A unified framework for capacitive series-parallel DC-DC converter design

This paper presents a design framework to select the best topology and conversion ratio of operation for series-parallel capacitive buck/boost DC-DC converters. The framework models all converter families providing design insights and tradeoffs among the various topologies. We select the 10 optimal topologies that always performs better than any of the 96 permutations that are possible for series-parallel converters. A logical extension of the framework includes the impact of parasitics and other second order effects including partial charging of bucket capacitors and finite tank capacitor size. The paper includes a step by step design methodology. Finally, we analyze a number of prior designs and one new design and show how they fit into our framework.