Electromagnetic interference (EMI) and electromagnetic signal interference reducing signal integrity cables of electronic noise. Partial differential mode EMI interference and common mode interference, the interference effect is differential mode interference in the two lines, between the L and N electrical circuits such as single-phase, the same current conducting direction and the current direction of the signal transmission interference, co interference effect between a mold, the parasitic capacitance formed between the signal line and the signal lines in two, a passage, each of the interference current flows through the one-half and two signal lines in the same direction, and to ground public loop.
Electromagnetic interference will destroy the integrity of the signal, such as current acoustic sound of thunder release of radio wave interference ......
Examples eliminate electromagnetic interference: a common ring cable data lines, signal lines are not generally shield, it tends to be a good conductor of a high frequency signal, receiving the surrounding clutter environment in a variety of high frequency signal. WiFi signal / cell phone signal ......
Twelve EMI ATX switching power supply circuit, ATX power supply itself can be used as an electromagnetic radiation source, reduce the stability of the PC, using the EMI filter circuit capacitor and the common mode choke coil characteristics to filter out the EMI generated by the power system or electronic , in fact, it plays the role of a low-pass filter.
Principle common mode choke coil of the common mode interference suppression: when a common mode current flowing through the coil, since an isotropic common mode currents will produce a magnetic field in the same direction inside the coil increases the coil inductance of the coil showed high impedance, it produces a strong damping effect, in order to attenuate the common mode current filtering purposes.
Reproduced in: https: //www.jianshu.com/p/756a40d07281