Isolate Noise

To limit the amount of signal noise, following these guidelines:

• Maintain the maximum possible distance between high-speed clocks and periodic signals going to high-speed differential pairs and any connector leaving the PCB (e.g., I/O connectors, control and signal headers, or power).
• To minimize crosstalk, keep the high-speed clock and periodic signal trace lengths that run parallel to high-speed signal lines as short as possible. Based on EMI testing, the minimum suggested spacing to clock signals is 50 mils.
• Keep high-speed signals clear of the core digital logic. Internal state transitions produce high-current transients, which can be very difficult to filter.