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Sun, Alcatel back spec for multilevel backplanes

Posted: 28 Nov 2003 ?? ?Print Version ?Bookmark and Share

Keywords:semiconductor? backplane system? pam4? xilinx? optical internetworking?

A group of seven semiconductor and systems companies has unveiled an alliance and draft specification on Nov. 26 for high-speed multilevel signaling, potentially gaining an edge over a group advocating a rival binary technology.

The Multi-Level Signaling Alliance was formed quietly in July to promote PAM4 signaling for serializer/deserializers (serdes) used in backplane systems. It expects to present to formal standards organizations its spec in the first quarter of next year. That's at least three months ahead of the timeline of a rival group led by Xilinx Inc. backing binary technology.

The MLS Alliance is chaired by Bill Hoppin, VP of marketing and strategic sales for interconnect startup Accelerant Networks. Other major members include Accelerant's ASIC partner Agere Systems, Ethernet switch startup Force10 and OEMs Alcatel and Sun Microsystems. Rambus is not listed as a member though the company designs PAM-4-based serdes.

The new alliance was formed as vendors have been battling behind the scenes over the use of binary or PAM4 technology in high-speed backplanes and edging to define standards for the technology at the 10Gbps level.

In early October, Xilinx Inc. and four partners unveiled ad hoc efforts to develop a physical layer standard for a 10Gbps serdes based on binary technology. The so-called Unified 10Gb Physical-Layer Initiative (UXPi) includes Applied Micro Circuits Corp., IBM Microelectronics, Infineon and Texas Instruments. UXPi is currently trying to recruit OEM members to review their draft spec which they hope to submit to formal standards groups by June.

The UXPi effort is seen as an outgrowth of work in the Optical Internetworking Forum to set 10Gbps backplane standards. Both alliances hope to influence the evolution of interconnects such as PCI Express and RapidIO as they move from 2.5- to 10Gbps data rates.

Binary technology, used widely today, is generally seen as the least complex of the two approaches, but harder to extend to 10Gbps data rates and beyond than PAM4.

A representative of the MLS Alliance was not immediately available for comment.

- Rick Merritt

EE Times

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