abstract: High-Resistivity Silicon (HRS) substrates are important for low-loss, high-performance microwave and millimeter wave devices in high-frequency telecommunication systems. The highest resistivity of up to ~10,000 ohm.cm is Float Zone (FZ) grown Si which is produced in small quantities and moderate wafer diameter. The more common Czochralski (CZ) Si can achieve resistivities of around 1000 ohm.cm, but the wafers contain oxygen that can lead to thermal donor formation with donor concentration significantly higher (~1015 cm-3) than the dopant concentration (~1012-1013 cm-3) of such high-resistivity Si leading to resistivity changes and possible type conversion of high-resistivity p-type silicon. In this research capacitance-voltage (C-V) characterization is employed to study the donor formation and type conversion of p-type High-resistivity Silicon-On-Insulator (HRSOI) wafers and the challenges involved in C-V characterization of HRSOI wafers using a Schottky contact are highlighted. The maximum capacitance of bulk or Silicon-On-Insulator (SOI) wafers is governed by the gate/contact area. During C-V characterization of high-resistivity SOI wafers with aluminum contacts directly on the Si film (Schottky contact); it was observed that the maximum capacitance is much higher than that due to the contact area, suggesting bias spreading due to the distributed transmission line of the film resistance and the buried oxide capacitance. In addition, an "S"-shape C-V plot was observed in the accumulation region. The effects of various factors, such as: frequency, contact and substrate sizes, gate oxide, SOI film thickness, film and substrate doping, carrier lifetime, contact work-function, temperature, light, annealing temperature and radiation on the C-V characteristics of HRSOI wafers are studied. HRSOI wafers have the best crosstalk prevention capability compared to other types of wafers, which plays a major role in system-on-chip configuration to prevent coupling between high frequency digital and sensitive analog circuits. Substrate crosstalk in HRSOI and various factors affecting the crosstalk, such as: substrate resistivity, separation between devices, buried oxide (BOX) thickness, radiation, temperature, annealing, light, and device types are discussed. Also various ways to minimize substrate crosstalk are studied and a new characterization method is proposed. Owing to their very low doping concentrations and the presence of oxygen in CZ wafers, HRS wafers pose a challenge in resistivity measurement using conventional techniques such as four-point probe and Hall measurement methods. In this research the challenges in accurate resistivity measurement using four-point probe, Hall method, and C-V profile are highlighted and a novel approach to extract resistivity of HRS wafers based on Impedance Spectroscopy measurements using polymer dielectrics such as Polystyrene and Poly Methyl Methacrylate (PMMA) is proposed. / Dissertation/Thesis / Ph.D. Electrical Engineering 2012

Com a redução das dimensões dos dispositivos nas tecnologias sub-micrônicas foi possível um grande aumento no número de IP cores integrados em um mesmo chip e consequentemente novas arquiteturas de comunicação são usadas bucando atingir os requisitos de desempenho e potência. As redes intra-chip (Networks-on-Chip) foram propostas como uma plataforma alternativa de comunicação capaz de prover interconexões e comunicação entre os cores de um mesmo chip, tratando questões como desempenho, consumo de energia e reusabilidade para grandes sistemas integrados. Por outro lado, a mesma evolução tecnológica dos processos nanométricos reduziu drasticamente a confiabilidade de circuitos integrados, tornando dispositivos e interconexões mais sensíveis a novos tipos de falhas. Erros podem ser gerados por variações no processo de fabricação ou mesmo pela susceptibilidade do projeto, quando este opera em um ambiente hostil. Na comunicação de NoCs as duas principais fontes de erros são falhas de crosstalk e soft errors. No passado, se assumia que interconexões não poderiam ser afetadas por soft errors, por não possuirem circuitos seqüenciais. Porém, quando NoCs são usadas, buffers e circuitos seqüenciais estão presentes nos roteadores e, consequentemente, podem ocorrer soft errors entre a fonte e o destino da comunicação, provocando erros. Técnicas de tolerância a falhas, que tem sido aplicadas em circuitos em geral, podem ser usadas para proteger roteadores contra bit-flips. Neste cenário, este trabalho inicia com a avaliação dos efeitos de soft errors e falhas de crosstalk em uma arquitetura de NoC, através de simulação de injeção de falhas, analisando detalhadamente o impacto de tais falhas no roteador. Os resultados mostram que os efeitos dessas falhas na comunicação do SoC podem ser desastrosos, levando a perda de pacotes e travamento ou indisponibilidade do sistema. Então é proposta e avaliada a aplicação de um conjunto de técnicas de tolerância a falhas em roteadores, possibilitando diminuir os soft errors e falhas de crosstalk no nível de hardware. Estas técnicas propostas foram baseadas em códigos de correção de erros e redundância de hardware. Resultados experimentais mostram que estas técnicas podem obter zero erros com 50% a menos de overhead de área, quando comparadas com a duplicação simples. Entretanto, algumas dessas técnicas têm um grande consumo de potência, pois toda essas técnicas são baseadas na adição de hardware redundante. Considerando que as técnicas de proteção baseadas em software também impõe um considerável overhead na comunicação devido à retransmissão, é proposto o uso de técnicas mistas de hardware e software, que podem oferecer um nível de proteção satisfatório, baseado na análise do ambiente onde o sistema irá operar (soft error rate), fatores relativos ao projeto e fabricação (variações de atraso em interconexões, pontos susceptíveis a crosstalk), a probabilidade de uma falha gerar um erro em um roteador, a carga de comunicação e os limites de potência e energia suportados. / As the technology scales down into deep sub-micron domain, more IP cores are integrated in the same die and new communication architectures are used to meet performance and power constraints. Networks-on-Chip have been proposed as an alternative communication platform capable of providing interconnections and communication among onchip cores, handling performance, energy consumption and reusability issues for large integrated systems. However, the same advances to nanometric technologies have significantly reduced reliability in mass-produced integrated circuits, increasing the sensitivity of devices and interconnects to new types of failures. Variations at the fabrication process or even the susceptibility of a design under a hostile environment might generate errors. In NoC communications the two major sources of errors are crosstalk faults and soft errors. In the past, it was assumed that connections cannot be affected by soft errors because there was no sequential circuit involved. However, when NoCs are used, buffers and sequential circuits are present in the routers, consequently, soft errors can occur between the communication source and destination provoking errors. Fault tolerant techniques that once have been applied in integrated circuits in general can be used to protect routers against bit-flips. In this scenario, this work starts evaluating the effects of soft errors and crosstalk faults in a NoC architecture by performing fault injection simulations, where it has been accurate analyzed the impact of such faults over the switch service. The results show that the effect of those faults in the SoC communication can be disastrous, leading to loss of packets and system crash or unavailability. Then it proposes and evaluates a set of fault tolerant techniques applied at routers able to mitigate soft errors and crosstalk faults at the hardware level. Such proposed techniques were based on error correcting codes and hardware redundancy. Experimental results show that using the proposed techniques one can obtain zero errors with up to 50% of savings in the area overhead when compared to simple duplication. However some of these techniques are very power consuming because all the tolerance is based on adding redundant hardware. Considering that softwarebased mitigation techniques also impose a considerable communication overhead due to retransmission, we then propose the use of mixed hardware-software techniques, that can develop a suitable protection scheme driven by the analysis of the environment that the system will operate in (soft error rate), the design and fabrication factors (delay variations in interconnects, crosstalk enabling points), the probability of a fault generating an error in the router, the communication load and the allowed power or energy budget.

Lors de la mise en place d’une interaction hôte-parasite, les principales barrières à franchir sont les mêmes quel que soit l’hôte considéré. Il faut que le parasite rencontre l’hôte puis qu’il soit capable d’échapper à ses systèmes de défenses. Pour cela, au-cours de la coévolution, les parasites ont ainsi développé des stratégies moléculaires leur permettant de pirater les réseaux de l’hôte, menant à l’établissement d’un dialogue moléculaire. Les microsporidies, qui sont des parasites intracellulaires obligatoires, ont, du fait de leur forte dépendance vis-à-vis de leur hôte, probablement développé des stratégies très poussées de piratage. L’objectif de cette thèse a été d’initier le décryptage du dialogue moléculaire qui s’établit entre une microsporidie et son hôte à deux niveaux d’intégration. Au niveau cellulaire, l’étude de la réponse protéique de cellules fibroblastiques humaines à l’infection par Anncaliia algerae a permis de suggérer l’existence d’une stratégie originale de leurre de l’hôte grâce à l’expression d’un élément transposable. Au niveau tissulaire, l’étude de la réponse protéique d’intestin d’abeilles infectées par Nosema ceranae a révélé une perturbation de l’homéostasie du tissu intestinal pouvant être à l’origine d’un impact négatif de l’infection sur le taux de renouvellement de l’épithélium. Un suivi du taux de multiplication des cellules souches intestinales lors d’une cinétique d’infection nous a permis de conforter cette hypothèse. Le suivi de l’expression de gènes impliqués dans les voies de signalisation contrôlant ce taux de renouvellement a confirmé une perturbation de l’homéostasie intestinale de l’abeille. Cependant, les mécanismes par lesquels les microsporidies arrivent à se développer chez leurs hôtes ne sont pas connus et méritent d’être explorés. / Within the host-parasite interaction, the parasite need to cross the same barriers whatever the host considered. First, the parasite has to meet its host and to escape its defense systems. For this purpose, the parasites have developed, during coevolution, molecular strategies allowing them to hijack the host networks, leading to the set-up of a real molecular crosstalk. Microsporidia, which are obligate intracellular parasites, have probably developed very sophisticated strategies to hijack their host cell functions as they are strongly dependent to their hosts. The objective of this thesis was to pave the way to the deciphering of the molecular dialogue that takes place during the interaction between a microsporidia and its host, at two different integration levels. At the cellular level, the study of the proteome response of human fibroblast cells to the infection by Anncaliia algerae allowed us to suggest the existence of a lure strategy used by A. algerae to bypass the host response. At the tissue level, the study of the midgut proteome response of honeybees infected by Nosema ceranae revealed a disturbance of the intestinal homeostasis. These results lead us to the hypothesis of a negative impact of the infection on the midgut epithelium renewal rates. This assumption was confirmed by a monitoring of the multiplication rate of intestinal stem cells during a kinetics of infection and of the expression of genes implicated in the signaling pathways controlling this renewal. However, the underlying mechanisms allowing microsporidia to develop in hosts are not known and deserve to be explored.

A comparison of the ability of different spatial filters to reduce the amount of crosstalk in a surface electromyography (sEMG) measurement was conducted. It focused on the influence of different properties of the muscle anatomy and detection system used on the amount of crosstalk present in the measurements. An analytical model was developed which enabled the simulation of single fibre action potentials (SFAPs). These fibres were grouped together in motor units (MUs). Each MU has characteristics which, along with the SFAPs, are used to obtain the motor unit action potential (MUAP). A summation of the MUAPs from all the MUs in a muscle leads to the electromyogram (EMG) signal generated by the muscle. This is the first model which simulates a complete muscle for crosstalk investigation. Previous studies were done for single fibres (Farina&Rainoldi 1999; Farina et al. 2002e; Farina et al. 2004a) or MUs (Dimitrova et al. 2002; Dimitrov et al. 2003; Winter et al. 1994). Lowery et al. simulated a complete muscle, but only investigated one spatial filter (Lowery et al. 2003a). This model is thus the first of its kind. EMG signals were generated for limbs with different anatomical properties and recorded with various detection systems. The parameters used for comparison of the recorded signals are the average rectified value (ARV) and mean frequency (MNF), which describe the amplitude and frequency components of an EMG signal, respectively. These parameters were computed for each EMG signal and interpreted to make recommendations on which detection system results in the best crosstalk rejection for a specific experimental set-up. The conclusion is that crosstalk selectivity in an sEMG measurement is decreased by increasing the thickness of the fat layer, increasing the skin conductivity, decreasing the fibre length, increasing the interelectrode distance of the detection system, placing the detection electrodes directly above the end-plate area or an increased state of muscle contraction. Varying the contraction force strength or placing the detection electrodes directly above the tendon area has no influence on the crosstalk selectivity. For most of the conditions investigated, the normal double differential (NDD) detection system results in the best crosstalk reduction. The only exceptions are a set-up with poor skin conductivity where NDD and double differential (DD) performed comparably, and the two simulations in which the muscle length is varied, where the DD filter performed best. Previous studies have found DD to be more selective for crosstalk rejection than NDD (Dimitrov et al. 2003; Farina et al. 2002a; Van Vlugt&Van Dijk 2000). Possible reasons for the contradictory results are the high value of skin conductivity currently used or influences of the muscle geometry. / Dissertation (MEng(Bio-Engineering))--University of Pretoria, 2007. / Electrical, Electronic and Computer Engineering / unrestricted

The aim of this thesis is to identify coupling mechanisms for three line microstrip, stripline and microstrip with dielectric overlay structures as either inductive or capacitive, quantify through simulation and measurement the amount of crosstalk to be expected in terms of scattering parameters. A new method of crosstalk suppression is implemented into each three line structure by placing uniformly spaced short circuits down the length of the center transmission line. All structures were simulated over various physical and electrical parameters. Select microstrip structures, shielded and unshielded, were fabricated and measured to validate the effectiveness of the shielding technique. Shielding effectiveness was calculated from the measurements, and their results showed that the isolation between lines was increased by up to 20dB.

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As FPGA use becomes more diverse, the shared use of these devices becomes a security concern. Multi-tenant FPGAs that contain circuits from multiple independent sources or users will soon be prevalent in cloud and embedded computing environments. The recent discovery of a new attack vector using neighboring long wires in Xilinx SRAM FPGAs presents the possibility of covert information leakage from an unsuspecting user's circuit. The work makes two contributions that extend this finding. First, we rigorously evaluate several Intel SRAM FPGAs and confirm that long wire information leakage is also prevalent in these devices. Second, we present the first successful attack on an unsuspecting circuit in an FPGA using information passively obtained from neighboring long-lines. Information obtained from a single AES S-box input wire combined with analysis of encrypted output is used to rapidly expose an AES key. This attack is performed remotely without modifying the victim circuit, using electromagnetic probes or power measurements, or modifying the FPGA in any way. We show that our approach is effective for three different FPGA devices. Our results demonstrate that the attack can recover encryption keys from AES circuits running at 50MHz. Finally, we present results from the AES attack performed using a cloud FPGA in a Microsoft Project Catapult cluster. These experiments show the effect can be used to attack a remotely-accessed cloud FPGA.

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No description available.

It is a known problem that a Spinal Cord Stimulator (SCS) can interact with an Implantable Cardioverter Defibrillator (ICD) when both devices are implanted in the same patient. Interactions between the SCS and ICD can cause inappropriate therapy which can be harmful to the patient. While ICD devices have a distinct narrowband sensing bandwidth, the pulse configurations that current SCS devices deliver were not designed with this frequency region in mind. In this thesis, I recommend a new pulse configuration for SCS devices that will minimize the interaction between the two devices. I produce a theoretical equation for each pulse configuration in the frequency domain using the Laplace transform and present the results in Matlab. I also design my own SCS device to deliver multiple pulse configurations and use it to gather empirical data. The theoretical and empirical results are used to show the extent of the improvement between the new pulse and existing pulse configurations. The results prove that the new pulse configuration will significantly reduce crosstalk within the desired ICD bandwidth. A reduction in crosstalk will decrease the probability that an SCS will interact with a ICD device.