For the two -layer board, because the number of plates is small, there is no problem with overlapping layers. Control EMI radiation is mainly considered from wiring and layout;

　　The electromagnetic compatibility of single -layer and double -layer boards is becoming more and more prominent. The main reason for this phenomenon is that the area of the signal circuit is too large, which not only produces strong electromagnetic radiation, but also makes the circuit sensitive to the external interference. To improve the electromagnetic compatibility of the line, the easiest way is to reduce the circuit area of the key signal.

　　Key signals: From the perspective of electromagnetic compatibility, the key signal mainly refers to the signal of strong radiation and a sensitive signal to the outside world. Signals that can generate strong radiation are generally cyclical signals, such as clocks or address low signals. A signal that is sensitive to interference refers to those lower levels of analog signals.

　　Single and double -layer boards are usually used in low -frequency simulation design below 10kHz:

　　1) On the same layer of power routing, the length of the length of the line is used;

　　2) When taking the power supply and ground line, approach each other; set a ground wire on the side of the key signal line. This ground line should be as close to the signal line as possible. In this way, a smaller circuit area is formed to reduce the sensitivity of differential radiation to external interference. When a ground line is added next to the signal line, a smallest loop is formed. The signal current will definitely get this circuit instead of other ground line trails.

　　3) If it is a dual -layer line board, you can get on the other side of the line board, close to the signal line, and lay a ground wire along the signal line, as much as possible on the front line. The thickness of the circuit formed in this way is equal to the thickness of the circuit board multiplied by the length of the signal line.