New Signal Generators Are Packing a Wallop of Functionality, Modularity

December 18, 2015

Signal generators come in many shapes and sizes and are called many different names depending on what type of output they can provide. Function generators, data pattern generators, waveform generators, and vector generators all fall under the signal generator category. But the new generation of signal generators is giving test engineers the capability to do battle with multiple, synchronous-signal scenarios.

Basically, a signal generator provides an external stimulus signal at the input of the device under test in order to examine the output. It can produce repetitive waveforms at a constant frequency, and it can come in many analog and digital flavors -- output sine waves, square waves, and triangular waves, among others, at different frequency ranges such as RF and microwave. There are special-purpose signal generators, such as those for video test applications. The ability to configure a signal generator to provide a specific type of signal for test purposes is one of its greatest merits.

In some areas of electronic test, a reliable signal source is needed. While not every test stand needs a signal generator, signal generators are mainstays in wireless communications engineering, which continues to grow in complexity and means that test engineers now need test stands that require multiple signals. Fortunately, technology is keeping abreast of the need for more sophisticated test solutions. It isn't surprising that advances in semiconductor technology are producing better signal generators.

I have always favored modular design in test systems because the resulting flexibility also means cost effectiveness amid changing customer test requirements. With the advent of more and more complex systems requiring test, test and measurement systems are following suit. We are seeing companies respond with new offerings that take into account needs such as synchronization, which has always been a challenge for test engineers working with different pieces of equipment.

Complex multi-channel scenarios require signal generators that can handle complex modulation schemes. An ingenious solution to this problem is to have one unit with multiple signal-generating capabilities that uses an internal trigger that ensures 100% synchronous signal generation, eliminating the synching problems that can occur when using multiple instruments.

The Rohde & Schwarz SMW200A, a "Best in Test Winner" selected by the editors of Design News' sister site EDN in 2014, might fit the bill. The unit seems to provide a very tidy solution to a variety of complex test scenarios, with a modular design that allows the user to select the options they require and configure them according to their specific needs. This particular model has options that include up to two internal baseband modules, four fading simulator modules, and two RF paths.

Busy test engineers need a signal source that can provide the complex digitally modulated signals that are required for today's wireless communications, such as MIMO applications. One of a test engineer's most important tasks is selecting the correct test and measuring equipment for the job. With the advent of more advanced, modular, configurable signal generators, that task has gotten easier.

Nancy Golden started her electronics career at Dallas Semiconductor and moved to Optek Technology where she was a test engineer for several years, eventually moving up to test engineering manager. Nancy became especially experienced in hall effect characterization and test and also gained experience with photologics, LEDs, VCSELs, and fiber optic transmission. She was also the first person to become a Certified TestPoint Application Specialist (CTAS) by Capital Equipment Corporation and has done contract work for Hitachi and Andrews Corporation and control room software for NBC in Testpoint. While employed at Optek Technology she also authored articles for Test and Measurement World on test system development. Nancy owns a small business called Golden Technical Creations, a service oriented company that provides consulting, teaching, PIC programming, course development and web design to its customers. She also has a M.A.R. with a focus on intercultural studies and is an adjunct faculty member at Dallas Christian College.

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