A 92.8% Efficiency Adaptive-On/Off-Time Control 3-Level Buck Converter for Wide Conversion Ratio with Shared Charge Pump Intermediate Voltage Regulator

This paper presents an efficient 3-level buck converter with cascode power stage and the proposed shared charge pump intermediate voltage $(V_{\text{MID}})$ regulator. The proposed charge pump (CP) shares flying capacitor $C_{\text{FLY}}$ and power switches in the 3-level buck converter to generate $V_{\text{MID}}=V_{\text{IN}}/2$ achieving both small size and low loss. Also, conversion ratio (CR) $V_{\text{OUT}}/V_{\text{IN}}$ is enhanced by using proposed adaptive-on/off-time (AOOT) control scheme. The control scheme switches between adaptive-on-time (AOnT) and adaptive-off-time (AOffT) mode according to the target CR. The proposed 3-level buck converter is implemented in a standard $0.25\mu \text{m}$ CMOS process showing 92.8% maximum efficiency and wide CR.