Embedded Inductors Using Composite Magnetic Materials for 12–1-V Integrated Voltage Regulators

Abstract

Substrate-embedded inductors enable the miniaturization of power modules and integrated voltage regulators (IVRs) with higher power efficiencies and performance. However, embedded inductors for single-stage 12- or 48–1-V high-conversion-ratio IVRs present new performance challenges due to limitations in magnetic materials, limited space, high frequency, and low duty cycle. In this work, we analyze seven embedded inductor designs fabricated with four metal-polymer composites magnetic materials. These inductors have inductances ranging from 20 to 500 nH, dc resistances between 14 and 40 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}\Omega $ </tex-math></inline-formula> , and saturation currents from 100 mA to over 5 A. Each inductor is characterized for its small-signal spectra with and without dc bias current and for its large-signal response. With all these measurements, a relation between the small- and large-signal losses is made, showing that using the new <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$R_{\mathrm{ acx}}$ </tex-math></inline-formula> metric, they are related by a factor <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\kappa $ </tex-math></inline-formula> . The measurements show that, in the megahertz range, the large-signal losses can be over four times larger than the small-signal ones. These analyses allow us to understand the material properties and modeling new magnetic materials targeted for high-conversion-ratio IVRs with input voltages greater than 5 V.