Modeling Systems With Software

System design was once considered a "near-mystical" segment of high-frequency electronics. A few decades earlier, component suppliers were at the mercy of system designers from military contractors such as E-Systems, Martin Marietta, Raytheon, and Westinghouse when it came time to explain why their power divider, or amplifier, or filter wouldn't allow their system to meet its required performance specifications.

In the modern era, system design tends to evoke images of cellular/PCS base stations, or repeaters, or digital radios in terrestrial links rather than the radar-warning receivers (RWRs) and interferometers of earlier electronic-warfare (EW) systems. Even given the sophistication of modern commercial communications systems, which rely on multiple-access and complex digital modulation formats, modern component suppliers have a huge advantage over their predecessors when dealing with systems designers: they now have access to computer-aided-engineering (CAE) programs that can reasonably estimate the performance of a system when different analog and digital components are connected together.

A growing number of system-level simulators are available on the commercial market, now mainly for personal-computer-based platforms (see the Special Report beginning on p. 33). Even for component-level designers who need not get involved with higher-level design, these simulation tools can provide tremendous insight into how a particular component behaves within a larger system. Knowing some of these system-level characteristics, for example, can provide a filter designer with invaluable knowledge when "negotiating" a set of performance specifications with a system-level customer.

A system-level simulator is a powerful tool, but not inexpensive. The operating interfaces for these software suites vary greatly, and the learning curve for proficiency on one of these complex software programs can often be as long as one year. In recognizing the need to simplify these tools for users who may lack system-level experience, many system-level CAE suppliers are to be commended for offering "design kits," which are essentially templates for a particular design, such as a Bluetooth radio or a WCDMA transmitter. And many more are providing detailed application-specific technical notes.

Not every component manufacturer needs a system-level simulator. But with access to such a tool, a component supplier can gain tremendous insight into system-level issues, and the language between component and system designers might become a bit less garbled.

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