568 research outputs found

    Power-Efficient Time-Domain Dispersion Compensation Using Optimized FIR Filter Implementation

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    We investigate fixed-point aspects and time-domain ASIC implementations of CD compensation. An optimized implementation gives significant power dissipation reduction for short links, with further reduction if pulse shaping is considered

    FPGA Implementation of Higher Order FIR Filter

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    The digital Finite-Impulse-Response (FIR) filters are mainly employed in digital signal processing applications. The main components of digital FIR filters designed on FPGAs are the register bank to save the samples of signals, adder to implement sum operations and multiplier for multiplication of filter coefficients to signal samples. Although, design and implementation of digital FIR filters seem simple but the design bottleneck is multiplier block for speed, power consumption and FPGA chip area occupation. The multipliers are an integral part in FIR structures and these use a large part of the chip area. This limits the number of processing elements (PE) available on the chip to realize a higher order of filter. A model is developed in the Matlab/Simulink environment to investigate the performance of the desired higher order FIR filter. An equivalent FIR filter representation is designed by the Xilinx FIR Compiler by using the exported FIR filter coefficients. The Xilinx implementation flow is completed with the help of Xilinx ISE 14.5. It is observed how the use of higher order FIR filter impacts the resource utilization of the FPGA and it’s the maximum operating frequency

    Residue Number Systems: a Survey

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    Low Latency Prefix Accumulation Driven Compound MAC Unit for Efficient FIR Filter Implementation

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    135–138This article presents hierarchical single compound adder-based MAC with assertion based error correction for speculation variations in the prefix addition for FIR filter design. The VLSI implementation of approximation in prefix adder results show a significant delay and complexity reductions, all this at the cost of latency measures when speculation fails during carry propagation, which is the main reason preventing the use of speculation in parallel-prefix adders in DSP applications. The speculative adder which is based on Han Carlson parallel prefix adder structure accomplishes better reduction in latency. Introducing a structured and efficient shift-add technique and explore latency reduction by incorporating approximation in addition. The improvements made in terms of reduction in latency and merits in performance by the proposed MAC unit are showed through the synthesis done by FPGA hardware. Results show that proposed method outpaces both formerly projected MAC designs using multiplication methods for attaining high speed

    Automatisoitu vuo suodinten laitteistokuvauksen tuottamiseen

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    Digitaalisia suotimia käytetään signaalien käsittelyyn monilla eri tekniikan alueilla, kuten telekommunikaatiossa, kuvankäsittelyssä ja lääketieteellisissä laitteissa. Ne ovat niin yleisiä, että insinöörit käyttävät paljon aikaa ja resursseja niiden toteuttamiseen ja verifioimiseen. Koska yleisimpien suotimien rakenne on melko yksinkertainen, niiden luominen voidaan automatisoida generaattorin avulla. Tässä diplomityössä Nokia Networksin vaatimukset kartoitetaan automatisoidun suodinten laitteistokuvauksen tuottamisvuon kehittämiseksi. Erilaisia tuottamismenetelmiä vertaillaan, mutta lopulta päädytään kehittämään oma generaattori. Se luo suotimia yhdistelemällä osia käsinkirjoitetusta RTL:stä. Lopputuloksena on automatisoitu vuo, joka tukee vakiokertoimilla varustettuja, yhden tai useamman kanavan FIR-suotimia. Käyttäjän tulee syöttää kertoimet ja haluttu datanleveys Matlab-skriptiin. Ajettaessa skripti luo suotimen ja verifioi sen. Vuo tukee sekä ASIC- että FPGA-teknologioita.Digital filters are used to process signals in many fields like telecommunications, image processing and in medical equipment. They are so omnipresent that engineers are building and verifying those all the time, using a lot of resources. As the structure of a basic filter is quite simple, savings could be made by automatizing the creation of filters. In this Thesis the requirements of Nokia Networks are analyzed to build an automatized filter generation flow. Different tools are evaluated, but finally a custom generator is built. It crafts filters from pieces of hand-written RTL. The end result is an automated flow which supports single and multichannel FIR filters with constant coefficients. The user has to input the coefficients to a Matlab script with the desired data widths. The filter is then generated and verified by running the script. The flow supports both ASIC and FPGA technologies

    Hardware-software codesign in a high-level synthesis environment

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    Interfacing hardware-oriented high-level synthesis to software development is a computationally hard problem for which no general solution exists. Under special conditions, the hardware-software codesign (system-level synthesis) problem may be analyzed with traditional tools and efficient heuristics. This dissertation introduces a new alternative to the currently used heuristic methods. The new approach combines the results of top-down hardware development with existing basic hardware units (bottom-up libraries) and compiler generation tools. The optimization goal is to maximize operating frequency or minimize cost with reasonable tradeoffs in other properties. The dissertation research provides a unified approach to hardware-software codesign. The improvements over previously existing design methodologies are presented in the frame-work of an academic CAD environment (PIPE). This CAD environment implements a sufficient subset of functions of commercial microelectronics CAD packages. The results may be generalized for other general-purpose algorithms or environments. Reference benchmarks are used to validate the new approach. Most of the well-known benchmarks are based on discrete-time numerical simulations, digital filtering applications, and cryptography (an emerging field in benchmarking). As there is a need for high-performance applications, an additional requirement for this dissertation is to investigate pipelined hardware-software systems\u27 performance and design methods. The results demonstrate that the quality of existing heuristics does not change in the enhanced, hardware-software environment

    Optimization of DSSS Receivers Using Hardware-in-the-Loop Simulations

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    Over the years, there has been significant interest in defining a hardware abstraction layer to facilitate code reuse in software defined radio (SDR) applications. Designers are looking for a way to enable application software to specify a waveform, configure the platform, and control digital signal processing (DSP) functions in a hardware platform in a way that insulates it from the details of realization. This thesis presents a tool-based methodolgy for developing and optimizing a Direct Sequence Spread Spectrum (DSSS) transceiver deployed in custom hardware like Field Programmble Gate Arrays (FPGAs). The system model consists of a tranmitter which employs a quadrature phase shift keying (QPSK) modulation scheme, an additive white Gaussian noise (AWGN) channel, and a receiver whose main parts consist of an analog-to-digital converter (ADC), digital down converter (DDC), image rejection low-pass filter (LPF), carrier phase locked loop (PLL), tracking locked loop, down-sampler, spread spectrum correlators, and rectangular-to-polar converter. The design methodology is based on a new programming model for FPGAs developed in the industry by Xilinx Inc. The Xilinx System Generator for DSP software tool provides design portability and streamlines system development by enabling engineers to create and validate a system model in Xilinx FPGAs. By providing hierarchical modeling and automatic HDL code generation for programmable devices, designs can be easily verified through hardware-in-the-loop (HIL) simulations. HIL provides a significant increase in simulation speed which allows optimization of the receiver design with respect to the datapath size for different functional parts of the receiver. The parameterized datapath points used in the simulation are ADC resolution, DDC datapath size, LPF datapath size, correlator height, correlator datapath size, and rectangular-to-polar datapath size. These parameters are changed in the software enviornment and tested for bit error rate (BER) performance through real-time hardware simualtions. The final result presents a system design with minimum harware area occupancy relative to an acceptable BER degradation

    Characterization and Design of High-Level VHDL I/Q Frequency Downconverter via Special Sampling Scheme

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    This study explores the characterization and implementation of a Special Sampling Scheme (SSS) for In-Phase and Quad-Phase (I/Q) down conversion utilizing top-level, portable design strategies. The SSS is an under-developed signal sampling methodology that can be used with military and industry receiver systems, specifically, United States Air Force (USAF) video receiver systems. The SSS processes a digital input signal-stream sampled at a specified sampling frequency, and down converts it into In-Phase (I) and Quad-Phase (Q) output signal-streams. Using the theory and application of the SSS, there are three main objectives that will be accomplished: characterization of the effects of input, output, and filter coefficient parameters on the I/Q imbalances using the SSS; development and verification of abstract, top-level VHDL code of the I/Q SSS for hardware implementation; and finally, development, verification, and analysis of variation between synthesizable pipelined and sequential VHDL implementations of the SSS for Field Programmable Gate Arrays (FPGA) and Application Specific Integrated Circuits (ASIC)

    Automatisoitu vuo suodinten laitteistokuvauksen tuottamiseen

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    Digitaalisia suotimia käytetään signaalien käsittelyyn monilla eri tekniikan alueilla, kuten telekommunikaatiossa, kuvankäsittelyssä ja lääketieteellisissä laitteissa. Ne ovat niin yleisiä, että insinöörit käyttävät paljon aikaa ja resursseja niiden toteuttamiseen ja verifioimiseen. Koska yleisimpien suotimien rakenne on melko yksinkertainen, niiden luominen voidaan automatisoida generaattorin avulla. Tässä diplomityössä Nokia Networksin vaatimukset kartoitetaan automatisoidun suodinten laitteistokuvauksen tuottamisvuon kehittämiseksi. Erilaisia tuottamismenetelmiä vertaillaan, mutta lopulta päädytään kehittämään oma generaattori. Se luo suotimia yhdistelemällä osia käsinkirjoitetusta RTL:stä. Lopputuloksena on automatisoitu vuo, joka tukee vakiokertoimilla varustettuja, yhden tai useamman kanavan FIR-suotimia. Käyttäjän tulee syöttää kertoimet ja haluttu datanleveys Matlab-skriptiin. Ajettaessa skripti luo suotimen ja verifioi sen. Vuo tukee sekä ASIC- että FPGA-teknologioita.Digital filters are used to process signals in many fields like telecommunications, image processing and in medical equipment. They are so omnipresent that engineers are building and verifying those all the time, using a lot of resources. As the structure of a basic filter is quite simple, savings could be made by automatizing the creation of filters. In this Thesis the requirements of Nokia Networks are analyzed to build an automatized filter generation flow. Different tools are evaluated, but finally a custom generator is built. It crafts filters from pieces of hand-written RTL. The end result is an automated flow which supports single and multichannel FIR filters with constant coefficients. The user has to input the coefficients to a Matlab script with the desired data widths. The filter is then generated and verified by running the script. The flow supports both ASIC and FPGA technologies
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