The windings of planar magnetic components such as inductors and transformers are the seat of physical phenomena (skin effects, proximity effects and the magnetic field produced by the component) leading to a non-uniform distribution of current in the conductors and an increase in Joule losses. The objective of this paper is to identify the physical phenomena at the origin of this non-uniformity of the current in the conductors. This work is conducted using a 3D finite element software. It highlights the predominant influence of the Hz component of the magnetic field produced by the component, perpendicular to the plane of the component.
This paper presents a study on the main characteristics of an integrated transformer i.e. the low and high cut-off frequencies (FCL and FCH) and the voltage gain within the bandwidth (G0). After a description of the integrated transformer and its micro-fabrication, the measured transformer frequency response is given. An equivalent circuit is derived ant the method to determine each element is shortly described. Then, the paper focuses on the influence of geometrical dimensions and a few characteristics of materials on the low and high cut-off frequencies (FCL and FCH) and on the voltage gain (G0). An analytical expression is derived for FCL, FCH and G0. The aim of this article is to identify the main parameters that limit the bandwidth and the voltage gain.