A Fully-Integrated Buck Converter Design and Implementation for On-Chip Power Supplies

A 5V-2.5V fully-integrated low-power buck converter was designed and implemented using 0.5μm CMOS technology. The critical circuits of the high frequency controller and an on-chip multi-layer spiral inductor were presented. The structure of multi-layer spiral inductor having parallel and series branches of the metal strip. As the result that the parallel branching structure greatly reduced the series resistance and the series branching structure greatly improved the series inductance of the inductor, the structure can achieve quality factor and current capability enhancement while compatible with conventional CMOS process. The quality factor was quantitatively analyzed with a scalable model and its origin was investigated at a structural point of view. From chip measurement results, when the converter is running at the rated load, the average output voltage of 2.5V, the output voltage ripple within ±2%, and the energy efficiency of 46% are achieved.