Electronic Design

Test & Measurement: Oscilloscopes

Oscilloscopes Open Windows Into The Virtual World

Real-time measurement bandwidths for today's oscilloscopes have leapt to 6 GHz. Now these scopes complement design-automation tools through various interfaces, allowing for an interchange between "real" and "virtual" worlds. This also makes it possible to correlate measured and simulated performance. Bringing together EDA software with measurement and analysis instrumentation accelerates the design process through helpful graphical data. With improvements in connectivity, designers can now feed oscilloscope waveforms into multiple applications like Java and Windows, vastly expanding their analysis capabilities. Graphical analysis tools now offer to design engineers what the "Spreadsheet" program gave financial professionals.

Digital storage oscilloscopes also are advancing in performance. With very deep memories, many can routinely handle 20 Gsamples/s with real-time bandwidths reaching 6 GHz. Some of the newest oscilloscopes include an FFT capability for frequency-domain analysis. Such instruments with deep memories essentially provide a cost-effective alternative to a spectrum analyzer when frequency-domain analysis is needed.

As waveform complexity increases, greater memory depths are required to keep pace with higher sampling rates to hold waveforms records of a given duration. Triggering also becomes more complex and will require greater sophistication.

Mixed-signal oscilloscopes are now coming into the fray. They measure both analog and digital signals simultaneously, and thus combine a conventional oscilloscope's detailed signal-analysis capability with a logic analyzer's multitiming measurements capability.

But oscilloscopes by themselves won't be enough. Increasing device complexities and shorter time-to-market, coupled with bulging testing costs, will spur the development of standardized test methodologies to tackle these issues. These test standards will govern the use of production test equipment, leaving the oscilloscope strictly for pure engineering measurements and evaluation.

In addition, the oscilloscope is assuming a greater role in places outside the traditional engineering laboratory. It's finding a home in many automotive, factory floor, communications, retail, and financial settings to handle new service applications in the field.

>MORE OSCILLOSCOPES WILL USE TOUCH-SCREEN INTERFACES for greater user-friendliness. This is particularly important in production testing, where faster user-instrument interactions translate into faster and more accurate testing, leading to lower testing costs. For instance, on the latest Infinium DSOs from Agilent Technologies, touch screens eliminate the need to employ external devices, like a mouse, touchpad, or trackball.

>THE GAP BETWEEN SAMPLING and real-time oscilloscopes will narrow. As real-time oscilloscopes gain bandwidths beyond the present 6-GHz mark, they'll approach those of sampling oscilloscopes, which now offer 55-GHz speeds. But they won't quite reach those levels because of limitations in real-time oscilloscope attenuator and amplifier front-end designs.

>ANALOG ISSUES LIKE NOISE, ringing, crosstalk, and overshoot will become greater challenges for digital storage oscilloscopes. That's due to digital signal edge rates inching below the 100-ps plateau and logic-level voltages shrinking down to a few hundred millivolts. As a result, it will be harder to distinguish between high and low logic states, and will call for more clever front-end designs.

>LOOK FOR MORE PORTABLE HANDHELD OSCILLOSCOPES to be developed as field-testing applications multiply. Some, like the ScopeMeter from Fluke, combine the oscilloscope with a digital multimeter. This 4-lb, dual-channel 200-MHz DSO has color displays that identify individual waveforms.

>OSCILLOSCOPES WILL FIND THEIR WAY into more closed-loop testing applications. Oscilloscope users will discover that it's easier to program test data and monitor the test results. That will narrow the gap between the traditional engineering test role for the oscilloscope and the production machine that tests the final device.

>THE FORM FACTOR AND PRICE RANGE of oscilloscopes will widen even further as more new applications emerge with different performance and price requirements. Expect to see oscilloscopes in everything from the aforementioned handheld field applications, to tabletop industrial applications, to benchtop engineering applications. This will ensure the oscilloscope's form, fit, and functional role in just about any application.

>GREATER OSCILLOSCOPE ANALYSIS CAPABILITY will be possible as designers begin to feed multiple waveforms into operating systems like Java and Windows using powerful data-acquisition software packages. Enhanced connectivity between oscilloscopes and PCs over well-known buses like the USB and Ethernet will fuel this trend.

>EXPECT HIGHER LEVELS OF INTEGRATION between digital storage oscilloscopes (DSOs) and PCs. This will enable DSOs to rapidly execute computationally intensive tasks, and give them more flexibility in implementing custom functions. One example is the LeCroy Wave Master 8500 DSO with an X-Stream architecture. It allows user-generated Visual Basic and Matlab scripts working with the Windows 2000 operating system.

>MIXED-SIGNAL OSCILLOSCOPES will continue to gain popularity. They will allow simultaneous measurement of analog and digital signals, and viewing of the complex interrelationships among all of the signals. One example is the 54642D from Agilent Technologies, which can measure and display two analog and 16 digital channels, with all 18 channels time-aligned.

>MORE POWERFUL DSOs with automated measurements will keep pace with advancing device technology. In addition to performing measurements on signal amplitudes, frequencies, rise and fall times, and slew rates, they will feature sophisticated analysis capabilities for extracting information, such as histograms, from those signals.

>EXPECT TO SEE MORE PROTOCOL ANALYZERS that offer powerful statistical-analysis capabilities, as well as displays at the command, packet, and state levels. Bus-specific products like the Bus Doctor from Data Transit will provide timing-analysis capability to protocol analyzers through ancillary pods that customize the protocol analyzer.

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