Modular architecture for ultra low power switched-capacitor DC-DC converters

Abstract

This work presents a novel modular architecture for a step-down Switched-Capacitor Converter for Ultra Low Power applications. The modularity of the architecture allows to generate any conversion ratio in the same way. Additionally a technique for increasing efficiency by recycling the charge stored in parasitic capacitances is presented, which reduced the losses due to this cause in 80%. An example of converter with four conversion ratios for a supply voltage of 2.8V, load current up to 100μA in a 0.5μm CMOS process was designed and electrically simulated. The efficiency achieved for the 4/5 conversion ratio is above 77% for one order of magnitude of the load current.