A switched-capacitor (SC) circuit and a resonant inductor are integrated with a boost converter to create a conversion system designed to be used primarily with fuel cells or photovoltaic arrays. A very large dc voltage gain even at high load, continuous input current, and soft-switching of all switches are obtained. A resonance process is used to boost the output voltage of the SC circuit, i.e., a resonant voltage peak becomes a useful phenomenon that creates no undesired over-voltage stresses. A detailed steady-state analysis allows for a trade-off design of the system elements for maximizing the energy processing efficiency. Experimental results of a 22V/100V, 250 W prototype confirm the expected performance of the proposed circuit.