We would like to talk to you about the layout of ground wires in different layers of PCB boards, which will be of great help to you when laying out ground wires on different PCB boards.
1. Ground wire layout of single-sided PCB board
In the process of grounding the single-sided PCB board, it is necessary to start the layout from the power supply design and the grounding design. The single-panel ground wire layout has certain limitations in the actual layout process, such as: it will have a very sensitive response to external radio frequency, and the necessary conditions for high-frequency circuits in the implementation process are limited, and there is no flux cancellation. conditions and the return path of the RF. Therefore, in the process of designing the power and ground wires, the radial routing method is first used to arrange the power and ground wires according to the shape of the branches. At the same time, the following three design requirements should also be met: first, when designing the ground wire, radial routing must be used to distribute the ground wire and power supply in all single-sided PCB boards to ensure the shortest overall line; second , When wiring, the power supply and grounding wires should be set close to each other; thirdly, avoid connecting different branches of the branch routing together to avoid the phenomenon of loop current.
2.The layout of the ground wire of the double-layer PCB board
In the design process of the double-layer PCB board, in the process of designing the digital circuit, when choosing the wiring method, the lattice wiring or the grid wiring can be preferred. This wiring method can minimize the ground impedance. In the process of laying the ground wire of the double-layer PCB board, there are mainly two wiring schemes that can be used. One is to treat the double-layer PCB board as a single-layer PCB board, and design it with single-layer design specifications. In either case, ground loop control must be ensured. Make sure to leave enough space for the power supply during the design process, and fill in the remaining part as a reference ground. Another solution is to separate the ground layer from the power lines and signals. This wiring method can effectively reduce the ground loop and ground impedance in the actual application process. However, in this solution, The resulting distance between the reference plane and the signal lines is already the same as 8 times the width of the printed lines, which makes it impossible for flux cancellation to work well. However, decoupling capacitors can be placed in close proximity between the IC supply lines and the ground plane.
3. Ground wire arrangement in multi-layer PCB board
In a multi-layer PCB board, it is necessary to place the power supply layer and the bottom line layer on the adjacent layers, and the main purpose of this placement is to ensure the maximum capacitance formed in the PCB board. When placing high-speed signal lines, it must be placed as close as possible to the ground plane, and other signal lines should be as close to the power plane as possible during the setting process. In the process of arranging the ground wire, as long as the ground wire is arranged reasonably, the ground impedance can be reduced to the greatest extent, thereby effectively reducing the electromagnetic interference.
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