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

Issue 6 • Date Jun 2000

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Displaying Results 1 - 24 of 24
  • Time domain sensitivity of linear circuits using sampled data simulation

    Publication Year: 2000 , Page(s): 948 - 957
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    This paper presents a new method for computation of time-domain sensitivity of linear networks. It is based on sampled data simulation (SDSIM) of linear circuits presented by Opal (1996). The method is accurate because no approximation is made, and efficient because some parts of the computations are performed only once, in a preprocessing step before simulation starts. Both sensitivity network and adjoint network approaches are discussed View full abstract»

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  • A recurrent neural network for online design of robust optimal filters

    Publication Year: 2000 , Page(s): 921 - 926
    Cited by:  Papers (2)
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    A recurrent neural network is developed for robust optimal filter design. The purpose is to fill the gap between the real-time computation requirement in practice and the computational complexity of the filter design in the case that the statistical properties of noise are unknown. First, an H requirement and an L2 requirement of the filter design problem are formulated as a group of linear matrix inequalities. On this basis, an optimization problem is introduced to solve the robust optimal filter design problem. Then, a recurrent neural network is deliberately developed for solving the optimization problem in real time. The effectiveness and efficiency of the recurrent neural network is shown by use of theoretical and simulation results View full abstract»

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  • A study of synchronization in chaotic autonomous Cuk DC/DC converters

    Publication Year: 2000 , Page(s): 913 - 918
    Cited by:  Papers (3)
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    The synchronization property of chaotic free-running dc/dc converters is studied in this paper The system under study consists of two Cuk converters operating under free-running current-mode control, with two converters connected in the well-known drive-response configuration similar to that studied by Pecora and Carroll. This paper studies, in particular, the synchronization property of the system when a capacitor voltage is chosen as the driving signal. The study includes the derivation of the describing differential equations and the calculation of the conditional Lyapunov exponents (CLE's) of the synchronizing system based on the differential equations. It is found that all the CLE's are negative for certain chosen parameters and, hence, synchronization is possible in this system. Exact computer simulations have been performed to verify the synchronization of the described circuits operating in the chaotic regime. With the drive-response system connected, synchronization is demonstrated using both exact time-domain simulations and PSPICE simulations. This paper reports for the first time the synchronization phenomenon in power electronic converters View full abstract»

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  • Novel CMOS current feedback op-amp realization suitable for high frequency applications

    Publication Year: 2000 , Page(s): 918 - 921
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (116 KB)  

    A novel CMOS current feedback operational amplifier (CFOA) is developed for wideband current-mode signal processing. The circuit has a very low input impedance over an exceptionally wide bandwidth and realizes an exact voltage-following action. Simulation results assuming 0.5 μm CMOS process shows that the impedance at the current input node is about 2 Ω and current and voltage transfer characteristics extend beyond 180 MHz View full abstract»

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  • Signal flow graph analysis of feedback amplifiers

    Publication Year: 2000 , Page(s): 926 - 933
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB)  

    A systematic way of transcribing the schematic of an integrated circuit into its signal flow graph (SFG) equivalent is presented. With this SFG, transfer functions, loop gains, and input and output impedances are readily computed. The analysis is valid for multiloop amplifiers and the computation of a three-stage amplifier with nested Miller compensation is presented to illustrate the robustness of the method. Two theorems of SFG relating the stability of networks are also derived View full abstract»

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  • On Lyapunov stability and normal forms of nonlinear systems with a nonsemisimple critical mode. II. Imaginary eigenvalues pair

    Publication Year: 2000 , Page(s): 850 - 859
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB)  

    For pt. I see ibid., vol. 47, no. 6 (June 2000). This paper studies nonlinear systems associated with or linked to a nonsemisimple (NSS) pair of imaginary eigenvalues. Stability criteria and Poincare normal forms (PNF's) are derived via explicit construction of Lyapunov functions. It is a counterpart and continuation of Part I, which considered the case with an NSS zero eigenvalue. While originating from stability analysis for a nonsemisimple critical mode, the development extends to coexisting (semi-) simple critical modes and to stable modes, as in Part I. The present NSS imaginary pairs (NSSIP) case is shown to possess certain characteristics common to NSS zero (NSSZ), such as the nonlinear lag and the staircase structure, but retains its own identities as well. These include the less surprising, the submodular variable-pair circles which emerge from the units of the potential generator and the more remarkable stricter specification in the dynamics, which is possibly attributable to the inherited conjugacy. An elementary partial differential equation traversing the development shows potential for nontrivial generalization View full abstract»

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  • Variable dimension Newton-Raphson method

    Publication Year: 2000 , Page(s): 809 - 817
    Cited by:  Papers (1)
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    The classical Newton-Raphson method is generalized to solve nonsquare and nonlinear problems of size m×n with m⩽n. Using this generalized Newton-Raphson method as a core, a new variable dimension Newton-Raphson (VDNR) method is developed. The VDNR method is verified to have a better convergence property than the classical Newton-Raphson method by benchmark testing View full abstract»

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  • Practical design of element simulation type SC filters

    Publication Year: 2000 , Page(s): 934 - 940
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (416 KB)  

    Results of theoretical and experimental investigations of the element simulation type switched-capacitor (SC) filters based on Lee-Chang imitators are discussed. The main characteristics of the filters, including frequency response, noise, and nonlinear distortion, are under consideration. Practically oriented methods for estimation of the noise and harmonics are proposed. The application of these methods is illustrated by examples of low-pass and bandpass SC-filter design View full abstract»

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  • A new sufficient condition for complete stability of cellular neural networks with delay

    Publication Year: 2000 , Page(s): 793 - 799
    Cited by:  Papers (60)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB)  

    This paper gives a new sufficient condition for cellular neural networks with delay (DCNNs) to be completely stable. A fixed-point theorem and a convergence theorem of the Gauss-Seidel method play important roles in the proof, while most conventional stability criteria were obtained by constructing Lyapunov functionals View full abstract»

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  • High efficiency PWM zero-voltage-transition boost converter: AC small signal analysis

    Publication Year: 2000 , Page(s): 860 - 867
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (244 KB)  

    A dc-dc boost converter operating under zero-voltage-transition conditions is presented. Its excellent performance deserves a detailed analysis. An equivalent circuit is derived in order to characterize the switching sequence. It contains an equivalent current source and an equivalent voltage source whose nonlinear functions take different forms for each switching topology. The small-signal open-loop and closed-loop transfer functions, including the audio susceptibility are derived. Design-oriented stability criteria are formulated. The theoretical time-domain response and Bode characteristics are checked by experiments or PSPICE simulation View full abstract»

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  • Analysis and design of power efficient class D amplifier output stages

    Publication Year: 2000 , Page(s): 897 - 902
    Cited by:  Papers (56)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (336 KB)  

    A Class D amplifier comprises a pulse width modulator and an output stage. In this paper we analyze the power dissipation mechanisms and derive the overall power efficiency of the output stage realized using the finger and waffle layouts. We compare the relative merits of these layouts; we propose two design methodologies to determine the aspect ratios of the transistors in the output stage for optimum power efficiency (optimum for a given fabrication process, supply voltage and load resistance): (1) optimization to a single modulation index point and (2) optimization to a range of modulation indexes. For the design of an output stage with optimum power efficiency (and small IC area), we recommend optimization to a range of modulation indexes and a layout realized by the waffle structure. The theoretical analysis and derivations are verified on the basis of computer simulations and measurements on fabricated prototype ICs View full abstract»

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  • A digital implementation of a frequency steered phase locked loop

    Publication Year: 2000 , Page(s): 818 - 824
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (120 KB)  

    A digital implementation of a new technique that delivers an extremely accurate and stable phase locked loop system (PLL) is presented. The new technique uses competing phase and frequency loops to incorporate an accurate local reference frequency into the phase locked loop structure. Disturbances on the phase loop caused by the digital frequency loop are identified and a method to mitigate the disturbances is developed. The implementation is primarily designed for high-speed clock and data recovery and experimental results from a clock recovery system for nonreturn to zero data streams at 155.52 MHz are presented View full abstract»

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  • On Lyapunov stability and normal forms of nonlinear systems with a nonsemisimple critical mode. I. Zero eigenvalue

    Publication Year: 2000 , Page(s): 838 - 849
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (336 KB)  

    This work evolved from an endeavor to derive stability criteria and Poincare normal forms for nonlinear systems associated with a nonsemisimple zero (in Part I) or a pair of imaginary eigenvalues (in Part II). The stability criteria are given in terms of the noninteracting vector restoring and restraining forces, which are motivated from the Lienard equation for nonlinear mass-damper-spring system models. Lyapunov functions are constructed explicitly to fulfill the La Salle invariant principle for local or global stability assertion. It turned out that the Lyapunov functions thus constructed apply to a wide variety of linear stability scenarios. By introducing the notions of restoring and restraining forces, how the Lyapunov functions, the stability criteria and the system dynamics interplay are also exhibited. Two distinct classes of nonlinearities which we referred to as being arithmetical and transcendental, emerged. In some sense, such systems carry nonlinear lags coexisting with the linear lead. In particular, a characteristic of the nonlinear dynamics, a staircase structure, is discovered. Further extension is also made to incorporate nondestabilizing perturbation, which bears important bifurcational implications View full abstract»

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  • General transformation for block diagonalization of weakly coupled linear systems composed of N-subsystems

    Publication Year: 2000 , Page(s): 909 - 912
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (112 KB)  

    A transformation is introduced for exact decomposition (block-diagonalization) of linear weakly coupled systems composed of N subsystems. This transformation can also be used for block diagonalization of block-diagonally dominant matrices and, under certain assumptions, it can be applied for block diagonalization of nearly completely decomposable Markov chains. A twelfth-order real-world power system example is included to demonstrate the efficiency of the proposed method View full abstract»

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  • The circle criterion and almost periodic inputs

    Publication Year: 2000 , Page(s): 825 - 829
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    We give a stability theorem concerning the response of systems to inputs that are asymptotically almost periodic. We also apply our theorem to the governing integral equation of a large class of circuits containing a nonlinear capacitor. We find that circuits for which a certain critical-disk condition is met are ap-stable in the sense that (a) small changes in the input result in small changes in the output and (b) the response to an asymptotically almost periodic input is an asymptotically almost periodic output whose almost periodic part does not depend on the transient part of the input, and the frequencies of the almost periodic part of the output have the property that they are restricted to the set {ω:ω=Σj=1qkjω jj∈Λ, kj⩾0 and q>0 integers} where h is the set of frequencies of the almost periodic part of the input View full abstract»

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  • System identification in communication with chaotic systems

    Publication Year: 2000 , Page(s): 800 - 808
    Cited by:  Papers (137)
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    Communication using chaotic systems is considered from a control point of view It is shown that parameter identification methods may be effective in building reconstruction mechanisms, even when a synchronizing system is not available. Three worked examples show the potentials of the proposed method View full abstract»

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  • Adaptive robust control schemes for a class of nonlinear uncertain descriptor systems

    Publication Year: 2000 , Page(s): 957 - 962
    Cited by:  Papers (8)
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    This paper presents new adaptive robust control schemes for a class of nonlinear uncertain descriptor systems. Taking both the structured and unstructured uncertainties into consideration, the first control scheme achieves asymptotic stability of the closed-loop descriptor system. To avoid any potential problems such as parameter drift by unmodeled dynamics, in the second control scheme the adaptation is ceased when the control performance gets into the desirable region. The new control scheme guarantees the uniform boundedness of the system and, at the same time, the system will enter the desired zone, which can be arbitrarily designated, in a finite time View full abstract»

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  • Stability of 1-D-CNN's with Dirichlet boundary conditions and global propagation dynamics

    Publication Year: 2000 , Page(s): 785 - 792
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (264 KB)  

    In this paper we face the problem of stability for monodimensional cellular neural networks (CNNs). The absence of periodic or chaotic behavior, which is guaranteed by complete stability, is a requirement for many applications. Though complete stability has been proven for wide classes of CNNs, even within the subset of monodimensional CNNs there are still some significant parameter ranges where no proof is available. Collecting results, one can observe that a stability proof is lacking for all CNNs characterized by global propagation dynamics and opposite sign template (C=[spr], 0<p-q<|r-s|, rs<0) with Dirichlet boundary conditions. We give here a proof of complete stability in the special case of antisymmetric template (C=[sp-s]), also known as the connected component detector. The proof is valid within a parameter range specified in the following. The methods here introduced appear suitable for extension to wider classes of CNN's View full abstract»

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  • Interference bounds for DS-CDMA systems based on chaotic piecewise-affine Markov maps

    Publication Year: 2000 , Page(s): 885 - 896
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (336 KB)  

    The performance of chaos-based asynchronous direct sequence-code division multiple access (DS-CDMA) systems are analyzed in the additive white Gaussian noise (AWGN) channel case. Previous upper bounds on the expected cochannel interference are improved and complemented with lower bounds accounting for maximum achievable performance. The bases for this investigation are mathematical tools from the statistical theory of dynamical systems and in particular some spectral properties of finite-dimensional restrictions of the Perron-Frobenius operator. A general lower bound is provided along with stricter upper and lower bounds in the particular case of piecewise-affine Markov (PWAM) maps used as spreading sequence generators. Detailed numerical examples of bound applicability are also provided View full abstract»

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  • Model reduction of discrete linear systems via frequency-domain balanced structure

    Publication Year: 2000 , Page(s): 830 - 837
    Cited by:  Papers (16)
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    In this paper, a novel model reduction technique for discrete linear time invariant systems is presented. The proposed technique is based on a conceptual viewpoint of the controllability and the observability Grammian balancing of a discrete system in an arbitrary frequency range of operation. It could be viewed as the generalization of the Moore's balance structure approach in a specific frequency range of operation. Two modified Lyapunov equations are derived for the proposed frequency-domain balancing. Various properties of the reduced model such as controllability, observability, stability, its uniqueness, and the error bound are examined. A comparison study of the proposed method with the Moore's time domain technique is presented using a sixth-order digital filter View full abstract»

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  • Harmonic analysis of nondeterministic switching methods for DC-DC power converters

    Publication Year: 2000 , Page(s): 868 - 884
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (468 KB)  

    The authors present a rigorous theoretical harmonic analysis of random pulse width modulation (RPWM) method and random pulse position modulation (RPPM) method for dc-dc converters. The theoretical relationships of discrete harmonics, continuous noise and output voltage ripple of the RPWM and RPPM schemes are established and compared with those of a standard deterministic PWM scheme in a buck converter. Limitations in the randomly switched dc-dc converters are highlighted. The theoretical predictions indicate that the randomized schemes generally have an inherent problem in achieving low output voltage ripple due to the low-frequency continuous noise within the pass-band of the converter filter. For dc-dc power conversion, the RPPM method offers much better output voltage performance than the RPWM method View full abstract»

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  • Chaotic attractor with a characteristic of torus

    Publication Year: 2000 , Page(s): 944 - 948
    Cited by:  Papers (2)
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    Torus doubling is known as one of the most interesting transition routes from a torus to chaos. In this paper, we investigate features of chaos observed after the end of a torus doubling which is generated in a four-dimensional (4-D) electrical circuit. It is clarified that this chaotic attractor remains strongly characteristic of a torus. This attractor is characterized by the Lyapunov exponents. The Poincare map of this attractor has one positive and one zero Lyapunov exponent. It behaves chaotically in the amplitude direction and behaves like a torus in the phase direction. The existence of a torus characteristic behind chaotic oscillation is well explained by an approximated one-dimensional (1-D) map obtained from the Poincare map View full abstract»

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  • An input-output approach to systems described using multiple models

    Publication Year: 2000 , Page(s): 940 - 943
    Cited by:  Papers (2)
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    This paper initiates a general theory of systems described by multiple models. A complete characterization of the stability of such a systems is given, based on the concept of stable motion between two states. The approach taken is based on a reformulation of the theory of input-output systems initiated independently by Sandberg and Zames. Our formulation in done in such a way that (1) it permits dealing with local models of a physical system, i.e., mathematical models are only assumed to be valid in a neighborhood on an operating condition and (2) the main stability results of the classical theory remain essentially unchanged View full abstract»

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  • An adaptive demodulator for the chaotic modulation communication system with RBF neural network

    Publication Year: 2000 , Page(s): 902 - 909
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (228 KB)  

    Chaotic modulation is an important spread spectrum (SS) technique amongst chaotic communications. The logistic chaotic signal acts as the modulation signal in this paper. An adaptive demodulator based on the radial basis function (RBF) neural network is proposed. The demodulator makes use of the good approximant capacity of RBF network for a nonlinear dynamical system. Using the proposed adaptive learning algorithm, the source message can be recovered from the received SS signal. The recovering procedure is on line and adaptive. The simulated examples are included to demonstrate the new method. For the purpose of comparison, the extended-Kalman-filter-based (EKF) demodulator was also analysed. The results indicate that the mean square error (MSE) of the recovered source signal by the proposed demodulator Is significantly reduced, especially for the SS signal with a higher signal-to noise ratio (SNR) View full abstract»

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