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High-Speed Data in Industrial, Automotive, Healthcare, and Data Centers 10 Learn More QSFP-DD Interconnect System & Cable Assemblies Achieving Higher Performance The adoption of new signal modulation techniques is key to the improved performance of the 400G network. Traditional data communications have depended on binary communications. Digital signals are transmitted in binary states (zeroes and ones), often called non- return to zero (NRZ). To expand the capacity, the latest systems use a technique known as four-level pulse amplitude modulation (PAM4). PAM4 is a signal modulation technique that uses four different signal levels to represent data instead of two. With this technique, the capacity or bandwidth can be doubled, but at the cost of requiring specialized hardware and cabling. The reason that the hardware needs to be upgraded is to preserve signal integrity. Signal integrity (SI) is the name given to the techniques and technology applied to preserve the quality of digital signals sent across wired, optical, or wireless media. For a signal to be received accurately, the medium over which it is sent must not degrade it to the point where the difference between the different states cannot be determined. For traditional NRZ signals that are transmitted in two states, the voltage difference between the states is easier to detect. Therefore, the system is more tolerant of electronic noise or interference. However, PAM4 uses four different states, and the difference in voltage between each state is smaller. Consequently, the integrity of the signal is more at risk of interference. Designers must turn to more advanced technology to protect the SI. High-Speed Media As mentioned, the medium over which the signals are sent has a significant impact on the performance of the system; the design of the transceivers, connectors, and cabling plays an essential role in preserving SI. For many years, system architects could depend on high- speed backplanes. Specialized printed circuit boards (PCBs) served as the highway for data traveling within the cabinet. However, the physical design of a PCB does not lend itself to transmitting data at high speeds. The planar nature of PCB design results in many parallel layers and side-by-side tracks unsuitable for high-speed signals. At a frequency of 13GHz, a PCB can introduce losses of 45dB in less than a meter. When consumers demand so much data so quickly, this poor performance will risk the unacceptable loss of signal integrity. As a result, system architects are turning to cables to provide connections even within the cabinet. For a few meters, twin axial cables deliver a far superior transmission medium compared to PCB. These are known as Direct Attach Cable (DAC) assemblies. They provide data rates as high as 400Gbps and can be manufactured in customized lengths for greater design flexibility. Molex manufactures DAC assemblies using their latest Quad Small Form-factor Pluggable Double Density (QSFP-DD) connectors. Developed from the QSFP28 module, this latest high-density form factor supports data rates up to 400Gbps and features twice as many channels as the older design but without an increase in overall size. When combined with the doubling of capacity achieved through PAM4 signaling, QSFP-DD can support the 400G network transmission for the newest systems. Molex QSFP-DD connectors deliver higher port densities than previous solutions, allowing data centers to conserve space and reduce costs. In addition, the superior performance of this new form factor enables system architects to scale their networks more efficiently to meet the growing demands of applications and services. This helps ensure that data centers continue operating effectively and efficiently as their needs evolve. Barriers to Entry With so much additional performance available, the benefits of 400G Ethernet are clear. However, moving from 100G to 400G Ethernet is not straightforward. The principal barrier to the adoption of this new technology is cost. Implementing 400G Ethernet requires significant investment in equipment and infrastructure. The cost of new transceivers, switches, and other devices is relatively high compared to previous generations of Ethernet. In addition, as 400G Ethernet is still relatively new, not all vendors can produce the necessary equipment.