FEBRUARY 4, 2009 -- Gennum Corp. (search for Gennum) this week announced two new CDR-based reference design kits that facilitate the development of high-performance Fibre Channel and Ethernet modules. Gennum says its SFP+ Copper Cable Assembly and SFP+ Optical Module Reference Design Kits (RDKs) are both based on the company's 8.5-Gbps and 10-Gbps clock and data recovery (CDR) technology and deliver SFP+ modules with the lowest output jitter on the market.
Moreover, the CDR-based approach to SFP+ designs will now significantly reduce system cost and power consumption, enabling these modules to be used in a variety of high-performance switch applications, such as data centers and storage area networks, say company representatives.
Gennum says the new design kits employ its ClearEdge CDR technology, which is used to enhance signal quality within the SFP+ module and improve the robustness of the system, reducing the output jitter by 75% to less than 0.15UI. CDRs ease the performance requirements that are typically placed on application specific integrated circuits (ASICs) interconnected with the modules. For SFP+ limiting links, a CDR-based approach eliminates the need for external line card components, such as electronic dispersion compensation (EDC) chips, saving up to 1W and $40 per port.
"CDRs allow you to reset the jitter budget within the module and ensure repeatable performance regardless of the type of system the cable or module is plugged into," explains Bharat Tailor, director of marketing, Networking, Storage and Computing, at Gennum. "This enables increased flexibility during system design and eliminates the severe design constraints that can occur as data rates reach 10 Gbps. The use of CDRs in the module or cable assembly lowers the overall cost and power of the end system since lower cost ASIC solutions and materials can be used and longer trace lengths and link lengths can be implemented, without system performance degradation," he notes.
Gennum's CDR-based 850-nm SFP+ Optical Module Reference Design Kit is a platform for next-generation SFP+ modules. The company says its SFP+ optical RDK integrates the CDR functionality into existing components within the module and does not increase the component count. By integrating the CDR with a limiting amplifier in the receive path and a VCSEL driver in the transmit path, Gennum is able to maintain a total module power of less than 1W. Implementing the CDR in the receive path of the module provides more design flexibility to have longer traces to the host, to use lower cost PCB material, or to use a lower cost ASIC. By using a CDR in the transmit direction, the transmit eye has a large optical eye mask margin, even with a noisy input to the module.
The Optical Module Reference Design Kit also leverages Gennum's GN3150 ROSA and GN4150 TOSA solutions, which are used for optical-to-electrical and electrical-to-optical conversion. These components offer best-in-class sensitivity and ensure exceptional crosstalk performance within the module, claim company representatives.
Gennum will offer 8.5-Gbps Fibre Channel and 10-Gbps Ethernet versions of both the optical and copper kits. The 8.5-Gbps and 10-Gbps CDRs are pin compatible, so only one design is required for both applications. The kits include the SFP+ module or assembly, Gerber files, schematics, and a design guide.
The CDR-based SFP+ Optical Module Reference Design Kit is available now.