Q: How to route USB 2.0/3.0 differential pairs on PCB with proper impedance control?
Answer
USB 2.0 (480 Mbps): route D+ and D- as a differential pair with 90 Ohm +-15% differential impedance. Keep intra-pair length match <75 um to avoid skew. Keep pair away from switching power supplies by >3 mm. Route on top or bottom layer with solid ground reference beneath. Use 45-degree bends not 90. Maintain consistent trace width and spacing – avoid via transitions mid-pair. For USB 3.0 SuperSpeed (5 Gbps): differential impedance 90 Ohm +-10% keep intra-pair <50 um. Route TX/RX pairs on adjacent layers with ground between them. Use retimer/redriver ICs for >20 cm traces at USB 3.0 speeds. Shield connector with solid ground ring.
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