Good USB Routing Practices

Trace length Matching

Intel suggests that USB traces be matched to 150 mils within each other in length.
Trace spacing is debated.
- Intel suggests 20 mils spacing between the USB traces.
- Texas Instruments suggests a minimum of 30 mils.
- Other sources suggest 5x the trace widths as trace spacing.
To forcefully match trace lengths, bend traces in a “zigzag” pattern at the mismatched end.
- Diagram from Texas Instruments PDF

Run USB lines in parallel at all times.
Avoid jumping voids in ground planes.
Lines may have to be routed non-parallel near connectors and controllers. If so, make sure the non-parallel area is within 0.25 inches of the connector and controller.
Don’t bend USB signal lines at right angles.
Try keeping the traces at least 100 mil from the edges of ground planes.
Don’t run the USB signals in parallel to other pulsating traces such as the keyboard matrix or LED backlighting. If this is required, keep the traces at least 50 mils away.
When the traces must go through parts (I.E. the 22-ohm resistors), keep the layout symmetric
- Diagram from Texas Instruments PDF