Proposed Inductor Power Loss Metric and Novel Embedded Toroidal Inductor for Integrated Voltage Regulators

High-density package-embedded inductors enable the miniaturization of high conversion ratio integrated voltage regulators (IVRs). In this work, we present a new embedded inductor structure along with a new performance metric called effective ac resistance per unit inductance and how the inductor sets constraints to the power stage topology. The proposed performance metric depends on the converter duty cycle and frequency and uses the inductor current harmonics, its inductance and resistance spectra, and the large-signal response to compute the inductor losses. No information of the inductor volume or its magnetic field distribution is used. The proposed embedded inductor structure shows a toroidal field distribution using a combination of slots through a magnetic sheet and vias through these slots. The new structure enables the fabrication of several inductors in the same magnetic substrate for multiphase IVR. The proposed inductors are fabricated and the metric is demonstrated with measurements using a high saturation magnetic material, where an interesting relation between the small- and large-signal losses was observed.