Unsymmetrical Parallel Switched-Capacitor (UP-SC) Regulator with Fast Searching Optimum Ratio Technique

Abstract

Different from conventional multiphase switched-capacitor (SC) DC-DC converters, the proposed unsymmetrical parallel switched-capacitor (UP-SC) regulator provides more controllable input variables to increase available conversion ratios for improved load regulation. Even under higher conversion ratio numbers, the UP-SC regulator uses the fast searching optimum ratio (FSOR) technique to search the destined ratio rapidly and to reduce the transient recovery time. Experimental results show the test chip fabricated in 0.25 mu m CMOS process increases the ratio number to 187 and 2389 in 3-stage and 4-stage SC regulators, respectively. Transient recovery time reduces from 26 mu s to 1.5 mu s in case of 7mA load current step.