What is the working principle of ferrite beads?
What is the working principle of ferrite beads?
Ferrite beads are common anti-interference components and tools that can be used for Anti-interference components of electronic communication equipment. Because ferrite can attenuate higher frequencies and let lower frequencies pass almost unimpeded, it has been widely used in EMI control. At the same time, it has better high-frequency filtering characteristics than ordinary inductors and shows resistance at high frequencies, so it can maintain high impedance in a fairly wide frequency range, so as to improve the effect of frequency modulation filtering.. Magnetic rings / beads for EMI absorption can be made into various shapes and are widely used in various occasions.
Ferrite beads have high resistivity and permeability, which is equivalent to resistance and inductance in series, but both resistance and inductance change with frequency. It has better high-frequency filtering characteristics than ordinary inductors, showing resistance at high frequencies, so it can maintain a high impedance in a fairly wide frequency range, so as to improve the effect of FM filtering.
For example, on PCB board, it can be added to dc/dc module, data line, power line, etc. It absorbs the high-frequency interference signal on the line, but it will not produce new zeros and poles in the system and will not damage the stability of the system. When it is used with power filter, it can well supplement the performance of the high-frequency end of the filter and improve the filtering characteristics of the system.
Ferrite magnetic beads can not only be used in power circuits to filter out high-frequency noise (DC and AC output), but also can be widely used in other circuits, and its volume can be made very small. Especially in digital circuits, because the pulse signal contains high-frequency harmonics, which is also the main source of high-frequency radiation of the circuit, it can play the role of magnetic beads in this occasion. Ferrite magnetic beads are also widely used in noise filtering of signal cables and wires.