Page 36 - 2020 Interconnect Innovations eBook
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The Impetus: Ever-Increasing Demand for Bandwidth
According to connector industry analyst Bob Hult, “It has always been about speed. From the earliest days of electronic computing and communications, engineers have continually pushed the bounds of established technology to increase the bandwidth of the device.” Demand for greater bandwidth continues to grow. 5G networks, high- performance computing, emulation, AI and machine learning, consumer demand for streaming video, and other applications are among the current drivers of this exponential internet data growth.
To meet this seemingly insatiable demand for data, data center architects and system designers are rolling out servers, switches, and networking equipment that support 56Gb/s PAM4/IEEE 200G system performance. Preliminary 112G PAM4/IEEE 400G systems double bandwidth again, but projected availability is not until 2025.
One frequently discussed option to meet these bandwidth requirements is optical networks. However, chassis, rack, and system architectures would need to be completely redesigned. Realistically, the industry is at least five to 10 years removed from this option because in-system optics adoption would require extensive changes and investment in manufacturing infrastructure.
So, how do we achieve these next-generation data rates with copper-based technology in the near-term?
Challenges of Increasing Bandwidth
System requirements of 56Gb/s, with an eye towards 112Gb/s, are nearing the physical limitations of traditional electronic hardware design elements, in particular traditional PCB laminates and component solutions. Developers are challenged with balancing increasing throughput, scalability, and density demands with concerns such as power consumption, thermal dissipation, signal integrity (SI), time-to-market, and cost. To achieve these data rates, designers are often required to use specialized PCB laminates with lower dielectric constants and dissipation factors.
Unfortunately, these materials are often more expensive and, even with these exotic materials, the higher data rates of the SI channel performance budget significantly compresses the allowed trace lengths. As shown in Figure 2, even when using high-performance, low-dielectric-constant PCB laminates, it’s difficult to have trace lengths of any significant distance.
» Figure 2: Comparison of trace lengths of different materials

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