There is today an important need for highly integrated microwave systems based on microelectronics and nanoelectronics engineering and featuring a high level of complexity in order to fulfil requirements of new telecommunications developments. However, in many applications, the complexity level is not the only important parameter of the system. The carrier to noise ratio optimization, or the minimisation of the parasitics signals, is crucial, together with the system reliability. This is the case of microwave and RF systems for space applications (telecommunications, imaging,…), for which integration, performance and reliability should be simultaneously achieved. Because our research group is located in Toulouse, our partnership with companies or agencies involved in the space and aeronautics market is strong and we are deeply involved in finding solutions to these problems.
However, even in mass market, the circuit performance (particularly in terms of noise) can be the discriminating parameter between two competitive companies. In this last field, the need for an ever increasing complexity leads to system on chip (SoC) taking benefit of analog and digital modules, of programming capabilities which allows the circuit or the system to adapt to different applications. Our challenge is to design such circuits, taking simultaneously all these parameters into account and improving the quality of the RF signals. This is achieved through device and circuit modelling, including original approaches on noise modelling.
However, in some cases, the classical MMIC circuit design approach is unable to reach the required level of performance. An important case is the one of resonators for which a high Q in a small volume can only be obtained taking benefit of different propagating waves : acoustic or optical. Microwave sources optimisation is one of the application field for which all these skills are required : phase noise modelling, microwave integrated circuit design and high Q resonators implementation. Two new approaches are addressed in order to design low phase noise sources : micro-machined resonators and optical resonators or delay lines. The last case is quite complex, because it requires the modelling in a single system of electrical and optical devices. However, the quality factors of these systems are very high.
Our research activity is further described in three main fields. These scientific fields rely on an important measurement platform, which includes some unique features. As an example, the noise measurement facilities allows us to characterize the devices low frequency noise (1/f noise), the devices high frequency noise (up to 40 GHz), the frequency sources phase noise (1 MHz – 40 GHz) and, finally, the optical devices noise (laser RIN and spectral width…). These scientific fields rely also on shared software and original approaches for design and modelling.