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A Big Blip on the Radar

 

June 14, 2005

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Exemplary teamwork in Agilent Labs on a digital-to-analog convertor (DAC) creates a test performance breakthrough destined to empower innovation in advanced defense system development

The competitive edge. In today’s technology-driven world, it’s what every organization wants from its equipment. It’s what every manufacturer of that equipment wants to provide to its customers. It’s what test instrument designers need so they can help those manufacturers push new technological boundaries. Most importantly, it’s what a small band of engineers in Agilent Labs provided in the form of a new breakthrough technology that will enable all of these organizations to gain that critical advantage they seek.

Now, for Agilent Technologies, “competitive edge” is what it has gained in the aerospace and defense marketplace since introducing an arbitrary waveform generator (AWG) in September 2004. The new product signifies an extraordinary leap in technology and a new solution for design-engineering customers, especially those working on next-generation, communications, radar and electronic-warfare systems.

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Agilent’s N6030A AWG

Agilent’s N6030A AWG provides both wide-bandwidth and high-dynamic range signals simultaneously in a single instrument—a test industry first. The AWG can produce signal with 500 MHz of instantaneous bandwidth while boasting a spurious free dynamic range (SFDR) of better than 65 dB. This powerful combination of speed and accuracy delivers a high-performance output that simulates real-world radar signals, assuring that designers of these systems will reduce costs and design time so that they can focus more on innovation and less on test.

“Our system provides more than twice the bandwidth of the nearest competitor and a 1,000-fold increase in accuracy—all in one instrument,” says Steve Fossi, vice president and general manager of Agilent’s Defense, Aerospace and Transportation Solutions Division.

But as Fossi quickly points out, it was the teamwork between his division and a small group of dedicated engineers within Agilent Labs that made this new performance threshold possible and to do it in record time—just over one year from proposal to shipping. Highlighting the importance of that contribution, Agilent Labs’ recognized its team of engineers recently with a coveted award given annually to Labs’ employees for outstanding accomplishments that demonstrate innovation, technical depth, and business value.

“Innovation is at the heart of our purpose in powering Agilent’s future through breakthrough technologies,” says Agilent Labs’ Director Darlene Solomon. “This technology has achieved world-leading performance for advanced radio-frequency (RF) applications, which we believe will lead to a very successful business for Agilent.”

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Too Fast to Handle
At the heart of the new AWG lies a new digital-to-analog converter (DAC) that converts signals from the digital domain to analog. The DAC translates a waveform represented by a sequence of digital values into analog electrical signals. The DAC processes waveform data at an astounding 1.25 billion samples per second (each sample is represented by a 15-bit data word). So 1,250 million times per second, the device outputs new voltage readings and with those data points, traces out the “clean” waveform that system designers seek. In fact, the DAC was so advanced in its ability to crunch numbers, Agilent did not have a data source capable of feeding the device with the fire-hose stream of data it needed for testing.

That’s where engineers from Agilent Labs’ Image and Signal Processing group joined the effort. In a quick-turnaround fashion, they designed a low-cost data-source solution capable of exploiting the speed of the new DAC. Instead of designing an expensive ASIC, which can require years to design and manufacture, these engineers relied on a significantly more economical, yet time-tested approach: a field-programmable gate array (FPGA). Although some feared that an off-the-shelf FPGA would be too slow for the task, these engineers used special digital-signal-processing (DSP) techniques to step the data rate up from 100 MHz of complex data pairs from an existing instrument to the 1200 MHz required for the new DAC. The data was also modulated and filtered to produce a 300-MHz intermediate frequency output with 80 MHz of bandwidth. The result was a digital interpolator (interpolation calculates the values of a function between known values) and modulator (modulation shifts the output signal to the desired center frequency or channel) capable of running many calculations simultaneously before passing them on to the DAC chip.

“For multi-tone test waveforms, we demonstrated a 30dB improvement in the distortion levels over previous methods,” says Paul Corredoura, one of the engineers who worked on the digital interpolator project. “That’s so significant, it may be the only time in my career where I’ll demonstrate a 30dB improvement in anything.”

Foregoing Tradeoffs
Clearly, high performance was the driving force behind this advancement. However, the key to getting that performance doesn’t necessarily rely on what these engineers did so much as what they didn’t do; that is, make major design tradeoffs. For instance, they didn’t need to reduce raw performance in favor of decreasing power consumption or deliver less accuracy to shrink the size of the chip. For the Agilent Labs’ engineers, who would be working with their division partner to design an instrument around the chip, it was an opportunity to put the pedal to the metal.

“Without the constraint of having to make major design trade-offs, you can far and away achieve better performance,” says Bob Jewett, one of the DAC designers. “This is one of the luxuries of working for Agilent Labs.”

Interdisciplinary research is another luxury researchers at Agilent Labs enjoy, and by all accounts, was key to the success of these projects. The company’s multi-disciplinary teamwork, combined with a culture of cooperation and collaboration, gave these engineers a technological license to push the boundaries of their work.

“We had people with a range of backgrounds involved in the effort and we all worked together to achieve something worthwhile,” says Corredoura, noting the involvement of experts in data converter design and high-speed DSP.

Big Winners
For their effort and success in “advancing the state-of-the-art in DACs and digital interpolators for RF-signal generation,” Jewett and Corredoura, along with Jacky Liu and Vamsi Srikantam, received the 2004 Barney Oliver Prize for Innovation. The Agilent Labs award honors standout technical achievements that often lead to a useful scientific result or a key business solution.

This year, with the introduction of an industry-leading product, there are several key beneficiaries of this work. For the company, the cutting-edge AWG product represents a new business opportunity by bringing a new, innovative solution to a contingent of loyal Agilent customers in the communication, aerospace and defense industry.

Moreover, it’s those customers who are the big winners. Because DSP and system designers who develop advanced defense systems no longer have to spend a large amount of their budgets and time stringing together “home-made” solutions, they can better focus on design innovation to provide their customers with the competitive edge they require.

So, what’s next in DAC and AWG system advancements? No one’s saying due to competitive issues. However, when asked his plans for future DAC development, ASIC Designer Jewett modestly quips: “We’ll try to do better next time.”

Related Information

For their efforts, the Agilent Labs team was honored with the Barney Oliver Prize for Innovation, awarded by Labs for outstanding technological contributions the demonstrate creativity, innovation, technical depth, and respect for business value.

Product Information: N6030A Arbitrary Waveform Generator

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