Comms chips

Agere Brings CMOS to 10-Gig

Agere Systems (NYSE: AGR/A) this week joined the ranks of the CMOS elite, laying claim to a device that can create serial 10 Gbit/s streams of data. Its new FlexPHY chip -- more formally named TSCV0110G -- is a physical-layer device (PHY) for Sonet/SDH, Ethernet, or Fibre Channel traffic.

Typically, high-speed devices are made in silicon germanium (SiGe) or a more exotic material first, then moved to complementary metal-oxide semiconductor (CMOS) processes later. CMOS -- the most commonly used silicon manufacturing process -- allows for cheaper chips that run at lower power, but the resulting signals aren't strong enough to stay coherent at high speeds.

With FlexPHY, Agere becomes only the second company to build a one-chip, serial, 10-Gbit/s Sonet PHY in CMOS, the other being Applied Micro Circuits Corp. (AMCC) (Nasdaq: AMCC) with its SuperPHY, which sampled earlier this year (see AMCC Premieres SuperPHY Family). Broadcom Corp. (Nasdaq: BRCM) comes close, with a 10-Gbit/s PHY product that comes in two chips.

The PHY chip is a multiplexer/demultiplexer combination that sits behind the optics, acting as a liaison between optics and electronics such as the framer. FlexPHY takes 16 streams of roughly 622-Mbit/s apiece and combines them into a single 10-Gbit/s signal. On the receiving end, it does the opposite, breaking an incoming 10-Gbit/s transmission into 622-Mbit/s feeds, which are more easily handled by the internal circuitry of framers, media access controllers (MACs), and other semiconductors.

Those speeds are approximate. FlexPHY handles signals between 9.95 Gbit/s and 10.71 Gbit/s, depending on the particular protocol in use.

Agere had produced a two-chip PHY before, with separate mux and demux chips, in SiGe. The CMOS-based FlexPHY manages even better performance, creating jitter of 30 milli-UI (UI meaning "unit interval," the inverse of frequency) compared with 80 mUI for a typical SiGe part.

That's partly due to the high-end CMOS process used, but it also stems from programmable on-chip elements that can alter the input amplitude and the phase of the clock sample. "It's not just your process, it's how you design your circuitry," says Kourosh Matloubi, FlexPHY product manager. "We know how to design circuits with low jitter."

Agere's next step will be a semiconductor core version of FlexPHY that can be integrated into other chips such as framers and media access controllers.

Whether Agere will rely on SiGe for its first 40-Gbit/s PHY "has not been determined yet," Matloubi says. One key factor will be the evolution of CMOS to line widths of 90 nm (the fashionable term for 0.09 micron), a key step that would increase the performance of "plain" silicon. Given the slow market, 90nm processes might emerge in time for companies like Agere to skip using SiGe for early 40-Gbit/s parts.

— Craig Matsumoto, Senior Editor, Light Reading

MrLight 12/4/2012 | 9:13:12 PM
re: Agere Brings CMOS to 10-Gig Interesting article in the Dec.02.02 issue of NetworkWorld that I subscribe to, available at
http://www.nwfusion.com/news/2... titled "10G or not 10G?", by By Phil Hochmuth.

The main point was "most existing Ethernet boxes have a kink: they really only deliver 8G bit/sec. Vendors will make up for that speed with next-generation chassis upgrades - which could come as early as next year. "

and maybe "even 8G bit/sec is generous. Bad implementations of features such as flow control, which regulates the flow of high-speed packet streams to a port, can cause throughput to dip below 7G bit/sec on some products, according to Brian Tolly, senior engineer and analyst with Tolly Group, a network testing and consulting firm."

and "The limitations of these chassis for handling 10G Ethernet are widely known, vendors claim."

So what does that mean to users, well the article states:

"So 8G bit/sec instead of 10G bit/sec - what's the difference? A lot when you consider 10G Ethernet pricing.

Dell'Oro Group says that customers can expect to pay an average of $25,000 per 10G Ethernet port this year. Long-reach 10G Ethernet ports from vendors such as Foundry, Cisco and Extreme can cost in the range of $75,000 to $80,000 for a single port on a module that takes up an entire slot in a chassis.

While Dell'Oro expects the per-port cost to drop to around $7,000 in 2005 (still five times what Gigabit cost in 1999), it is expected that the technology will appeal to only the largest shops. IDC expects that only 45,000 10G Ethernet ports will ship this year, as opposed to 8 million Gigabit ports worldwide.

Meanwhile, eight 1G ports would cost about $10,000 to $16,000.

Ten Gigabit might be on the distant horizon for many corporations, but users looking to make a chassis-switch purchase now could be caught in the middle of a major upgrade cycle by their respective vendors."

So looks like 10GE chipset vendors still have a bit of breathing room to get their designs out.

MrLight ;-)
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