Introduction to Coupling

Before getting into the term coupling, let's look at an example of a stereo phono amplifier circuit. , each speaker is directly connected to the amplifier, there will be no sound without the amplifier; at the same time, the amplifier and the stereo phono are also directly connected.

However, the left and right speakers are not directly connected. We can unplug one speaker at will without affecting other devices. It can be seen that the coupling between the speaker and other devices is extremely weak. The coupling between them is very loose (loose), that is, the modules can be separated by simply unplugging the plug without using a soldering iron to desolder the wires or solder tabs on the printed board. On the contrary, if we connect the modules by wire welding, the coupling between them will be tighter.

In an electronic circuit, when several circuits form a network with a common impedance, a change in voltage or current in one circuit can cause corresponding changes in other circuits. According to the nature of the common impedance, it can be divided into resistance coupling, inductive coupling, capacitive coupling and resistance-capacitive coupling, etc.