CAPACITIVE COUPLING

 

CAPACITIVE COUPLING

A coupling capacitor is a capacitor which is used to transfer energy from one circuit to another.

It links only AC signal between circuit and blocks DC signal.

That is, it prevents DC signal entering in to the second circuit.

Where the capacitor should be placed in the circuit?

 

The capacitor is connected in series with the load to be coupled.

It blocks low frequencies such as DC signals and allows only high frequency signals.

It acts as high impedance for DC signal and low impedance for AC signal.

It is used wherever we need only AC signal output while DC signal is used to give power to the circuit parts.

For Example: In case of microphone circuit, we need DC power to operate and the output speech is AC signal. While the speech signal transfers from microphone to output device the DC power shouldn't influence it. There is the need for Capacitive Coupling.

The most significant uses of capacitive coupling is in the field of medical. Many of the medical instruments tap signals from human body at that time the DC power shouldn't influence on the other signals. If DC signal affects it then there is a severe chance of electrical shock. That is why we are using capacitive coupling in this place.