Switched capacitor converter topology using a compensation inductor for charge transfer

Abstract

Circuits and methods are provided for soft switching within a switched-capacitor DC/DC converter, so as to reduce switching losses and improve efficiency. This is accomplished, in preferred converters, by coupling a compensation inductor between one half-bridge of an output rectifier and another half-bridge of the output rectifier. The compensation inductor functions to transfer charge from or to the capacitance of switches within the converter while the switches are off, such that the voltage across each switch is reduced to zero before that switch is turned on. This provides zero-voltage switching (ZVS) and its associated high efficiency. The efficiency associated with the ZVS makes ideal zero-current switching (ZCS) less important, such that high-precision capacitors and inductors forming the resonant tanks required by near-ideal ZCS are not required. The resultant circuits are physically smaller and less expensive than other converters that require near-ideal ZCS, but achieve similar or better efficiency.