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Common mode inductance filter circuit, La and Lb are common mode inductance coils. In this way, when the normal current in the circuit passes through the common mode inductance, the reverse magnetic fields generated by the currents in the inductance coils wound in the same phase cancel each other out. In this case, the normal signal current is mainly affected by the coil resistance. When the common mode current When passing through the coil, due to the isotropy of the common mode current, a magnetic field in the same direction is generated in the coil, which increases the induction of the coil, and makes the coil appear as high impedance and produces a strong damping effect. It is often used to filter common-mode electromagnetic interference signals in switching power supplies. EMI filtering is used to suppress electromagnetic waves generated by high-speed signal lines from radiating outward.

Common mode inductance filter circuit, La and Lb are common mode inductance coils. The two coils are wound on the same iron core with the same number of lights and phases. In this way, when the normal current in the circuit passes through the common mode inductance, the reverse magnetic fields generated by the currents in the inductance coils wound in the same phase cancel each other out. In this case, the normal signal current is mainly affected by the coil resistance. When the common mode current When passing through the coil, due to the isotropy of the common mode current, a magnetic field in the same direction is generated in the coil, which increases the induction of the coil, makes the coil appear high impedance, and produces a strong damping effect.
In fact, when one end of the filter circuit is connected to the interference source, and the other end is connected to the interference device, La and C1, Lb and C2 form two sets of low-pass filters, which can control the line common mode EMI signal to a low level . This circuit can not only suppress the incoming of external EMI signals, but also attenuate the EMI signals generated by the line itself, which can effectively reduce the intensity of EMI interference. A domestically produced small common mode inductor, adopts high-frequency noise suppression countermeasures, common mode choke coil structure, no signal attenuation, small size, easy to use, good balance, easy to use, high quality and other advantages. It is widely used in double-balanced tuning devices, multi-frequency transformers, impedance transformers, balanced and unbalanced transformers, etc.
Common mode inductor means that two coils are wound on the same iron core, the windings are opposite, the number of turns and phase are the same. It is often used to filter common-mode electromagnetic interference signals in switching power supplies. EMI filtering is used to suppress electromagnetic waves generated by high-speed signal lines from radiating outward.