We all know that when doing PCB planning, the general PCB board only needs to do a precise planning of the mechanical scale. However, if you encounter high-frequency signals, load lines or long lines, etc., these lines must be specially treated. Otherwise, it is likely to cause a series of signal disturbances such as reflection and crosstalk between lines. problem. Therefore, when we are doing PCB planning, especially when doing high-speed PCB planning, we must do a good job in line signal imitating interference, and shielding measures are often necessary.

Next, let's talk about how to plan the electromagnetic compatibility for PCB planning and wiring:

1. Appropriate wire width
When selecting the wire width, it is necessary to ensure both electrical performance and ease of production. It is usually confirmed by the minimum current value it bears. In order to reduce the electromagnetic disturbance impact of the transient current on the PCB board, it is necessary to control the line width in the planning. Transient disturbance is generally caused by the inductance of the wire, and its inductance is proportional to the length of the wire and inversely proportional to the line width. Regarding signal lines, there are often very large transient currents, and short and wide wires should be adopted. If the layout space permits, the tic-tac-toe mesh layout structure should be used as much as possible.

2. The key to meta-equipment wiring
In the planning of meta-equipment wiring, several aspects should be considered first:
The first is electrical performance; when wiring, we try to put the equipment closer to the connection together. The layout of the high-speed line should be as short as possible, and the power equipment and small signal equipment should be separated.
The second is the location; whether the plan is beautiful and regular, whether it is convenient for function testing, later interface and connection use. In a high-speed system, the transmission delay of grounding and interconnecting lines is also the first planning factor we need to consider. The transmission time of signal transmission lines has a great impact on the overall system rate of the circuit. If it is used where high-speed lines are used The general interconnection line will increase the delay time, making the system speed drop greatly.

3. Wiring rules for high-frequency and high-speed signals
Generally, equal wiring can reduce the inductance between wires, but in order to suppress the crosstalk of PCB circuit wires, we should try our best to prevent long-distance equal wiring when planning the wiring; when planning printed wires, we should prevent rapid turns and try to plan into It has a uniform curve with a certain radian; there are high-current components on the circuit, and the ground wire should be separated as far as possible to prevent noise interference. Grounding is set between small signal or sensitive signal wires; high-speed signals use differential signal wiring planning, The two differential lines in the positive and negative pairs are always coupled to each other on the transmission line, effectively reducing the electrical noise effect of the signal.