Very High Frequency IVR for Small Portable Electronics With High-Current Multiphase 3-D Integrated Magnetics

As today's small portable electronics (smartphones, tablets, e-readers, etc.) becomes lighter, thinner, quicker, and smarter, the voltage regulator for the processor is expected to be efficient, miniaturized, integrated, and placed closer to the processor. In this paper, a concept of a very high frequency [tens of megahertz (MHz)] three-dimensional integrated voltage regulator (IVR) for small portable electronics is proposed. The magnetic characterization technique at tens of MHz is investigated, and the issues of and solutions for permeability and loss measurement are demonstrated. The LTCC and NEC flake materials are characterized and compared for the IVR inductor development. Both single-phase and five-phase integrated inductors are designed, fabricated, and experimentally tested at 20 MHz, featuring a simple single-via winding structure, small size, ultralow profile, ultralow DC resistance (DCR), high current-handling ability, air-gap-free magnetics, multiphase integration within one magnetic core, and lateral nonuniform flux distribution.