The Industry’s First and Broadest PCIe® 7 Portfolio Powers AI Within and Beyond the Rack
At a Glance:
- PCIe 7 unlocks the massive bandwidth AI needs while pushing signal integrity to its limit
- For links beyond the rack, we introduce our first optical connectivity products
- Within the rack, Aries Smart Retimers and Redrivers help extend challenging copper links
On October 2, 2019, Astera Labs shipped its very first product: the Aries Smart Retimer for PCIe 4.0/5.0. In many ways, Astera Labs and PCIe have matured together, alongside the increasingly realized potential of the AI applications they help power and always in lockstep with our flagship signal conditioning product.
PCIe has now advanced to its seventh generation, and the blazing data rates possible in this generation bring with them new infrastructure challenges to solve. Within the rack, every channel is harder to close, loss link margins are razor thin, and finely tuned signal conditioning matters more than ever. At the same time, architects must design for a scale-up domain that has stretched well beyond the rack without adding significant signal loss or latency along the way.
So today, we’re announcing the latest generation of Aries products: the industry’s first and broadest PCIe 7 signal conditioning portfolio, comprising an expanded copper connectivity family and the very first optical connectivity products Astera Labs has brought to market. Aries 7 Smart Retimers, Redrivers, Cable Modules, Optical Drivers, and Optical TIAs deliver the long reach signal conditioning PCIe 7 speeds demand for applications modern data center architectures require.
Aries brought us to this moment, and we’re proud to share how this growing family will help write AI’s next chapter.
PCIe 7: New Signal Challenges, New Opportunities
PCIe 6 brought the industry’s first big signal modulation shift in years: While the Nyquist frequency held steady to avoid immediate hardware disruption, a move from NRZ to PAM4 signaling doubled maximum theoretical bandwidth from 64 GB/s for an x16 slot to 128 GB/s.
PCIe 7 doubles this bandwidth again, but it does so by retaining PAM4 signaling and doubling the Nyquist frequency to 32 GHz. However, the channel loss budget for the PCIe 7 specification has only grown by 4 dB, from 32 dB to 36 dB. That means PCIe 7 channels are proportionally more constrained than PCIe 6 channels were — the rate at which signal loss increases with doubled frequency outpaces this modest increase in budget. This jump exposes the entire channel to extreme high-frequency attenuation, forcing a mandatory upgrade across the hardware ecosystem: ultra-low-loss PCB material, next-gen high-density connectors, and active copper or optical cabling are now non-negotiable to survive 32 GHz insertion loss.
At the same time, the PCI-SIG spec has doubled the number of retimers permitted on a channel from two to four for PCIe 7. Put those two changes together and the implications are significant: More channels across the platform now require signal conditioning, and the specifications allows more signal conditioning devices to be used to close them, even at the expense of power consumption and latency.
PCIe 7 Beyond the Rack: Optimizing for Reach With Optical Connectivity
Copper alone can’t cover the reach required for expanding cluster sizes at PCIe 7 speeds. System modularity means PCIe is no longer staying inside the box: It’s connecting across chassis and across racks. As PCIe fabrics expand across systems and racks, copper and optics are coming together to power next-gen AI clusters with copper driving dense in-rack links and optics extending across racks.
To enable this hybrid connectivity architecture, we’ve chosen this moment to expand the Aries 7 family into optics. Both the Aries PCIe Smart Optical Drivers and Aries PCIe Smart Optical TIAs are high-performance, low-power, high-density devices purpose-built for linear pluggable optics (LPO) and near-packaged optics (NPO) applications. At the transmit side (Drivers) and receive side (TIAs) of optical links, these devices provide, the electrical-to-optical and optical-to-electrical conversion needed to travel at PCIe 7 speeds up to 50+ meters.
This isn’t a hypothetical use case. We are actively working with multiple customers to build larger clusters of accelerators by extending PCIe fabrics beyond the rack with high-density NPO modules designed with Aries Smart Optical Drivers and TIAs. It’s the same progression we’ve seen play out before: connectivity moving from the chassis level, to the rack level, and now to the pod level. With this optical launch, our product portfolio now extends the PCIe fabric, optically, to the pod level.
Both Smart Optical Signal Conditioners are tied together — and tied to the rest of the Aries copper signal conditioning portfolio — by COSMOS real-time link intelligence, enabling resilient deployment beyond the rack, across and between clusters, with end-to-end optical link management for deployment at scale.
A second, related trend is disaggregation. In conventional systems, CPUs, XPUs, SSDs, and NICs all live together in one box, and these racks are linked together into a larger cluster. Increasingly, though, operators are separating systems and racks into collections of similar devices instead: a rack that’s all CPUs, all NICs, or all SSDs. This disaggregation is already common for storage but is increasingly applying to compute and switching in data centers as well.
Disaggregation is a distinct trend from simply building bigger clusters, but it has the same effect on interconnect: It drives longer distances between devices, and it pushes more of the fabric toward signal-conditioned copper and optics.
For inter-rack links that can be closed by copper, our Aries PCIe Smart Cable Modules extend reach up to 3 meters for active copper cables and 6 meters for active electrical cables, providing rack-to-rack links at PCIe 7 data rates of up to 128 GT/s. When these links stretch across multiple racks, our Aries optical products take over.
PCIe 7 Within the Rack: On-Board Signal Conditioners and Internal Cable Modules
Whether designers are simply adding signal conditioners to existing architectures to accommodate the PCIe 7 transition or designing entirely new topologies from scratch, the fact is that the majority of PCIe 7 channels are going to need some form of signal conditioning. What kind of signal conditioner is the more important question going forward.
Smart Retimers and Smart Redrivers in PCIe 7 Racks
As signal conditioning devices multiply across the rack, power becomes an increasingly important optimization factor. While they provide full signal regeneration and superior margin recovery to redrivers, retimers draw more power. It may not be optimal to simply choose the higher-performing option in every possible location across every channel.
This is why we’ve made the decision to add Aries PCIe Smart Redrivers as a complement to our Aries PCIe Smart Retimers, and to design both devices to support Smart Swap pin-compatibility via the common OCP Signal Conditioner Standard Footprint. There is an emerging set of edge-case channels which require a degree of signal conditioning at PCIe 7 speeds but can be closed without full signal regeneration at lower power; for these use cases, redrivers can be the optimal solution.
Designers have traditionally been hesitant to use redrivers in AI racks because they’ve provided less visibility into the signal than a retimer. Our PCIe 7 Aries Smart Redrivers boast several telemetry and diagnostic features like auto-adaptive EQ and eye monitoring to accelerate tuning and bring-up via our COSMOS telemetry platform.
Connectivity Within the Chassis: Cable and PCB Options
The signaling described above establishes the general need for signal conditioning, but there’s a second, independent trend reinforcing it: Some architects today are relying more on modular PCBs to connect layers inside the rack instead of internal cabling. Systems are being built at such high volume, at such a rapid pace, that companies want to automate assembly wherever possible, and rigid, board-based interconnect is easier to manufacture at scale than hand-routed cabling.
But when you’re doubling frequency and dealing with a lossier channel because of the PCB itself, and then using more PCBs to build longer channels, the emphasis on signal conditioning only grows. Moving away from internal cables for manufacturing reasons ends up putting more pressure on signal conditioning silicon to keep those longer, PCB-heavy channels viable.
That said, this trend isn’t absolute. Internal PCIe cable modules remain in active use, and we have included the updated Aries PCIe Smart Internal Cable Modules in the expanded family.
Looking Back and Looking Ahead
From that first Smart Retimer in 2019 to today’s expanded copper and optical portfolio, Astera Labs has grown alongside PCIe through every generational leap.
As the protocol pushes further into scale-up infrastructure that spans racks, rows, and pods, we remain committed to this vital open standard — and to giving system architects the broad portfolio of copper and optical building blocks they need to keep it running at full speed well into AI’s future.