Design and Demonstration of Single and Coupled Embedded Toroidal Inductors for 48V to 1V Integrated Voltage Regulators

Claudio Alvarez, Srinidhi Suresh, Madhavan Swaminathan, Rao Tummala, Daisuke Sasaki, Kazuki Watanabe, Ryo Nagatsuka, Cheng Ping Lin, Tatsuyoshi Wada, Naoki Watanabe

Research output: Chapter in Book/Report/Conference proceedingConference contribution

11 Scopus citations


High-efficiency High-Voltage Integrated Voltage Regulators (HV-IVR) will allow the next generation of data centers and servers to operate with higher efficiency while delivering more computing power. High-density embedded inductors operating at frequencies over 10 MHz allows the miniaturization of power modules enabling their integration closer to the SoC. However, single stage 48V to 1V IVR present new challenges that are not seen in low voltage converter such as 3.3V or 1.7V to 1V. In this work, a novel expandable interleaved toroidal inductor cell with vias-in-slot thru magnetic sheet is presented. In addition, we present a new metric for magnetic material and inductor technologies to describe their efficiency under different duty cycle conditions. Using the analysis of two available magnetic sheets with permeability 50 and 150 at 10MHz, we present the magnetic properties of a magnetic sheet to obtain 95% of inductor efficiency, an inductance density of 113 nH/mm3 at 10 MHz, a saturation current over 2.5A, and DC resistance around 20 mΩ. These inductor requirements are given by the possible power stage topologies that can be used to achieve 48V to 1V, where some of them use single inductor while others use coupled or tapped inductors. The efficiency conditions for the inductor presented in this work must be matched by the power stage topology, leading to a co-design between power inductor and the power stage topology. In this work we present why the duty cycle must be extended by a factor of 4 in order to obtain a 95% efficiency in the inductor. We provide a process for the fabrication of these inductors. Finally, a test inductor is fabricated that shows an inductance density of 77 nH/mm3 and correlates well with the simulation model. This allows to predict with good accuracy the inductor performance with the proposed inductor design and magnetic sheet properties.

Original languageEnglish (US)
Title of host publicationProceedings - IEEE 70th Electronic Components and Technology Conference, ECTC 2020
PublisherInstitute of Electrical and Electronics Engineers Inc.
Number of pages9
ISBN (Electronic)9781728161808
StatePublished - Jun 2020
Event70th IEEE Electronic Components and Technology Conference, ECTC 2020 - Orlando, United States
Duration: Jun 3 2020Jun 30 2020

Publication series

NameProceedings - Electronic Components and Technology Conference
ISSN (Print)0569-5503


Conference70th IEEE Electronic Components and Technology Conference, ECTC 2020
Country/TerritoryUnited States

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering


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