UC Berkeley

This paper describes a resonant Dickson-based topology that achieves complete soft-charging with two-phase operation and a convenient 50% duty cycle at all odd conversion ratios. A brief analysis is presented that shows how the resonant switching frequency can be calculated as a function of inductor and capacitor values. One solution sets all capacitors and both inductors equal, and results in switching devices experiencing a constant blocking voltage that is largely independent of load and fly capacitor voltage ripple. The requirement for capacitor matching and subsequent low capacitance density C0G dielectrics is compensated by a weakly bounded voltage swing: no switching devices are present on intermediary nodes connecting L and C elements allowing for very large voltage ripple and highly effective utilization of each fly capacitor's energy density. A discrete 1:5 prototype validates the proposed topology with measured waveforms illustrating 50% two-phase operation and a load-independent maximum blocking voltage across switching devices. An output power of 129 W with a 94% peak efficiency was measured for an input voltage of 20 V. Measuring 11.45 mm × 12.95 mm × 2.8 mm, this prototype achieves a very high power density of 311 kW/liter (5, 096 W/inch3) despite the use of diodes for simplicity and 66% of the converter's volume being comprised of PCB and free space.