Common mode disturbance is a noise current that has leaked via a stray capacitance or something similar that passes through ground and returns to the power supply line. These types of noise are conducted emissions. However, noise currents are flowing in power supply lines, and therefore, noise is radiated.
Common-mode disturbances have the following meanings:
-
Interference that appears on both signal leads (signal and circuit return), or the terminals of a measuring circuit and ground.
-
A form of coherent interference that affects two or more elements of a network in a similar manner (highly coupled) as distinct from locally-generated noise or interference that is statistically independent between pairs of network elements.
Common mode disturbance may be isolated from the desired signal by various means:
-
Common mode disturbance may be sensed and fed back negatively into object providing the signals.
-
Both signal and signal-return may be applied to the primary of a transformer, with the signal taken from the secondary. As common-mode interference will not cause current to be induced in the primary, no signal from this source will be seen in the secondary, while differential signals on the primary will cause current in the primary and therefore cause induced voltage in the secondary.
-
A signal transformer may have a center-tapped primary to ground, with the signal and signal return operating as a balanced line (push-pull technique). This is advantageous; its resistance to signals raised on ground due to ground loop induction and ground circuit resistance.
-
The signal (line and return) may be used to drive the LED in an optoisolator. An optoisolator (also known as an optical coupler) is a semiconductor device that uses a short optical transmission path to transfer an electrical signal between circuits, or elements of a circuit, while keeping them electrically isolated from each other.
You may also refer to the following Power Management video for additional overview information about power.
Comments
0 comments
Please sign in to leave a comment.