Photocoupler

The reading: the capacitor can complete the coupling, filtering, bypass, decoupling, resonance, neutralization, compensation and other functions. Among them, the capacitor used to complete the coupling function is called the coupling capacitor. This paper mainly describes how the capacitor is coupled. What is the function of the coupling capacitor?

First, the principle of capacitive coupling - - Introduction

Coupling capacitor, the English name is Coupling capacitor, also known as electrostatic coupling or electric field coupling. Coupling refers to the phenomenon that a signal will be transmitted during the transmission of the signal from the front to the back to hinder the transmission of information. The coupling capacitor is Refers to the capacitor used to complete the coupling function. Corresponding to the coupling, there is also a phenomenon of decoupling, that is, filtering to eliminate the interference noise to complete the normal transmission of the signal from the previous stage to the latter stage.

Second, the principle of capacitive coupling - - coupling

There are many ways in which noise affects the signal transmission process. The coupling modes can be divided into direct coupling, common impedance coupling, capacitive coupling , electromagnetic induction coupling, radiation coupling, and leakage coupling. Among them, direct coupling means that interference signals directly enter the signal transmission system to generate interference; common impedance coupling means that the two circuits have common paths and cause interference to the system; capacitive coupling refers to interference phenomena due to the existence of distributed capacitance; Magnetic induction coupling refers to the coupling phenomenon caused by the interaction between electric and magnetic fields.

Third, the principle of capacitive coupling

In the DC circuit, the capacitor is equivalent to an open circuit, and the current cannot pass; and in the AC circuit, as the voltage of the capacitor is gradually increased, the accumulated charge on the electrode plate connected to the leg is gradually increased, and the voltage is gradually increased. Lowering, the charge accumulated on the corresponding electrode plate is also gradually reduced. In the whole process, the capacitor actually has no current passing through, but it seems that there is current passing through, so the coupling capacitor can be approximated in the AC circuit in this way. The transfer from the level to the next level.

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