Is Your System 25Gbps-Ready?
As data-transmission speeds continue rising, design engineers are tasked with delivering scalable systems to ease the transition from 10Gbps speeds to 25Gbps. The proliferation of high-speed and broadband systems in telecom, datacom, networking and other industrial and commercial applications yields greater potential for signal-integrity problems. As bandwidth, signal speed, and port density increase, so too the number of links (or ports), upping the likelihood of signal loss, cross talk, reflection, and mode conversion problems degrading performance, in addition to the potential for serious electromagnetic interference (EMI) and power integrity issues.
Commercial viability is also a consideration when upgrading data transmission. Expensive, over-designed components drive up price and drive away consumers. Systems must be wisely priced, scalable to 25Gbps, and deliver desired performance. Each component along the signal path must be analyzed to determine its effect on the link’s performance. Fortunately, there are viable predictive analytical tools that provide accurate, component-level and end-to-end channel models for analyzing and achieving the optimal balance of price versus performance. Three analysis tools can help system designers minimize design risk by confirming that a proposed system will work—and be cost effective.
Passive and active link analysis performs a sensitivity analysis of each channel component to help determine how each component affects overall link performance. Link analysis results can help designers select the optimal components, minimize time-to-market, and avoid costly mistakes. In the past, link analysis was typically passive, excluding critical silicon components. Today, AMI tools allow for more generic platforms to analyze both active and passive components and compare products and bit error rates of multiple silicon chip vendors. Molex engineers choose representative “corner cases” (unique cases that include multiple, worst case scenarios) and use a passive channel analysis and sensitivity analysis to determine the appropriate solutions. They then perform active link analysis using AMI platform tools. Component and channel model correlation studies are performed. Prototype correlation platforms are built to measure corner cases to demonstrate the models meet the measurements and will work in the field.
The second crucial tool is PCB power-integrity analysis, which is affected by increasing voltages and power consumption, reduced layer counts (lowers cost, improves via effects) and finer pitch BGA footprints (port density). Achieving DC voltage and current efficiencies in 10Gbps systems poses challenges. Supporting 25Gbps systems will require new power design approaches as driving these speeds over long distances requires additional power. Power fluctuations affect the signal delay budget in silicon packages and can produce noise in the PCB. New modeling tools allow board-level power integrity analysis. Other tools can help analyze the power delivery and distribution systems and their effect on system level thermal rise, showing “hot zones” in different mesh densities that could cause chips to overheat. Emerging power and cooling technologies, coupled with optimized interconnect systems that support higher current loads and increasing data rates, will likely prevail in the market.
Electromagnetic Interference (EMI) analysis is the most challenging of the three. EMI (or RFI) is a disturbance that may interrupt or degrade an electrical circuit due to electromagnetic conduction or electromagnetic radiation emitted from an external source. Predictive analytical EMI modeling tools are emerging, but not fully mature. EMI analysis requires measurements of actual systems in EMI chambers. Molex components undergo optimization studies that involve build/measure/model cycles to ensure optimal component performance with minimal electromagnetic emission. This level of testing is critical in high-speed internal and external I/O applications, as well as some internal board-to-board applications. It is particularly important to minimize the potential effect of EMI inside computing devices. If a device emits large amounts of EMI, it may not comply with certain FCC standards.
Leveraging the right tools to support best-in-class 25Gbps performance requires close collaboration between all of the stakeholders in the physical link, including OEMs, component suppliers, silicon suppliers, PCB and raw cable suppliers, and contract manufacturers. Molex is focused on developing optimized interconnect solutions through strategic partnerships with these partners to ensure we are providing “complete solutions” that offer the ideal balance of performance versus price.