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Mouser Electronics White Paper The fifth generation of PCIe (PCIe 5.0) uses non-return-to-zero (NRZ) signal modulation to achieve transfer rates of up to 32 gigatransfers per second (GT/s). NRZ modulation uses two voltage levels to carry one bit of data per clock cycle. The sixth generation (PCIe 6.0) doubles this data rate using pulse amplitude modulation 4-level (PAM4). This technique uses four voltage levels instead of the two employed by NRZ signaling, meaning 2 bits of data can be transmitted per clock cycle, thereby doubling the overall data transfer rate. PCIe connectors are vertically or horizontally mounted card-edge sockets (depending on the form factor) that affix directly to a board (Figure 1). They allow for quick installation of any PCIe-compatible device, including GPUs, ASICs, and other high-speed peripherals. These connectors enable high-bandwidth data transfer, helping to minimize latency and prevent issues across the system. Cross- Generational Compatibility Regardless of the generation, PCIe connectors conform to a standard physical form factor and PCB footprint, making them scalable and flexible. The standardized interface allows users to upgrade individual modules in response to changing demands. Alternatively, the backward compatibility of PCIe connectors allows existing equipment to be reused where performance allows. Choosing the connector that matches each requirement allows the user to balance performance with cost. Beyond speed and compatibility, PCIe connectors offer reliable data transmission. At high data rates, signal integrity is important because even minor disruptions can cause data loss. Connectors must minimize insertion loss, return loss, and crosstalk across multiple high-speed lanes. Effective electromagnetic interference (EMI) shielding is also essential to protect sensitive signals from external noise, especially in tightly packed server environments. Mechanical durability matters, too. Connectors must handle repeated insertions, thermal shifts, and vibrations without degrading performance (Figure 2). With these various data transmission requirements, the multifaceted characteristics of high-performance connectors make them essential to data center architecture, ensuring that infrastructure can grow with changing demands. Figure 2: Connectors must be designed for durability and signal integrity in dense data center environments (Source: Matthias/stock.adobe.com) Amphenol manufactures a comprehensive range of PCIe connectors (Figure 3) that conform to the widely accepted standard and exceed the performance required for even the latest applications. Amphenol PCIe connectors support data rates up to 64 GT/s and are rated for 50 mating cycles, offering the signal integrity and durability required for high-performance data center applications. While reliable data connections are essential for data center operations, they are not designers' only consideration. Without the power to feed the many GPUs, accelerators, and network connections, data centers cannot deliver the full potential of AI. Power to the Data Center Connectors do more than just move data in a data center. They also play a critical role in power delivery. Even before the widespread emergence of AI, data centers were considerable power consumers. Estimates from the International Energy Agency (IEA) state that energy consumption in data centers during 2022 represented about 2 percent of global energy production. This number was recorded just before the sharp rise in generative AI workloads. 4 The full effect of this growth in AI services is reflected in the potential rise of energy consumption. The IEA report also predicts that data center energy use will likely double by 2026, representing approximately 4 percent of the global energy market. Figure 3: Amphenol Communications Solutions PCIe M.2 Gen 5 High-Density Card Edge Connectors. (Source: Mouser Electronics)

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