Cut time-to-market for wireless designs

RF and microwave applications are proliferating, with wireless capabilities extending into a plethora of consumer products. This proliferation is presenting challenges to design and test engineers, who find that they need an effective way to link their RF simulation tools and instruments to get quality wireless products to market quickly and cost-effectively.

The proliferation results from what Mihir Ravel, National Instruments' (Austin, TX; www.ni.com) VP of technology and corporate development, calls "the democratization of RF"—the penetration of wireless technology into everything from handheld computers to washing machines that automatically notify service personnel when they're out of order.

Figure 1. The PNA vector network analyzer works within the Connected Solutions framework to provide system-level component verification. Courtesy of Agilent Technologies.

Test strategies, too, require an integrated approach. Logic designers have long understood that effective designs must take test into account—witness the prevalence of scan capability within chip designs and the growing popularity of boundary scan within printed-circuit board and system designs. Furthermore, standards such as the IEEE P1500 Standard Test Interface Language (STIL) have emerged to facilitate test development from design data.

For mixed-signal wireless designs, however, de facto standards like scan and real standards like P1500 have been nonexistent. To address the need for design-for-test technologies for RF/microwave products, vendors are developing coordinated design and test strategies that should aid engineers who can no longer conveniently partition RF/microwave circuitry from baseband circuitry and hand off the RF portion to experts in that field. Similarly, the strategies can help to ensure cooperation among design and test personnel.

The strategies take two tacks: Agilent Technologies (Palo Alto, CA; www.agilent.com) is promoting its Connected Solutions approach, in which it integrates its own electronic-design-automation software and test instruments, while National Instruments is touting an interface between its ubiquitous LabView graphical development environment for test applications and Ansoft's (Pittsburgh, PA; www.ansoft.com) Ansoft Designer high-frequency EDA toolset.

Agilent's Connected Solutions program builds on the company's instrument line-up as well as on its position as the fourth largest EDA company (behind Synopsys, Cadence Design Systems, and Mentor Graphics), according to Charles Plott, product marketing section manager of the Agilent EEsof EDA division. Plott emphasizes that Connected Solutions isn't a product. "It's more than a file download," he says, adding, "It's a synergistic application of our instruments and software."

Plott cites several advantages of employing the Connected Solutions approach with the company's instruments and ADS design software. First, he says, is that the combination lets you extract ADS models from existing components. You might, he says, choose an off-the-shelf component that doesn't come with a convenient Spice model. With Connected Solutions, you can use Agilent instruments in conjunction with ADS to extract Spice models from off-the-shelf components. Those models can then serve within the simulation environment.

Figure 2. A link between Ansoft Designer and NI LabView facilitates teh acquisition of measurement data that can be formatted for use in the simulation of linear and nonlinear behavioral models. (1) A continuous-wave sweep of a DUT produces frequency-dependent compression data for a behavioral model, (2) waveform data from Ansoft Designer or LabView drives DUT measurements and simulations, and (3) Ansoft Designer imports measured modulation responses for comparison with simulation results . Courtesy of Ansoft and National Instruments.

With full control over the design-software and test-hardware portions of the Connected Solutions strategy, Agilent is unlikely to open up applications programming interfaces (APIs) within ADS that would enable other instrument makers to develop their own Connected Solutions-like approach.

But National Instruments, which lacks a full portfolio of RF EDA software and RF instruments, has no qualms about embarking on an open-API approach for linking RF design and test. NI has entered into an agreement with Ansoft to provide an API that integrates the Ansoft Designer EDA package with NI's LabView.

NI's Ravel points out that the many low-cost instruments that can operate within the LabView environment provide flexibility lacking in some dedicated benchtop instruments—such as the ability to analyze certain spurs at specified frequencies. Rather than simply extracting S-parameters, he says, you could develop custom sets of measurement data showing relationships among parameters such as power consumption, transmitter output level, and error vector magnitude.

Further, he says, LabView opens the door to PXI instruments, which afford faster instrument-to-instrument triggering capabilities than do GPIB instruments. And he notes that LabView can perform the data reduction necessary to make sense of megabytes of measurement data.

Finally, Ravel says that the democratization of RF is requiring that RF instruments play well with other instruments—those that provide for motion control and visual inspection, for example. Such a combination of RF and other instruments is critical, he says, for testing the RF segments plus the components such as keypads and displays that make up cell phones and other RF-capable consumer products.

With costs of RF implementations falling, you can expect exponential increases in RF applications. RF's proliferation is likely to leave room for various design-and-test integration approaches—that of National Instruments, Agilent, and others in the RF/microwave design-and-test space.