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

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 multimegahertz 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 2 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 $\mu \text{H}$ and peak quality factors of 15.1 at 8.3 MHz.