# How to jumper differential pair wires for USB 3.0 Superspeed?

Building a USB 2.0 speed cable is almost trivial. Simply connecting D+ and D- through any sort of wiring seems to allow full 480 MBps speeds.

Now I want to jumper a USB-C connector to a USB3.0 Type-A connector as shown. The distances involved are short as you can tell.

I can achieve USB 2.0 speeds no problem by connecting D+ and D- using jumper wire. Easy.

However, using twisted pair wires to jumper SSTX+/SSTX- to TX2+/TX2-, and SSRX+/SSRX- to RX2+/RX2- fail to allow the device to negotiate up to USB3 Superspeed. Note: The device still connects as a USB 2.0 device and operates properly at USB2 speeds.

If I connect the device directly to the computer, it properly negotiates USB3 superspeed and operates at USB3 speeds.

Yes, the same problem occurs if I use TX1 and RX1 - the orientation of the USB-C doesn't matter.

Help?

Note: The USB-C cable is actually a USB-A to usb-C superspeed cable. Yes, I have verified continuity on the breakout PCBs shown by connecting them to both ends of the same cable. Circuit continuity between the differential pair pins is verified.

• Does your "twisted pair" have the required differential impedance ($90\Omega \pm 7\Omega$)? A mismatch, even if it's only a few inches long, can seriously degrade the waveform at 5 Gbps. Note that even Cat6 Ethernet cable, with a nominal impedance of $100\Omega$, falls outside this specification. BTW, you've had better luck than I have with high-speed USB -- I've had all kinds of subtle problems trying to pass it through various board-to-board and board-to-wire connectors. – Dave Tweed Aug 16 '18 at 13:11
• Thanks. I'll try again with 90 ohm differential impedance wiring for the differential pairs. I am working with Appendix C of the USB3 spec to determine conformance to the spec. usb.org/developers/docs/devclass_docs/… – hype Aug 16 '18 at 14:26
• What is the purpose of this exercise? – Ale..chenski Aug 17 '18 at 2:20
• To jumper these two boards together. – hype Dec 14 '18 at 14:23