PCB Wiring Rules: Key Signal Line Priority

1. Prioritizing Key Signals

• Power supply
• Analog signals
• High-speed PCB signals
• Clock signals
• Differential signals
• Synchronization signals
• Other key signals

2. Wiring Requirements for Key Signals

Analog Signal Cabling

Analog signals are susceptible to interference, requiring protection during wiring:

• Shorten wiring for enhanced anti-interference capability.
• Relax impedance control for thicker wiring in some cases.
• Confine analog wiring away from digital signals to minimize interference.

High-Speed Signal Wiring

High-speed circuits demand specific wiring considerations:

• Utilize multi-layer boards for integration and interference reduction.
• Minimize lead bending to reduce foreign signal coupling.
• Prefer shorter leads to avoid impedance issues.
• Reduce layer alternation for improved speed.
• Monitor and mitigate parallel cross interference.
• Avoid branches and stubs in wiring for signal integrity.
• Route signal cables through inner layers to reduce radiation.

Clock Signal Cabling Requirements

Proper wiring for clock signals is crucial for circuit performance:

• Organize the clock tree and understand clock relationships.
• Maintain optimal routing layer for clock signals.
• Avoid crossing partitions or routing along partition areas.
• Maintain a minimum distance between clock signals and other signals.
• Ensure proper matching of clock signals.
• Use a star structure for clock signals and keep wires connecting crystal oscillator terminals short.

Differential Signal Wiring

Ensure consistency in differential signal transmission:

Maintain parallelism with uniform line width and spacing.

PCB Key Signal Wiring:

PCB Signal Integrity Best Practices

• Equal Length: It’s crucial to make sure that both lines are maximized in length to uphold opposing polarities and minimize common-mode interference.
• Equal Width and Spacing: Maintaining uniform line widths and consistent spacing is essential for preserving parallelism.

Don’t forget: Reserve specific layers for critical signals such as clocks, high-frequency transmissions, and sensitive signals. Implement proper shielding and adhere to recommended safety distances to uphold signal integrity.