{"id":2567,"date":"2023-12-20T10:11:09","date_gmt":"2023-12-20T02:11:09","guid":{"rendered":"https:\/\/www.jingpengpcb.com\/?p=2567"},"modified":"2026-10-02T17:33:48","modified_gmt":"2026-10-02T09:33:48","slug":"nine-high-speed-pcb-signal-routing-rules","status":"publish","type":"post","link":"https:\/\/www.jingpengpcb.com\/en\/blog\/nine-high-speed-pcb-signal-routing-rules\/","title":{"rendered":"Nine Rules for High-Speed PCB Signal Tracing"},"content":{"rendered":"

To ensure the performance and stability of printed circuit boards, there are a number of key high-speed PCB design rules that must be followed. This article will introduce nine high-speed PCB design rules that will help reduce electromagnetic interference (EMI) and improve circuit performance.<\/p>\n

\"Nine<\/p>\n

Shielding Rules for High-Speed Signal Cables<\/h2>\n

In high-speed PCB design, critical high-speed signal lines, such as clock lines, must be shielded. Failure to shield them, or shielding only a portion of the signals, will result in EMI leakage. Therefore, it is recommended to drill holes to ground every 1,000 mils to ensure complete shielding of the signal lines.<\/p>\n

Closed-Loop Rules for High-Speed Signals<\/h2>\n

In high-density PCB design, closed-loop errors can easily occur, especially in high-speed signal networks such as clock signals. Closed loops can cause antenna effects and increase EMI radiation levels. Therefore, closed loops must be avoided during the design process.<\/p>\n

Open-Loop Rules for High-Speed Signals<\/h2>\n

In contrast to closed loops, open loops can also cause EMI radiation. When high-speed signal networks form open loops on multilayer PCBs, they create linear antennas, which also increase EMI radiation. Therefore, open loops should be avoided as much as possible.<\/p>\n

Continuity Rule for Characteristic Impedance of High-Speed Signals<\/h2>\n

When switching between layers on high-speed signal traces, it is essential to ensure continuity of the characteristic impedance. This means that the trace width must remain consistent within the same layer, and the impedance of the signal traces must also be continuous across different layers to minimize EMI radiation.<\/p>\n

Rules for Routing Directions in High-Speed PCB Design<\/h2>\n

Trace routing between adjacent layers must follow the principle of vertical routing to avoid crosstalk between traces and thereby reduce EMI radiation. Simply put, adjacent routing layers should use a vertical routing direction to suppress crosstalk.<\/p>\n

Topology Rules in High-Speed PCB Design<\/h2>\n

High-speed PCB design requires controlling the characteristic impedance of the circuit board and considering the topological structure under multiple-load conditions. This directly affects the success of the product. In the design process, it is recommended to use a star-symmetric structure rather than a daisy-chain topology to achieve better performance.<\/p>\n

Resonance Rules for Trace Lengths<\/h2>\n

It is very important to check whether the length of the signal line and the signal frequency create resonance. When the line length is equal to one-quarter or an integer multiple of the signal wavelength, resonance occurs, which can cause interference. Therefore, it is necessary to carefully control the line length.<\/p>\n

Backflow Path Rules<\/h2>\n

All high-speed signals must have a good return path. Make every effort to ensure that the return paths for high-speed signals, such as clock signals, are as short as possible to minimize the radiated area and thereby reduce EMI emissions.<\/p>\n

Rules for Placing Decoupling Capacitors on Components<\/h2>\n

The placement of decoupling capacitors is critical. Improper placement may result in poor decoupling performance. Decoupling capacitors should be placed as close as possible to the power supply pins, and the area enclosed by the capacitor\u2019s power and ground traces should be kept as small as possible.<\/p>\n

By following these nine key rules, high-speed PCB design engineers can improve circuit performance, reduce EMI emissions, and ensure product reliability and stability.<\/p>\n

\n

5 Common Questions (FAQs)<\/strong><\/p>\n

What is high-speed PCB design?<\/strong><\/p>\n

High-speed PCB design is a method of circuit board design that focuses on handling high-frequency signals and high-speed data transmission.<\/p>\n

Why is it important to avoid closed-loop and open-loop systems?<\/strong><\/p>\n

Closed-loop and open-loop systems can cause electromagnetic interference (EMI), which affects circuit performance and reliability.<\/p>\n

What is characteristic impedance?<\/strong><\/p>\n

Characteristic impedance is the combination of resistance and inductance in a circuit's signal lines, and it is very important for high-speed signal transmission.<\/p>\n

What is crosstalk?<\/strong><\/p>\n

Cross-talk refers to mutual interference between adjacent signal lines, which can cause signal distortion.<\/p>\n

Why is it important to control resonance in trace lengths?<\/strong><\/p>\n

Resonance caused by long trace lengths can generate interference and degrade circuit performance.<\/p>","protected":false},"excerpt":{"rendered":"

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