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Microsystems Based on Wide Band Gap Materials for Future Space Transmitting Ultra Wideband Receiving Systems

Final Report Summary - SATURNE (Microsystems Based on Wide Band Gap Materials for Future Space Transmitting Ultra Wideband Receiving Systems)

Executive Summary:
The European Space Technology Platform mentioned in its last SRA a need to support non-dependence on critical technologies from outside Europe for future space applications. In particular, one action under bullet to reduce critical ITAR dependence is to secure access to high-performance microwave components used in satellite communication/navigation payloads, and earth observations/science instruments such as radars. Future satellite services will require novel types of microwave components to meet the demands in terms of more flexibility (ultra-wide-band UWB frequency allocation) and mass reduction. Two technologies are now emerging to face these challenges:
- Wide Band Gap (WBG) semiconductors such as GaN are expected to play a fundamental role in the development of Intelligent Micro Systems (IMS), yielding unprecedented power performance, efficiency and, along with suitable UWB re-configurable architectures.
- RF-MEMS switches as a complementary low-loss switch technology in order to achieve the re-configurability required for future IMS.
The route towards re-configurability of high power systems requires the merging of these key technologies and functions but they have not been co-integrated so far. Therefore, the main concept of SATURNE is to realize such novel types of microwave functions (re-configurable front-ends) using WBG MMICs integrated with RF-MEMS. The technological trends for transmit and receive front-end systems for many kinds of applications will be considered like:
- Re-configurable and highly power efficient communications satellite payloads with narrow-, multi- or wide-band channel allocation;
- Civilian space applications like environmental monitoring and cartography in X-band.
The SATURNE consortium is confident that the realization of its ambitious objectives will assist Europe to achieve technological leadership in domains that are targeted by ESA.
Project Context and Objectives:
The implementation of such Intelligent Micro Systems (IMS) will require the achievement of new components that are able to manage simultaneously and efficiently high RF powers and re-configurability properties (such as changing output power and bandwidth requirements). A successful integration of wide band-gap (WBG) devices and RF Micro Electro Mechanical Systems (RF-MEMS) switches will enable miniaturized reconfigurable microwave components and systems with very high power handling capability (e.g. adaptive transmitters and frequency-agile robust receivers). The route towards re-configurability of high power systems will depend on the merging of these technologies and this has not been demonstrated so far. Therefore, the main concept of SATURNE is to realize novel types of microwave functions (reconfigurable front-ends) using WBG MMICs (Monolithic Microwave Integrated Circuits) and RF-MEMS low-loss switching networks.

The main objectives of SATURNE are:
· To prove the feasibility and inherent advantages of using WBG and RF-MEMS based technologies in Intelligent Micro Systems for future space transmitting ultra wideband (UWB) receiving systems. This will be achieved via the integration (monolithic and hybrid) of WBG devices such as GaN based MMICs (LNA and HPA) and RF-MEMS switching networks for the realization of different active subsystems required for IMS (§B.1.1.1). This will be done in work packages 1 to 4.
· The GaN and RF-MEMS based circuits will be used to realize three types of very compact (small size and low weight) antenna breadboards for a proof-of-concept: (1) a smart active antenna made up of several Transmitter / Receiver (T/R) modules (§B.1.1.2) (2) a miniaturized reconfigurable front-end (§B.1.1.3) and (3) a frequency-agile T/R module (§B.1.1.4). This will be done in work package 5.

We will also show the general trends for transmit and receive front-end systems. We will also discuss the choice concerning the substrates to be used during this project. Finally, we will show the relevance of this project to topics addressed by the call .

Project Results:
Within the project a re-configurable RF MEMS based matching networks and high power SPDT switches has designed and manufactured on GaN based substrate in order to realise a smart active antenna based on a T/R module using a monolithic approach. For this purpose, a design of a T/R module has been developed for the specifications of SATURNE project. The T/R module modelled integrates a DRIVER, a HPA, a LNA and a SPDT based on capacitive RF MEMS switches. This design is based on MMIC components purchased by UMS for a further industrialisation.
The T/R modulewith the RF MEMS switches have been carried out in order to define the design of the T/R module. the T/R module developedSeveral simulations have been carried out from this device in order to check its performance in the two configurations: emitter and receiver. According the design and the process flow developed for this project, a set mask design has been developed corresponding to the technological steps.All the characterisation on RF MEMS switches or transistors show the feasibility of the monolithic integration of MMIC circuits based capacitive RF MEMS switches on 3-inch GaN/SiC substrate. The RF or DC characterisations show results in good agreement with those expected. These measurement have to be confirmed on microstrip devices

Potential Impact:
The evolution of space modules and equipment hardware market is strictly related to the progress of enabling technologies in terms of available high reliable processes and devices, and high repeatability production systems.
In particular, the short-term evolution of future space based imaging radar systems envisage for two main requirements: the modularity and the compactness. The former oriented to help the re-use of the units and therefore to reduce the costs, the latter more oriented to save mass and weight and improve the reliability of the system. In such a trend the density of RF functions in a single housing have to be increased. So the evolution of these systems is towards the design of more and more highly integrated microwave hybrid circuits. In this framework the development of advanced interconnection and packaging technologies together with the improvement of microcircuit technology is mandatory to be economically competitive.
In this project advanced solutions based on RF-MEMS will be studied for strategic equipment to be integrated in active phased array radar. Standard hybrid technology is evolved to this purpose towards two compatible approaches:
· Advanced packaging and interconnection technologies based on LTCC;
· Advanced microcircuit technologies.
RF-MEMS has been integrated on both microcircuits and on LTCC, on different demonstrators. So, within the framework of this project, all the state of the art RF-MEMS technologies has been developed. Now at the end of the project the participants have the possibility to trade off between all these approaches in the design of future space circuits in order to choose the best economical solution.The overall impact of SATURNE extends well beyond the satisfaction of the scientific and technical objectives of the Space priority since the technology addressed in the project will have a major societal impact. Technologies of the proposed type will enable a number of components and systems to be developed that not only will improve currently available system specifications but will also permit the control of environment conditions, efficiency of processes and in-situ diagnosis of equipment status. Overall, it is expected that the society will be able to confront better the challenges expected to be faced over the next decade by the existence of components based on the SATURNE approach.
The diversity of skills is not available in one country and the need to create an EU critical mass of expertise is important in order to ensure success. The representation of partners from all different regions also underlines the integrative aspect of the project. Networks of scientific partners and SME-based suppliers will be expanded by the partners of the SATURNE project. The international cooperation between customers and material producer in SATURNE will speed up the development of new product and its applications. The whole supply chain for smart system integration will be European based. This will be one piece of a puzzle to break the domination of Japanese and American based suppliers.
Smarter, smaller and complex systems, combining micro and nano system technologies with intelligence, power supply and communication ability, pose strong challenges to the engineers involved in the modelling and fabrication of micro and nano-systems, electronics and wireless communication domains.
The expansion of the Nanoelectronics industry will create a pool of industrially focused research engineers. It will also create highly skilled jobs in the resultant semiconductor, equipment and materials manufacturing, systems integration, product design, product manufacturing, and service sectors, generating as many as ten indirect jobs for every direct worker in the Nanoelectronics industry itself. It will also promote infrastructures in which industry will stimulate innovation-focused scientific research and training, in cooperation with academic institutions. The creation of such environment will have also a positive impact on the creation of high-tech SMEs and start-ups, which will exploit the innovation of the research centres in emerging segments of the overall economic value chain. The semiconductor manufacturers themselves will be the first customers of high-tech SMEs, especially in the fields of design and design tools, equipment and materials.
But there are currently too few specialists available in the area of heterogeneous integration, where Nano- and Micro- electronics meet. The partners are conscious of the need to attract young people who are displaying less and less interest in pursuing engineering and science as careers. The increasing demands of European Industry and research for qualified human resources in this area are addressed in SATURNE by several means. The number of scientist with a basic know-how will be enlarged by the organization of trainings and workshops and by influencing university curricula. This will constitute an elite group of highly qualified people capable of generating and undertaking innovative research as well as implementing practical solutions in this field. Gaining knowledge concerning the micro- and nano-scale is only attainable in combination with simulation and experimental tools requiring a new interdisciplinary curriculum in this area. The SATURNE consortium had defined the appropriate components and build up the material for these courses. The training will have an optimized blend of experimental, theoretical, and in several cases applied developmental work.

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