On the impedance modeling of switched capacitor converters with arbitrary output nodes

Demand for high power density and miniaturization are pushing the application limits of Switched Capacitor Converters (SCCs) to new areas. Their benefit has up to now been used only in low power application ICs such as memories, or mobile phone backlighting where efficiency is not critical and magnetic components are not available. Recently, research in SCCs is demonstrating that their benefits can be extended to high power density systems, achieving efficiency levels comparable to classical inductive SMPS. These new concepts consider advanced control schemes or hybrid combinations of SCCs and inductive switching, and require better understandings of the SCC and its appropriate models. This work presents a new methodology to model hybrid combinations of SCCs and inductors. The well-known vector charge flow analysis for Switched Capacitor Converters is reviewed and extended in order to accurately model the behavior of a SCC when any of the internal nodes is loaded and controlled by Pulse-Width-Modulation. Results of the analysis compare favorably to behavioral simulations.