A fully integrated battery-connected switched-capacitor 4:1 voltage regulator with 70% peak efficiency using bottom-plate charge recycling

This work presents a switched-capacitor (SC) DC-DC voltage regulator that converts a 3.7V battery voltage down to ∼0.8V in order to power the ‘brain’ SoC of a flapping-wing microrobotic bee. A cascade of two 2:1 SC converters offers high efficiency for a 4:1 conversion ratio. A charge recycling technique reduces the flying capacitor's bottom-plate parasitic loss by 50% and overall conversion efficiency reaches 70%. The output droop is less than 10% of the nominal output voltage for a worst-case 47mA load step.