The filtering principle of China Common-mode inductor products

Release time:

Mar 27,2022

When a common mode current is generated on the wire, strong electromagnetic radiation will be generated on the wire, which will cause electromagnetic interference to electronic products and affect the performance of the product. At this time, it is necessary to use China Common-mode inductor products.

The filtering principle of China Common-mode inductor products:
The filter circuit of China Common-mode inductor products, La and Lb are common mode inductor coils. The two coils are wound on the same core with the same number of turns and phases (winding reversed). In this way, when the normal current in the circuit flows through the China Common-mode inductor products, the currents generate opposite magnetic fields in the inductive coils wound in the same phase and cancel each other out. At this time, the normal signal current is mainly affected by the coil resistance (and a small amount of Damping due to leakage inductance); when there is a common mode current flowing through the coil, due to the same direction of the common mode current, a magnetic field in the same direction will be generated in the coil and the inductive reactance of the coil will be increased, making the coil appear as high impedance , resulting in a strong damping effect, thereby attenuating the common mode current to achieve the purpose of filtering.
Precautions for the use of China Common-mode inductor products:
Usually, at the same time, pay attention to selecting the frequency band to be filtered. The larger the common-mode impedance, the better. Therefore, when choosing China Common-mode inductor products, you need to look at the device data, mainly based on the impedance-frequency curve. In addition, pay attention to the influence of differential mode impedance on the signal when selecting, mainly focus on differential mode impedance, and pay special attention to high-speed ports.