I'm looking for a 3-meter USB-C cable that supports USB 3.2 Gen 2x2 at 20Gbps. Some listings claim to provide that speed, including cables around 2.5–3 meters long, but I thought the specification limited passive cables to about 1 meter. Are these longer cables genuinely capable of 20Gbps, or should I expect signal problems, reduced speeds, or occasional dropouts?
2 Answers
An e-marker is not the same thing as a retimer. E-markers identify the cable’s capabilities to the host, such as supported power levels, USB speeds, and cable type. They do not normally amplify or regenerate the high-speed data signal. A long 20Gbps cable needs suitable construction and, if it is active, additional signal-conditioning hardware. Some inexpensive listings may advertise the maximum speed without reliably achieving it, so independent testing is worth checking.
The roughly 1-meter limit generally applies to passive USB 3.2 Gen 2x2 cables. Longer cables can work if they use active electronics, such as a repeater or retimer, inside one of the connectors. Those components restore the signal so it can travel farther, although the cable may cost more and have other limitations.
Would those active components be the same as the e-marker chips mentioned in many product listings?