What Is Capacitive Coupling?

Capacitive coupling: also known as electric field coupling or electrostatic coupling, is a coupling method due to the presence of distributed capacitance. Coupling refers to the process of transmitting signals from the first stage to the second stage. Generally, it refers to AC coupling when not specified.

Capacitive coupling: also known as electric field coupling or electrostatic coupling, is a coupling method due to the presence of distributed capacitance. Coupling refers to the process of transmitting signals from the first stage to the second stage. Generally, it refers to AC coupling when not specified.

Chinese name

Capacitive coupling

Foreign name

capacitive coupling

Capacitive coupling definition

Decoupling refers to taking further filtering measures on the power supply to remove the influence of the interference between the signals between the two stages through the power supply.

Coupling constant refers to the time constant corresponding to the product of the coupling capacitance value and the input impedance value of the second stage.

Decoupling serves three purposes:

1. Remove the high-frequency ripple in the power supply, and cut off the high-frequency signals of the multi-stage amplifier through the path of crosstalk between the power supplies;

2. During large-signal operation, the circuit requires more power, causing power fluctuations. Decoupling reduces the impact of power fluctuations on the input stage / high-voltage gain stage during large signals;

3. To form a floating ground or a suspended power supply, complete the coordination of each part of the ground wire or power supply in a complex system, and the high-frequency switching noise generated by the active device during switching will propagate along the power line.

The main function of the decoupling capacitor is to provide a local DC power supply to the active device to reduce the propagation of switching noise on the board and guide the noise to ground.

Coupling method of capacitive coupling interference

The interference signal generated by the interference source has electromagnetic interference on the electronic control system through a certain coupling channel. The coupling mode of interference is nothing more than electrical wires, spaces, public wires, etc. acting on the electronic control system.

There are several types of analysis.

Direct coupling: This is the most direct way of interference intrusion, and it is also the most common way in the system. For example, the interference signal directly invades the system through the wire and causes interference to the system. For this coupling method, filtering decoupling can be used to effectively suppress the introduction of electromagnetic interference signals.

Common impedance coupling: This is also a common coupling method. It often happens that the currents of the two circuits have a common path. There are two types of common impedance coupling: common ground and power source impedance. To prevent such coupling, the coupling impedance should approach zero, so that there is no common impedance between the source of interference and the victim.

Capacitive coupling: also known as electric field coupling or electrostatic coupling, is a coupling method due to the presence of distributed capacitance.

Electromagnetic induction coupling: also known as magnetic field coupling. It is a coupling method induced by the electromagnetic field in the internal or external space. A common method to prevent this coupling is to shield the components or circuits that are easily interfered.

Radiation coupling: The radiation of the electromagnetic field will also cause interference coupling, which is a kind of random interference.

This interference can easily be transmitted to the system through the power cord. In addition, when signal transmission lines are longer, they can radiate interference waves and receive interference waves, which is called the large line effect.

Leakage coupling: The so-called leakage coupling is the resistive coupling. This interference often occurs when the insulation is reduced.