An effective method for filtering high frequency power supply noise and cleanly sharing similar voltage supply rails (that is, analog and digital rails for mixed-signal ICs) while preserving high frequency isolation between the shared rails is the use of ferrite beads. A ferrite bead is a passive device that filters high frequency noise energy over a broad frequency range. It becomes resistive over its intended frequency range and dissipates the noise energy in the form of heat. The ferrite bead is connected in series with the power supply rail and is often combined with capacitors to ground on either side of the bead. This forms a low-pass filter network, further reducing the high frequency power supply noise.You could often seen it in your Mobile Phone Data Cables,Computer Charger Cables and so and so on.
Ferrite Beads are also used in Electronics Circuits for the effective filtration of high frequency noises. The image shown is the smd version of Ferrite beads used for filtration in Electronics circuits.
