The USB Implementers Forum (USB-IF) introduced USB4 version 2.0 in fall 2022, and systems and devices featuring this technology are expected to emerge later this year and into the next. These forthcoming products will largely rely on Intel’s Barlow Ridge controller, which is a comprehensive Thunderbolt 5 controller surpassing the baseline USB4 v2 specifications. Although highly capable, Intel’s Thunderbolt controllers do come at a premium price, and Barlow Ridge is anticipated to be no exception. Fortunately, for vendors needing a basic USB4 v2 solution, ASMedia is also developing its own USB4 v2 controller.
At Computex 2024, ASMedia showcased a prototype of its upcoming USB4 v2 physical interface (PHY). This PHY will support USB4 v2’s new Gen 4 (160Gbps) data rates and the associated PAM-3 signal encoding. The prototype utilized an FPGA as the company has yet to finalize the completed controller.
Ultimately, the aim of showcasing an FPGA-based PHY at Computex was to enable ASMedia to demonstrate their current PHY design. With the transition to PAM-3 encoding for USB4 v2, ASMedia (and the rest of the USB ecosystem) need to develop significantly more complex controllers, and a robust and reliable PHY design is pivotal.
As part of their demonstration, ASMedia presented a classic eye diagram display. The eye diagram featured a clear central opening, indicative of good signal integrity. A larger eye opening suggests less distortion and noise. The horizontal width of the eye opening represents the time window for correctly sampling the signal, so a narrow horizontal spread indicates minimal jitter and consistent signal transitions. Moreover, the vertical height of the eye opening, denoting signal amplitude, suggests a high signal-to-noise ratio (SNR), indicating a strong signal relative to any noise present.
ASMedia is one of the major suppliers for discrete USB controllers, making the availability of its USB4 v2 chip essential for widespread adoption of the standard. While Intel will lead the industry with their Barlow Ridge Thunderbolt 5/USB4 v2 controller, ASMedia’s controller is expected to be featured in a much broader range of devices. Therefore, the significance of the company’s USB4 v2 PHY demonstration is substantial.
Apart from demonstrations, ASMedia is hopeful to tape out the chip soon. If everything proceeds smoothly, the company expects to launch their first USB4 v2 controllers in the market in the second half of 2025.
