Determination of Equivalent Coupling Surface of Ferrite Beads and related Filter Design Stakes for Multi-Sourcing

The risk of shortage and multi-sourcing for all electronic components has increased in the last few years and will speed up in the coming years. In order to limit this consequence, a strategy for reducing the EMC requalification of products, when components reference are changing, has been developed. The equivalence of products, in terms of EMC performances, is now shifted from product level to component level in order to avoid redoing a complete qualification on product. It means that, if components are equivalent in terms of EMC related characteristics, products will be considered as equivalent. For the definition of an equivalence between two components, one of the key parameters is the equivalent coupling surface, that corresponds to its capability of coupling a magnetic field. The methodology for equivalent coupling surface determination of ferrite beads is, thus, presented in this paper. That procedure is based on TEM (Transverse ElectroMagnetic) cell measurements. All the related stakes regarding the particular structure of ferrite beads and regarding filter design are also presented in this paper.

I. Introduction

Multi-sourcing is more and more at the center of product design and is slightly introduced in [1] and [2]. Actually, in order to limit the risk and consequences coming from components shortage, the diversification of supply sources is one of the keys. This way, if two components are equivalent, in terms of EMC performances, products can be considered as equivalent also. Therefore, for cost and time concerns, EMC requalification is not mandatory.