2 Interface USB 3.0 SuperSpeed
2.9 USB 3.0 cabling

The following figure shows cross section of cable in USB 3.0 specification. There are three visible groups of wires - signaling pair UTP (Unshielded Twisted Pair), crossed pairs (shielded differential pairs SDP (Shielded Differential Pairs)) and the power and ground wires.

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Cross section of cable in USB 3.0 specification

UTP is designed for transmission of signals USB 2.0, SDP are for USB SuperSpeed specification. It is evident from the name, SDP pairs have their own shielding for signal integrity and limitation of EMI. Additionally, each shielded pair of has additional wire, called as DRAIN, which is connected to the grounded pin connector (different from the ground power supply, denoted as GND_DRAIN).

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Diagram of cable in USB 3.0 specification

Shielding closing all cable wires is realized by a metallic braiding connected to a metal part of the connector and it serves to eliminate the EMI disturbance. The colors in the images match with the colors of insulated wires.

The cable length is not limited by specification, but it is limited by losses to build of connection and voltage drop on the whole cable length. These losses for the cable must not exceed the limit of 20 dB. This corresponds to the maximum recommended cable length up to 3 m.