Comment by zeusk
11 hours ago
> copper can barely support 10G and is terribly power hungry when it does that.
AFAIK, thunderbolt cables are also copper - so what trickery do they use for supporting USB4-80? i believe both connectors use differential pair wires for signalling.
The longer Thunderbolt (which is actually just USB4) cables internally use fiber optics for data transmission, with converters to copper in each connector. Even the medium-distance (3 meter) ones have signal quality boosters in each connector matched to the kind of signal degradation that kind of cable will experience.
Completely passive TB4/TB5 cables max out at about 80 centimeters.
It's simply length. Ethernet is expected to work on 50-100m runs, while USB4 specifies maximum cable lengths of 2m even for just 5gbps (at least for passive cables). 80gbps is 0.8m