Symmetric and Multiphase-Interleaved Ladder Bucks for DC Capacitors Elimination

To improve power density, a symmetric switched-capacitor (SC) ladder buck (SLB) is proposed in this brief that eliminates the fixed ladder in an SC ladder buck (SCLB) by tying the dc nodes in two 180°-phase-shifted cells together. Unlike flying capacitor multilevel converters (FCMCs) that minimize the inductor current ripple, the ladder topology within an SCLB splits the inductor current optimally among the ladder switches, such that the overall equivalent output resistance is minimized. M-phase interleaving is proposed in this brief to allow SLB to regain this current splitting capability when operating via duty cycles larger than 0.5. Simulation results of a six-level four-phase design in 180-nm CMOS verify the performance advantages of the proposed topology.