| This thesis presents a new approach towards an improved architecture of the telecommunications receivers. The topological issues are covered both in terms of analytical treatment of information and characterization of technological parameters. One of our research goals was to show the possibility of obtaining a cost-effective receiver, in a direct conversion variant, and designing special techniques to alleviate some disadvantages of this architecture compared to the classical super-heterodyne receiver.; From a chronological point of view, our project followed some works on direct receivers based on six-ports junction and we analyzed this approach respective to an evident difference between the initial application as reflectometer and the specification of a receiver.; After making a critical review of previous published techniques for demodulation in direct receivers, we introduced a new method to compensate the hardware imperfections. The novel algorithm based on neural networks theory, adaptively changes the actual response of the receiver and corrects the linear errors of gain & phase imbalance. The method is not dependent on modulation type and can be applied to any orthogonal modulation scheme, usually used in today communication systems (n-QAM, n-PSK etc.). In this case the software is completely portable on commercial available signal processors (DSP) and can actually adapt itself to the incoming signal, proving itself as a member of the soft-radios class.; A second area of development was to build an in-house facility of fabrication, characterization and design for MMIC components in collaboration with University of Sherbrooke. All three aspects of the MMIC technology are discussed and we show our results, which in our knowledge are the first tries at academic levels in Canada to obtain such facility at microwave range.; At the beginning of this project, no MMIC fabrication and characterization means were available at PolyGrames Research Center. A special effort was dedicated to build the infrastructure for automatic parameters extraction for on-wafer measurement. Different calibration techniques and models alternatives are presented to give a complete picture of the measurement capabilities developed during this work. (Abstract shortened by UMI.)... |
