When antennas are placed closely spaced together, the mutual coupling and spatial correlation effects undermine the advantages provided by multiple input and multiple output (MIMO) antennas. In this thesis, we compare and analyze the performance of digital beamforming, fixed radio frequency (RF) beamforming and element based patterning with closely spaced antenna systems. In the case where only one RF-chain is available, we have demonstrated performance improvements using RF beamforming-based MIMO processing instead of element-based MIMO processing with closely spaced metamaterial antennas. The result indicates that even without mutual coupling, antenna based MIMO processing is greatly impacted when moving from rich to correlated scattering environments. In the second half of the thesis, we investigate the switch and examine receiver combining (SEC) technique. We derive the switching rate of SEC and show that even though it has the same outage probability as traditional selection combining, it has a significantly lower switching rate.

When antennas are placed closely spaced together, the mutual coupling and spatial correlation effects undermine the advantages provided by multiple input and multiple output (MIMO) antennas. In this thesis, we compare and analyze the performance of digital beamforming, fixed radio frequency (RF) beamforming and element based patterning with closely spaced antenna systems. In the case where only one RF-chain is available, we have demonstrated performance improvements using RF beamforming-based MIMO processing instead of element-based MIMO processing with closely spaced metamaterial antennas. The result indicates that even without mutual coupling, antenna based MIMO processing is greatly impacted when moving from rich to correlated scattering environments. In the second half of the thesis, we investigate the switch and examine receiver combining (SEC) technique. We derive the switching rate of SEC and show that even though it has the same outage probability as traditional selection combining, it has a significantly lower switching rate.

No description available.

Cette thèse discute le problème de test de production en grand volume des circuits radio-fréquences (RF) et à ondes millimétriques (mm-wave). Le test des fonctionnalités RF et à ondes millimétriques est très onéreux. Le test intégré est une alternative prometteuse pour faciliter la procédure et réduire les couts, mais il est difficile à mettre en œuvre car il ne faut en aucun cas qu'il réduit la performance du circuit sous test (CUT). Dans cette thèse, nous étudions une technique du test intégré qui repose sur l'utilisation de capteurs non-intrusifs qui prend en compte la variabilité du procédé de fabrication. Cette technique est extrêmement intéressante pour les concepteurs des circuits RF et mm-wave car il leur permet de dissocier le test de la conception. Les capteurs non-intrusifs sont constitués d'étages analogiques triviaux et de composants simples qui sont copiés de la topologie du CUT et sont placés sur la puce à proximité du CUT. Ils offrent simplement une "image" des variations du procédé de fabrication, ce qui leur permet de suivre les variations de performance du CUT. En substance, cette technique tire parti des phénomènes non désirés de variabilité de procédé de fabrication. Le paradigme du test alternatif est utilisé pour estimer les performances du CUT à partir des mesures des capteurs non intrusifs, afin de remplacer les tests standards qui mesurent les performances directement. Ce principe de test est appliqué à deux différents CUTs, nommément un amplificateur à bas bruit à 2.4GHz réalisé en CMOS 65nm et un amplificateur à bas bruit large bande à 60GHz réalisé en CMOS 65nm. Nous démontrons qu'en ajoutant quelques capteurs non-intrusifs sur la puce, qui n'engendrent pratiquement pas de surcout de surface, et en obtenant de ces capteurs non-intrusifs certaines mesures dans le domaine continu et à basse fréquence, nous sommes capable de suivre les variations de toutes les performances du CUT avec une erreur de prédiction moyenne inférieure à l’écart-type de la performance, et une erreur de prédiction maximum qui est inférieure ou au moins comparable aux erreurs de mesure dans un équipement de test automatisé conventionnel. / This thesis addresses the high-volume production test problem for RF and millimeter-wave (mm-wave) circuits. Testing the RF/mm-wave functions of systems-on-chip (SoCs) incurs a very high cost. Built-in test is a promising alternative to facilitate testing and reduce costs, but it is challenging since it should by no means degrade the performance of the Circuit Under Test (CUT). In this work, we study a built-in test technique which is based on non-intrusive variation-aware sensors. The non-intrusive property is very appealing for designers since the sensors are totally transparent to the design and, thereby, the test is completely dissociated from the design. The non-intrusive sensors are dummy analog stages and single layout components that are copied from the topology of the CUT and are placed on the die in close physical proximity to the CUT. They simply offer an “image” of process variations and by virtue of this they are capable of tracking variations in the performances of the CUT. In essence, the technique capitalizes on the undesired phenomenon of process variations. The alternate test paradigm is employed to map the outputs of the non-intrusive sensors to the performances of the CUT, in order to replace the standard tests for measuring the performances directly. The proposed test idea is applied to two different CUTs, namely a 2.4GHz CMOS 65nm inductive degenerated Low-Noise Amplifier (LNA) and a wide-band mm-wave 60GHz CMOS 65nm 3-stage LNA. We demonstrate that by adding on-chip a few non-intrusive sensors of practically zero area-overhead and by obtaining on these non-intrusive sensors DC or low-frequency measurements, we are able to track variations in all performances of the CUT with an average prediction error lower than one standard deviation of the performance and a maximum prediction error that is lower or at least comparable to the measurement and repeatability errors in a conventional Automatic Test Equipment (ATE) environment.

The performance of our hearing system degrades with age, causing a reduction in our ability to understand speech. This thesis describes the design of a personal audio system, aimed at enhancing the audio signal from a TV, for hard of hearing listeners. Such system generates a zone of high acoustic pressure in a specific area of a room, whilst minimising the sound radiated to other zones. In order to obtain a very narrow sound radiation, superdirective techniques are used. Such techniques improve the performance of an array of small dimensions at mid and low frequencies, but they can require the use of a large amount of power and can be very sensitive to errors in the source transfer functions. A practical balance between performance and array effort is achieved in a design that uses phase-shift sources. Two arrays have been built. The first array uses 8 phase-shift sources and provides a high directionality in the free field. The second array uses 4 phase-shift sources vertically plus 8 horizontally and is more directional in a 3D sense, hence reducing the reverberant field excitation. The design of superdirective filters has been considered in both time and frequency domains. The effect of the reverberant field in the performance of superdirective radiators has also been investigated, by first examining how the radiation pattern is modified, and then by observing how the reverberant field affects the robustness of the control. The performance has been assessed by means of off-line simulations with point source Green functions and measured transfer responses, and by real time measurements in free-field and reverberant environments. The later chapters of the thesis consider the subjective assessment of arrays as an aid for speech intelligibility. The assessment has first been performed using an objective metric, in particular the speech transmission index (STI). The performance has also been assessed in a subjective study, in which 30 participants have judged the increase in intelligibility. A cochlear model has also been utilised to investigate equalisation methods that minimise masking and provide a better speech intelligibility, particularly for the hearing impaired. Although this has not been tested with behavioural experiments, STI simulations have predicted that it can lead to an intelligibility improvement.

Skeletal muscle contractions emit a low frequency sound (<100Hz) that can be detected by vibromyography (VMG) or mechanomyography (MMG). The aim of this study was to determine the future application of the VMG signal as a clinical tool in reflecting the physiological state or function of muscle during rehabilifation and diagnosis. In order to achieve this aim, the following was investigated. A) The technical characteristics: Three different transducers (the capacitance and piezoelectric accelerometers and the contact sensor) and the transducer/ amplifier system. B) The repeatability of the VMG signal at different force levels. C) Physiological characteristics of the VMG signal comparing 'normal' and 'abnormal' muscle function. Past studies on VMG have revealed that these three areas have received little attention. The VMG signal was taken from the biceps brachii muscle at different contraction levels 10%, 50% and 80% maximum voluntary contraction (MVC) for within day (n=3) and between day (n=17) recordings. The signal from asymptomatic (n=29) and symptomatic (n=23) low back pain subjects was then compared. Recordings were taken from the erector spinae muscle at an incremental increase in voluntary contraction (10%-100%MVC). These recordings were repeated on the next day. Results from this study have revealed the following: A) Technical characteristics : the lower cut-off frequency is important and insufficient attention in past studies has been given to the transducer-amplifier system. Additionally, the capacitance accelerometer was the favoured transducer due to its greater sensitivity to low frequencies, simplicity of use and ease of stabilising and coupling techniques to the skin. B) Repeatability of the VMG signal: For successive recordings, compared with precision (%C.O.V and L.O.A) and reliability (I.C.C), correlation (r value) of the VMG signal appears a much stronger and a more consistent statistic in the time and frequency domains. C) Physiological Characteristics: Although having a high individual variation, the erector spinae demonstrated a strong curvilinear relationship with increasing submaximal voluntary contraction (%MVC) reflecting the recruitment and rate coding strategies for this muscle. The VMG RMS for symptomatic low back pain subjects was considerably less than asymptomatic subjects suggesting a deficiency in muscle function. In contrast, the PSD was less favourable in distinguishing between the two subject groups. Reasons for these findings are discussed. In future, the clinical application of the VMG RMS values may quantitatively assess paraspinal muscle force reflecting physiological changes in recruitment and rate coding strategies in 'normal' and 'abnormal' muscle function during rehabilitative care.

No description available.

Dans l’optique de développer de nouveaux système RF les plus intégrés possibles, les technologies above-IC compatibles avec les technologies silicium ouvrent des perspectives prometteuses sur un plan économique pour l’industrie du semi-conducteur. En effet, a contrario des résonateurs SAW et céramiques, les résonateurs à ondes acoustiques de volume (BAW) peuvent être fabriqués en utilisant des matériaux compatible CMOS VLSI pour des performances électriques comparables, voir supérieures dans certains cas en termes de fréquence et de puissance. Les travaux de cette thèse ont connus deux grandes partie ; la première a été focalisée sur le développement d’une nouvelle topologie de filtre BAW accordable pour des applications de quatrième génération de téléphone mobile (4G). La seconde partie a été orientée vers une étude de faisabilité d’un filtre BAW-SMR autour d’une fréquence de travail à 7GHz pour une application spatiale. / Abstract

L’extension des systèmes de télécommunication génère de plus en plus des ondes électromagnétiques dans notre environnement aux fréquences et puissances très variées. Le temps est venu de faire une étude approfondie sur les possibilités potentielles que nous avons d’utiliser l’énergie contenue dans les ondes électromagnétiques pour alimenter des applications électroniques. L’idée est d’utiliser une ou plusieurs antennes pour récupérer les ondes électromagnétiques disponibles, suivies par un convertisseur des signaux RF/DC. / The work of this thesis is focuse on designing, measuring and testing an antenna and rectifiercircuit (RECTENNA) optimized for incoming signals of low power density (~651W/m²). The rectenna is used to harvest the ambient electric energy from the RF signals that have been radiated by communication and broadcasting systems at (1GHz-3GHz) without matching circuit and the second is a narrow band (1.8GHz-1.9GHz) with a matching circuit between the antenna and the rectifier.

Associations among personality, coping, and psychopathology have long been established (e.g., Folkman, Lazarus, Gruen, & DeLongis, 1986; Kobasa, 1979; Wheaton, 1983). This study assessed reported distress on the MMPI-2-RF (Ben-Porath & Tellegen, 2008), coping and appraisal styles via the Cognitive Emotion Regulation Questionnaire (CERQ; Garnefski, Kraaij, & Spinhoven, 2001, 2002) and Proactive Coping Inventory (PCI; Greenglass, Schwarzer, & Taubert, 1999), personality traits on the International Personality Item Pool (IPIP; Goldberg, 1999), and exposure to and perception of stressors on the Adolescent Perceived Events Scale (APES; Compas, Davis, Forsythe, & Wagner, 1987). In the current study mediational analysis was employed to assess whether coping helped explain how and why the relationship between personality and psychopathology exists. Additionally, exposure to and perception of stressors was measured and compared to psychopathology and coping styles. Although coping did not mediate the relationship between personality and psychopathology as conceptualized in this study, implications are discussed regarding the associations among constructs.