Two-Phase Patterned-Magnetic-Flux Coupled Inductor for Vertical Power Delivery

This paper presents the design and implementation of a two-phase patterned-magnetic-flux (PMF) coupled inductor for high-density vertical power delivery (VPD) voltage regulator modules (VRMs). The PMF structure enables the windings of a coupled inductor pair to conduct current straight through the inductor in the same direction while maintaining flux cancellation by patterning the flux to wrap around the conductors. A two-phase PMF coupled inductor for vertical power delivery is fabricated with 8 mm × 8 mm × 1.5 mm dimensions. The VPD PMF inductor is used in a two-phase buck VRM designed for 6 V input with 3 mm total height suitable for placement on the backside of a microprocessor. The PMF VPD converter achieves 89% peak efficiency at 0.8 V output and 1.5 MHz switching frequency, with a current density of 0.6 A/mm².