Steady-state analysis and design of a switched-capacitor DC-DC converter

A switched capacitor DC-DC power converter topology which consists of n stages of semiconductor switches and capacitors is described. The switches connect the capacitors across the input source during the charging phase and then across the load during the discharge phase to step down the input voltage by a nominal ratio n. Further control of the output voltage is possible via current, resistive, or duty-ratio control. Based on the observation that the ripple on the capacitor voltages is generally linear in practice, state-space averaging is used to derive the average state-space equations for a generalized n-stage switched capacitor converter circuit. Both exact and approximate equations which are useful for design are derived for the practical performance parameters. A design procedure based on these equations is described. The analytical results have been verified by extensive simulation by PSPICE