Parasitic Capacitance

Power supply manufacturers often struggle with resonance peaks in conducted emission tests that filtering can't eliminate. Learn how to locate noise sources using RF current probes and near-field probes, plus effective mitigation strategies.

In this column, the author offers a brief summary of a more systematic approach for using ferrite cores on cables. This summary can serve as a “ferrite core checklist” for design and test engineers.

Most EMI issues are caused by a resonance that is excited somewhere in the system. It may be a resonance of a cable acting as an antenna or a heatsink energized by the power electronics switches bolted to it, becoming a good radiator. In this article, we look at the indicators that signal the presence of structural resonances and provide techniques for fixing the EMI issues. Practical case studies are presented to demonstrate the techniques.

Many individual components in electrical and electronic systems and devices are integrated into systems that are required to function as a whole. Examples of such systems include large electric vehicles, fixed industrial installations, novel scientific products such as quantum computers, and more. There are two EMC-related aspects to consider: intra-system EMC and inter-system EMC. This article focuses on the intra-system EMC aspect while also considering the inter-system aspect.

Bias tees are an important tool for many applications including vector network analysis. As accurate understanding and modeling of power electronic components becomes increasingly important for the study of their electromagnetic emissions, so do broadband measurements with bias tees. This paper describes the composition of such a special bias tee in terms of the necessary geometries and circuitry.