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

Hoa Thanh Le, Yasser Nour, Zoran Pavlovic, Cian O'Mathuna, Arnold Knott, Flemming Jensen, Anpan Han, Santosh Kulkarni, Ziwei Ouyang*

*Corresponding author for this work

    Research output: Contribution to journalJournal articleResearchpeer-review

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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


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


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