The function of magnetic beads is mainly to eliminate the RF noise of the circuit element symbols of magnetic beads existing in the transmission line structure (circuit). The 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 these unwanted signal energies, chip beads are used 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 frequency range, thereby improving the effect of FM filtering.
As power filter, inductance can be used. The circuit symbol of magnetic beads is inductance, but it can be seen from the model that magnetic beads are used. In terms of circuit function, magnetic beads and inductors are the same, but the frequency characteristics are different.
The DC component is the useful signal needed, while the RF energy is useless electromagnetic interference transmitted and radiated along the line (EMI). To eliminate these unwanted signal energies, a chip magnetic bead is used to act as a high frequency resistor (attenuator), which allows direct current signals to pass through and filter out AC signals. Usually the high frequency signal is above 30MHz, but the low frequency signal is also affected by the chip magnetic beads. The magnetic beads have high resistivity and permeability, which are equivalent to the series connection of resistance and inductance. In a circuit, a wire can pass through it. The high frequency current emits in the form of heat. Its equivalent circuit is a series of inductors and a resistance. The values of the two components are proportional to the length of the magnetic beads. Some magnetic beads have multiple holes, which can increase the impedance of the component (through the square of the number of beads). Ferrite beads can not only be used to filter high frequency noise in power supply circuits (for DC and AC output), but also be widely used in other circuits.
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