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Realistic sights and sounds come to life on small screens in today’s digital world. Behind the scenes are an array of hardware and software technologies, and not to be overlooked is the role of the Universal Serial Bus (USB) standard. In particular, USB4 Version 2.0 delivers a blazingly fast 80Gbps of data transfer speed, just what’s needed for anyone working on multimedia presentations, editing videos, or juggling an array of projects across several monitors.
Delivering increased speed with each version, USB has always been popular. What has vaulted the interface into its status as the most popular wired interconnect interface was the 2014 release of the flexible USB Type-C connector. In a small, reversible form factor, Type-C connectors can simultaneously carry power up to 240W as well as data and video. Users can then use the same connector to charge their devices, transfer data, or output video.
USB4 Version 2.0 specification, announced by the USB Implementers Forum in October 2022, should start to appear in products anytime now. Meantime, designing products to support the new version does come with some unique challenges. Read on to learn more about the latest iteration of the USB standard, and how IP can help pave the way to high-performing SoCs with USB4 v2 functionality.
How Does USB4 v2 Work?
USB4 enables a simple, single-cable docking station solution for laptops and similar devices. The interface tunnels USB 3.x, DisplayPort, PCIe, and optional host-to-host traffic in one transport, allowing USB docks and devices to extract tunneled USB, PCIe, and DisplayPort traffic as needed. Featuring its own protocol and error correction, USB4 eliminates some legacy transport protocol overhead to increase available bandwidth.
Faster than ever, USB4 has been embraced by major chipset manufacturers, so you can find laptops, desktops, and an array of peripherals with Type-C connectors. With greater availability of host devices, more users will recognize that they’ve got a connection to support very high-performance peripherals, such as ultra-fast external hard drives and HD monitors and displays.
USB4 v2 doubles the performance capabilities of the USB wired connection, delivering more fuel to those external drives and 4K and 6K displays. The standard uses a new PHY architecture based on PAM-3 signal encoding over existing 40Gbps Type-C passive cables as well as newly defined 80Gbps Type-C active cables. When configured asymmetrically, USB4 v2 can deliver up to 120Gbps in one direction, maintaining 40Gbps in the other direction.
Where Can USB4 v2 Be Used?
With USB4 v2, content creators can store HD video on very fast external drives, accessing the footage very quickly and with little latency for tasks such as video editing. The latest iteration of the interface also supports mobile and network storage applications. Since next-gen laptops with USB4 v2 support will be able to combine video, audio, data (and power) on a single cable, it’ll make moving between the office, meeting rooms, and home office more seamless.
There’s another intriguing potential use case for USB4 v2 involving AI accelerators. Rather than sending all the data to the cloud for AI processing, for edge applications, there’s the possibility of using a USB4 v2 cable to send data to a local AI accelerator for post-processing. In a future where AI becomes even more pervasive, and perhaps there isn’t enough bandwidth to send data up to the cloud and back while delivering real-time performance, this approach could take some of the load off the cloud.
Silicon Success with First USB4 v2 PHY Test Chip
When designing for USB4 v2, channel loss is one of the key issues to be aware of, as the new interface defines a channel loss at each of its different ends. Channel loss can lead to a reduction in the effective range of USB4 v2 devices, as well as increased error rates and lower overall system performance. As such, it’s important to minimize channel loss as much as possible.
Silicon-proven controller and PHY IP can help mitigate the effects of channel loss through robust error correction, while also helping to maximize performance of USB4 v2 devices. At DesignCon 2024, Synopsys demonstrated the first USB4 v2 PHY IP test chip at 80G; see the video demo below. The PHY can operate at burst or asymmetrically, and transmit at 120G and receive at 40G. Synopsys USB4 v2 PHY IP can be used in the personal and office compute space for enhanced video, audio, and data connectivity.
In addition to PHY IP, Synopsys offers a complete portfolio of USB4 IP solutions that includes controllers, routers, and verification IP. Backed by more than 20 years of experience developing USB solutions, our IP is created to help designers mitigate the risks of integrating USB4 functionality into their SoCs.
Summary
For nearly three decades, the USB wired interface standard has enabled computers and a host of peripherals to talk to each other. The latest iteration, USB4 v2, promises a blazingly fast bump-up in speed, enabling laptop users to move seamless between different work environments. With the increasing pervasiveness of AI, there’s potential for using USB4 v2 to enhance AI acceleration at the edge, too.
Designing SoCs with USB4 v2 functionality comes with its own challenges, a primary one being channel loss. Channel loss can degrade overall performance. One of ways to mitigate the effects of channel loss is through robust error code correction, handled by the PHY IP. PHY IP, along with controllers, routers, and verification IP, can together help maximize the performance of USB4 v2 SoCs. By making reliable high-speed data transmission possible, USB4 v2 and its supporting IP ecosystem not only sustain but also drive our fast-paced digital world, enabling us to experience more than ever before.
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