New-Tech Europe | Q3 2026 | Digital Edition

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This allows the system designer to select the transmission medium according to the distance and performance requirements without necessarily changing the fundamental package-level interface. The distinction becomes increasingly relevant as system architectures combine very short high-bandwidth connections with longer links. Copper remains attractive where reach permits, while optical connectivity can extend the same architecture beyond practical passive-copper distances. The significance is therefore not simply copper versus optics. It is the possibility of treating the package-level interface as a common starting point for both. 224 Gbps is not the endpoint Although the Samtec paper focuses on achieving reliable 224 Gbps PAM4 connectivity, the architectural implications extend beyond a single generation. The company notes that its Bulls Eye test systems are being used for characterization at data rates above 200 Gbps per channel and for signal characterization extending to 448 Gbps . That makes the move toward package-level connectivity more than a response to the immediate challenges of 224 Gbps. As data rates continue to increase, the electrical cost of every transition in the channel becomes harder to absorb. Vias, BGA structures, PCB traces and connector transitions that were manageable at lower speeds increasingly consume a significant portion of the available signal budget. The direction described in the paper is therefore clear: shorten the electrical path, reduce unnecessary transitions and move high-speed connectivity progressively closer to the silicon. At 224 Gbps PAM4, this shift is already changing the role of the PCB in high-performance systems. The board remains fundamental for power, control and system integration, but carrying every high-speed signal across it is no longer necessarily the default architecture. The question for the next generation of system designers may therefore be less about how to make the PCB channel faster - and increasingly about how much of that channel still needs to be on the PCB at all.

Samtec describes an approach in which the same Si-Fly HD interface can be used with passive copper cable assemblies for shorter connections or with optical solutions where greater reach is required.

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previously have been relatively insignificant can consume a meaningful portion of the available margin. Samtec examines this problem in both PCB and Twinax transmission structures. According to the paper, tightly coupled Twinax cable provides improved control of differential-pair skew and impedance compared with PCB transmission lines. The company's Eye Speed Hyper Low Skew Twinax cable specifies intra-pair skew of up to 1.75 ps per metre . That figure becomes easier to appreciate when compared with a unit interval of only about 9 ps. The paper also considers what happens when cables are used in realistic mechanical conditions rather than remaining perfectly straight. Maintaining stable impedance and skew while a cable is bent or routed through a system is important because physical installation can otherwise alter the electrical relationship between the conductors. For system designers, skew therefore becomes more than a cable specification. At 224 Gbps, it forms part of the overall timing budget of the channel. Copper and optics on the same interface Co-Packaged Connectivity also creates an interesting architectural option: the physical interface can support different transmission media depending on the required reach. Samtec describes an approach in which the same Si-Fly HD interface can be used with passive copper cable assemblies for shorter connections or with optical solutions where greater reach is required.

Based on: Achieving 224 Gbps PAM4: New Interconnect Methods to Ensure Signal Integrity, Samtec, October 2025. Courtesy: Samtec Inc.

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