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USB PCB Design Guide

Master USB 2.0, 3.0, and USB4 PCB layout. Learn differential pair routing, Type-C connector design, and signal integrity requirements for all USB generations.

USB Design Checklist

  • 90Ω differential impedance (±10%)
  • P/N length match within 5 mils
  • Maintain pair coupling throughout
  • Reference solid ground plane
  • Add ESD protection near connector

USB Specifications by Version

VersionSpeedImpedanceDiff PairsMaterialNotes
USB 2.0480 Mbps90Ω diff1FR-4D+/D- only
USB 3.05 Gbps90Ω diff2FR-4+SuperSpeed TX/RX
USB 3.110 Gbps85Ω diff2Mid-lossGen2
USB 3.220 Gbps85Ω diff4Mid-loss2x2 lanes
USB440 Gbps85Ω diff4Low-lossTunneling
USB4 v280 Gbps85Ω diff4Low-lossPAM3

USB Routing Guidelines

USB 2.0 (High-Speed)

  • 90Ω differential, 45Ω single-ended
  • Keep D+/D- pair together, minimize spacing
  • Max trace length ~6 inches without hub
  • Avoid stubs and vias in signal path

USB 3.x SuperSpeed

  • Separate TX and RX pairs (full duplex)
  • AC coupling caps 100nF near connector
  • Consider redriver for long traces
  • Mid-loss material for Gen2 (10G)

FAQ

What impedance is required for USB 3.0?

USB 3.0 SuperSpeed requires 90Ω ±10% differential impedance for both TX and RX pairs. The legacy USB 2.0 D+/D- pair in the same connector also requires 90Ω. Use controlled impedance stackups and maintain consistent trace geometry throughout the route.

How do I route USB Type-C for reversibility?

USB Type-C uses a symmetrical pinout for reversibility. Route both TX1/RX1 and TX2/RX2 pairs. A mux IC or Type-C controller handles lane switching. Keep both routing paths length-matched. The CC pins determine orientation and negotiate power/data modes.

What is the maximum USB 3.0 trace length?

USB 3.0 typically supports 3-5 inches of PCB trace without equalization. Longer routes require redriver/retimer ICs. USB 3.1 Gen2 (10G) is more sensitive - limit to 4 inches. Loss budget is ~8dB total at Nyquist. Use channel simulation to verify.