Balancing scheme for phase current and flying-capacitor voltage in three-level DC-DC converter

A balancing scheme for phase current and voltage of the flying capacitor in a fully integrated multi-level multi-phase DC-DC converter is proposed. The proposed balancing scheme based on the ripple voltage of the flying capacitor can simultaneously mitigate the imbalance of phase current and voltage of the flying capacitor. A mathematical analysis shows the proposed scheme can obtain the current information of the flying capacitor during charging and discharging operations and finally obtain the average inductor-current value. A prototype 4-phase 350 MHz three-level DC-DC converter shows <4.7% voltage imbalance of the flying capacitor and <36 mA phase-current imbalance at output voltage and maximum load current of 0.9 V and 1.2 A, respectively.