Analogix Claims 25 Gbit/s Over Copper

SANTA CLARA, Calif. -- Analogix Semiconductor has introduced a new family of physical-layer transceiver ICs that lets system designers replace fiber-optics with less expensive copper media in system-to-system interconnects, yet still achieve the high performance associated with fiber.

Analogix's new D-PHY xGC family of physical-layer transceiver (PHY) chips includes the first device to deliver 6.25 gigabits per second raw serial performance per copper twisted pair. With an aggregate capacity of 25 Gbps full-duplex over a single InfiniBand copper cable at up to 30 meters, it offers twice the speed and distance of today's standard 10GBASE-CX4 chips.

This D-PHY 5GC device is also the first high-speed transceiver to operate over unshielded twisted pair, providing a less costly alternative to InfiniBand cable at a time when a high-speed UTP-based standard could be up to two years away. It offers designers major advantages in high- speed, short-distance interconnect scenarios, such as stackable switches or cross-rack clusters, where costly fiber was previously the only choice.

The D-PHY 5GC and a standards-based counterpart, the D-PHY 2.5GC, are already sampling to customers. The D-PHY 2.5GC, designed for customers connecting heterogeneous multi-vendor systems over copper media, is fully compliant with the 10GBASE-CX4 standard, offering 4x3.25-Gbps performance. However, it operates over distances of up to 40 meters - nearly triple the 15-meter specification of the standard.

A second generation of the D-PHY xGC devices, offering serial speed of up to 12.5 Gbps and aggregate capacity of 50 Gbps over InfiniBand cable and 25 Gbps over UTP, will be available in 2005. Like the 5-gigabit devices being introduced today, the two upcoming 10-gigabit D-PHY xGC devices will include both a standards-based version (the emerging IEEE 10GBASE-T standard) and a proprietary version offering higher speed and media flexibility.

Ted Rado, vice president of marketing for Analogix, said, "Today's system designers are between a rock and a hard place: if they need performance of more than a gigabit, they must use expensive fiber-based interconnect devices and perform electrical-optical conversions on both sides of the link. But fiber is overkill in the many cases where distance requirements are well under 100 meters - applications with single-vendor stackable switches or server blades, for example, or racked clusters of add-drop multiplexers or optical cross-connects.

"Standards efforts, while critical to the industry, do little to help these 'virtual backplane' types of applications, characterized by distances of 20 meters or less between like systems," Rado said. "The current 10GBASE-CX4 standard is limited to 3.125G serial performance and works only on InfiniBand cable. The new 10GBASE-T standard will offer much higher speeds and will be UTP-specific - but, even when it is finalized in the next 18-24 months, won't work with the ubiquitous Category 5e cable. The D-PHY xGC family fills this gap with an all-electrical solution that combines high performance with the flexibility to work with the user's choice of copper media."

Analogix Semiconductor Inc.