Q: What is the correct way to route differential pairs for USB HDMI and Ethernet?
Answer
Maintain consistent differential impedance throughout: 90 Ohm +-10% for USB 2.0/3.0 100 Ohm +-10% for Ethernet. Keep intra-pair length mismatch < 0.25 mm for USB 2.0 and < 0.15 mm for USB 3.0 (5 Gbps). Route differential pairs with constant spacing not tapered or asymmetric. Avoid 90-degree corners - use 45-degree mitered bends or rounded corners. Separate differential pairs by at least 3x the trace-to-plane height from other signals. Use ground stitching vias within 3 mm of pair discontinuities. Do not route over split planes or through connectors with asymmetric pinout. For HDMI TMDS keep lengths matched per pair.
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