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Creating a comfortable workspace for high-speed digital designers

Smartphones and other edge devices rely on an evolving mix of radio-frequency (RF) and digital technologies. On the RF side, digital technology is moving closer to the antenna. In the digital realm, signals behave in unexpected ways as serial data reaches gigabit rates.

 

In cubicles around the world, these trends are creating varying levels of uncertainty and discomfort for product developers. Fortunately, there are effective solutions that blend design tools, simulators, and real-world measurements into a virtual workspace that lets designers work with their preferred tools—digital, RF, or both.

 

Scanning the issues

In RF design, the encroachment of digital toward the antenna is being driven in part by low-power digital-signal-processing (DSP) engines. These engines enable increasingly complex modulation schemes and maximize data bandwidth over present and future wireless infrastructures. For digital designers working at gigabit rates, RF effects can cause distorted square waves and other signal-integrity problems. Both types of designers will continue to face the unexpected as smartphones are equipped with ever more functionality: multiple cellular bands and formats; Bluetooth and Wi-Fi connectivity; GPS; a digital camera; a music player; a video player; and so on.

 

Beyond designer discomfort, schedule delays are another undesirable side effect. They affect a company’s ability to hit a window of opportunity in the marketplace. This is especially problematic in a category such as smartphones, which saw sales growth of 40% in 2010. According to some forecasts, that number could double over the next three years.

 

The situation is equally troublesome in the world of test and measurement. As an example, it might seem simpler to deal with a single serial line rather than multiple parallel lines. To move an equal amount of data in the same time, however, serial connections must run at much higher rates than do parallel links. Said another way, serial has less width than parallel, but is faster, deeper, and more complex.

 

Highlighting possible solutions

In the realm of high-speed digital circuitry, those who debug and fix the glitches will benefit from a toolset that includes two major elements: measurement and simulation. To cover the digital and RF aspects of the problem, these tools must operate in the time and frequency domains. Combining these capabilities—measurement and simulation across the time and frequency domains—provides multiple views that help reveal the underlying problems, suggest solutions, and lead to compliant designs.

 

One key to success is a combination of software and instrumentation, as it gives designers the ability to navigate the entire design cycle: design and simulation, analysis, debug, and compliance testing. This range of tools should let the designer work where he or she is most comfortable—in the time or frequency domain and with measurements, simulations, or a combination.

 

As an example, Agilent’s approach makes it possible to shift between the time and frequency domains—or straddle both—to pinpoint the underlying causes of difficult RF/digital problems. With these tools, designers can use measurement data to enhance RF and microwave simulations of tough modeling problems, such as long, lossy interconnects or crosstalk in densely packed interconnects. They can also combine simulations with actual measurements to optimize performance before hardware is designed or fabricated.

 

Today, smartphone users enjoy services that are extremely data-hungry. If current usage trends hold, traffic levels will grow from terabytes per month to exabytes. To handle this massive growth in volume, width seems to be making a comeback. Some connectivity methods are using multiple high-speed serial lanes operating in parallel. As a result, the complexity of design and test will continue to grow.

 

If current technology trends hold, we can confidently assume that there will be more RF effects in the digital realm and more digital circuitry encroaching on the antenna. Creating a comfortable place for RF and digital designers to work—and collaborate—starts with flexible measurement and simulation capabilities that span the time and frequency domains.

Jay Alexander is vice president and general manager of the oscilloscope business within Agilent’s Digital Test Division. He earned a bachelor’s degree in electrical engineering from Northwestern University and a master’s degree in computer science from the University of Colorado. He is a licensed professional engineer and a Senior Member of IEEE, and holds 24 US patents.
Jay Alexander is vice president and general manager of the oscilloscope business within Agilent’s Digital Test Division. He earned a bachelor’s degree in electrical engineering from Northwestern University and a master’s degree in computer science from the University of Colorado. He is a licensed professional engineer and a Senior Member of IEEE, and holds 24 US patents.
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