High-level power optimisation for Digital Signal Processing in Recon gurable Logic

This thesis is concerned with the optimisation of Digital Signal Processing (DSP) algorithm implementations on recon gurable hardware via the selection of appropriate word-lengths for the signals in these algorithms, in order to minimise system power consumption. Whilst existing word-length optimisation work has concentrated on the minimisation of the area of algorithm implementations, this work introduces the rst set of power consumption models that can be evaluated quickly enough to be used within the search of the enormous design space of multiple word-length optimisation problems. These models achieve their speed by estimating both the power consumed within the arithmetic components of an algorithm and the power in the routing wires that connect these components, using only a high-level description of the algorithm itself. Trading o a small reduction in power model accuracy for a large increase in speed is one of the major contributions of this thesis. In addition to the work on power consumption modelling, this thesis also develops a new technique for selecting the appropriate word-lengths for an algorithm implementation in order to minimise its cost in terms of power (or some other metric for which models are available). The method developed is able to provide tight lower and upper bounds on the optimal cost that can be obtained for a particular word-length optimisation problem and can, as a result, nd provably near-optimal solutions to word-length optimisation problems without resorting to an NP-hard search of the design space. Finally the costs of systems optimised via the proposed technique are compared to those obtainable by word-length optimisation for minimisation of other metrics (such as logic area) and the results compared, providing greater insight into the nature of wordlength optimisation problems and the extent of the improvements obtainable by them

Hardware accelerated real-time Linux video anonymizer

Dissertação de mestrado em Engenharia Eletrónica Industrial e ComputadoresOs Sistemas Embebidos estão presentes atualmente numa variada gama de equipamentos do quotidiano do ser humano. Desde TV-boxes, televisões, routers até ao indispensável telemóvel. O Sistema Operativo Linux, com a sua filosofia de distribuição ”one-size-fits-all” tornou-se uma alternativa viável, fornecendo um vasto suporte de hardware, técnicas de depuração, suporte dos protocolos de comunicação de rede, entre outros serviços, que se tornaram no conjunto standard de requisitos na maioria dos sistemas embebidos atuais. Este sistema operativo torna-se apelativo pela sua filosofia open-source que disponibiliza ao utilizador um vasto conjunto de bibliotecas de software que possibilitam o desenvolvimento num determinado domínio com maior celeridade e facilidade de integração de software complexo. Os algoritmos deMachine Learning são desenvolvidos para a automização de tarefas e estão presentes nas mais variadas tecnologias, desde o sistema de foco de imagem nosmartphone até ao sistema de deteção dos limites de faixa de rodagem de um sistema de condução autónoma. Estes são algoritmos que quando compilados para as plataformas de sistemas embebidos, resultam num esforço de processamento e de consumo de recursos, como o footprint de memória, que na maior parte dos casos supera em larga escala o conjunto de recursos disponíveis para a aplicação do sistema, sendo necessária a implementação de componentes que requerem maior poder de processamento através de elementos de hardware para garantir que as métricas tem porais sejam satisfeitas. Esta dissertação propõe-se, por isso, à criação de um sistema de anonimização de vídeo que adquire, processa e manipula as frames, com o intuito de garantir o anonimato, mesmo na transmissão. A sua implementação inclui técnicas de Deteção de Objectos, fazendo uso da combinação das tecnologias de aceleração por hardware: paralelização e execução em hardware especial izado. É proposta então uma implementação restringida tanto temporalmente como no consumo de recursos ao nível do hardware e software.Embedded Systems are currently present in a wide range of everyday equipment. From TV-boxes, televisions and routers to the indispensable smartphone. Linux Operating System, with its ”one-size-fits-all” distribution philosophy, has become a viable alternative, providing extensive support for hardware, debugging techniques, network com munication protocols, among other functionalities, which have become the standard set of re quirements in most modern embedded systems. This operating system is appealing due to its open-source philosophy, which provides the user with a vast set of software libraries that enable development in a given domain with greater speed and ease the integration of complex software. Machine Learning algorithms are developed to execute tasks autonomously, i.e., without human supervision, and are present in the most varied technologies, from the image focus system on the smartphone to the detection system of the lane limits of an autonomous driving system. These are algorithms that, when compiled for embedded systems platforms, require an ef fort to process and consume resources, such as the memory footprint, which in most cases far outweighs the set of resources available for the application of the system, requiring the imple mentation of components that need greater processing power through elements of hardware to ensure that the time metrics are satisfied. This dissertation proposes the creation of a video anonymization system that acquires, pro cesses, and manipulates the frames, in order to guarantee anonymity, even during the transmis sion. Its implementation includes Object Detection techniques, making use of the combination of hardware acceleration technologies: parallelization and execution in specialized hardware. An implementation is then proposed, restricted both in time and in resource consumption at hardware and software levels

Energy-Efficient Digital Circuit Design using Threshold Logic Gates

abstract: Improving energy efficiency has always been the prime objective of the custom and automated digital circuit design techniques. As a result, a multitude of methods to reduce power without sacrificing performance have been proposed. However, as the field of design automation has matured over the last few decades, there have been no new automated design techniques, that can provide considerable improvements in circuit power, leakage and area. Although emerging nano-devices are expected to replace the existing MOSFET devices, they are far from being as mature as semiconductor devices and their full potential and promises are many years away from being practical. The research described in this dissertation consists of four main parts. First is a new circuit architecture of a differential threshold logic flipflop called PNAND. The PNAND gate is an edge-triggered multi-input sequential cell whose next state function is a threshold function of its inputs. Second a new approach, called hybridization, that replaces flipflops and parts of their logic cones with PNAND cells is described. The resulting \hybrid circuit, which consists of conventional logic cells and PNANDs, is shown to have significantly less power consumption, smaller area, less standby power and less power variation. Third, a new architecture of a field programmable array, called field programmable threshold logic array (FPTLA), in which the standard lookup table (LUT) is replaced by a PNAND is described. The FPTLA is shown to have as much as 50% lower energy-delay product compared to conventional FPGA using well known FPGA modeling tool called VPR. Fourth, a novel clock skewing technique that makes use of the completion detection feature of the differential mode flipflops is described. This clock skewing method improves the area and power of the ASIC circuits by increasing slack on timing paths. An additional advantage of this method is the elimination of hold time violation on given short paths. Several circuit design methodologies such as retiming and asynchronous circuit design can use the proposed threshold logic gate effectively. Therefore, the use of threshold logic flipflops in conventional design methodologies opens new avenues of research towards more energy-efficient circuits.Dissertation/ThesisDoctoral Dissertation Computer Science 201

Image Processing Using FPGAs

This book presents a selection of papers representing current research on using field programmable gate arrays (FPGAs) for realising image processing algorithms. These papers are reprints of papers selected for a Special Issue of the Journal of Imaging on image processing using FPGAs. A diverse range of topics is covered, including parallel soft processors, memory management, image filters, segmentation, clustering, image analysis, and image compression. Applications include traffic sign recognition for autonomous driving, cell detection for histopathology, and video compression. Collectively, they represent the current state-of-the-art on image processing using FPGAs

Advanced Timing and Synchronization Methodologies for Digital VLSI Integrated Circuits

This dissertation addresses timing and synchronization methodologies that are critical to the design, analysis and optimization of high-performance, integrated digital VLSI systems. As process sizes shrink and design complexities increase, achieving timing closure for digital VLSI circuits becomes a significant bottleneck in the integrated circuit design flow. Circuit designers are motivated to investigate and employ alternative methods to satisfy the timing and physical design performance targets. Such novel methods for the timing and synchronization of complex circuitry are developed in this dissertation and analyzed for performance and applicability.Mainstream integrated circuit design flow is normally tuned for zero clock skew, edge-triggered circuit design. Non-zero clock skew or multi-phase clock synchronization is seldom used because the lack of design automation tools increases the length and cost of the design cycle. For similar reasons, level-sensitive registers have not become an industry standard despite their superior size, speed and power consumption characteristics compared to conventional edge-triggered flip-flops.In this dissertation, novel design and analysis techniques that fully automate the design and analysis of non-zero clock skew circuits are presented. Clock skew scheduling of both edge-triggered and level-sensitive circuits are investigated in order to exploit maximum circuit performances. The effects of multi-phase clocking on non-zero clock skew, level-sensitive circuits are investigated leading to advanced synchronization methodologies. Improvements in the scalability of the computational timing analysis process with clock skew scheduling are explored through partitioning and parallelization.The integration of the proposed design and analysis methods to the physical design flow of integrated circuits synchronized with a next-generation clocking technology-resonant rotary clocking technology-is also presented. Based on the design and analysis methods presented in this dissertation, a computer-aided design tool for the design of rotary clock synchronized integrated circuits is developed

A survey of scan-capture power reduction techniques

With the advent of sub-nanometer geometries, integrated circuits (ICs) are required to be checked for newer defects. While scan-based architectures help detect these defects using newer fault models, test data inflation happens, increasing test time and test cost. An automatic test pattern generator (ATPG) exercise’s multiple fault sites simultaneously to reduce test data which causes elevated switching activity during the capture cycle. The switching activity results in an IR drop exceeding the devices under test (DUT) specification. An increase in IR-drop leads to failure of the patterns and may cause good DUTs to fail the test. The problem is severe during at-speed scan testing, which uses a functional rated clock with a high frequency for the capture operation. Researchers have proposed several techniques to reduce capture power. They used various methods, including the reduction of switching activity. This paper reviews the recently proposed techniques. The principle, algorithm, and architecture used in them are discussed, along with key advantages and limitations. In addition, it provides a classification of the techniques based on the method used and its application. The goal is to present a survey of the techniques and prepare a platform for future development in capture power reduction during scan testing

PRITEXT: Processor Reliability Improvement Through Exercise Technique

With continuous improvements in CMOS technology, transistor sizes are shrinking aggressively every year. Unfortunately, such deep submicron process technologies are severely degraded by several wearout mechanisms which lead to prolonged operational stress and failure. Negative Bias Temperature Instability (NBTI) is a prominent failure mechanism which degrades the reliability of current semiconductor devices. Improving reliability of processors is necessary for ensuring long operational lifetime which obviates the necessity of mitigating the physical wearout mechanisms. NBTI severely degrades the performance of PMOS transistors in a circuit, when negatively biased, by increasing the threshold voltage leading to critical timing failures over operational lifetime. A lack of activity among the PMOS transistors for long duration leads to a steady increase in threshold voltage Vth. Interestingly, NBTI stress can be recovered by removing the negative bias using appropriate input vectors. Exercising the dormant critical components in the Processor has been proved to reduce the NBTI stress. We use a novel methodology to generate a minimal set of deterministic input vectors which we show to be effective in reducing the NBTI wearout in a superscalar processor core. We then propose and evaluate a new technique PRITEXT, which uses these input vectors in exercise mode to effectively reduce the NBTI stress and improve the operational lifetime of superscalar processors. PRITEXT, which uses Input Vector Control, leads to a 4.5x lifetime improvement of superscalar processor on average with a maximum lifetime improvement of 12.7x