Workshops and Short Courses

Reconfigurability/tunability has become an essential feature of modern agile RF and future mm-wave apparatuses and systems for wireless communications, sensing and imaging. In the coming decades there will be a paradigm shift towards smart, cognitive and agile wireless sensing (including imaging) and communication systems. The use of mm-wave frequencies will lead to communications systems showing very high data-rate capabilities along with sensing and imaging systems with high spatial resolution. These include frequency-agile/softwaredefined and cognitive radios to cope with extendable and reconfigurable multi-service/standard and multi-band operation as well as with efficient spectrum and power utilization. These concepts will reduce significantly the number of components, hardware complexity, cost and human radiation exposure compared to today’s radio technology, which relies on incompatible communications systems with inflexible hardware. Space-agile antenna configurations for flexible and efficient beam-scanning, beam-focusing, and beam-forming allow for precisely focusing the microwave energy into well-defined areas. This workshop will focus on tunable circuits using promising technologies for mm-wave applications such as liquid crystal, MEMS, BST and CMOS. One specialist from academia and industry on each technology will focus on their advantages and disadvantages with examples and results, comparing the state-of the-art within their technology and between technologies. Programme 14:20 14:30 Welcome 14:30 15:15 Liquid-crystal-based tunable circuits for mmwave applications Rolf Jakoby, Technische Universität Darmstadt, Germany  Abstract 15:15 16:00 Integrated Ferroelectric Circuits up to mmwaves Fabio Coccetti, LAAS-CNRS, Toulouse, France  Abstract 16:00 16:30 Coffee Break 16:30 17:00 MEMS a promising technology for tunable mmwave circuits Gustavo Pamplona Rehder, University of São Paulo, Brazil  Abstract 17:00 17:30 Recent advances of CMOS/BiCMOS tunable components for mm-wave applications Thomas Quémerais, STMicroelectronics, France  Abstract 17:30 18:00 Recent advances of CMOS/BiCMOS tunable circuits for mm-wave applications Emmanuel Pistono, University of Grenoble-Alpes, Grenoble, France  Abstract 18:00 18:10 Discussion WORKSHOPS AND SHORT COURSES 14:30 15:15 Liquid-crystal-based tunable circuits for mmwave applications Rolf Jakoby, Technische Universität Darmstadt, Germany Abstract Tunable microwave components such as phase shifters are needed as key components in phased-array antennas for automotive radar sensors and future generations of mobile communication systems. In recent years, strong research interests have been focused on passive tunable microwave components based on tunable dielectric materials, mainly ferroor paraelectric materials, as promising alternatives to active semiconductor devices. Planar devices integrated on tunable dielectrics combine the key benefits of small size, lightweight, low cost, low power consumption and continuous electronical tuning. Another promising option for tunable dielectrics are anisotropic nematic Liquid Crystals (LC) that are well known from optical Liquid Crystal Displays (LCD). One of the key advantages of this material is that its loss tangent decreases with frequency. This workshop proposes an overview of LC-based circuits that are under development for mmwave applications. 15:15 16:00 Integrated Ferroelectric Circuits up to mmwaves Fabio COCCETTI, LAAS-CNRS, Toulouse, France Abstract The recent achievements based on advanced industrial fabrication processes and specialized design strategies, targeting a new class of ferroelectric (BST) capacitors metal-insulator-metal (MIM) tunable capacitors will be here presented. Endowed with high tunability and high quality factor potentialities, these devices have been optimized through accurate lumped elements equivalent circuits modeling accounting for demanding industrial process constraints. The results have been experimentally validated up to 67 GHz, demonstrating a maximum tunability of more than 80 % (0-20 V bias), and an improved Q-factor superior to 30 % (at 0 V) at 1 GHz. These varactors have been exploited in the design of reconfigurable filters, with a filter centered at around 1 GHz and tuned up to 112 %. However, owing to their promising features these materials have been exploited to design small-size capacitors allowing pushing the limit of their validity up to the mm-wave frequencies. The work that will be presented demonstrated tunabilities and FoMs superior to the state-of-the-art, and represent the first example of BST varactor at mm-wave. In fact in terms of insertion loss, size, figure of merit, and figure of merit per bias they show a remarkable improvement with respect to the state-of-the-art of ferroelectric based devices, thus proving that the BST represents a promising candidate to operate into mm-wave frequency band. 16:30 17:00 MEMS a promising technology for tunable mmwave circuits Gustavo Pamplona Rehder, University of São Paulo, Brazil Abstract Microelectromechanical systems (MEMS) used for RF applications have shown to be a viable solutions for tunable circuits applications. However, at microwave frequencies, the complex encapsulation and reliability issues related to MEMS result in a disadvantage when compared to CMOS technology, even if they show better performance in terms of linearity, insertion loss and power handling, when compared to MOS varactors and switches. As the frequency increases in the mmwave frequency range, the quality factor of the semiconductor tuning elements decrease drastically and MEMS become an interesting alternative, especially because the well-known reliability issues are being resolved. This workshop proposes an overview of MEMS-based tuning elements as well as circuits that are being developed using MEMS for mm-wave applications. In particular, a distributed approach based on the use of slow-wave transmission lines will be described. 17:00 17:30 Recent advances of CMOS/BiCMOS tunable components for mm-wave applications Thomas Quémerais, STMicroelectronics, France Abstract The advanced micro-and nano-technologies now allows the design of high frequencies integrated circuit with transistors operating at mm-wave frequencies and beyond. This evolution led silicon foundries to develop industrial test tools to characterize and validate the models of these transistors. Moreover, the increase in frequency has constraints such as very significant losses in the measurement passive elements (mechanical tuners for instance), cables and probes, and in addition beyond D band, power sensors and noise sources are not available on the measurement tools market. Due to these constraints and the lack of characterization tools at these frequencies, the direct integration on silicon of very high frequencies bench for noise and power characterization is studied. In particular, example of noise figure and load pull characterizations based on the use of an impedance synthesizer (impedance tuner) will be described. The tuner design imply using tunable components like varactors, DTC (Digital Tunable Capacitances) or switch using travelling wave topologies. These devices will be first described for mm-wave and sub mm-wave applications. Then, the development of in-situ tuners, i.e. integrated on-wafer, used to achieve tests in mm-wave and sub mm-wave bands will be described and examples will be presented on advanced CMOS/BICMOS technologies. 17:30 18:00 Recent advances of CMOS/BiCMOS tunable circuits for mm-wave applications Emmanuel Pistono, University of Grenoble-Alpes, Grenoble, France Abstract Advanced CMOS/BiCMOS technologies, as described by Thomas Quémerais in Talk 4, provide access to high-performance tunable components. In that context, new topologies of tunable mm-wave circuits must be developed in order to take advantage of these new components. In that context, this talk will be focused on tunable circuits dedicated to beam-forming systems (antenna arrays), signal generation and differential tunable systems. An overview of existing circuits will be given, and new paradigms based on distributed tunable circuits based on slow-wave and coupled slow-wave tunable transmission lines will be explored.