Nowadays, the sensitivity of electronic equipment is getting higher and higher, which requires the anti-interference ability of the equipment to be stronger and stronger. Therefore, in PCB design, how to improve the anti-interference ability of PCB has become the focus of many engineers. The following are the methods summarized by PCB engineers to reduce noise and electromagnetic interference in PCB design:
1. Do not use high-speed chips if you can use low-speed chips.
2. A resistor can be connected in series to reduce the speed of the control circuit.
3. Use the lowest frequency clock that meets the system requirements.
4. The clock generator should be as close as possible to the device using the clock.
5. Use the ground wire to surround the clock area, and keep the clock wire as short as possible.
6. Try to use a 45-degree folded line instead of a 90-degree folded line for the printed circuit board to reduce the external emission and coupling of high-frequency signals.
7. The printed circuit board is partitioned according to the frequency and current switching characteristics, and the noise components and non-noise components should be farther apart.
8. Clock, bus and chip select signals should be kept away from I/O lines and connectors.
9. The analog voltage input line and the reference voltage terminal should be kept away from the digital circuit signal line as far as possible.
10. The component pins should be as short as possible, and the decoupling capacitor pins should be as short as possible.
11. The key line should be as thick as possible, and protective ground should be added on both sides. High-speed lines should be short and straight.
12. Lines sensitive to noise should not be paralleled with high-current, high-speed switching lines.
13. Do not route wires under the quartz crystal or under noise-sensitive devices.
14. For weak signal circuits, low frequency circuits, do not form a current loop around them.
15. The signal should not form a loop. If it is unavoidable, make the loop area as small as possible.