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Circuits and Systems, 1991., IEEE International Sympoisum on

Date 11-14 June 1991

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  • 1991 IEEE International Sympoisum on Circuits and Systems (Cat. No.91CH3006-4)

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    Freely Available from IEEE
  • On SVD for estimating generalized eigenvalues of singular matrix pencil in noise

    Page(s): 2780 - 2783 vol.5
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    Several algorithms for estimating generalized eigenvalues (GEs) of singular matrix pencils perturbed by noise are reviewed. The singular value decomposition (SVD) is explored as the common structure in three basic algorithms: direct matrix pencil algorithm, Pro-ESPRIT, and TLS-ESPRIT. It is shown that several SVD-based steps inherent in those algorithms are equivalent to the first-order approximation. Also, Pro-ESPRIT and TLS-Pro-ESPRIT are shown to be equivalent, and TLS-ESPRIT and LS-ESPRIT are shown to be asymptotically equivalent to the first-order approximation. For the problem of estimating superimposed complex exponential signals, the state space algorithm is shown to be also equivalent to the previous matrix pencil algorithms to the first-order approximation. The threshold phenomenon is illustrated by a simulation result based on a damped sinusoidal signal. An improved state space algorithm is found to be the most robust to noise.<> View full abstract»

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  • A neural network approach for solving integral equations

    Page(s): 1416 - 1419 vol.3
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    A strategy for solving integral equations using a Hopfield-type network is presented. The major advantage of this strategy is the guaranteed convergence to the globally optimum solution ensured by the causality property of the network and the continuous nature of the feedback to each node. The algorithm consists of deriving the two function minimization equations, one for the energy function of the network and the other for the least squares solution of the discretized integral equation with regularization conditions. By comparing similar terms of the two equations, the circuit parameters of the network are estimated. The network is then simulated to obtain the solution of the integral equation. Initial simulation results are presented View full abstract»

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  • High frequency active compensation of integrators using CCII and their stability analysis

    Page(s): 1432 - 1435 vol.3
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    A novel scheme for a noninverting integrator is presented. A complete analysis of the circuits is provided for both their performance and their stability. The stability analysis shows that the basic circuits are unstable. Modifications to stabilize these circuits are suggested View full abstract»

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  • An efficient adaptive cascade IIR filter

    Page(s): 444 - 447 vol.1
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    Adaptive cascade IIR (infinite impulse response) filters which have an easy stability check and low parameter sensitivities are studied. A novel concept is proposed which suggests backpropagating the desired signal through the inverse all-pole second-order sections and producing intermediate errors to be minimized. This concept is applied to a cascade IIR structure, resulting in an efficient adaptive cascade IIR filter. It is shown that the equation-error formulation is just a special case of backpropagation of the desired signal View full abstract»

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  • Symbolic analysis of mixed continuous and sampled-data systems

    Page(s): 798 - 801 vol.2
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    A computer program capable of generating the input-output relationship in a symbolic form between the initial node and the last node of the signal flow graph representing a given block diagram of mixed continuous and sampled-data systems is presented. The system is given as an interconnection of continuous and discrete subsystems and synchronous samplers. The computer program can generate the transfer function H(z) if both the input and output are sampled, or an expression for the continuous output if the input is not sampled View full abstract»

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  • LDI z-domain images of lossless LC ladders

    Page(s): 144 - 147 vol.1
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    Discrete-time images of lossless LC one-port ladder networks are presented. Such images are obtained by expanding discrete-time reactance functions into continued fractions to obtain the discrete-time counterparts of Cauer-1, Cauer-2, and mixed-Cauer expansions. The existence of these expansions is proven and a methodology for synthesis of these expansions is given similar to the one known for synthesis of the continuous-time reactance function. The type of reactance functions used is related to the continuous-time counterpart by the lossless discrete integrator (LDI) s-to-z transform. Simple first and second order discrete-time reactance networks are proposed and used in a step-by-step procedure to realize higher-order networks. The resulting discrete networks are considered images of LC one-port ladders in the z-domain View full abstract»

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  • Complex wave digital ladder filters using complex port references

    Page(s): 2447 - 2450 vol.5
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    Complex wave digital ladder filters are realized using a generalization, to the complex domain, of voltage wave digital filters. The port references are now allowed to be complex and all of the familiar wave digital concepts are preserved. The filters realized do not require the property of one-realness. Necessary complex wave digital equivalents are derived for both the dynamic and nondynamic one-ports, as well as for the nondynamic two-ports. The complex 3-port series and parallel adaptors are derived and the scattering matrix of the reflection-free 3-port series adaptor is found to be identical to the real case. Ladder filters are realized using complex reference networks that contain general reciprocal first-order sections. Realizations composed exclusively of inductors (complex parallel adaptors) or capacitors (complex series adaptors) are possible. An illustrative example is also given View full abstract»

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  • Solution of ill-conditioned load flow equation by homotopy continuation method

    Page(s): 2897 - 2899 vol.5
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    A homotopy continuation method is used to solve ill-conditioned load flow equations. It presents the predictor step effective for following the path of homotopy functions formulated from the load flow equation. The aim is to solve the ill-conditioned load flow equation, the solution of which has long been discussed. Using the homotopy method described, it is concluded that the ill-conditioned load flow equation discussed has no solution View full abstract»

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  • Hierarchical symbolic analysis of large-scale systems using a Mason's signal flow graph model

    Page(s): 802 - 805 vol.2
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    The author presents an approach to the symbolic analysis of large-scale systems. The method depends on the partitioning of the system into smaller subsystems which are then symbolically analyzed individually and non-iteratively using Mason's signal flow graph models of these smaller subsystems. The resulting solutions which are reduced signal flow graphs (transfer functions) for the subsystems are then hierarchically combined to produce the final solution or solutions (transfer functions) for the whole system. The advantage of such an approach is the tremendous reduction in the number of symbolic terms compared to the conventional approaches that can only handle very small circuits. The result of the analysis is a series of equations that have an upward hierarchical dependency on each other View full abstract»

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  • Neural networks for direction finding via a stochastic model

    Page(s): 2546 - 2549 vol.5
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    A neural network approach is presented for finding the approximate maximum likelihood estimates of the direction-of-arrival (DOA) of plane waves. Based on the model of the maximum likelihood (ML) estimator, the direction finding problem is mapped onto the Lyapunov energy function of the Hopfield model neural network. To make the network converge to a valid solution at a low SNR value, the information of source numbers is also constrained in the network's energy function. Simulation results are presented to illustrate the improved performance achieved by this new approach View full abstract»

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  • The imbedding-based methods: computing the zeros of models of power systems

    Page(s): 868 - 871 vol.2
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    The authors develop an imbedding-based method to reduce the computational complexity in finding all or some of the zeros of the so-called deficient systems, with particular focus on power systems. This method reduces considerably the computational effort required in the existing homotopy continuation methods and allows for the computation of only some of the zeros if desired. The method is particularly efficient in the case of re-computing zeros of systems having the same topology but with different parameter values. This reduction in computational effort allows the method to compute some or all of the zeros of large-sized power systems. The method is implementable directly on digital sequential and parallel processors View full abstract»

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  • Analysis and design of regular structures for robust dynamic fault testability

    Page(s): 1968 - 1971 vol.4
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    The authors analyze various regular structures such as adders, arithmetic logic units, comparators, multipliers, and parity generators to determine if they are testable for dynamic faults, or how they can be modified to be testable for dynamic faults while still maintaining good area and performance characteristics. In addition to minimizing the area and delay, another key consideration is to get designs which can be scaled to an arbitrary number of bits while still maintaining complete testability. In each case, the emphasis is on obtaining circuits which are fully path-delay-fault testable. In the process of design modification to produce fully robustly testable structures, the authors derive a number of new composition rules that allow cascading individual modules while maintaining robust testability under dynamic fault models. Where complete robust path-delay-fault testability is not achievable without significant area or speed penalties, methods of obtaining circuits that are fully testable in weaker fault models, such as transistor stuck-open-fault and robust gate-delay-fault, are analyzed View full abstract»

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  • FIR filter design using quadratic programming

    Page(s): 148 - 151 vol.1
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    The optimum design of FIR (finite impulse response) filters is formulated as a quadratic program. An algorithm is described for the efficient use of computer memory and for guaranteed convergence to the solution of the original problem. Examples illustrating the design of decimation filters for sigma-delta A/D converters using the new technique are also presented. The quadratic programming approach is more flexible and often yields better results than the previously reported least-squares design approaches View full abstract»

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  • Limit cycles in periodically switched circuits

    Page(s): 1073 - 1076 vol.2
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    Examines the existence, uniqueness, and stability of limit cycles in periodically switched circuits, such as those used in power electronic and power conditioning applications. The main results relate the existence and uniqueness of limit cycles in these switched circuits to the analogous properties of equilibrium points in nonswitched averaged models for these circuits. The results are applicable to two types of circuits. First, the author considers circuits built from incrementally passive (or locally passive) elements including DC sources and ideal switches in which the switches are operated periodically in an open-loop manner. Second, the author introduces an averaging procedure based on the describing function method. This procedure is then used to study limit cycle stability in closed-loop DC-DC converters View full abstract»

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  • Implementation of `multiply-add' FFT algorithms for complex and real data sequences

    Page(s): 480 - 483 vol.1
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    Multiply-add FFT algorithms are FFT algorithms that take advantage of computer architectures with a multiply-add feature. Various FFT algorithms can be implemented on this type of architecture to give the multiplications for free. In the present work, some of these FFT algorithms are reviewed: the split-radix FFT algorithm for 2k transform sizes, the multiplicative algorithms for prime transform sizes, and the prime factor algorithm for transform sizes with relatively prime factors. Both complex and real data sequences are considered, and operational counts are evaluated in terms of total floating-point operations. Tensor product formulation is used throughout for producing variants of algorithms matching to computer architecture View full abstract»

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  • A neural network using oscillators

    Page(s): 782 - 785 vol.2
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    The authors propose the oscillator neural network, in which the sigmoid nonlinearity of the Hopfield neural network is replaced by the Van der Pol oscillator. The oscillator neural network has the advantage that no simulated annealing is necessary to obtain a reasonable solution. They demonstrate that the 4-b analog to digital (A/D) converter problem, the 10-city traveling salesman problem and the associative memory problem, can be solved by the proposed neural network View full abstract»

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  • Adaptive recursive filtering using a conjugate directions algorithm

    Page(s): 436 - 439 vol.1
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    The authors discuss the application of a conjugate gradient algorithm for solving the adaptive recursive filtering problem. This algorithm, based on the technique of classical conjugate direction optimization, is shown to provide superior convergence compared to the stochastic gradient techniques. Algorithms are developed for direct form and lattice form implementations. Examples are provided to illustrate the performance of the method View full abstract»

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  • Vector quantization using matrix decompositions of codebooks for image coding

    Page(s): 308 - 311 vol.1
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    Methods of using vector quantization combined with singular value decomposition (SVD) and simplified least square estimation (LSE) compensation are proposed. The complexity of computation is decreased by determining a simpler scheme to obtain the same optimal estimated singular values as the LSE. With the assistance of the matrix-decomposed codebooks, edge degradation and compression rate can be improved by using a few least-square-compensated singular values. Avoiding the high computational complexity of SVD during the encoding and decoding procedures and achieving good quality of image coding are the main contributions of the present work View full abstract»

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  • Cross-coupled GaAs MESFET-based circuits for potential MMIC applications

    Page(s): 1853 - 1856 vol.3
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    GaAs MMIC design techniques and technology can only be accepted if adequate circuit performance is obtained, including wide bandwidth and good linearity. It is shown that the cross-coupled MESFET pair can be viewed in a rather general way with the advantage that it facilitates implementation of a whole range of interesting linear circuit building blocks, potentially useful for MMIC applications, including linearized amplifiers, signal splitters, signal combiners, circulators and tunable filters View full abstract»

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  • An efficient SPICE model for lossy and dispersive coupled transmission lines

    Page(s): 2713 - 2716 vol.5
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    A simple circuit model for the time domain study of multiconductor transmission lines with CAD standard software such as SPICE is presented. The model consists of a group of decoupling networks, implemented with dependent voltage and current sources, which are obtained from a nodal analysis in the frequency domain and decoupled dispersive lines. These lines are modeled with ordinary lossless TEM lines and analog filters, which are designed to have the required propagation characteristics View full abstract»

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  • Symbolic approximation strategies and the symbolic analysis of large and nonlinear circuits

    Page(s): 806 - 809 vol.2
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    The authors give an overview of some recent developments in the field of symbolic analysis of analog integrated circuits. The importance of approximation (or simplification) of thesymbolic expressions is indicated, and an efficient and reliable approximation algorithm is presented. A method is described for the symbolic analysis of harmonic distortion in weakly nonlinear circuits, both for single-input and multiple-input circuits. Also, methods are suggested for the hierarchical symbolic analysis and approximation of large circuits. Finally, for efficiency comparisons, the concept of a set of benchmark circuits is proposed View full abstract»

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  • Error bounds of piecewise-linear approximation

    Page(s): 2881 - 2884 vol.5
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    A description is given of upper bounds on the error caused by piecewise-linear approximation of a nonlinear element T in a feedback loop, where T represents a nonlinear operator whose domain is the set of the z-transform of the sampled sequences. Let W' (z) be the solution of W' (z)=X (z)+H (z) T' [W' (z)] which approximates the exact input-output relation W (z)=X (z)+H (z) T [W (z)]. In order to discuss an upper bound on the norm of the approximation error || W' (z)-W (z) ||, the generalized parametric norm of an operator is proposed. The obtained upper bound is sufficiently small compared with a bound by the conventional norm in many cases View full abstract»

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  • A feedforward technique for wideband amplifier design

    Page(s): 2550 - 2552 vol.5
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    A method to stabilize feedback amplifiers is presented. The phase shift of the amplifier is modified for stability using a simple feedforward amplifier. The procedure used to define the design parameters of the feedforward amplifier is given. It is shown that the amplifier can be stabilized with a bandwidth close to its uncompensated bandwidth View full abstract»

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  • Construction of Lyapunov functions for a class of nonlinear dynamical systems

    Page(s): 872 - 875 vol.2
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    A problem of constructing Lyapunov functions for nonlinear dynamical systems is considered. A method to construct the Lyapunov function via the construction of a polytope is proposed. The requirement that the polytope be balanced, which was assumed in previous analyses, is removed. This improvement reduces the conservatism in the stability analysis of nonlinear systems. An algorithm to construct a polytope is proposed. The authors give an example to demonstrate the usefulness of the result View full abstract»

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