The new era of automated test

For more than 30 years, the technology community has witnessed Moore’s Law in action

BY MATTHEW FRIEDMAN
Senior Product Marketing Manager
National Instruments
www.ni.com

The reality of Moore’s Law — that transistor density doubles every 18 months — has led to significant advances in the performance of electronic devices. This is evident not only in performance capabilities of the latest Intel i7 processors but also in the shrinking of size of electronics, such as 64 GB solid-state drives (SSDs), which are as small as a postage stamp. And these technological advances translate into considerable cost reductions — LCD video screens that previously cost hundreds of dollars are now available in low-cost greeting cards.

With devices that are faster, smaller, and lower cost than ever, the industry has seen an explosion of new products that combine the functionality of gadgets like a GPS, digital camera, and phone into a single, integrated tool. What’s more, these tools are software-defined, so users can download apps to customize each device to their exact needs. But with increased technological innovation comes the challenge of testing each new breakthrough. For instance, adding wireless LAN capability to a next-generation product typically introduces 50 new tests that must be performed at the same time as previous-generation product tests. Fortunately, Moore’s Law also applies to the next generation of test platforms and modular instrumentation. Coupled with a software-defined solution, these test systems are more than capable of keeping pace with the new developments in devices under test (DUTs).

From rack and stack to PXI

For decades, engineers have built automated test systems by taking the same traditional box instruments they use on the engineering bench and placing them in a rack, stacked one on top of the other. The rack is connected over an instrument control interface to a computer, where a software program automates the system. While these rack-and-stack systems are functional, they do not apply the instruments as they were intended to be used.

Traditional box instruments are often designed to be used singularly on a bench, when an engineer or technician wants to manually test or troubleshoot a device. In a rack, redundant instruments’ screens, knobs, and buttons can often become a waste of space and money. Furthermore, these instruments are not necessarily designed for the measurement speed or data throughput required in automated uses.

Over the last few years, the industry reached a tipping point in automated test and is now making a large-scale switch to PXI. Optimized for automated test, PXI provides a solution that is faster, smaller, and more cost-effective than rack-and-stack options (see Fig. 1 ).

Fig. 1: Unlike traditional rack-and-stack instruments, engineers can increase PXI system performance throughout its lifetime by upgrading the controller to the latest processing capabilities.

Traditional box instrument vendors are also making a large investment in PXI. For example, Agilent Technologies announced its commitment to the PXI platform in September 2010 while launching more than 40 PXI modules. Agilent joins more than 60 vendors in the PXI Systems Alliance, an industry consortium that promotes and maintains the PXI Standard, who are making investments in the open, multivendor standard.

Moore’s Law takes PXI into the future

Using commercial off-the-shelf technology, PXI benefits immensely from Moore’s Law. With transistors 2,000 times smaller than those created 20 years ago, vendors provide high-performance RF instrumentation in a compact 3U package that is 10 times smaller than a comparable box instrument. This translates to less rack space as well as a reduction in weight and power usage.

The effect of Moore’s Law is also evident in the processing capability of PXI. With a modular controller architecture, engineers can add extra processing capabilities by simply swapping the controller while keeping the same chassis and instrumentation. To improve performance, they can easily switch a system built in 2001 operating at 2.5 GFLOPS with a controller running the latest Intel core i7 processor at over 35 GFLOPS. Advanced processing power is important in computationally intense applications like RF signal processing and analysis. For example, TriQuint Semiconductor saw a 6 to 14 times reduction in GSM, EDGE, and WCDMA test times during the characterization of its power amplifiers by switching to a PXI-based system from traditional bench instruments. Using PXI modular instruments, the company reduced characterization of new parts from two weeks to about a day.

Beyond providing a smaller and faster solution, PXI continues to push the boundaries of measurement performance in instruments of any platform. For example, the NI PXIe-5665 vector signal analyzer (see Fig. 2 ), or VSA, delivers best-in-class RF performance including industry-leading phase noise, amplitude accuracy, and dynamic range, while being 40% less expensive and 1/10 the size of comparable box solutions.

Fig. 2: The new NI PXIe-5665 provides industry-leading RF performance and is 40% less expensive and 1/10 the size of comparable rack-and-stack solutions.

The evolution of software

While PXI provides a faster, smaller, and more cost-effective option, its real power lies in offering a truly software-defined solution. Unlike most traditional box instruments, whose functionality is set by the their manufacturers, PXI test systems are defined by the software that is written for them. Just like engineers can use apps to customize their smartphones, they can now customize test systems with software for their exact DUTs.

PXI system software continues to evolve as DUT complexity increases. When engineers test a device like a WLAN system on a chip (SOC), they no longer perform simple stimulus and response tests to verify components. Instead, the test systems often need to communicate over real-time digital protocols such as I2 C, PCI Express, and SPI to exercise the device and synchronize the RF measurement on the back end (see Fig. 3 ). This level of complexity requires new levels of software abstraction to model, control, and test these systems.

Fig. 3: Testing complex systems like WLAN on a chip requires new levels of test software abstraction and capabilities.

Tools such as NI LabVIEW graphical system design software simplify the abstraction process. The graphical programming lets test engineers model complex systems of stimuli and responses, including intricate timing and synchronization. Furthermore, engineers can download this same code directly to user-accessible FPGAs on PXI instrumentation for in-line signal processing, custom protocol communication, and more.

As Moore’s Law dictates, newly developed devices are faster, smaller, and lower cost than ever before. To keep up with their DUTs, test engineers must switch to PXI-based test systems. ■