Electronic – Can USB 3.0 tracks be closer together than 5W if they’re quite short

crosstalkdifferentiallayoutpcbusb

I am currently laying out a space constrained PCB which contains some USB 3.0 Superspeed differential pairs. These USB signals are confined to the PCB, going from a Cypress CX3 chip to a USB 3.0 Hub chip. They do not go to or come from a connector. The signals are approximately 30mm long from start to end.

USB 3.0 differential pairs

According to the advice, the Superspeed pairs should be separated from each other by at least 5x the differential pair spacing. (This is known as the 5W rule)

Since the signals are fairly short, and do not go through a connector or cable, would it be possible to push them a little closer than 5W? Say, 4W or 3W?

Best Answer

The document you linked says this: -

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Does that help you? Can you place ground between or can you route on different layers separated by a ground plane? See also section 7.2 of that document.