Microfabricated V-Groove Power Inductors for High-Current Low-Voltage Fast-Transient DC-DC Converters

Microfabricated thin-film inductors for high-frequency DC-DC power conversion at high currents and low voltages with fast transient response have been fabricated and tested. Inductors with a Co-Zr-O thin-film core and a copper conductor have been fabricated in a silicon substrate. Prototype inductors have been characterized and applied in a 3.3-V-to-1.1-V, 8-A, 5-MHz DC-DC converter and have been shown to exhibit efficiency of up to 89% and power density up to 96 W/cm² of substrate area. The inductors discussed in this paper emerge as strong candidates for high-efficiency, high-power-density DC-DC converters for advanced digital systems such as microprocessors wherein the fast transient response of the microfabricated inductors can result in significant reduction in the converter´s output capacitance