The USB Implementers Forum (USB-IF) wants to finalize a new USB specification by November 2022. USB4 Version 2.0 or USB4 2.0 for short doubles the transfer rate via Type-C ports to up to 80 Gbit/s. At the same time, updates for other transmission protocols, such as USB 3.2 Gen 2×2, the DisplayPort Alt Mode and USB Power Delivery.
New controllers are required in the devices for USB4 2.0. New cables, on the other hand, are not absolutely necessary: Passive type C cables that can transmit 40 Gbit/s should be used also be sufficient for the new speed level, according to the announcement. For longer connections, however, the USB-IF provides new active cables.
The revised transmission protocols enable faster data connections when a USB4 controller tunnels a USB 3.2 signal, for example. So far, USB 3.2 Gen 2×2 with 20 Gbit/s was the end – in the future even more will be possible. In addition, the developers want to support the current DisplayPort and PCI Express standards via USB4 2.0, which would be DisplayPort 2.0 and PCIe 5.0.
Who thinks up the version numbers?
In the end, the naming leaves question marks again. With the update, there are three speed levels for USB4, all of which are eligible for certification: 20, 40 and 80 Gbit/s. How fast a connection to a device is only becomes clear when you look at the data sheet or when the manufacturer shows a speed specification next to the Type-C port.
As early as 2021 there was speculation about a new Thunderbolt version with a transfer rate of 80 Gbit/s as well. An Intel presentation that accidentally became public at the time named ternary pulse amplitude modulation (PAM-3 instead of PAM-2) as a core change to increase the transmission rate. The amplitude in the modulation signal is evaluated for three different states (-1, 0, +1). Two clocks thus effectively transfer three bits.
Whether the USB-IF goes the same way is open, but would be realistic due to the relationship between USB4 and Thunderbolt 4.
(mma)