A Survey on Microtransformers

The miniaturization of magnetic devices is a subject of enduring interest, since inductors and transformers of very small dimensions are constantly being required for integration into microchips and electrical circuit boards. The main objective of this survey is to supply a compilation of the published research on microtransformers, and to work as a support material, helping in the choice of the most appropriate technology and device configuration for a particular application. The text describes the historical development of microtransformers, the structures in which these devices might be assembled, the various proposed geometries, the fabrication processes, and the type of core used. A brief discussion of equivalent circuit modeling is presented. The current state of the technology in relation to commercial devices is then examined, pointing out some unsolved problems that warrant further studies.