- Buyers Guide
The Future of RFIC Test Strategy
Ron Williamson Aeroflex Test Solutions, Plainview, NY
The future of Radio Frequency Integrated Circuit (RFIC) test strategy is a provocative topic these days. This is especially true for the consumer RF and connectivity integrated circuit (IC) markets, where ramping volumes and surging competition are shifting the market's mindset. Driven by cell phones, tablets, and other mobility devices, most RF devices are approaching commodity status, including the discrete power amplifier, front-end module, Bluetooth, WiFi and tuner segments. Price pressure is so extreme that a once-manageable test strategy is now overkill for low-end to mid-range devices. IC vendors are pulling all the punches to procure "just enough" production test capability.
For the past 20 years, standard automated test equipment (ATE) served this segment well. Competent RF technology led the way, augmented by reliable production worthiness. The general-purpose nature of production test was also suitable for the few silicon vendors whose product portfolio spanned the entire RF offering. But as we have seen in recent years, the technology has branched out. Multiple protocol standards, varying foundry processes and distinct Served Available Markets have created a more specialized supplier base.
This specialization has unearthed fertile soil for many new fabless companies. For example, in the Asia Pacific (APAC) region, accessible IC design technology and a maturing regional supply chain has fostered aspirations of dominating local markets. These players are especially sensitive to cost and are keen to "blaze a new trail" by adopting new test strategies. If these strategies are proven out, they will offer time-to-market advantages. These advantages may allow APAC suppliers to challenge the "blue chip" suppliers in the US and Europe in the years to come. However, the APAC suppliers have one primary dilemma – RF test is still an enigma in most Asian technology centers. Their local subcontracted manufacturers, although owners of many indigenous or legacy testers, possess limited RF test options. They see RF test capability as their final puzzle piece. They need to find a solution, either through low cost means and/or augmenting their current installed base with RF functionality.
These APAC "upstarts" are not the only IC vendors seeking alternative RF test solutions. IC manufacturers whose core competencies are digital or mixed signal are now integrating antennas into their devices. This creates significant test challenges. The IC manufacturing supply chain also possesses a large installed base of production test equipment with limited RF functionality. They want to view the RF pin as "just another device pin." But the question remains: How do they validate RF quality without overhauling their production strategy and/or excessively increasing their cost of test?
As we have seen in digital test over the past 20 years, the $8,000/digital pin in 1993 has become less than $500/pin in many current testers. Can the same economies be realized in RF? Commercial off-the-shelf (COTS) RF instrumentation is capable, proven, relatively inexpensive, and readily plays within industry standard form factors. Using these tools, can someone develop a cost-sensitive, focused solution for commoditized RF semiconductors? The ideal solution would:
- Meet the RF functionality requirements with seamless integration
- Be modular in nature, and offer a multitude of capability options
- Be production worthy with high reliability and throughput
- Stand alone, or assume a slave role for integration into a current tester environment
At Aeroflex, we believe the answer is yes – a solution can be developed. A precedent has already been set in semiconductor validation and characterization labs. These labs have successfully employed standard instruments to validate and debug their initial devices. VME, VXI and stand-alone instruments have all found a place in semiconductor test lore. However, the integration was usually custom, slow, cable-awkward and manual by nature.
Today's COTS instrumentation is a different beast. The PXI form factor has revolutionized the lab environment and is universally accepted. In the RF space, powerful instruments like 13 GHz sources and analyzers, vector network analyzers, single slot bi-directional port modules, local oscillators, intermediate frequency arbitrary waveform generators (AWG) and digitizers are one click away. Other non-proprietary standard technologies are building momentum as well. AXIe, PXI's big brother, has a quickly growing instrument portfolio, including RF AWGs, 48-channel digital pin electronics, 12-channel device power supplies, relay and load board controls, plus logic and protocol analyzers.
But the tipping point in RFIC ATE goes well beyond instrument functionality. Integration of the components by a team that understands semiconductor test is paramount. Moreover, PXI/AXIe instrumentation and infrastructure are proving to have exceptional reliability, fast data/signal busses and valuable multi-stage triggering. All of these benefits translate to key elements of a production test environment – high MTBF, fast test times and system coherency. The proof manifests itself in the cell phone manufacturing lines where 30 to 40 percent of all phones are tested with PXI solutions. Leveraging our cell phone success, coupled with the ever-increasing adoption of the PXI and AXIe form factors, Aeroflex recently introduced two industry standard, instrument-based test solutions that uniquely meet the four requirements above, including the AXRF RF Subsystem and AX-Series RF Characterization and Production Test System (PXI and AXIe).
In summary, competition and market dynamics in the consumer RFIC space has changed the industry mindset about RF product testing. Specialization and end-user product diversity opened doors for new and current IC vendors willing and eager to take risks for a market advantage. They see production test as a means to an end. They have pushed the test and measurement industry to accommodate their needs. This solution would not have come to fruition two years ago. Functionality alone did not create the tipping point. It took many intangibles to breach the precipice – customer adoption of PXI/AXIe instruments, proof of production worthiness in real world manufacturing, architectural improvements for fast test times with high accuracy, and most importantly, semiconductor-savvy teams to integrate the entire solution into a sophisticated, competent and user-friendly tool.