Doubling Down on Celero

CapitalG is proud to co-lead Celero’s $275M Series C less than a year after leading their Series B as they redefine AI-scale networking.

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We're thrilled to share that we are co-leading Celero's $275 million Series C alongside Atreides Management and Valor Equity Partners, with continued support from existing investors Sutter Hill Ventures and Maverick Silicon. Less than a year after we led the Series B, both Celero's technology and the market it serves have advanced at unprecedented speed.

Celero designs next-generation coherent digital signal processors (DSPs), a critical optics technology purpose-built for AI data centers. Over the past year, we’ve watched firsthand as the incredible team, led by co-founders Nariman Yousefi and Oscar Agazzi, have rapidly innovated to push the frontier on what’s possible in optics. Since we led their Series B, the company has taped out the industry's first 2nm coherent DSP silicon, combining their proprietary DSP design with advanced analog technology to achieve groundbreaking performance and efficiency. The result is an architecture that carries more data per link vs. traditional PAM4, uses less power to do so than legacy coherent, and scales from 1.6T to 3.2T and beyond as AI advancements continue to push data center infrastructure to its limits.

As Celero has advanced its technical roadmap, the broader market for AI compute and networking has moved toward Celero as well. Inside the cluster (what the industry calls scale-up), model training and inference now run across pods of thousands of XPUs that require rapidly increasing optical bandwidth. As these systems scale, existing copper and legacy optical technologies face growing limitations in bandwidth, reach and fiber efficiency, creating an increasing role for coherent connectivity. At the same time, the largest workloads now span across multiple data center buildings (what the industry calls scale-across) - at these distances and current and future bandwidths, legacy PAM4 DSPs cannot provide sufficient signal while traditional coherent solutions are overpowered and overpriced. Celero’s coherent technology is the critical unlock that supports both next-generation scale-up and scale-across

We led Celero’s Series B because we believed coherent DSPs would become essential infrastructure for AI at scale, and we believed this team was one-of-a-kind to tackle this problem. Everything we have seen since has deepened that conviction, and the opportunity in front of the company is multiples larger today than it was a year ago. We're proud to co-lead Celero’s Series C, and we look forward to continuing our partnership with Nariman, Oscar, and the entire Celero team as they build the networking foundation the next generation of AI will run on.

Read our blog post copied in full below from November 2025, when CapitalG led Celero’s $100 million Series B.

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Celero: Bringing Coherence to AI-Scale Networking

By James Luo, Jamie Rosen | November 2025

We're thrilled to announce our lead investment in Celero and our partnership with CEO Nariman Yousefi, CTO Oscar Agazzi, and the rest of Celero's exceptional team. Celero is building a new class of coherent digital signal processing (DSP) platforms to tackle one of modern computing's most pressing challenges: the networking bottleneck that throttles AI-scale infrastructure.

The AI Revolution's Networking Bottleneck

The rise of AI has completely redefined the scale of modern computing. Training and serving today's frontier models and AI applications requires linking thousands of GPUs / XPUs spread across racks, rows, and even entire buildings, all operating as a single, synchronized brain. At this scale, networking has quickly become a defining constraint: It's no longer just about building faster compute chips; it's about moving massive volumes of data across thousands (and in the future, millions) of those chips with minimal latency and near-perfect coordination. As individual data centers scale from isolated servers and racks to campus or even region-wide compute fabrics, the network has become the critical backbone and bottleneck that determines how efficiently AI infrastructure can perform.

There's just one problem: Yesterday's networking technology wasn't designed to operate at this new level of scale. As clusters grow and data flows intensify, existing interconnects are hitting their physical limits. At the center of this challenge lies the digital signal processor (DSP), the tiny chip inside every optical transceiver that converts electrical signals from a GPU / XPU into pulses of light for transmission over fiber. This translation process dictates the speed, efficiency, and cost of every connection. Currently, data center architects are caught between two imperfect options:

• PAM4: The long-time workhorse of the data center. While it can be cost-effective, it hits a wall at the bandwidths and data rates tomorrow's AI compute fabrics require (1.6T or 3.2T+), resulting in greater noise, more signal degradation, and significantly shorter reach.

• Legacy Coherent: Technology borrowed from the telecom world. While it can handle high data rates over long distances, it is over-engineered for the data center, loaded with features that make it far too costly and power-hungry to deploy at scale.

The Celero Approach: Coherence for the Data Center

Celero is bridging this gap by developing a new class of coherent DSPs designed specifically for the demands of AI-scale networking. Celero delivers the performance of telecom-grade systems with the power efficiency and cost profile required for dense data centers. Its purpose-built architecture enables high-speed optical links without the usual energy or economic tradeoffs, making coherent interconnects practical for use within and across data centers.

Delivering on this vision requires a uniquely qualified team - and Celero is one of the few in the world with the expertise to do it. The company is led by co-founder and CEO Nariman Yousefi, who previously was an SVP at Broadcom, the CEO of DSP startup ClariPhy (acquired by Inphi), and the leader of the coherent DSP businesses at both Inphi and Marvell. He's joined by co-founder and CTO Oscar Agazzi, one of the industry's most accomplished DSP architects, who led advanced design efforts at ClariPhy, Inphi, and Marvell.

Together, they've built a 100-person (and quickly growing) team with exceptional depth in DSP design, drawing top talent from Marvell, Inphi, and Broadcom. Many of these engineers helped develop the most widely deployed DSPs in use today and have a proven record of taping out complex optical technologies. This deep expertise, combined with Celero's strong foundry relationships and innovative designs, gives the company a rare ability to bring a new generation of coherent DSPs into production.

CapitalG's Investment in Celero

We're proud to lead Celero's $100 million Series B alongside Sutter Hill Ventures, Valor Equity Partners, Atreides Management, and Maverick Capital. We're excited to partner with Nariman, Oscar, and the entire Celero team as they tackle one of the most pressing challenges in modern infrastructure and, in doing so, help unlock AI's full potential.