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PCB Tech

PCB Tech

PCB Tech

PCB Tech

How to carry out the anti-interference design of PCB circuit board?
2021-10-04
View:36
Author:Downs

The following is the anti-interference and design of the PCB circuit board

PCB design

The anti-interference problem is a very important link in modern circuit design, which directly reflects the performance and reliability of the entire system. The anti-jamming design of the printed circuit board is closely related to the specific circuit. Next, we will make some explanations on several common measures of PCB anti-jamming design.

1. Power cord design

According to the size of the printed circuit board current, try to increase the width of the power line to reduce the loop resistance. At the same time, make the direction of the power line and ground line consistent with the direction of data transmission, which helps to enhance the anti-noise ability.

pcb board

2. Ground wire design

The digital ground is separated from the analog ground. If there are both logic circuits and linear circuits on the circuit board, they should be separated as much as possible. The ground of the low-frequency circuit should be grounded in parallel at a single point as much as possible. When the actual wiring is difficult, it can be partially connected in series and then grounded in parallel. The high-frequency circuit should be grounded at multiple points in series, the ground wire should be short and thick, and the grid-shaped large-area ground foil should be used around the high-frequency component as much as possible.

The grounding wire should be as thick as possible. If a very thin line is used for the grounding wire, the grounding potential changes with the current, which reduces the noise resistance. Therefore, the ground wire should be thickened so that it can pass three times the allowable current on the printed board. If possible, the grounding wire should be 2~3mm or more.

The ground wire forms a closed loop. For printed boards composed only of digital circuits, most of their grounding circuits are arranged in loops to improve noise resistance.

3. Decoupling capacitor configuration

One of the conventional methods of PCB design is to configure appropriate decoupling capacitors on each key part of the printed board.

4. Methods to eliminate electromagnetic interference in PCB design

①Reduce loops: Each loop is equivalent to an antenna, so we need to minimize the number of loops, the area of the loop, and the antenna effect of the loop. Ensure that the signal has only one loop path at any two points, avoid artificial loops, and try to use the power layer.

②Filtering: Filtering can be used to reduce EMI both on the power line and on the signal line. There are three methods: decoupling capacitors, EMI filters, and magnetic components.

③Shielding.

④ Reduce the speed of high-frequency devices as much as possible.

⑤ Increasing the dielectric constant of the PCB board can prevent high-frequency parts such as the transmission line close to the board from radiating outward; increasing the thickness of the PCB board and minimizing the thickness of the microstrip line can prevent the electromagnetic wire from overflowing and also prevent radiation.