Electronic Design

USB-IF Gets Ready To Ratify 3.0

It looks like the USB Implementers Forum (USB-IF) will issue the final ratification of the new USB 3.0 standard soon. It is an amazing advance from the current standard, which has near universal adoption as a PC peripheral interface. With its 4.8-Gbit/s data rate, USB 3.0 opens entirely new application possibilities.

According to Chris Loberg, senior marketing manager for performance products at Tektronix, the data transfer needs that have developed in the consumer space are among the main drivers for the new standard. The demand for fast transfer of video and audio is increasing as more consumers download, store, transfer, and use huge video and audio files. There also are needs in the external hard-drive market and with RAID users.

One potential application lies in using 3.0 in small server clusters to replace more expensive InfiniBand and similar technologies. A new cable and backward-compatible connector can provide a range of up to 15 m. The new cable contains the usual four-wire USB 2.0 connections plus a pair of differential lines that carry the 4.8-Gbit/s data stream using an 8B/10B encoding scheme. This new standard leverages the technology developed for PCI Express and Serial ATA in their Gen 2 formats.

With regard to test and measurement needs, the bandwidth requirements for an oscilloscope are rather severe. Assuming a minimum bandwidth of five times the data rate to see decent waveforms, an oscilloscope with a bandwidth of 12.5 GHz minimum (two channels of 2.5 Gbits/s × 5 = 12.5 Gbits/s) is needed to see the eye diagrams and data signal details. Existing scopes are available, but you can probably expect some new enhancements in the way of software for protocol analysis as well as new receiver test procedures that are necessary to meet the standards testing requirements forthcoming.

USB Implementers Forum

www.usb.org

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