Ferrite bead

Conversely, if there are other sources of EMI, such as household appliances, the bead prevents the cable from acting as an antenna and receiving interference from these other devices.

In addition, various smaller ferrite beads are used internally in circuits—on conductors or around the pins of small circuit-board components, such as transistors, connectors, and integrated circuits.

Beads can block low-level unintended radio frequency energy on wires intended to be DC conductors by acting as a low-pass filter.

Inside the bead component, a coil of wire runs between layers of ferrite to form a multi-turn inductor around the high-permeability core.

[4] Ferrite beads are used as a passive low-pass filter by dissipating radio frequency (RF) energy as heat by design.

A ferrite bead can be added to an inductor to improve, in two ways, its ability to block unwanted high frequency noise.

A design that uses a ferrite bead to improve noise filtering must consider specific circuit characteristics and the frequency range to block.