Field programmable gate arrays (FPGAs) are an increasingly popular technology for implementing digital signal processing (DSP) systems. By allowing designers to create circuit architectures developed for the specific applications, high levels of performance can be achieved for many DSP applications providing considerable improvements over conventional microprocessor and dedicated DSP processor solutions. The book addresses the key issue in this process specifically, the methods and tools needed for the design, optimization and implementation of DSP systems in programmable FPGA hardware. It presents a review of the leading-edge techniques in this field, analyzing advanced DSP-based design flows for both signal flow graph- (SFG-) based and dataflow-based implementation, system on chip (SoC) aspects, and future trends and challenges for FPGAs. The automation of the techniques for component architectural synthesis, computational models, and the reduction of energy consumption to help improve FPGA performance, are given in detail. Written from a system level design perspective and with a DSP focus, the authors present many practical application examples of complex DSP implementation, involving: high-performance computing e.g. matrix operations such as matrix multiplication; high-speed filtering including finite impulse response (FIR) filters and wave digital filters (WDFs); adaptive filtering e.g. recursive least squares (RLS) filtering; transforms such as the fast Fourier transform (FFT). FPGA-based Implementation of Signal Processing Systems is an important reference for practising engineers and researchers working on the design and development of DSP systems for radio, telecommunication, information, audio-visual and security applications. Senior level electrical and computer engineering graduates taking courses in signal processing or digital signal processing shall also find this volume of interest.

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FPGA-based Implementation of Signal Processing Systems

The availability of an intellectual property core for recursive least squares (RLS) filtering could enable the RLS algorithm to replace the least mean squares algorithm in a wide range of applications. The goal of this study is to develop a parameterizable generic architecture for RLS filtering in the form of a hardware description language (HDL) description, which can be used to generate highly efficient silicon layout. The key issue is to develop a family of circuit architectures that are 100% efficient and locally connected. This paper presents a generic mapping for RLS filtering and circuit architectures that can be mapped to a range of application requirements. It outlines the transition from array to architecture covering detailed design issues such as timing and control generation. The result is a family of QR designs, which are parameterized in terms of architecture size, wordlength, performance, and arithmetic processor timing.

Design of a parameterizable silicon intellectual property core for QR-based RLS filtering

This paper presents the design of a novel single chip adaptive beamformer capable of performing 50 Gflops, (Giga-floating-point operations/second). The core processor is a QR array implemented on a fully efficient linear systolic architecture, derived using a mapping that allows individual processors for boundary and internal cell operations. In addition, the paper highlights a number of rapid design techniques that have been used to realise this system. These include an architecture synthesis tool for quickly developing the circuit architecture and the utilisation of a library of parameterisable silicon intellectual property (IP) cores, to rapidly develop detailed silicon designs.

Linear QR Architecture for a Single Chip Adaptive Beamformer

This paper presents a novel hierarchical approach for pipelining and folding the large CORDIC-based systolic array of a QR decomposition-based recursive least square algorithm (QRD-RLS) adaptive filter to a small fixed size array. With the annihilation-reordering look-ahead transformation, the iteration bound of a QRD-RLS adaptive filter can be reduced linearly with respect to the look-ahead factor. This paper presents, for the first time, how to pipeline and fold such a look-ahead transformed QRD-RLS adaptive filter. Unlike the previously published algorithms, this approach has low complexity and can result in a physical array of any size. In addition, a mathematical model for evaluating these transformations is developed. Using this model, it is shown how a combination of look-ahead, pipelining, and folding transformations can lead to a large increase in throughput and large reduction in area or power consumption. Therefore, the proposed approach is of great significance for application-specific IC chip design, high-level hardware synthesis, and special-purpose processor design. The optimally designed QRD-RLS adaptive filters can be used for adaptive digital beamforming applications, which play an important role in radar, sonar, and mobile/wireless communication systems.

Hierarchical pipelining and folding of QRD-RLS adaptive filters and its application to digital beamforming

This paper presents a novel architecture mapping technique which was essential in the design of a QR array which forms the core processor of a single chip adaptive beamforming system. The mapping technique assigns a QR triangular array of 2m/sup 2/+3m+1 cells down onto a linear architecture of m+1 processors. The mapping results in a linear systolic architecture with one hundred percent hardware utilisation, local interconnects and individual processors for boundary and internal cell operations. In addition, this paper highlights the effect latency has on the validity of the linear architecture.

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Novel mapping of a linear QR architecture

Current rapid synthesis approaches for reusable dedicated hardware components (cores) for digital signal processing systems are ineffective since they fail to capture and exploit the manner in which the resulting components are used as part of a heterogeneous system. This leads to counter-productive core redesign for each use of the core. This paper presents a solution to this issue which combines a novel but intuitive system modeling technique and associated core generation and integration methodology which generates reuable core architectures which may be optimised via algorithm level transformations. For an example design problem, these provide an effective rapid core synthesis and implementation exploration flow which allows a factor 3.9 throughput increase with no extra hardware expense.

Multidimensional DSP Core Synthesis for FPGA

This paper presents the design of a single chip adaptive beamformer which contains 5 million transistors and can perform 50 gigaflops. The core processor of the adaptive beamformer is a QR-array processor implemented on a fully efficient linear systolic architecture. The paper highlights a number of rapid design techniques that have been used to realise the design. These include an architecture synthesis tool for quickly developing the circuit architecture and the utilisation of a library of parameterisable silicon intellectual property (IP) cores, to rapidly develop the circuit layouts.

Rapid design of a single chip adaptive beamformer

A scheduling method for implementing a generic linear QR array processor architecture is presented. This improves on previous work. It also considerably simplifies the derivation of schedules for a folded linear system, where detailed account has to be taken of processor cell latency. The architecture and scheduling derived provide the basis of a generator for the rapid design of System-on-a-Chip (SoC) cores for QR decomposition.

Generic scheduling methods for a linear QR array SoC processor

The design of a generic QR core for adaptive beamforming is presented. The work relies on an existing mapping technique that can be applied to a triangular QR array in such a way to allow the generation of a range of QR architectures. All scheduling of data inputs and retiming to include processor latency has been included within the generic representation.

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R. Walke

Papers

Multidimensional DSP Core Synthesis for FPGA

Rapid design of a single chip adaptive beamformer

Generic scheduling methods for a linear QR array SoC processor

Parameterisable QR core