DesignCon celebrated its 20th anniversary this year, and Bob Hult was there to report on the newest developments in high-speed connector technology.
DesignCon 2015 celebrated its 20th anniversary as the premier showcase for high-speed chip, connector, and PCB board technology. More than 170 technical sessions organized in 14 conference tracks and three keynote addresses provided attendees with the latest developments across the industry. The exhibit floor was expanded to 27,000 square feet to accommodate 157 exhibitors, 26 of which were high-performance connector- or cable assembly-related. The booths of several of these manufacturers were updated and expanded. Sponsorships of this year’s DesignCon increased by 25%.
One of the most evident changes from last year was the rapid evolution from 25Gb/s channels to demonstrations of 50-56Gb/s links in both backplanes and I/O interfaces. In some cases, existing products have been fine-tuned to permit higher performance while others such as the FCI ExaMAX and TE STRADA Whisper backplane connectors have experienced a specification upgrade. These speeds are accomplished using both Non-Return-to-Zero (NRZ) as well as PAM-4 multilevel signaling technology. Several connector suppliers reported that major OEMs had committed to using PAM-4 chips in upcoming products.
In an effort to assure system designers that multiple packaging and performance options are available within a single backplane connector family, suppliers have tooled their flagship high-speed interfaces to provide standard backplane, midplane, orthogonal midplane, orthogonal direct, mezzanine, and cable configurations. For the same reason, backplane connector families are being upgraded to provide tiers of performance that can more closely match the specific data rate and cost requirements of current systems. Providing a roadmap that demonstrates the ability to support next-generation equipment without starting over with a new backplane connector system allows OEMs to leverage design and manufacturing experience and reduce cost and time to market.
Similar upgrades are occurring in SFP+ and QSFP+ I/O connectors. Connector suppliers anticipate continuing improvements in the connector and PCB launch which will allow these interfaces to support up to 56Gb/s per channel signaling.
Demonstrations of these capabilities were everywhere. Granted, running one channel in an ideal backplane environment may not reveal challenges encountered in production systems, but demonstrating the “potential” to achieve 56Gb/s NRZ signaling in one differential pair is impressive. The parameters of these demonstration systems continue to be better defined in terms of materials, length, number of retimers, and other signal conditioning techniques employed.
The ongoing escalation of data rates was also reflected in the number of subminiature coaxial connector vendors exhibiting, including Hirose, HUBER+SUHNER, I-PEX, Micro-Coax, and Southwest Microwave. Applications are found in production systems as well as test equipment.
Some of the most notable products shown this year include the introduction of the new Paladin high-speed backplane connector from Amphenol TCS. Intended to be the successor to the XCede family, Paladin is designed for up to 56Gb/s NRZ or PAM-4 using highly balanced differential pair construction and an optimized footprint.The initial release is a four-pair-per-column, right-angle receptacle and vertical header but will be expanded to include cable, orthogonal, and direct-attach configurations.
FCI also introduced the BarGuide connector system designed to support 60A to 250A in bus bar applications.
Additionally, FCI joined the ranks of connector suppliers that now offer an on-board optical transceiver. The new Leap transceiver is designed to provide 12 transmit and 12 receive optic channels, each operating at 25Gb/s.
Molex featured its Nano-Pitch I/O connector, which is the chosen OcuLink interface defined by the emerging PCI Express 4.0 specification. Sporting 42 contacts on 0.5mm pitch, this connector is being tooled in both vertical and right-angle headers. A full metal shell assures durability and EMI protection in both internal and external I/O applications. Mating cable assemblies will also be available from Molex.
The performance of the Molex Impel backplane connector has been bumped up to 40Gb/s with an upgraded Impel+ version in the developmental pipeline that will be rated to 56GB/s NRZ. Data rates of pluggable I/O connectors have increased significantly over the past year. Molex demonstrated zQSFP+ connectors at 50Gb/s NRZ per channel over three meters of cable. The company also showed its CDFP connector running at 32Gb/s over one meter of cable.
Samtec increased its presence with a new and enlarged booth featuring its many high-speed/density interconnects. It supplements its product lines by second-sourcing successful competitive products.
The new Z-Ray ultra-low-profile micro interposer is compatible with Neoconix high-density arrays. Up to 1,000 compressive contacts are available on a 0.80 or 1.0mm pitch with custom configurations available. Samtec also demonstrated its ExaMAX second-source equivalent to the FCI high-speed backplane connector. Its demonstration board ran 28Gb/s over 30 inches of backplane and anticipated the ability to reach 56Gb/s NRZ using 3mm column-spaced IMLAs. Licensing of the FCI connector and acquisition of Teraspeed Consulting adds Samtec to the select ranks of major connector suppliers with the products and technical resources to offer high-speed backplane interconnect systems.
The TE Connectivity booth was studded with active demonstrations including a QSFP+ assembly split into four SFP+ connectors, each running at 26Gb/s.
Multiple demonstrations featured the STRADA Whisper backplane connector including:
- A card cage illustrating standard backplane, midplane, orthogonal, and orthogonal direct configurations running at 26Gb/s
- A cable backplane over 46″ of cable running at 50Gb/s
- A cable backplane over seven meters of cable running 40Gb/s using PAM-4
- A one-meter backplane running at 28Gb/s using one retimer
- A one-meter backplane running at 50Gb/s using PAM-4
Recognizing the challenge that excessive heat creates in I/O interfaces, TE demonstrated a 2X3 stacked QSFP assembly with an integrated heat pipe and sink.
Yamaichi demonstrated its CFP4-to-CFP2 assembly running 28Gb/s NRZ over seven meters of an active copper cable assembly. It also showed a prototype CFP2-to-QSFP+ assembly designed for up to 56Gb/s performance.
The near-doubling of target system data rates in conventional copper connector systems over the past year seems to indicate that the connector industry is tracking its own version of Moore’s Law. It is unclear exactly how designers will create cost-effective production systems operating at 56Gb/s, but the migration path is clearer. Processor performance, power consumption, and thermal management continue to drive the high-performance connector design and development roadmap.