Differential mode current and common mode current (ZT)

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Differential mode current and common mode current (ZT) [Copy link]

An important basic concept about radiation is that "current causes radiation, not voltage". Static charge produces electrostatic field, constant current produces magnetic field, and time-varying current produces both electric field and magnetic field. Common mode current and differential mode current exist in any circuit. Generally speaking, differential mode signals carry data or useful signals (information). Common mode is the negative effect of differential mode. 2. Differential mode current is equal in magnitude and opposite in direction (phase). Due to the distributed capacitance and inductance of the wiring, the discontinuous impedance of the signal wiring, and the unexpected path of the signal return path, the differential mode current will be converted into the common mode current. 3. The common mode current is not necessarily equal in magnitude, but the direction (phase) is the same. The external interference of the equipment is mostly common mode, and differential mode interference also exists, but the strength of the common mode interference is often several orders of magnitude greater than the differential mode strength. External interference is also mainly common mode interference. Common mode interference itself generally does not cause harm to the equipment. However, if the common mode interference turns into differential mode interference, the interference will be serious because the useful signals are all differential mode interference.