USB4 Leverages Thunderbolt 3 Protocol Doubling Speeds To 40Gbps

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The USB Promotors Group has just officially announced the arrival of the USB4 specification, which will supersede the newly formed (and highly confusing) USB 3.2 protocol. USB4 promises to double the transfer speeds of USB 3.2 thanks in part to a critical move made by Intel.

Intel has made its Thunderbolt 3 protocol royalty-free, which will allow competing chipmakers to offer implement the standard at lower costs. It also means that USB4 is based on the underlying Thunderbolt 3 protocol. As a result, maximum speeds for USB4 double to 40 Gbps using existing certified cables, matching the speeds offered by Thunderbolt 3.

“By collaborating with the USB Promoter Group, we’re opening the doors for innovation across a wide range of devices and consumer experiences to maximize adoption of Thunderbolt compatible products," said Jason Ziller, Intel's GM for the Client Connectivity division.

Just as important, USB4 is backwards compatible with Thunderbolt 3, USB 3.2 [PDF] and USB 2.0. Also taking a page from Thunderbolt 3's playbook is the ability to deliver 100W of power and enough bandwidth to support a single 5K display or two 4K displays. The USB Type-C connector is still in use, which has expanded over the years to not only supports devices like smartphones and external storage devices, but also external displays and other peripherals.

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However, one thing is very clear: USB4 and Thunderbolt 3 will coexist in the same space, and the former is not replacing the latter. However, given the open nature of USB4 versus the closed Thunderbolt 3 system, you should expect to see an explosion of compatible devices offering 40 Gbps speeds at more affordable price points. Right now, there are only 463 certified Thunderbolt 3 devices on the market.

This development should be especially welcome to those that use high-speed external docks. Reputable Thunderbolt 3 docks (offering 100W Power Delivery, multiple USB ports, 4K60 HDMI, GbE, etc.) can cost a couple hundred bucks or more, so the inevitable proliferation of USB4 will hopefully allow the prices to come down dramatically.

“The primary goal of USB is to deliver the best user experience combining data, display and power delivery over a user-friendly and robust cable and connector solution,” said Brad Saunders, who serves as the Chairman of the USB Promoter Group. “The USB4 solution specifically tailors bus operation to further enhance this experience by optimizing the blend of data and display over a single connection and enabling the further doubling of performance.”

According to the USB Promotors Group, the full USB4 specification will be published during the second half of 2019.