Miniaturized Low-Voltage Power Converters With Fast Dynamic Response

This paper demonstrates a two-stage approach for power conversion that combines the strengths of variable-topology switched capacitor techniques (small size and light-load performance) with the regulation capability of magnetic switch-mode power converters. The proposed approach takes advantage of the characteristics of complementary metal–oxide–semiconductor (CMOS) processes, and the resulting designs provide excellent efficiency and power density for low-voltage power conversion. These power converters can provide low-voltage outputs over a wide input voltage range with very fast dynamic response. Both design and fabrication considerations for highly integrated CMOS power converters using this architecture are addressed. The results are demonstrated in a 2.4-W dc–dc converter implemented in a 180-nm CMOS IC process and co-packaged with its passive components for high performance. The power converter operates from an input voltage of 2.7–5.5 V with an output voltage of ≤1.2 V, and achieves a 2210 W/in $^{3}$ power density with ≥80% efficiency.

I. Introduction

The advent of portable electronics and low-voltage digital circuitry has created a need for improved dc–dc converters. Power converters that can provide a low-voltage output (<2.0 V) regulated at high bandwidth while drawing energy from a wide ranging (≥2:1 range), higher-voltage input are particularly useful for supplying battery-powered portable electronics. Unfortunately, the power converters for these applications often account for an undue portion of system size, owing especially to the passive energy storage components needed for the conversion process. Moreover, the size, the cost, and the performance advantages of integration make it desirable to integrate as much of the dc–dc converter as possible, including control circuits, power switches, and even passive components, on die and/or into a surface-mount package. In this paper, we treat the design and packaging of low-voltage power converters to address these issues. The proposed approach is based on a two-stage power conversion architecture integrated on a single complementary metal–oxide–semiconductor (CMOS) die and copackaged with the passive components to form a miniaturized, integrated surface mountable power converter.