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We're doing a PCB for a customer that has Impedance controlled tracks for a microcontroller that seemingly might be max USB2.0, judging from lack of multiple data lines and the fact it goes in a micro-usb connector. The data lines are made naturally with differential pair.

We're doing the board buildup according to the specified 100ohm impedance, but I was still wondering, is it really required at these speeds? As far as I remember the data line for USB2.0 is like 240MHz, so not really in the GHz ranges.

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  • \$\begingroup\$ Have you come across the concept of signal reflections causing data errors? \$\endgroup\$
    – Andy aka
    Commented Apr 18 at 9:31
  • \$\begingroup\$ Impedance control is as necessary as any other high-speed application, in relation to the signal levels and thresholds / eye diagram, and the bit rate to the length of impedance mismatch/discontinuity in question. What trace lengths will you board use? \$\endgroup\$
    – Tim Williams
    Commented Apr 18 at 11:19
  • \$\begingroup\$ USB2 signals definitely extend up past 1 GHz. \$\endgroup\$
    – user1850479
    Commented Apr 18 at 12:56
  • \$\begingroup\$ @TimWilliams 67 millimeters \$\endgroup\$
    – Jakesan
    Commented Apr 19 at 6:09

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