November 18, 2008 -- At SC08 in Austin, TX, Gennum announced what it claims is the industry's first quad 10 gigabits per second (Gb/s) clock and data recovery (CDR) solution aimed at optical modules, backplanes, line cards and active copper cable assemblies, designed to significantly extend the performance and reach of high-performance computing and networking interconnects.
Used to restore and clean digital signals at extremely high data rates, the quad 10 Gb/s CDR, dubbed the GN2406, provides a retimed interface for Infiniband quad data rate (QDR), 40 Gigabit Ethernet (XLAUI) and 100 Gigabit Ethernet (CAUI) applications. As a result, using the product, the company maintains that module and system designers can more easily design robust, high density, low cost systems.
"High-performance computing applications, such as Infiniband QDR, largely rely on low cost copper interconnects and at 10 Gb/s, the impact of signal distortion and noise is significantly more pronounced than at 5 Gb/s or lower rates," remarks Bharat Tailor, director of marketing, networking, storage and computing at Gennum. "The GN2406 device solves these issues by integrating a CDR, which effectively re-sets the system jitter budget at both ends of the link resulting in a much more robust system level solution. The end result is the highest level of performance and signal integrity for emerging Inifiniband QDR and 40 GbE and 100 GbE applications."
According to Gennum, the GN2406 is a quad 10 Gb/s CDR with output de-emphasis, which is a form of transmit equalization that compensates for the loss of the transmission medium. Using the GN2406, copper cable or backplane trace losses of up to 25 dB can be compensated, thus enabling cable lengths of up to 15 meters or backplane link lengths greater than 1 meter. Each channel in the GN2406 independently locks to data rates from 9.95 Gb/s to 11.3 Gb/s. To support legacy data rates, half rate (5 Gb/s) and quarter rate (2.5 Gb/s) operation is also supported. When used with a copper cable, backplane trace or an optical link, the CDR effectively re-sets the system jitter budget, minimizing the impact of impairments such as jitter and crosstalk on system performance.
The GN2406 CDR also functions without the need for a reference clock, which is important in active cable assembly or optical module applications where clocks are not necessarily available or desirable. With a power consumption of only 180 mW per lane, the GN2406 is well suited for modules or active cable assemblies utilizing the QSFP or similar form factors, contends the company.
Further, the company maintains that there is a need for a simple chip-to-chip or chip-to-module interface in 40 GbE (XLAUI) and 100 GbE (CAUI) applications, with up to 10 lanes of 10 Gb/s. The GN2406's ability to integrate four 10 Gb/s CDRs into a single package enables this interface, significantly simplifying system design. Additionally, the high sensitivity limiting amplifiers at the input make the GN2406 suitable for use in 40 GbE or 100 GbE optical modules.
According to The Linley Group's Jag Bolaria, "The development of the 40 GbE and 100 GbE standards is well underway, with Infiniband QDR set to ramp through 2009. Gennum has developed a timely solution to address the signal integrity issues these systems will encounter."
Gennum contends that in a typical high-speed networking chassis design, the trace lengths from an ASIC on a line card to an ASIC on a switch card can exceed one meter in length with two connectors in the path. When crosstalk and other impairments are considered, there is a significant burden placed on the ASIC's receiver to compensate for the large losses and tolerate the excessive amount of jitter built up. The use of a high jitter tolerance CDR like the GN2406 as a backplane repeater greatly increases the robustness of the link and provides a simple retimed interface for ASIC communication.
Commenting on the applicability of the GN2406 in serial backplane applications, Ryan Price, global product manager for Molex's backplane components unit, comments, "We are extremely excited to be able to demonstrate real-world 10 Gb/s performance of our backplane interconnect technology enabled by Gennum's GN2406. As the industry broadens its adoption of multi-gigabit systems, a demonstration of error-free data transmission at 10.3 Gbit/sec over a 1 meter FR408 I-Trac backplane channel provides an important assurance of practicality and robustness of such systems."
Pricing for the GN2406 is $29.00 per unit in quantities of 10,000. The chip will sample in November, with full production slated for April 2009. Evaluation boards for the GN2406 will be available in December, with a full copper cable reference design and backplane reference design available in January 2009.