Electromagnetic compatibility problems a printed circuit board, the first consideration is how to arrange layer. Typically, a single layer PCB panel consists essentially of the power supply, signal layers, and they will decide the orientation in which the single-sided PCB electromagnetic compatibility.
The actual number of PCB by a single panel power, signal password signal, and integration of the overall performance of single-sided PCB, PCB to establish a single panel layers. In the control circuit in the digital signal processor, having the following multiple power: + 15V-A, + 15V-P, EX5V, VDD1.8 like. In these multi-channel power supply, + 15V-A conditioning circuit can be powered, EX5V circuitry capable of communicating, VDD1.8 core supply can be performed. At the same time, also it has a lot of variety, in which mainly include DGND, PGND, EXGND. DGND is represented digitally, the PGND represents a protection circuit, the communication is represented EXGND circuit ground.
To prevent interlace signal power occur, while ensuring that the ground has integrity, it is preferable to use a four-layer plate structure. Wherein the top layer belonging to the signal layer, the intermediate layer composed of a ground plane and a power plane. Not too thick core plate between the ground plane and power, distributed capacitance may be employed to achieve the purpose of decoupling.
In the control circuit of the signal processor, the division circuit according to all the various functional circuit module. The main circuit is divided into a power supply circuit, A / D circuit, a conditioning circuit, a communication circuit or the like. In the process of the printed circuit board design, the signal flow through the actual situation, the division circuit module, try to make shorter the wiring path, but do not appear when interleaving between all parties, reduce the degree of the mutual interference of the various modules .
The signal frequency can be divided into two kinds of high and low frequency circuits. Typically, high-frequency circuit traces be shorter, it is possible to avoid sensitive circuit.
Circuit layout according to the signal flow, try to make a major high-speed signal traces shorter, but also to make some neat circuit board. The clock signal to be as short as possible. Also shield the signal lines that are sensitive.