An Integrated Regulated Resonant Switched-Capacitor DC-DC Converter For PoL Applications

This paper proposes an integrated regulated resonant switched-capacitor DC-DC converter for a 2.5 V to 1.2 V, 3 A conversion designed in a 130 nm CMOS technology. The voltage is regulated through a combined frequency/time shift on-chip controller that operates thanks to a zero-crossing detector for the tank current. By using such control technique, an output voltage greater than Vin/2 can be reached. The integrated circuit also implements a medium-load and a light-load control modes that maximize the efficiency at every load condition. The external resonant tank is composed of a 12 nH air-core inductor and a 4.7 μF capacitor in a 0805 package, achieving high power density. In this paper, the operation principle and the control techniques are discussed, demonstrating that the inductor value can be reduced by a factor of more than 8 compared to an integrated buck converter designed for the same application, without incurring in a significant efficiency degradation.