Tech World

On September 18, 2007, Pat Gelsinger demonstrated USB 3.0 at the Intel Developer Forum. USB 3.0 is targeted at ten times the current bitrate, reaching roughly 4.8 Gbit/s (for a highly theoretical maximum 600MB/s) by utilizing two additional high-speed differential pairs for "Superspeed" mode at a clock frequency of 2.5GHz , and with the possibility for optical interconnect. The two new differential pairs make the cable about as thick as an ethernet cable and provide full-duplex transfers.[32] The USB 3.0 specification was 90% complete as of August 13, 2008[33] and commercial products are expected to arrive in 2009 or 2010.[ USB 3.0 is designed to be backwards-compatible with both USB 2.0 and USB 1.1 and employs more efficient protocols such as 8b/10b encoding to conserve power while increasing the maximum power available for connected devices.

USB 2.0 cables worked off of four lines – a pair for in/out data transfer, one line for power, and the last for grounding. USB 3.0 adds five new lines (the cable is noticeably thicker), but the new contacts sit parallel to the old ones on a different plane, as opposed to being adjacent to them. This means you’ll be able to differentiate between 2.0 and 3.0 cables just by looking at the ends.With USB 3.0, two new lanes will be dedicated to transmit data, while another pair will handle receiving data. This not only accounts for the significant speed boost, but also allows USB 3.0 to both read and write at the same time from your portable storage device. In the old spec, the pair of lanes used for data transfer weren’t split between send and receive – they only could handle traffic in one direction. Bi-directional data transfer will be very useful for syncing up information on PDAs and storage backup. They’ll carry more power, too. The USB-IF recognizes the growing number of portable devices that charge via USB (cellphones, MP3 players, digital cameras), and have bumped the power output from about 100miliamps to 900 milliamps. That means not only will you be able to power more than 4 devices from a single hub, but the increase current will let you charge up heftier hardware as well.

Like the upgrade from USB 1.1 to 2.0, the new 3.0 connectors and cables will be physically and functionally compatible with hardware from the older specs. Of course, you won’t be able to maximize your bandwidth unless you’re using a USB 3.0 cable with Superspeed devices and ports, but at least plugging a 3.0 cable into a 2.0 port won’t blow up your PC. The spec’s compatibility lies in the design of the new connectors

According to electronicdesign.com cables will be limited to 3 m at full speed. The technology is similar to PCI Express 2.0 (5-Gbit/s). It uses 8B10B encoding, linear feedback shift register (LFSR) scrambling for data, spread spectrum. It forces receivers to use lowfrequency periodic signaling (LFPS), dynamic equalization, and training sequences to ensure fast signal locking.

The connector will be divided into two parts. The first part is the USB 2.0 four-wire version with UTP data pair and power with ground. The second part will have five connections: two UTP lane (one is uplink and one is downlink) and a ground. An optical connector and cable will be available in the future.