The function of the magnetic bead is mainly to eliminate RF noise existing 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, chip magnetic beads are used to act as high frequency resistors (attenuators).
Magnetic beads have very high resistivity and permeability, which is equivalent to resistance and inductance in series, but the resistance value and inductance value vary with frequency. It has better high-frequency filtering characteristics than ordinary inductors, showing resistance at high frequency, so it can maintain a relatively high impedance in a wide frequency range, so as to improve the effect of frequency modulation filtering.
As a power filter, inductors can be used. The circuit symbol of the magnetic bead is the inductance but the model number shows that the magnetic bead is used. In circuit function, magnetic beads and inductors are the same principle, only the frequency characteristics are different.
The DC component is needed as a useful signal, while the RF energy is useless electromagnetic interference transmitted and radiated along the line (EMI). To eliminate this unwanted signal energy, a chip magnetic bead is used to act as a high-frequency resistor (attenuator), a device that allows DC signals to pass through while filtering out AC signals. Usually high frequency signals are above 30MHz, however, low frequency signals can also be affected by chip beads. Magnetic beads have very high resistivity and permeability, equivalent to resistance and inductance in series. As long as the wire runs through it in the circuit. The equivalent circuit is an inductor and a resistor in series. The values of both components are proportional to the length of the magnetic bead. Some magnetic beads have more than one hole, the wire through can increase the component impedance (through the square of the number of magnetic beads). Ferrite magnetic beads can not only be used to filter high-frequency noise in power supply circuit (can be used for DC and AC output), but also can be widely used in other circuits.
Magnetic beads have excellent performance of suppressing electromagnetic interference, and are widely used in computer, VCD and other fields.
Magnetic beads on high frequency signal has a larger obstruction effect, the general specification has 100 euro /100MHZ, it is much smaller than the inductor resistance at low frequency.