fJscaler, GF, and Cadence Collaborate to Scale Optical Interconnects for AI

Unified EIC/PIC Co-Design and Strategic Foundry Collaboration Helps fJscaler Develop Advanced Optical Engines for AI Infrastructure

fJscaler is named after a unit of energy so small that it takes a quadrillion of them to make a single joule. That is the point. A mixed-signal analog semiconductor company headquartered in Beaverton, Oregon, fJscaler designs the chips that move data through the optical fiber of AI data centers. The two numbers that matter in that business are bandwidth and energy per bit.

To manufacture these highly sophisticated systems at scale, fJscaler works with GlobalFoundries (GF) as its close strategic fabrication partner for its photonic integrated circuits (PICs). This creates a powerhouse ecosystem where fJscaler's architectural innovation, Cadence's specialized electronic/photonic design automation (EPDA) environment, and GF's leading silicon photonics manufacturing platforms converge to advance the entire industry's photonics portfolio.

On a Friday in September, three of the company's leaders sat down at fJscaler's Berlin office to explain how they design those chips, and why the electronic and photonic portions of the chip are now built on the same Cadence platform.

From left to right: Marco Vitali, CTO, Samir Desai, SVP Corporate Development, and Andrea Zanzi, PIC Design Manager at the fJscaler Berlin office.

Light, Not Copper

Every generation of data communications has ended up running on light. Co-founder Samir Desai traces the pattern from the telecom boom of the late 1990s through the cloud data centers of the 2010s, and he sees AI as the third wave.

"Photonics and optical communications are central to any data communications market," Desai says. "Similarly, for the AI market, optical comm and photonics serve a very central role in both scale-up, scale-out, as well as scale-across for these AI data centers."

The reason is physics. Copper links carry digital signals across a board or from card to card, but the distances and data rates of an AI cluster push them past their limits in reach and noise. Past that point, as Desai puts it, "you must go to optical comm."

Silicon made photonics affordable at volume, and Desai has a ready comparison for it: "Silicon photonics is doing the same for the photonics industry what CMOS did to digital electronics." By manufacturing on GF's production-proven silicon photonics platforms, fJscaler can translate complex optical architectures into reliable, mass-producible semiconductor reality.

What AI adds is scale, in unit volumes he calls unprecedented for any hardware stack in the history of electronics or photonics, and a pace of product refreshes that leaves no room for a chip that only fits one generation. For fJscaler, that means customized electronics and photonics for every link, because, as Desai puts it, "one size will not fit all."

CTO Marco Vitali describes what the company ships in plain terms. "fJscaler helps our customers because we provide the next-generation optical interconnects, which bring 1.6 terabits (TB) of data into a single optical fiber. This allows more traffic connecting GPUs, CPUs, and data centers together," Vitali says.

Optics also lets operators space their power-hungry racks farther apart, which Vitali says means "better cooling and better data center architecture."

Engines, Not Chips

Vitali does not talk about designing chips. He talks about designing "engines": an electronic IC, a package, and a photonic IC that function as a single unit. Above 100GHz, every interface between them becomes important, and a poorly optimized transition anywhere in the chain costs performance that cannot be won back.

"Co-design is the fundamental aspect of the design. We need to design engines: electronic IC, package, and photonic IC. Every interface at 10GHz becomes important. If you do not optimize every step, every transition, you may degrade the performance, and you cannot achieve the performance requested by our customer," Vitali says.

Andrea Zanzi, who joined the company in February 2026 as PIC Design Manager after more than a decade in silicon photonics, gives the receiver as an example. The transimpedance amplifier that turns a photodiode's current into a usable signal can only be tuned properly if the photodiode's behavior is captured in an accurate model first.

"It's fundamental to be able to co-design electronics and photonics. The interdependency is important," Zanzi says.

The traditional photonic toolchain works against that. In Zanzi's experience, the tools are "scattered all over the place, from device to scripting to measurement," and the glue between them is custom scripts that eat design time and introduce errors. "What we need is a unique platform," he says.

fJscaler test setup for photonic chips in their Oregon lab.

One Platform, One Language

fJscaler already had one for its electronics. "When it comes to mixed-signal analog, Cadence has always been the go-to design tool. We have used Cadence from day one of the inception of fJscaler, and we are doing quite a few designs on our electronics and now adding several more designs on the photonics side as well," Desai says.

"We chose the Cadence Photonics Platform because our design team has more than a decade of experience with Cadence. Using the same platform, we could leverage the experience of our team, and we could use the same layout tool, the same environment, the same optimization that we have on the electronic IC design and move it to the photonic IC design," Vitali says.

Zanzi saw the effect on the people before he saw it in the tools. Electronic and photonic engineers come from different backgrounds and hold different mental pictures of the same chip. In the shared environment, an electronic engineer can pick up a photonic device and "treat that as an electronic component," Zanzi says, "without seeing everything that goes underneath." The two disciplines, in his phrase, "speak the same language."

"The biggest aha moment for us when using the Cadence Photonics Platform was when we saw both electronic engineers and photonic engineers working on the same platform and discussing the same software. We could discuss and get things done on the same platform, which was great for us," Zanzi says.

For Vitali, the defining breakthrough came when the team could finally simulate photonics and electronics simultaneously. Electronic designers have relied on corner and Monte Carlo analyses for decades, but bringing photonic components into the same simulation framework has been a game-changer. It gave the team a new level of confidence in the system's behavior and transformed the way they design integrated photonic solutions.

"The Cadence Spectre Photonics Option is a really valuable tool for our team, because it allows us to quickly design the full circuits through schematics and testbenches. We already have an idea of the performance at the different corners, both in temperature and wavelength, and that gives us an immediate idea of the yield we could expect for a specific product," Zanzi says.

Five Chips in Two Months

The result shows up where it counts, in the tapeout calendar. "Cadence Virtuoso Studio allows us to design both the electronic and the photonic simultaneously, and this has boosted productivity. In the latest engineering run, we had five photonic chips, and these were co-designed in two months. This is unprecedented, according to my experience," Vitali says.

This rapid execution relies entirely on the close-knit, three-way symbiosis between the design team, the software provider, and the foundry. Cadence optimizes its EPDA environment for GF's manufacturing processes, meaning its high-performance Process Design Kits (PDKs) are natively integrated right into the Cadence cockpit.

The same flow makes a change in the foundry process or an optimization tweak a routine event rather than a restart. "When a customer comes to us, for both PIC and EIC, with a specific requirement, Cadence allows us to seamlessly switch to the new PDK on both sides. Then we can design, prototype, verify, and tape out in a quick time without any kind of issue," Zanzi says. In the final weeks before tapeout, the layouts are checked with Cadence's Pegasus Physical Verification Platform for both LVS and DRC to ensure they match GF's exact fabrication tolerances.

Desai sees the payoff at the level of the whole product. "The commonality in our design flow with electronics and photonics allows us to deliver the full link solution, the full end-to-end solution, at a very great turnaround time. This is the big deal for fJscaler with the Cadence design flow and our manufacturing roadmap with GlobalFoundries," he says.

A Mutually Beneficial Alliance

This partnership acts as a three-way catalyst that elevates each company's silicon photonics portfolio:

• For fJscaler: It bridges the gap between ultra-high-frequency design and physical yield. They gain immediate access to GF's leading-edge features—such as monolithic RF-CMOS and advanced co-packaged optics capabilities—while using Cadence tools to design error-free architectures at unprecedented speeds.
• For GlobalFoundries: Collaborating with an aggressive innovator like fJscaler provides real-world design stress-testing on their silicon photonics platforms. This field validation helps GF refine its PDKs and hardware architectures, enabling them to introduce industry-defining platforms like the SCALE™ (Silicon photonics Co-packaged Advanced Light Engine) solution to the broader AI market.
• For Cadence: This tight feedback loop allows Cadence to perfect its automated EPDA software. By seeing how fJscaler's engineers utilize the software to target GF's processes, Cadence can consistently deliver best-in-class, production-proven tools that keep them at the forefront of the mixed-signal and optical compute industry.

Talent Where It Lives

Engineers who can design analog circuits above 100GHz are rare, and fJscaler has decided it is easier to go to them than to bring them to Oregon. That decision shaped where the design environment itself lives.

"Our strategy for right-sizing the talent for fJscaler is to find the talent where they are. They could be in the Americas, in Europe, in Asia. For that to work efficiently, we elected to go with Cadence OnCloud. Our entire EDA is housed at Cadence OnCloud, and this allows all our engineers across the globe to very efficiently work on any design, at any time," Desai says.

There is a certain logic to a company that sells into AI data centers running its own design work in the cloud, and Desai does not miss it. "At the end of the day, if we're servicing the AI cloud market, we must also be users of the same infrastructure," he says.

Asked to sum up the value of this integrated ecosystem, Zanzi needs only one sentence, and then adds the plan for the years ahead: "Seamless integration of photonics and electronics in the same platform. We are looking forward to the next years of work together with our partners Cadence and GlobalFoundries."

Discover how fJscaler is using Cadence technology in this Designed with Cadence video, and learn more about Cadence OnCloud and our collaboration with GlobalFoundries.