High-Q 3D Microfabricated Magnetic-core Toroidal Inductors for Power Supplies in Package

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Integration of power inductors is a roadblock in realizing highly miniaturized power supply in package (PwrSiP) and power supply on chip (PwrSoC). Inductors in such power system are used for energy storage and filtering, but they dominate in size and loss. This paper presents a novel 3D through-silicon via (TSV) magnetic-core toroidal inductor for PwrSiP. The magnetic-powder-based core is embedded into TSV air-core inductor using a casting method. The unique air-core inductor design with a hollow core and suspended windings enable a complete core filling with microscale magnetic powders. TSV magnetic-core inductors are fabricated in a compact size of 2.4 x 2.4 x 0.28 mm with the core content varying from 63 to 88 weight percent of soft ferrite NiZn powders. Small-signal measurements show a three-fold higher inductance of 112 nH and a 30% higher quality factor of 14.3 at 12.5 MHz for TSV magnetic-core inductors compared to similar TSV air-core inductors. The results are verified by the modelled results. The total core loss is characterized by large-signal measurements. A suitable inductor is implemented in a zero-voltage-switching 12-MHz buck converter. The converter achieves a peak efficiency of 72% and the output power of 2.4 W converting 12 to 5 VDC.
Original languageEnglish
JournalI E E E Transactions on Power Electronics
Issue number1
Pages (from-to)74-85
Publication statusPublished - 2018
CitationsWeb of Science® Times Cited: No match on DOI

    Research areas

  • Microfabrication, Inductor, Through-silicon vias (TSV), Magnetic materials, PSiP
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