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Circuits and Systems I: Fundamental Theory and Applications, IEEE Transactions on

Issue 1 • Date Jan. 2003

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Displaying Results 1 - 24 of 24
  • Editorial

    Page(s): 1 - 2
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    Freely Available from IEEE
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  • A VLSI crossbar switch with wrapped wave front arbitration

    Page(s): 135 - 141
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    Crossbar switch is a key component of communication switches used in networks. Allocation of resources has a direct impact on packet transmission. A poor allocation results in long transmission delays. Hence, switches must include an arbiter that efficiently allocates the crossbar's resources. In this brief, a novel VLSI CMOS implementation of a high performance wrapped wave front arbitration (WWFA) for crossbar switches is described. Arbitration time is one of the critical factors that affect network performance. WWFA requires a two-dimensional arbitration that incorporates a rotating priority to provide fair arbitration. In this brief, we describe the design and implementation of this arbiter. The arbiter is capable of performing an arbitration in 1.15 ns using 0.5-μm technology, for a 4 × 4 crossbar. We also include the description of interface and crosspoint (CP) control circuitry, i.e., request-acknowledge circuit and CP controller circuit respectively. View full abstract»

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  • On the applicability of the self-linearization technique for linearizing real PN junction based circuits

    Page(s): 89 - 97
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    New theoretical and experimental results pertaining to the self-linearization phenomenon are presented. The possibility of linearizing the U-I characteristics of a real PN junction by means of only one linear resistance is investigated. The effect of the junction diffusion capacitance is also investigated. A highly accurate approximation for the frequency-dependent coefficients of the first, second, and third harmonics is developed. Dual series and parallel linearizing circuits are theoretically analyzed and experimentally tested. The results show that the third-order and all even-order nonlinearities are suppressed. Measurements of DC U-I characteristics and high-frequency spectra of linearized (to the fifth order) PN junction based circuits of both series and parallel configurations are presented. The linearity is enhanced by a factor exceeding 40 dB. The presented principle and circuits can be applied to both discrete and integrated circuits. At present, this linearization phenomenon seems to be a rather promising method. View full abstract»

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  • Robust Kalman filtering for continuous time-lag systems with Markovian jump parameters

    Page(s): 98 - 105
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    The problem of continuous-time Kalman filtering for a class of linear, uncertain time-lag systems with randomly jumping parameters is considered. The parameter uncertainties are norm bounded and the transitions of the jumping parameters are governed by a finite-state Markov process. We establish LMI-based sufficient conditions for stochastic stability. The conditions under which a linear delay-less state estimator guarantees that the estimation error covariance lies within a prescribed bound for all admissible uncertainties are investigated. It is established that a robust Kalman filter algorithm can be determined in terms of two Riccati equations involving scalar parameters. The developed theory is illustrated by a numerical example. View full abstract»

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  • Nonconcurrent error detection and correction in fault-tolerant discrete-time LTI dynamic systems

    Page(s): 45 - 55
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    This paper develops resource-efficient alternatives to modular redundancy for fault-tolerant discrete-time (DT) linear time-invariant (LTI) dynamic systems. The proposed method extends previous approaches that are based on embedding the state of a given DT LTI dynamic system into the redundant state-space of a DT LTI dynamic system of higher state dimension. These embeddings, as well as the embeddings studied in this paper, preserve the state evolution of the original system in some linearly encoded form and allow error detection and correction to be performed through concurrent parity checks (i.e., parity checks that are evaluated at the end of each time step). The novelty of the approach developed in this paper relies on carefully choosing the redundant dynamics of the fault-tolerant implementation in a way that allows parity checks to capture the evolution of errors in the system and, based on nonconcurrent parity checks (e.g., parity checks that are evaluated periodically), uniquely determine the initial value of each error, the time step at which it took place and the state variable it originally affected. The resulting error detection, identification, and correction procedures can be performed periodically and can significantly reduce the overhead, complexity and reliability requirements on the checking mechanism. View full abstract»

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  • Finding all solutions of piecewise-linear resistive circuits using the simplex method

    Page(s): 160 - 165
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    Recently, an efficient algorithm was proposed for finding all solutions of piecewise-linear (PWL) resistive circuits using the simplex method, which could solve a problem where the number of PWL resistors is 200 and the number of linear regions is 10200. In this work, an improved version of this algorithm is proposed, which can be applied to a broader class of PWL resistive circuits and could solve problems where the number of PWL resistors is 500 and the number of linear regions is 10500 in practical computation time. View full abstract»

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  • A note on the stability of linear time-delay systems with impulsive inputs

    Page(s): 149 - 152
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    This brief derives sufficiency-type stability results for time-delay linear systems with constant point delays under impulsive inputs of impulses of state-dependent amplitudes occurring separately through time. It is proved that the amplitudes of the impulses and the time intervals between impulses may be chosen sufficiently large if the delay-free dynamics is sufficiently stable compared to the delayed one. It is also seen that faster input impulses of appropriate amplitudes and signs may achieve stabilization if the delay-free dynamics is not exponentially stable. View full abstract»

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  • Pseudorandom bits generated by chaotic maps

    Page(s): 123 - 126
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    Different possibilities of using chaotic maps as pseudorandom number generators are discussed. A class of chaos-based pseudorandom bit generators is constructed. We give simple arguments to explain the unpredictability of the generators. View full abstract»

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  • Wavelet-based texture analysis and synthesis using hidden Markov models

    Page(s): 106 - 120
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    Wavelet-domain hidden Markov models (HMMs), in particular, hidden Markov tree (HMT), were recently proposed and applied to image processing, where it was usually assumed that three subbands of the two-dimensional discrete wavelet transform (DWT), i.e., HL, LH, and HH, are independent. In this paper, we study wavelet-based texture analysis and synthesis using HMMs. Particularly, we develop a new HMM, called HMT-3S, for statistical texture characterization in the wavelet domain. In addition to the joint statistics captured by HMT, the new HMT-3S can also exploit the cross correlation across DWT subbands. Meanwhile, HMT-3S can be characterized by using the graphical grouping technique, and has the same tree structure as HMT. The proposed HMT-3S is applied to texture analysis, including classification and segmentation, and texture synthesis with improved performance over HMT. Specifically, for texture classification, we study four wavelet-based methods, and experimental results show that HMT-3S provides the highest percentage of correct classification of over 95% upon a set of 55 Brodatz textures. For texture segmentation, we demonstrate that more accurate texture characterization from HMT-3S allows the significant improvements in terms of both classification accuracy and boundary localization. For texture synthesis, we develop an iterative maximum likelihood-based texture synthesis algorithm which adopts HMT or HMT-3S to impose the joint statistics of the texture DWT, and it is shown that the new RMT-3S enables more visually similar results than HMT does. View full abstract»

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  • Pseudoresistive networks and the pseudovoltage-based cocontent

    Page(s): 56 - 64
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    Using the concept of a transistor as a pseudoresistor, many resistive networks can be mapped to transistor based equivalents. Pseudoresistors are two-terminal circuit elements whose current is a function of the instantaneous difference in the pseudovoltage across the two terminals, where the pseudovoltage is a nonlinear function of the voltage at each terminal. A transistor with fixed gate and bulk voltages is a linear pseudoresistor between the drain and source over a wide range of currents including strong and weak inversion. Motivated by this, we extend the cocontent, defined for two-terminal resistors, to the pseudovoltage-based (PVB) cocontent, defined for two terminal pseudoresistors. We show that the PVB cocontent has similar properties as the cocontent in characterizing the DC-operating points of transistor networks and their stability, but under more restrictive conditions. As examples, we derive the total PVB cocontent for several neuromorphic circuit networks including the diffuser grid, a linear pseudoresistive network, and the winner-take-all circuit of Lazzaro, a nonlinear pseudoresistive network. This work establishes that these circuits can be viewed in terms of function minimization, which may lead to better intuition about their operation as well as the development of new circuit architectures. View full abstract»

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  • Adaptive control of a class of 2-D discrete systems

    Page(s): 166 - 172
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    In the past two decades, research on systems involving more than one independent variable, such as two-dimensional (2-D) systems, has received great attentions. Adaptive control is an effective way of controlling unknown dynamical systems. While many research results on one-dimensional adaptive control are available, little has been accomplished in the area of 2-D system theory. The main reason is due primarily to the difficult algebra of 2-D systems and the complexity of the underlying theory. In this work, we propose an indirect adaptive controller for single-input-single-output 2-D discrete systems. Analysis shows that the designed adaptive controller that consists of a parameter estimator and a linear controller can stabilize the given class of 2-D systems. View full abstract»

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  • A two-stage dynamic-based narrowband interference cancellation technique and its application to power-line communications

    Page(s): 127 - 134
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    The problem of narrowband interference cancellation (NBIC) in chaos communication systems is investigated here. A novel two-stage NBIC algorithm based on a dynamic-based estimator called the minimum phase space volume technique is proposed. This two-stage NBIC algorithm can be applied to different kinds of chaos communication systems. In particular, two representative categories of chaos communication systems, namely, differential chaos shift keying and chaotic parameter modulation are considered here for the NBIC investigation. It is shown that the proposed two-stage NBIC algorithm is effective for both chaos communication systems. In addition, chaos based communication systems are found to have improved interference suppression capability with respect to the conventional statistic-based spread spectrum (SS) system. The proposed two-stage dynamic-based NBIC technique is applied to suppress NBI when the chaos modulation techniques are applied in power-line communications. View full abstract»

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  • A property of Jacobian matrices and some of its consequences

    Page(s): 153 - 155
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    It is proved that the multidimensional differential operator is an annihilator of the adjoint matrix associated with a Jacobian matrix. Some of the consequences of this result to other distinguished matrices are pointed out and its relevance in the derivation of a multidimensional wave digital filter structure from a passive multidimensional Kirchhoff network is confirmed. View full abstract»

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  • A genetic algorithm approach to the problem of factorization of general multidimensional polynomials

    Page(s): 16 - 22
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    In this paper, a solution to the problem of the multidimensional (m-D) polynomial factorization is attempted by using genetic algorithms (GAs). The proposed method is based on an appropriate minimization of the norm of the difference between the original polynomial and its desirable factorized form. Using GAs, we can obtain better results than with other methods of minimization (numerical techniques, neural networks, etc.). The present methodology, which can also be used for every type of m-D factorization, is illustrated by means of a numerical example. View full abstract»

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  • A simple strategy for optimized design of one-level carry-skip adders

    Page(s): 141 - 148
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    In this brief, a novel strategy to design carry-skip adders is proposed. It allows to distribute bits into groups to achieve minimum delay, and consists of two steps. The first is a preliminary analytical sizing based on timing considerations, the second is a successive refinement to achieve the desired number of bits. The strategy is simple, systematic and general, thus, it is helpful to design in a pencil-and-paper approach, as well as providing an in-depth understanding of the optimum group sizing. Moreover, it allows to analytically estimate the minimum delay achievable before carrying out the design. The strategy proposed has been validated by applying it to the design of more than 50 adders, varying delay of logic gates used and number of bits. Analysis confirms that the strategy provides minimum delay in practical cases. View full abstract»

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  • Differential and linear probabilities of a block-encryption cipher

    Page(s): 121 - 123
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    We establish that the block-encryption algorithm proposed recently by Jakimoski and Kocarev (see ibid., vol.48, no.2, p.163-169, 2001) is secure against differential and linear attacks. View full abstract»

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  • Small-signal model of PWM converters for discontinuous conduction mode and its application for boost converter

    Page(s): 65 - 73
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    A small-signal circuit model for pulsewidth-modulated DC-DC converters operated in discontinuous conduction mode is presented. The model is composed of controlled current sources, an independent voltage source and resistances. The principle of energy conservation approach is used to take into account parasitic resistances of the transistor and diode and the diode threshold voltage. The proposed model is suitable for small-signal, frequency-domain representation of the converters. This model is used to derive the expressions for a boost converter control-to-output transfer function, input-to-output voltage transfer function, input impedance and the output impedance. Bode plots are also given for these transfer functions. The predicted and experimental results were in excellent agreement. View full abstract»

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  • Spectral properties of chaos-based FM signals: theory and simulation results

    Page(s): 3 - 15
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    This paper addresses the problem of generating constant-envelope wideband (CEW) signals, for which applications are emerging both in telecommunications (as information carriers) and in digital/power electronics (to aid the synthesis of timing signals which favor electromagnetic compliance). A flexible generation technique consists in driving a frequency modulation (FM) modulator with random or chaotic sequences. Mathematical tools for predicting some spectral properties of random-FM and chaotic-FM CEW signals are herein introduced by commenting on recent results and presenting novel ones in a coherent framework. View full abstract»

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  • Passivity analysis for dynamic multilayer neuro identifier

    Page(s): 173 - 178
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    In this work, dynamic multilayer neural networks are used for nonlinear system online identification. The passivity approach is applied to access several stability properties of the neuro identifier. The conditions for passivity, stability, asymptotic stability, and input-to-state stability are established. We conclude that the commonly-used backpropagation algorithm with a modification term which is determined by offline learning may make the neuro identification algorithm robustly stable with respect to any bounded uncertainty. View full abstract»

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  • A technique for dynamic CMOS noise immunity evaluation

    Page(s): 74 - 88
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    While dynamic CMOS logic is considered an attractive circuit technique, it suffers from noise problems. Noise may affect dynamic CMOS circuits in many ways. In this paper, new models have been developed that consider a noise pulse on one of the circuit inputs or on the clock input. These models specify the circuit noise immunity in terms of both the amplitude and the duration of a noise pulse. HSPICE simulations confirm the validity of these models for both long and short-channel MOSFETs. As dynamic circuits are designed around the constraint of noise, the models presented here clearly indicate parameters that affect noise and their influence, and how it could aid digital circuit designs. View full abstract»

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  • Global asymptotic stability of a general class of recurrent neural networks with time-varying delays

    Page(s): 34 - 44
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    In this paper, the existence and uniqueness of the equilibrium point and its global asymptotic stability are discussed for a general class of recurrent neural networks with time-varying delays and Lipschitz continuous activation functions. The neural network model considered includes the delayed Hopfield neural networks, bidirectional associative memory networks, and delayed cellular neural networks as its special cases. Several new sufficient conditions for ascertaining the existence, uniqueness, and global asymptotic stability of the equilibrium point of such recurrent neural networks are obtained by using the theory of topological degree and properties of nonsingular M-matrix, and constructing suitable Lyapunov functionals. The new criteria do not require the activation functions to be differentiable, bounded or monotone nondecreasing and the connection weight matrices to be symmetric. Some stability results from previous works are extended and improved. Two illustrative examples are given to demonstrate the effectiveness of the obtained results. View full abstract»

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  • Global robust stability of delayed neural networks

    Page(s): 156 - 160
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    This work presents a sufficient condition for the existence, uniqueness, and global robust stability of the equilibrium point for Hopfield-type delayed neural networks. The result imposes constraint conditions on the boundary values of the network parameters independently of the delay parameter. This result is compared with the previous results derived in the literature. View full abstract»

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  • Roundoff noise minimization of state-space digital filters using separate and joint error feedback/coordinate transformation optimization

    Page(s): 23 - 33
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    This paper investigates the problem of minimizing roundoff noise under l2-norm dynamic-range scaling constraints in state-space digital fibers by means of error feedback as well as joint error feedback/coordinate transformation optimization. First, several techniques, for the determination of optimal full-scale, diagonal, and scalar error-feedback matrices for a given state-space digital filter are proposed, where three realization schemes, namely, the general state-space realization, input-balanced realization, and optimal realization in the sense of Hwang-Mullis-Roberts are examined. Furthermore, an iterative approach is developed for jointly optimizing a scalar error-feedback matrix and a coordinate transformation matrix so as to minimize the roundoff noise subject to the l2-norm dynamic-range scaling constraints. The proposed method may be regarded as an alternative, but much simpler and more general, approach to Hwang's method for synthesizing the optimal filter structure with minimum roundoff noise. A case study is included to illustrate the utility of the proposed techniques. View full abstract»

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