Common Mode and Differential Mode Noise

Designers have to live with the differential mode noise and this part of the return current generated from the noise sources of the circuit. Differential  mode noise can be eliminated by the chokes that are to be used in the live path and return path.

Common mode noise is something generated from the circuit due to parasitic capacitance of the noise components to ground. The common mode noise can be eliminated by using common mode chokes in the circuit.

The common mode noise and differential mode noise are generated by power supplies at harmonics of the switching frequency.

Common mode and Differential mode noise cause conducted emission problem in the circuits and radiated emission issue due to external cables.