Find Out What the Newest COBO Working Group Is Up To

By Amy Goetzman | April 26, 2022

The COBO MWIS Working Group aims to advance the increase of bandwidth and reduce power consumption for printed circuit board interconnect systems.  


As streaming video, IoT technologies, industrialized automation, and the rapid addition of billions of new connected devices push data center workloads to exponentially higher levels, the need to move activity from enterprise data centers to the cloud is becoming critical. Highly efficient board designs and quality interconnects used in high-speed architectures is key to managing the even greater demands that are coming soon with a new generation of connected cars, 5G-enabled technologies, and other bandwidth-intensive activities. To help standardize successful solutions for these challenges, the Consortium for On-Board Optics (COBO) is developing specifications for interchangeable and interoperable optical modules that can be mounted onto printed circuit boards. Connector suppliers that have joined the effort include Amphenol Communications Systems, BizLink, Hirose Electric, I-PEX, Samtec Inc., TE Connectivity, Rosenberger, US CONEC, along with founding members Broadcom, Cisco, IBM, Microsoft, Ranovus, and others.

COBO has three working groups: CPO, developed to guide the development and standardization of co-packaged optics, Data Center Networking, and Multi-Mode Waveguide Interconnect System (MWIS), newly formed in late 2021 to increase bandwidth and reduce power consumption of PCB Interconnect Systems.

Co-packaged optics applies the power-saving concept of bringing the optical module inside the box from the faceplate, where the conventional pluggable optics are present, thereby reducing the copper trace length, overall insertion loss, and the number of taps of digital equalizers.

The MWIS working group focuses on the replacement of copper traces with multi-mode waveguides. By adding an extra-thin interface for electrical/optical and optical/electrical conversion within close proximity to the electrical component, additional efficiencies can be achieved. Based on this work, COBO announced an official proposal for a novel MMWG interconnection architecture to address system power consumption and bandwidth limitations for data center applications. The MMWG system replaces copper traces with optical multimode waveguide embedded in PCB layers for high-speed signal path to increase overall power efficiency and traffic bandwidth. To learn more and see detailed diagrams on MMWG architectures, see the paper on COBO Hirose presented at DesignCon 2022.


Joshua Kihong Kim, Principal Engineer at Hirose Electric and COBO MWIS Working Group Chair

Joshua Kihong Kim, Principal Engineer at Hirose Electric and COBO MWIS Working Group Chair, said MWIS is composed of three key channel elements: Media adaptor (MA), photonic integrated circuit connector (PICON), and multimode waveguide embedded in PCB (MMWG). Hirose is contributing Proof of Concept product of MA. Background technology can be further reviewed through this webinar on multimode system design for photonic circuit integration and this whitepaper on MMWG as an alternative to copper traces. To view a prototype of a system with embedded multimode waveguides, see this presentation.

“Although embedded optical waveguides in printed circuit boards have been researched for decades, now is the time for the industry to work together to address the imminent bandwidth and power issues associated with copper interfaces,” said Kihong Kim. “In the development of on-board optical systems, this is one of the missing pieces of the puzzle, and COBO is stepping up to develop specifications to enable an industry ecosystem.”

Interconnects designed to support earlier COBO designs are available now.

TE Connectivity’s COBO form factor enables at least 32 of the 400G modules in 1RU equipment with full height heat sink and distributed thermal load.

COBO adopted Samtec Inc’s two-piece surface mount connector system based on Samtec’s FireFly™ Micro Flyover System™ for its standardized on-board optical modules.


Samtec’s solution for on-board optics applications consists of a card-edge connector for the high-speed function and a one-piece z-axis connector for management interface and power contacts.

As part of the miniature footprint, the power/control connector reduces the size of on-board optical modules while increasing port density in data center and HPC applications. Additionally, the Samtec connector was selected for the Power/Control connector for all low-speed signals on x8 and x16 lane full-duplex options of the COBO modules. The built-in positive latching capabilities of the new connector enhance ruggedness in on-board optical modules.

Like this article? Check out our other board-to-board, and high-speed articles, our Datacom & Telecom Market Page, and our 2022 Article Archive

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Amy Goetzman
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