In just six years, DRAM interfaces multiplied by a factor of six. As an example of the instrumentation required by the new standards, the latest 3.125-Gb/s XAUI implementation calls for eye-pattern measurements made using an oscilloscope with a bandwidth at least 1.8× the data rate figure. As parallel buses stretch toward 2-GHz bit rates, a new class of multilane buses has emerged with bit rates of 2.5 to 6 GHz and beyond.
Yet, not all new buses and protocols will survive. The protocol-of-the-month hype and over-funding of the past are gone as system architects look for fundamental value and differentiation. Today’s designers think very pragmatically about the interfaces they choose.
As a result of these developments, designers and engineering managers are looking at test equipment with a new perspective. These dramatic changes in both performance and complexity create new challenges for designers and the test and measurement industry alike.
Implications for Test and Measurement
Engineers are looking for solutions that can handle the raw performance of the latest buses and, equally important, distill complex and time-consuming compliance testing into fast, simple procedures. This statement puts the challenge to the industry in a nutshell: Deliver the banner specs and the complete solutions that make characterization and compliance testing easy.
To keep pace with market demand, the test and measurement industry must drive significant banner-spec improvements in performance. Banner specs enable an instrument to do its fundamental job.
Banner specs always will be promoted because they summarize the instrument’s characteristics with a few basic numbers. Bandwidth, sample rate, channel count, and record length have been and will remain the defining values for oscilloscopes, logic analyzers, and signal sources.
For test and measurement vendors, however, banner specs must not be delivered at the cost of important secondary performance attributes. For example, an oscilloscope’s signal fidelity, how the instrument is reproducing the signal, is critical to troubleshooting, compliance testing, and mask measurements—just about everything a designer does with an oscilloscope. It is a reflection of the instrument’s bandwidth, linearity, signal-to-noise ratio (SNR), and more.
It certainly is possible to trade off linearity or SNR to achieve a bandwidth figure that looks good in the headlines but doesn’t translate to real-world utility for designers. Engineers instinctively understand the importance of acquiring signals cleanly. They know that measurement-system errors can corrupt their work and delay their projects. Designers today need high-confidence measurements as much as they need high bandwidth.
What’s more, test and measurement vendors must understand both the analog and the digital challenges their customers face and offer tools that can efficiently bridge these two domains. This may involve using more than one type of instrument. These tools must work together seamlessly and efficiently to provide the complete data context for the designer.
Beyond the banner specs and secondary performance attributes, there is a new emphasis on solutions, and the test and measurement industry must deliver turnkey solution packages—from probing to software—that support new technology standards.
For example, test and measurement vendors could offer a PCI Express package for oscilloscopes that performs compliance tests automatically or additional analysis packages such as jitter, Gigabit Ethernet, or DVI that support specific applications. They also could offer logic-analyzer probing and bus support packages that include fixture adapters as well as analysis software.
In addition, test and measurement vendors must place bets on which standards to support, ultimately determining which will be useful and, hopefully, adopted. To credibly support any standard, test and measurement vendors must immerse themselves in standards committees or work closely with customers who are leaders in standards organizations and stay involved with the stand-ard as it continues to evolve throughout its lifecycle.
Simply put, vendors must deliver the banner specs, secondary performance attributes, and the turnkey solution packages that make characterization and compliance testing easy. Having this capability delivers results fast and spares the engineer from learning the intricacies of each and every standard.
Some Thoughts for Engineering Managers
Pay attention to banner specs but ask the tough questions. In an oscilloscope, look for the bandwidth you need to support your application, but make sure the product delivers the signal fidelity you need. In a logic analyzer, a great data rate must be balanced by high resolution. In both cases, remember to check out the probing tools. Do they bring bandwidth to the test point? Do they offer easy connectivity to your device or bus?
Think in terms of complete solutions. Designers want an instrument that has been optimized for the standard they are working with. The complete solution should provide automatic setup, easy capture of the signals, and properly scaled results. For example, leading logic analyzers offer bus support packages with bus probe adapters and disassemblers.
Similarly, some oscilloscopes provide turnkey application packages for serial bus compliance tests as well as software tools for jitter-measurement and even power-supply tests. Complete solutions help the engineer focus on design issues.
Be sure the test and measurement vendor is committed to supporting your standard. Has your vendor selected and committed to the standards you’ve chosen? Does the vendor participate on committees or work with industry leaders to keep pace with important emerging standards? Standards typically will continue to evolve, and support for them doesn’t end with the initial release.
Look for solutions that speed the designer’s work. If it saves time, effort, or tedious learning, it is a tool engineers will use. Automated measurement packages can help meet this goal as can time-saving tools such as those that capture both oscilloscope (analog) and logic-analyzer (digital timing and protocol) signals through the same probes.
Understand the level of support provided by your instrument vendor. Occasionally, you may need applications support or other expert help from your test and measurement provider. Does the vendor have a responsive organization to serve these needs? Does the vendor keep pace with market requirements by introducing timely solutions?
Innovation and invention are not dead. Demand for the latest technology will fuel the need for the latest test and measurement solutions. Innovation is not limited to engineers developing fast, new bus-based products, and invention is not just for designers working at the cutting edge.
Banner specs have long driven decision-makers as they plan test-equipment purchases. Banner specs remain the first cut in the process, and you will continue to see test and measurement vendors push the instrument performance envelope in this area.
While they are important, banner specifications alone are not enough to make a general-purpose tool into a solution for compliance testing and characterization. A solution that eases your design team’s growing validation burden should provide domain expertise, application-specific tests, automation, and even reporting. Banner specs are indispensable, but hardware and software acting in concert to solve a defined problem make a solution.
About the Author
Dave Brown is vice president of Central Engineering at Tektronix. Previously, he was vice president of the Manufacturing and Service, Video, and Networking Division at the company. His career includes 27 years of experience at Tektronix in program, engineering, and manufacturing management spanning 15 generations of product architectures and development. Mr. Brown holds an M.S.E.E. from Oregon State University and a B.S.E.E. from the University of Washington. He also serves on the Engineering Technology Industry Council (ETIC) for high-technology education funding in the State of Oregon.
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