A Compact Coupled Inductor for Interleaved Multiphase DC-DC Converters

A compact coupled inductor structure is proposed for interleaved multiphase synchronous buck converters used to power computer processors and memories that require high current and fast current slew rate. The new coupled-inductor structure reduces the winding resistor power loss and makes it possible to utilize ferrite magnetic material with low core loss. In this letter, several proposed converter implementations to achieve inverse inductor coupling are illustrated, and inductance and coupling coefficient variations are studied through a simplified reluctance model and Maxwell magnetic simulation. The inductor structure not only can be extended to multiple phases but also can be simplified to a single phase. The operation of the inductor is experimentally verified in a two-phase synchronous buck converter at switching frequency of 1 MHz.