What is a Ferrite Bead?

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- everything RF

Jun 18, 2019

A Ferrite bead or ferrite choke is used to attenuate high-frequency electromagnetic interference (EMI) in a circuit. It works like a low pass filter that allows only low frequency signals to pass through a circuit and eliminates the high-frequency noise. Ferrite beads are used in most electronic devices like mobiles, laptops, TV tuners and gaming systems to minimize interference and ensure signal integrity. 

There are of two types of Ferrite Beads - Chip and Wirewound.

Wirewound Ferrite beads provide a high magnitude of attenuation over a wide frequency range, while traditional Chip Ferrite Beads have limited options for both attenuation and frequency range. Wirewound ferrite beads also have lower DC resistance (DCR) and higher current ratings.

All ferrite beads can operate up to a certain DC current, above which they get damaged. This value of current that a ferrite bead can handle is drastically affected by heat i.e., as the temperature increases the rated current value decreases.