Three Principles in PCB Design
In order to reduce crosstalk between lines in PCB design, the 3W principle should ensure that the line spacing is large enough. When the line center spacing is not less than 3 times the line width, most of the electric fields can be kept from interfering with each other. This is the 3W rule. The 3W principle means that when multiple high-speed signal lines are routed over a long distance, the spacing should follow the 3W principle. For example, clock lines, differential lines, video and audio signal lines, reset signal lines and other system key circuits need to follow the 3W principle. Not all wiring on the board is mandatory to comply with the 3W principle. Satisfying the 3W principle can reduce the crosstalk between signals by 70%, while meeting 10W can reduce the crosstalk between signals by nearly 98%. Although the 3W principle is easy to remember, it should be emphasized that there are previous conditions for the establishment of this principle.