The USB Implementers Forum (USB-IF) has published the specifications for USB4, the next-generation USB architecture first teased back in March 2019.

USB4 will be a ‘major update’ that builds on the existing USB 3.2 and USB 2.0 architectures. It will be based on Intel Corporation's Thunderbolt protocol specification and will double ’the maximum aggregate bandwidth of USB and enables multiple simultaneous data and display protocols,’ according to the announcement.

The USB-IF says USB4 is backwards compatible with USB 2.0, USB 3.2 and Thunderbolt 3, and will feature a maximum speed of up to 40Gb/s, twice the current 20Gb/s maximum. Since it will be using the same USB Type-C connection, manufacturers won’t need to alter designs to use the new ports. USB Power Delivery will also be a requirement in USB4 devices.

Despite the specification being finalized, it’ll likely take some time to market. Historically, it’s taken roughly a year from the time the specifications have been released to the time we see it in the first devices, but it’s always possible that precedent could be broken.