Modeling and Performance Limits of Switched-Capacitor DC–DC Converters Capable of Resonant Operation With a Single Inductor

This paper explores generalized output impedance models and develops a new performance-limit figure of merit (FOM) for switched-capacitor (SC) dc-dc converters that can be resonated or soft-charged with a single inductor. Compared to past work, the output impedance model is greatly simplified through a two-port charge multiplier treatment, yet it maintains accuracy across conversion ratios and is valid in both slow- and fast-switching operation. Building on previous analytical treatments of SC and ReSC converters, the model is expanded to derive optimizations that include both conduction and switching losses. The process is used to identify a new FOM for hybrid-resonant SC converters that can be used to identify the most suitable architectures for a given conversion ratio and relevant (energy or area) constraints on flying capacitors. This is used to highlight the active-device and capacitance utilizations of common topologies, as well as which are most favorable for hybrid-resonant operation.