An 83mA 96.8% Peak Efficiency 3-Level Boost Converter with Full-Range Auto-Capacitor-Calibrating Pulse Frequency Modulation

Abstract

A 3-level boost converter substantiates integration and miniaturization by enabling higher voltage operation with lower voltage technology process, i.e. 2.5V devices are implemented to generate a maximum of 5V OUT , and concurrently providing inductor size reduction. However, flying capacitor balancing across a wide load and conversion range remains a challenge. This work proposes an auto-capacitor-balancing pulse frequency modulation (ACC-PFM) controller, combining peak and valley current mode control for continuous high step-up power conversion along with full-range V OUT regulation and embedded capacitor balancing. Moreover, a proposed delay-equalized level shifter generates duty ratios with only sub-ns deviations, resolving asymmetrical rising and falling delays that induce capacitor imbalance. It ensures the full-range operation for more than 90MHz inductor current frequency. This prototype is implemented in a 65nm CMOS process with 0.28mm2active area. Measurement results show that the converter achieves $\gt7\mathrm{X}$ step-up conversion and 96.8% peak efficiency, operating from 0.3-${3.0V}_{IN}$ to 2.4-5.0V OUT with 83mA peak output current.