Electronic Design

Test & Measurement: Logic, Bus, Protocol Analyzers

Analyzers Rev Up Their Engines

Logic analyzers continue to make strides in performance and ease of use, with bandwidths now topping out at 8 GHz (125-ps timing). Some, like Tektronix's TLA7Axx family, are the first to offer such a wide bandwidth simultaneously with state acquisition from an 800-MHz clock. They minimize input capacitance on the measured signal and increase signal-acquisition fidelity with a connectorless probing system that features a total capacitance of only 0.7 pF.

On another front, logic analyzers are being used with oscilloscopes to facilitate the correlation of digital data with the signal's analog characteristics. New tools make this correlation more meaningful. Enhanced memory depths of today's oscilloscopes provide the logic analyzer with a window of analog data around the analyzer's trigger position, which is about 500 times larger than what was previously available.

Still, there's a strong demand for analysis tools designed for specific protocols. Although they don't provide timing analysis, protocol analyzers perform better software analysis and debugging than logic analyzers. That's because they feature deeper memories and can configure triggering and filtering at a high level, without the user having to know how bus signals behave.

Many new analyzers are on hand for examining popular protocols like Bluetooth, Ethernet, Fibre Channel, General Packet Radio Services (GPRS), Hypertransport, InfiniBand, SCSI (Small Computer System Interface), Storage Area Networks (SANs), and the USB. These analysis instruments, many of which are designed for portable field applications, face several daunting challenges (i.e., small size and weight, low power dissipation, and low cost). This is particularly difficult to overcome because designers are currently working on leading-edge gigahertz RF signals and protocol technologies.

Protocol analyzers are also taking on more functions. For example, Version 1.7 of the USBTracer bus and protocol analyzer from Computer Access Technology combines the analysis capability with signal generation. It was developed to handle the latest USB 2.0 specification, the On-The-Go (OTG) specification. OTG lets users obtain peer-to-peer device connections without host computers.

However, complex devices like SoCs will push the development of standardized test methodologies, such as DFT and BIST. Specialized, inexpensive core test equipment will result, accelerating the production testing process.

TOP TEN
>LOGIC ANALYZERS SHOULD ATTAIN greater bandwidths with deeper memories, and begin to resemble software tools. The present 8-GHz bandwidth mark will likely go to 10 GHz and higher, with memory depths jumping from 1 Mbyte to tens of megabytes.

>EXPECT A GREATER SYNERGY between analyzers and design-automation tools. Advanced software design packages, coupled with power vector analyzers, will accelerate the IC design process. One example is Agilent's Advanced Design System EDA software package, combined with the company's 89600 vector signal analyzer.

>MORE FLEXIBLE AND SIMPLER INTERCONNECTIONS between logic analyzers and microprocessors will continue. As a result, the processor analysis and testing task should become easier when linking the logic analyzer to the device under test (DUT) over popular microprocessor buses like the PCI and DDR. High-density programmable-grid-array (PGA) and standard interposer probing solutions will lead the way.

>LOGIC ANALYZERS WITH MULTI-GIGABYTE/SECOND DATA-TRANSFER rates are inevitable. This will enable the capture and display of multiple time-correlated snapshots of data traffic on system buses. Thus, the logic analyzer becomes a powerful tool that presents microprocessor- and bus-specific time-correlated views of increasingly complex systems.

>SOFTWARE WILL ASSUME A GREATER ROLE in logic-analysis instrumentation. This will be driven by the realization that mainly software errors, not hardware errors, cause major computer-system failures. We may yet see the "software logic analyzer," designed from the ground up with software analysis and testing in mind.

>THE WORLD WIDE WEB WILL PLAY A LARGER ROLE in facilitating test and measurement solutions. More test and measurement companies will offer Web-based services that include instrument drivers and I/O connectivity. One such example is a free version of the Agilent Developer Network (ADN Basic) for designers who work in PC-based development environments like Microsoft Visual Studio .Net and who import data into Microsoft Office applications.

>EXPECT MORE PROTOCOL ANALYZERS with powerful statistical analysis, and displays at the command, packet, and state levels. Bus-specific products like the Bus Doctor from Data Transit will bring timing-analysis to protocol analyzers through ancillary pods for customization.

>MORE USER-FRIENDLY SCREEN INTERFACES will appear on newer logic analyzers, making it easier for a first-time analyzer user to come up to speed. Many new logic analyzers incorporate familiar Windows icons that allow users to access the instrument's most common features. Advanced features will also become more available through pull-down menus and menu bars.

>MULTI-MONITOR DISPLAYS will grow more commonplace for logic analyzers, minimizing both how often a user must scroll down and up on a single-screen display and the number of window toggles necessary. Tektronix's TLA715/721 analyzer mainframes represent one such example.

>INTEGRATED LOGIC ANALYZER/OSCILLOSCOPE INSTRUMENTS will also surface thanks to software packages. This is a boon to designers who need to quickly solve signal-integrity problems on the highest-speed microprocessors and buses. Tektronix's iView package, which ties together a 4-GHz oscilloscope waveform to the company's TLA600/700 series logic-analyzer displays, is a precursor of this type of system.

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