Serdes deal to push copper server interconnect to 100Gbit/s

A licensing deal with GlobalFoundries has provided chipmaker Aquantia with the ability to speed up development of a 100Gbit/s interface for copper wiring that can take over from fibre in short-reach links within data centers.

Phil Delansay, Aquantia’s founding CEO and senior vice president of business development, said the intention behind developing a high-speed copper interconnect for data centers is to “fill the gap left by cost issues with existing fiber-optic modules.

“This is a 100Gbit/s technology that’s able to cover distances up to 3m. Although the connectivity needs of hyperscale data centers go all the way from a few meters to kilometres, 3m is a distance that represents the majority of the connectivity in the data center,” Delansay added.

Market research by Aquantia pointed to the way in which scale-out applications spread workloads across multiple blades and servers as being the key driver behind the high number of fast but very short connections across racks.

Cost targets

“Optical has a big issue of cost with very short connections. You are paying a lot of additional cost for electrical to optical conversion. Experts from Facebook and Juniper have been saying that even as recently as the last OFC. The target from the hyperscale data center guys is ‘give me a dollar per gigabit per second and I will deploy’.”

One issue with the cost of adopting fiber-optic communication at 100Gbit/s is that the market-ready options demand data be split across four 25Gbit/s connections – increasing not just module cost but that of serializing data bytes as they move to and from the interfaces.

At this stage, Aquantia is saying very little about the techniques it is employing to push copper connections to 100Gbit/s but Delansay stressed it is a single physical connection. To implement the interface and obtain a manufacturing source for the interface chips that Aquantia will make, the company licensed a 50Gbit/s serdes from GlobalFoundries.

Serdes springboard

“We have the expertise to develop a 25Gbit/s serdes or a 50Gbit/s serdes. We have the DNA to build this kind of circuitry. But for this quantum leap, to achieve 100Gbit/s over 3m, the secret sauce required was not in designing such a serdes. So, we decided to start from an existing 50Gbit/s core and sought to license that from someone. We found that the best core came from IBM Microelectronics, the group that GlobalFoundries acquired two years ago,” Delansay said.

“We have the rights to modify the core and so we have augmented with our architecture. As part of the agreement we are licensing the 100Gbit/s QuantumStream IP back to GlobalFoundries so they can deliver the core as part of their ASICs, which will broaden the ecosystem,” Delansay explained.

The interface technology will be deployed on GlobalFoundries’ 14nm finFET process. “It is a phenomenal process node with advantages in cost cost and density,” Delansay claimed.