The function of magnetic bead is to eliminate the RF noise of the circuit symbol of magnetic bead in the transmission line structure (circuit). RF energy is the ac sine wave component superimposed on the dc transmission level, and the dc component is the useful signal needed. To eliminate this unwanted signal energy, the chip magnetic beads act as high frequency resistors (attenuators).

Magnetic beads have high resistivity and permeability, which are equivalent to series resistance and inductance, but the resistance and inductance vary with frequency. Compared with ordinary inductors, it has better high frequency filtering characteristics and presents resistance at high frequency, so it can maintain high impedance in a wide range of frequencies, thus improving the effect of FM filtering.

As a power filter, inductors can be used. The circuit symbol of the magnetic bead is the inductor, but it can be seen from the model that the magnetic bead is used. Magnetic beads and inductors work the same way, but with different frequency characteristics.

Dc components are needed for useful signals, while RF energy is useless for electromagnetic interference along the line transmission and radiation (EMI). To eliminate this unwanted signal energy, the chip magnetic beads act as high frequency resistors (attenuators) that allow dc signals to pass through and filter out ac signals. Usually, the high frequency signal is over 30MHz, however, the low frequency signal will also be affected by the chip magnetic bead. Magnetic beads have high resistivity and permeability, equivalent to series resistance and inductance. In a circuit, you just pass the wire through it. High frequency current is distributed in the form of heat, and its equivalent circuit is a inductor and a resistor in series. The values of both components are proportional to the length of the magnetic bead. Some magnetic beads have multiple holes through which a wire can increase the impedance of the component (the square of the number of passes through the magnetic beads). Ferrite magnetic beads can not only be used to filter high frequency noise in power circuits (they can be used for dc and ac output), but also can be widely used in other circuits.