USB4 Version 2.0 Said to get 120 Gbps Asymmetric Mode

It was only yesterday that the USB Promoters Group announced the USB4 Version 2.0 spec with support for speeds of up to 80 Gbps, something TechPowerUp mentioned at the end of our USB4 articleback in June. Now details of a 120 Gbps asymmetric mode has popped up, courtesy of Angstronomics and we’ve managed to confirm that it is indeed something that is coming from one of our own sources. We were in fact told back in June that the 80 Gbps mode was meant to be asymmetric, but this was not mentioned in the recent press release.

The 120 Gbps mode will use three of the four data pairs for upstream data and the fourth 40 Gbps data pair will be for downstream data from and to the host controller.Asymmetric data transfers are nothing new over USB Type-C cables, as the DP Alt Mode is already taking advantage of this. This is possible because USB4 Version 2.0 will move to PAM3 (Pulse-Amplitude Modulation) data encoding from today’s 64/66- or 128/132-bit encoding. The next generation of Thunderbolt is also expected to use PAM3 encoding to reach the rumoured 80 Gbps speeds that were posted somewhat by mistake by an Intel executive last year.