How Do EMI Ferrite Cores & Beads Work?

Ferrite Core & Beads are passive electronic components that can suppress high frequency signals on a power supply line. They are normally placed around a power or ground line pair that is incoming to a particular device, such as the power cord for your laptop. These beads work according to Faraday’s Law: the magnetic core around a conductor induces a back EMF in the presence of a high frequency signal, essentially attenuating the ferrite frequency response.

How Do EMI Ferrite Cores & Beads Work

How Do EMI Ferrite Cores & Beads Work

Ferrites are magnetic materials, and placing this material in a ferrite clamp around the power supply/ground line allows provides a source of inductive impedance for signals passing through the line. Because ferrite bead impedance is inductive, ferrite bead inductors are used to attenuate high-frequency signals in electronic components. When a ferrite bead choke is placed on the power line connecting to an electronic device, it removes any spurious high frequency noise present on a power connection or that is output from a DC power supply. This ferrite clamp use is one of many approach to noise suppression, such as that from a switched-mode power supply. This application of ferrite beads as a ferrite filter provides suppression and elimination of conducted EMI.

If you want to know how to select a ferrite bead for a design, you just have to pay attention to a bead’s specifications.

Ferrite Ceramic Cylinder Magnet 10mm x 10mm C5 / Y30BH

Hard Ferrite Cylindrical Magnet Bar Y30BH 4mm x 5mm

C8 Anisotropic Ceramic Cylinder Rod Bar Magnet Not Plated

Anisotropic Cylindrical Bar Ceramic Magnet C8

Shuttering Magnets for Precast

C1 Ceramic Bar Cylindrical Magnet for Medical Devices, Sensors, Electronics

C8 Ceramic Cylinder / Rod Magnet 6mm x 9.5mm