10-Gbit/sec off-the-shelf components flourish in the shadow of 40 Gbits/sec

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By STEPHEN HARDY

TECHNOLOGY

While work progresses on the 40-Gbit/sec components expected to spur the next wave of optical communications, the range of 10-Gbit/sec off-the-shelf devices continues to expand. Recent new-product announcements include transceivers, modules, preamplifiers, and modulator drivers.Th Acfd2e

The VSC7991 EAM/laser-diode driver from Vitesse Semiconductor Corp. represents one of several new 10-Gbit/sec devices that has recently debuted.

For example, Blaze Network Products Inc. (Dublin, CA) unveiled its Afterburner 10-Gigabit Ethernet transceiver product line, the device the company hoped would inspire support for 850-nm coarse wavelength-division multiplexing (CWDM) among the IEEE P802.3ae Task Force now working on the 10-Gigabit Ethernet standard. Blaze's effort fell short of its goal (see sidebar), but Kirk Bovill, the company's director of product marketing, expressed confidence that the product will still find favor among system houses looking to get 10-Gigabit Ethernet systems to the market quickly and inexpensively.

Sample quantities should be available in the first quarter of next year, with volume shipments possible by the second half of the year. At a unit cost of less than $200 in quantity, the device will provide a price point other 10-Gigibit Ethernet options will find difficult to match, Bovill believes.

Blaze also will target the transceiver at high-speed Fibre Channel and OC-192 Very Short Reach (VSR) applications. Bovill says the CWDM technology remains under consideration by the T11 Committee, which oversees Fibre Channel standards, and the Optical Internetworking Forum, which is working on VSR specifications. In addition, Blaze plans to offer the transceiver technology for future pluggable versions of 10-Gigabit Ethernet transceivers under the XGP effort.

One step up the component food chain, Network Elements Inc. (Beaverton, OR) announced its SmartModule family of 10-Gbit/sec optical-networking modules for use in 10-Gigabit Ethernet, IP switch, SONET/SDH, and DWDM termination equipment applications. The modules will provide optical-electrical-optical conversion, clock/data recovery, transmit clock frequency multiplication, and serialization/ deserialization (SERDES).

The first module, the ONM10PHY-SR, will measure 2.5x3.5x0.5 inches and perform physical-layer functions, according to Network Elements' director of business development, Raj Savara. It will feature short-reach 1,300-nm Fabry-Perot serial optics that support a link distance of 2 km over singlemode fiber. Savara describes the devices as jitter-compliant with GR-1377, featuring an OIF 1999.102 SFI-4 16b SERDES interface and a built-in I2C communications port for API interface. It will be available in volume production in this quarter at a cost of $5,000 in quantities of 1,000.

Savara envisions the module will prove popular for 10-Gigabit Ethernet equipment, terabit switch/routers, optical-network-to-router interconnect, optical-switch interconnects, SONET/

SDH and DWDM termination equipment, metropolitan-area-network aggregation, IP switch equipment, and network monitoring equipment. However, Network Elements will add proprietary ASIC technology to extend the feature set of the module in the future, according to Savara. These ASICs will enable the module to support packet-over-SONET and 10-Gigabit Ethernet LAN and WAN applications sometime in the first quarter of next year. The product road map calls for 40-Gbit/sec modules later in 2001 and Layer 3-7 functionality in 2002.

Several chip-level products for 10 Gbits/sec have also debuted recently. In this vein, Conexant Systems Inc. (Newport Beach, CA) has leveraged its HotRail acquisition with the announcement of the Quad SkyRail CX27204 transceiver, a 12.5-Gbit/sec four-channel serial device. According to Elie Massabki, director of marketing for the high-speed interconnect product line at Conexant's Broadband Inter-networking Systems unit, the new transceiver builds upon HotRail's single-channel 3.125-Gbit/sec technology by providing four such channels along with alignment circuitry on a single die, fabricated in a 0.25-micron process. Users can concatenate four chips for a total of 50 Gbits/sec without additional synchronization circuitry.

The CMOS chip, a 256-pin ball grid array, targets switch, router, and other network equipment applications where data must move from line card to line card, blade to blade, and across a backplane, coaxial cable, or optical fiber. It integrates transmitter, receiver, serializer/deserializer, clock data recovery, 8B/10B encoding, 10B/8B decoding, termination resistors, word alignment logic, FIFO buffers, and channel-to-channel and chip-to-chip synchronization circuitry in a single device.

Samples of the chip are already available, and volume production should begin next month. The chip costs $79 in quantities of 10,000.

Meanwhile, Cognet Microsystems (Los Angeles) has introduced a 10-Gbit/sec transimpedance amplifier (TIA) in CMOS. The company has aimed the device at both SONET/SDH and 10-Gigabit Ethernet applications. The new TIA dissipates 60 mW of power and operates from a 1.8-V supply. It features broadband analog bandwidth of direct current to 9 GHz and a single-ended transimpedance gain of 500 ohms. The company is currently sampling the device.

Finally, Vitesse Semiconductor Corp. (Camarillo, CA) and JDS Uniphase Corp. (San Jose, CA, and Nepean, Ontario) announced 10-Gbit/sec modulator drivers. The Vitesse product, the VSC7991, is an OC-192 electroabsorption modulator/laser driver that operates at data rates up to 10.7 Gbits/sec to accommodate the overhead necessary for forward error correction. It features 3-Vpp output swing; its 50-ohm resistive back-termination of differential outputs simplifies impedance matching to the driven optical device. It also features rise and fall times of less than 35 psec and dissipation of less than 2 W; it requires a single 6.5-V power supply and operates over a range from -40° to +85°C. The maximum current delivered to the load is 65 mA.

The device is available now and can be obtained in die form or in a 32-pin glass-walled flat pack. In the latter package, the cost is less than $200 in quantities of 5,000 units.

JDS Uniphase has designed its new model H301 Optical Modulator Driver for external modulators such as EML, EAM, and Mach-Zehnder devices. The driver consumes 4.9 W and amplifiers 2.4888- to 12.2-Gbit/sec signals up to 7-Vpp drive levels. It features a frequency response of 75 kHz to 10 GHz, gain of 14 to 24 dB, and a maximum gain ripple of ±1.5 dB. It is available now in production quantities.

Barbara Tuck, senior editor of Integrated Communications Design, a sister publication, contributed to this article.

Meeting in New Orleans last month, the IEEE P802.3ae Task Force charged with establishing the 10-Gigabit Ethernet standard reached a conclusion on the contentious issue of multimode physical-media-dependent (PMD) interfaces for multimode optical fiber.

Having settled on 1,550- and 1,300-nm PMDs for singlemode applications involving distances of 40, 10, and 2 km in a meeting last July, the task force faced the prospect of choosing among three options for the remaining two PMDs on its plate: interfaces for 300-m and 100-m multimode applications. The group debated three options-a 1,300-nm wide WDM (WWDM) proposal, an 850-nm coarse WDM (CWDM) offering, and an 850-nm serial option.

While details were scarce at press time, it appears that proponents of the 1,300-nm WWDM and 850-nm serial options succeeded in banding together to galvanize support for their positions. The two options were joined in a single proposal, which achieved the 75% approval necessary to remain in the standards discussion.

In addition, the 100-m distance specification was shortened to 65 m, which more closely matched the capabilities of 850-nm serial devices. The CWDM option failed to receive the necessary 75% approval and is currently no longer part of the 10-Gigabit Ethernet standard discussions.

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