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How does the signal frequency of the flat magnetic ring suppress the interference signal?
Edit:Dongguan Yufu Magnetic Material Technology Co., Ltd.   PublicDate:2019-05-15

Absorbing a flat magnetic ring, also known as a ferrite flat magnetic ring , referred to as a flat magnetic ring. The flat magnetic ring is a commonly used anti-interference component in electronic circuits, and has a good inhibitory effect on high-frequency noise, and is generally made of ferrite flat magnetic ring material (Mn-Zn).

The flat magnetic ring has different impedance characteristics at different frequencies. Generally, the impedance is small at low frequencies, and the impedance of the flat magnetic ring rises sharply when the signal frequency increases.

As we all know, the higher the signal frequency of the flat magnetic ring, the easier it is to radiate out (to buy a high-quality computer case is also to reduce electromagnetic leakage), and the general signal lines are not shielded, then these signal lines become A good antenna that receives all kinds of messy high-frequency signals in the surrounding environment, and these signals are superimposed on the originally transmitted signals, and even change the useful signals originally transmitted.

Different applications of different magnetic rings

1. The absorption filter composed of the magnetic ring to the ferrite magnetic ring and the magnetic beads, except for the consumable materials with high magnetic permeability, the resistance of the high-frequency components in the line is about ten to several hundred. Ω, so its role in high-impedance circuits is not obvious, on the contrary, it will be very effective in low-impedance circuits such as power distribution, power or RF circuits.

Second, in the high frequency band (greater than 10MHz), the inductive reactance remains small, and the impedance is so large that when the energy of the high-frequency signal passes through the magnetic material, it is converted into heat, which hinders the passage of the high-frequency signal and suppresses The interference of high-frequency signals, usually the optimal suppression frequency range is related to the ferrite suppression component. Generally, the higher the magnetic permeability, the lower the suppression frequency, the larger the ferrite volume, and the better the suppression effect. When the volume is constant, Long and thin than the short and thick suppression effect, the smaller the internal strength, the better the suppression effect.

Third, the magnetic ring has different impedance characteristics at different frequencies. Generally, the low frequency is small impedance, and the impedance rises sharply at high frequency. The higher the signal frequency, the easier the magnetic field radiates out. The general signal line is unshielded. For example, now I am The CAN bus used, these signal lines become the perfect antenna. This antenna constantly receives the surrounding high-frequency signals. The superposition of these signals changes the actual signal to be transmitted. The magnetic ring can pass the useful signal very well. At the same time, high frequency interference signals are suppressed.

4. When suppressing common mode signal interference, the magnetic ring can pass the signal (connected differential signal line) or the power line (positive and negative line) through the magnetic ring at the same time. In order to increase the effect, a circle can be symmetrically wound on the magnetic ring. Increase the inductance and enhance the absorption of the common mode signal, but it has no effect on the differential signal. The component should be installed close to the interference source. For the input and output circuit, it should be as close as possible to the inlet and outlet of the shielding box.

Then, under the action of the flat magnetic ring , the normally useful signal can pass well, and the high-frequency interference signal can be well suppressed, and the cost is low.

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