switched Capacitor Converter with >65% Efficiency over 1000x Load Current Range and One Clock Cycle Transient Response

Abstract

This work presents a fully-integrated switched-capacitor dc-dc design with consistent power conversion efficiency in wide-load current range and active transient response. A fully-integrated centralized dual-lower-bound hysteresis controller with delay compensation techniques is proposed and implemented in 180-nm technology to extend the maximum load current. A dual-mode design provides a flexible trade-off between ripple and speed reduced sampling frequency and more phases. With power-frequency scaling, a consistent efficiency overall > 1000x load-current range, which is measured to have >65% efficiency from <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$5.3\ \mu W$</tex> to 6.9 mW, is guaranteed. Meanwhile, a 1 clock cycle transient response time is achieved by state-detection in frequency control, which can be further improved by providing external activation signal at system level. As power consumption decreases and capacitor density increases with advanced technology nodes, this approach is expected to provide a competitive approach with its consistent performance over wide load current range.