A Three-Level Boost Converter With Full-Range Auto-Capacitor-Compensation Pulse Frequency Modulation

A three-level boost converter enables efficient voltage step-up power conversion with high power density by reducing the inductance and blocking voltage requirements in a conventional boost converter. An auto-capacitor-compensation pulse frequency modulation (ACC-PFM) controller, combining peak and valley current-mode controls, is proposed to resolve the issue of unbalanced flying capacitor voltage, as well as to regulate the output voltage. The capacitor balance is further strengthened through a delay-equalized level shifter that generates duty ratios with only sub-nanosecond deviations. The step-up power conversion from the input voltage of 0.3-3.0 V to the output voltage of 2.4-5.0 V is demonstrated through a prototype converter implemented in a 65-nm CMOS process with 0.28 mm ² active area. This converter achieves 96.8% peak efficiency and an 83-mA peak output current, with an 8$\times $ peak step-up conversion ratio.