Microfabricated Racetrack Inductors With Thin-Film Magnetic Cores for On-Chip Power Conversion

Abstract

This paper presents design methods and electrical performance measurements for microfabricated racetrack power inductors. Magnetic components with sputtered Co-Zr-O thin-film magnetic cores are demonstrated in a multi-megahertz dc-dc converter for solid-state lighting applications. The high-power-density and high-efficiency dc-dc converter is designed to transfer 25 W of power at switching frequencies between 1 and 30 MHz. Utilizing our magnetic components, the converter achieves a 90% conversion efficiency at 4 MHz with an inductor power density of 1 W/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> of substrate area. Small-signal measurements of the inductors are compared with modeled predictions to validate the design optimization approach. Fabricated components achieved inductance values of 1.2 μH and peak quality factors of 15.1 at 8.3 MHz.