AN 958: Board Design Guidelines

ID 683073
Date 1/28/2022
Document Table of Contents Differential Trace Routing

To maximize signal integrity, proper routing techniques for differential signals are important for high-speed designs. Figure 25 shows a differential pair using the microstrip layout.

Figure 25. Differential Trace Routing
Note: Use the following guidelines when using two differential pairs:
  • D = Distance between two differential pair signals; W = Width of a trace in a differential pair; S = Distance between the trace in a differential pair; and H = Dielectric height above the group plane.
  • Make sure D > 2S to minimize the crosstalk between the two differential pairs.
  • To minimize reflection noise, place the differential traces S = 3H as they leave the device.
  • Keep the distance between the differential traces (S) constant over the entire trace length.
  • Keep the length of the two differential traces the same to minimize the skew and phase difference.
  • Avoid using multiple vias, because they can cause impedance mismatch and inductance.

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