The rise of digital transformation as a catalyst for industry growth has seen a concurrent rise in the adoption of digital technologies in multiple sectors. Amongst these sectors, the telecom space has witnessed tremendous growth as 5G technology is slowly becoming a reality in India. Many major service providers in the country have already begun working towards the goal of beginning 5G rollout by late 2020, even stating that the lag present in 4G adoption will not be repeated. The evolutionary pace of 5G technology, however, has placed a greater emphasis on the simultaneous development of test and measurement strategies that are capable of verifying optimal product operation.

5G T&M: The challenges ahead

The expansion of operable frequencies in the telecom sector has been one of the major factors in this rise in importance donated to the test and measurement space. The major challenge today lies in verifying operation in more frequency bands with larger channels, and working with more complex, higher bandwidth waveforms. Millimeter wave (mmWave) frequencies in particular (between 24 to 44 GHz) have led to significant changes as antenna elements become smaller and beamforming technology takes precedence. Manufacturers now have moved towards the development of Antenna-in-Package (AiP) devices as a means of integrating mmWave technology into devices, leading to significantly higher test complexity. The industry must thus rethink and transform existing test techniques, optimizing them for faster signal processing, multi-band operation, higher channel count and rapid execution.

OTA testing to the rescue

One of the foremost testing strategies that is capable of addressing the challenges raised by mmWave-compatible components is Over-the-air (OTA) testing. In general terms, semiconductor test can be classified into wafer-, packaged IC-, and board-level requirements and solutions. At the wafer level, engineers use probed solutions that have the ability to address mmWave RF signal needs. At the AiP IC level, however, OTA test resolves the issue of a lack of direct electro-mechanical contact to the antennae. Engineers can choose to light up the full antenna array and beamform in specific directions, rather than each antenna element individually, to evaluate aggregate RF performance. This makes it hard for test engineers to identify specific broken or weak connections between the die and package substrate, but it gives them an overall picture of the quality of the device within the package. During initial production ramp, vendors may choose to run full parametric OTA tests, and then switch to a sub-set of the tests for full volume production.

Additionally, most conversations around OTA test solutions also raise the issue of requiring a proper RF chamber for design characterization, validation, compliance, and conformance tests. These chambers involve the use of large amounts of production floor space, disruptions in material handling flows, and increased capital expenses. Manufacturers have looked to address these concerns by producing OTA-capable IC sockets and small RF enclosures with integrated antennae, enabling semiconductor OTA test functionality in a reduced form factor. Though RF chamber-based OTA testing comes with its own set of challenges such as an inability to make accurate beamformed measurements due to reduced socket size, it could represent a cost-effective solution to test contemporary 5G semiconductor devices in larger volumes.

Conclusion

As the industry moves closer to the commercial availability of 5G technology, industry players are looking to manage test and measurement requirements for both 5G NR as well as for legacy 2G/3G/4G standards. Given today’s rapid development cycles, flexible and scalable test methodologies will be critical for OTA testing. The wireless industry requires modular, software-defined test strategies and solutions to control capital expenses and keep pace with the wireless industry’s ever-evolving test needs.

- Alejandro Buritica, Senior Solutions Marketing Manager, National Instruments