Resonant switched capacitor converter with high efficiency

Conventional switched capacitor converters have an inherent drawback that their efficiency is much decreased as the output current is increased. This inherent drawback is due to a periodical forced charging and discharging operation in the internal switched capacitors accompanied by a large capacitor current, so that their efficiency can not be increased by decreasing its internal resistance. As a result, conventional switched capacitor converters have been limited to be used with a very small output current. This paper presents some novel switched capacitor converter topologies that use a resonant operation instead of the forced charging and discharging operation. Their advantage over conventional switched capacitor converters is a high efficiency even in a high output current region. The operation analysis and steady-state characteristics are described in detail for a half buck type switched capacitor converter, and they are confirmed by experiments.