Feasible evaluations of coupled multilayer chip inductor for POL converter

Point of load (POL) converters are required smaller size and high efficiency performance in IT industrial applications, etc. Interleaved technique, magnetic integration techniques and application of GaNFETs are well known as good approaches to satisfy these demands. Although coupled inductors for POL converters have been proposed in several studies, a coupled multilayer chip inductor has not examined because of the difficulty of its construction. In this paper, a novel coupled multilayer chip inductor for interleaved POL converters is proposed. This novel coupled inductor has a winding pair with inversely coupled in the magnetic core. Further, magnetic material of the coupled inductor is Fe-based metal composite powder (Fe-Si-Cr). In addition, Fe-based powder in the magnetic core has been processed electrical insulation by highly crystallized oxide nano-layer in order to reduce eddy-current losses. Its high efficiency performance is evaluated by interleaved step down chopper circuit prototype using normally off typed GaNFETs with 1MHz switching frequency.