By Peter A. Rabbeni, Director, RF Segment Marketing and Business Development, GLOBALFOUNDRIES
Faster connections and greater network capacity for wireless technologies such as LTE, WiFi, and the Internet of Things is driving the demand for more complex radio circuit designs and multi-band operation. In addition the emergence of wirelessly connected smart wearables is not only driving localized high performance processing power but also extended battery life, two goals which are often in conflict. The predicted explosion in the IoT is shown in Figure 1.
The rapid growth in smartphones and tablet PCs and other mobile consumer applications has created an opportunity and demand for chips based on RF-SOI technology, particularly for antenna interface and RF front end components such as RF switches and antenna tuners. As a low cost and more flexible alternative to expensive gallium arsenide (GaAs) technologies, the vast majority of RF switches today are built on RF-SOI.
To address the highly complex, multi-band and multi-standard designs, RF front-end modules (RF FEM) require integration of multiple RF functions like power amps, antenna switches, and transceivers, as well as digital processing and power management. Today these functions are addressed by different technologies. The RF SOI process technology enables design flexibility by integrating multiple RF functions like power amps, antenna switches, and transceivers, as well as digital processing and power management to be integrated—all on the same die. The benefit of integrated radios is they consume less power and smaller area than traditional radios. Therefore, mobile devices that exploit radio integration using RFSOI can offer more functions with better RF performance at competitive cost.
Mobile devices that implement RF SOI for RF Front End module functions benefit from higher levels of integration that combine with improved linearity and insertion loss, which translates to better transmitter efficiency and thus longer battery life enabling longer talk times (lower power) and faster downloads (higher signal-to-noise ratio).
Emerging technologies like RF-SOI and even FD-SOI have unique properties and capabilities beneficial in enabling RF circuit innovation and integration levels never before seen in silicon-based technologies. Device ft, gm/I, well bias control and inherent isolation of the substrate all contribute to improved system level performance over competing technology resulting in the ability to achieve higher linearity, lower power, low loss, and low cost/small size.
An innovative technology that is currently addressing the ever-increasing challenges of RF front-end design is UltraCMOS 10 (Figure 2). This customer specific process, co-developed by GLOBALFOUNDRIES and Peregrine Semiconductor, demonstrates SOI’s ability to create highly integrated and reconfigurable mobile radio antenna interface solutions. For designers, it dramatically reduces the required engineering and validation time. And, for the end-user, they benefit from longer battery life, better reception, faster data rates and wider roaming range. With the qualification process complete, UltraCMOS 10 technology is now a fully qualified technology platform.
High speed digital-to-analog converters (DAC) are an essential component for direct-to-RF conversion architectures. Faster converter sampling speeds and greater peak-to-peak signal fidelity hold high promise in moving mobile digital signal processing closer to the antenna. It has been demonstrated that DACs on fully depleted SOI, achieve high linearity and very low power for nyquist bandwidths as wide as 5.5GHz. The RF architecture with a high-performance DAC results in lower power dissipation while synthesizing very wideband signals (Figure 3). This further demonstrates SOI ability to move high frequency digital sampling and processing closer to the antenna.
Agile radio architectures are another key area that can address mobile architecture challenges and cost. Today, the analog RF frontend duplicates much of the circuitry for each band. To simplify, new advancements (Figure 4) in tunable structures and filters are being made to provide a single radio for multi-band/multi-mode frequency. SOI technology offers the possibility to develop tunable/reconfigurable RF FEMs to improve RF performance at competitive cost.
Creating an Ecosystem to Extend SOI to RF
As RF FEM architectures and design challenges become more and more complex, it becomes necessary to relieve some of the increased burden at all levels of the value chain. In order to provide better RF products—from system design and RF integrated circuits down to engineered substrate design—development teams can no longer expect to design in silos and be successful. Collaboration and co-optimization are becoming much more important as a result of the changing dynamics of the design-technology landscape.
Investing in the future is critical to address certain RF challenges such as radio architecture design in multiband, multimode mobile radios and ultra-low power (ULP) wireless devices. Successful collaboration will require adherence to standards to enable interoperability, otherwise, in this fragmented market, the industry won’t see the full benefit of all of the technology innovation. To succeed, we need collaboration at different levels, from R&D to ensure we have the world’s best talent trying to solve all of these problems, all the way through to business models.
There is no doubt that demand on our networks will continue grow and there are advanced chip technology challenges the industry needs to address to enable a higher level of integration and lower power consumption for future wireless communication. GLOBALFOUNDRIES is committed to enabling an SOI portfolio and ecosystem—from process, device, and circuit through system level IP— to lower customer design barriers and complexity and introduce new RF architectures that leverage SOI-based technologies.
1. E. Olieman, A.-J. Annema and B. Nauta, “A 110mW, 0.04mm2, 11GS/s 9-bit interleaved DAC in 28nm FDSOI with >50dB SFDR across Nyquist,,” in VLSI Circuits Digest of Technical Papers, 2014 Symposium on , Honolulu, 2014.
2. Joeri Lechevallier, Remko Struiksma, Hani Sherry, Andreia Cathelin, Eric Klumpernik, Bram Nauta, “A Forward-Body-Bias Tuned 450MHz Gm-C 3rd-Order Low Pass Filter in 28nm UTBB FD-SOI with >1VdBVp IIP3 over a 0.7 to 1V Supply”, ISSCC, San Francisco, 2015.