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

Issue 6 • Date Jun 1997

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Displaying Results 1 - 12 of 12
  • Digital coding via chaotic systems

    Page(s): 562 - 565
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (160 KB)  

    The concept of time-discontinuous coupling of two identical chaotic systems called sporadic coupling is addressed. The conditions for the occurrence of synchronization between two sporadically coupled chaotic systems are given. Amplitude quantization of the driving signal in addition to the sporadic coupling allows digital exchange of digital information signals between the sporadically coupled chaotic systems View full abstract»

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  • A CMOS quadrature modulator for wireless communication IC

    Page(s): 559 - 561
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    This brief presents a CMOS digital quadrature modulator, which is based on a CMOS digital modulator and a five-level digital-to-analog converter, for wireless communication IC. In the digital modulator, a circular shift register is used to produce a continuous sinusoidal wave with different phases. With this technique, the quadrature modulator has advantages in low power consumption, small area, and expansion capability View full abstract»

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  • Uniform approximation of multidimensional myopic maps

    Page(s): 477 - 500
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    Our main result is a theorem that gives, in a certain setting, a necessary and sufficient condition under which multidimensional shift-invariant input-output maps with vector-valued inputs drawn from a certain large set can be uniformly approximated arbitrarily well using a structure consisting of a linear preprocessing stage followed by a memoryless nonlinear network. Noncausal as well as causal maps are considered. Approximations for noncausal maps for which inputs and outputs are functions of more than one variable are of current interest in connection with, for example, image processing View full abstract»

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  • Application of Newmann's principle to electromagnetic N-ports

    Page(s): 513 - 520
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    Application of Newmann's principle, well known in crystallography, to electromagnetic N-ports is demonstrated. Using this approach, it is possible to find those symmetrical structures which can be considered as candidates for implementation of the electromagnetic functions including the nonreciprocal ones. Starting from the ideal scattering matrix, a systematic procedure is suggested to find the symmetry of this matrix and the corresponding symmetry of the geometrical structure and dc magnetic field. Two examples from the field of ferrite devices are given in order to illustrate the method View full abstract»

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  • A new crosstalk compensation method in line inversion TFT-LCD's

    Page(s): 552 - 555
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    This brief presents a novel method to compensate a common electrode signal distortion caused by capacitive coupling between the data-lines and a common sheet electrode through a parasitic capacitor in TFT-LCD's. We designed a compensation circuit whose role is to give a negative feedback to the common electrode by detection of the amount of distortion and generation of the dependent voltage source to cancel off the distortion. By experiment, we found that the newly designed compensation circuit greatly reduced the distortion caused by crosstalk in large size line inversion TFT-LCD's View full abstract»

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  • 2-D arithmetic Fourier transform using the Bruns method

    Page(s): 546 - 551
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    The arithmetic Fourier transform (AFT) has been shown to perform competitively with the classical fast Fourier transform (FFT) in terms of accuracy, complexity, and speed. The new technique of calculating AFT based upon Bruns' method proved to be an advancement of the previous version of the arithmetic transformation, since it provides a more balanced scheme of computation of the even and odd coefficients of a Fourier series. This brief develops the concept of two-dimensional AFT using the Bruns method. A VLSI architecture is suggested for the proposed two-dimensional AFT algorithm View full abstract»

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  • Generalized iterative methods for enhancing contaminated chaotic signals

    Page(s): 501 - 512
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    Generalized iterative methods for reducing noise in contaminated chaotic signals are proposed. These methods minimize a cost function composed of two parts: one containing information that represents how close enhanced signals are to the observed signal and another composed of constraints that fit the dynamics of the system. The convergence conditions and the error systems of the proposed methods are investigated. The proposed methods are compared via numerical experiments with Farmer's method which may be regarded as a special case of this general framework View full abstract»

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  • Limit cycles in delta-operator formulated 1-D and m-D discrete-time systems with fixed-point arithmetic

    Page(s): 529 - 537
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    In this paper, the problem of global asymptotic stability of δ-operator formulated one-dimensional (1-D) and multidimensional (m-D) discrete-time systems is analyzed for the case of fixed point implementations. It is shown that the free response of such a system tends to produce improper equilibrium points if conventional quantization arithmetic schemes such as truncation or rounding are used. Explicit necessary conditions for global asymptotic stability are derived in terms of the sampling period. These conditions demonstrate that, in many cases, fixed-point arithmetic does not allow for global asymptotic stability in δ-operator formulated discrete-time systems that use a short sampling period. This is true for the 1-D as well as the m-D case View full abstract»

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  • Analysis of Chua's circuit with transmission line

    Page(s): 556 - 558
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    The purpose of this brief is that, by an application of the method of characteristics, we analyze chaotic phenomena in Chua's circuit with lossy transmission line. The transmission line is replaced by the equivalent lumped circuit and a time-delayed element so that it can be solved efficiently by the Runge-Kutta method. It is found from numerical experiments that the circuit has complicated and interesting chaotic attractors View full abstract»

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  • Qualitative analysis of the dynamics of the time-delayed Chua's circuit

    Page(s): 486 - 500
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    Several variants of the Chua's circuit have been recently proposed in order to enlarge the class of nonlinear phenomena that can be generated by relatively simple circuits. In particular, Sharkovsky et al. proposed the so called time-delayed Chua's circuit (TDCC), where the original lumped LC resonator is substituted by an ideal transmission line, thereby generating an infinite dimensional system, The TDCC has been studied in details in the absence of the capacitor C, the only lumped dynamic element left in the circuit. This paper studies the effects of the presence of C on the dynamics of the circuit. After recasting the circuit equations in a suitable normalized form, their characteristic equation is theoretically investigated and the regions in the parameter space where all the eigenvalues have negative real part are exactly evaluated along with all the possible qualitative eigenvalue distributions. This analysis allows for a qualitative description of the TDCC dynamics in presence of the capacitor C. In particular, it is shown that, for particular sets of circuit parameters, an even small value of C, e.g., a parasitic element, may completely change the behavior of TDCC and that, on the other hand, any TDCC, exhibiting the period-adding phenomenon for C=0, stilt continues to present this phenomenon even if a small capacitor C is added to the circuit View full abstract»

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  • An integrated analog/digital random noise source

    Page(s): 521 - 528
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    An integrated noise source (INS) has been fabricated in a standard 1.2 μm digital CMOS technology. Wideband white noise is generated from the amplified thermal noise of large resistors, which in turn is coupled into a comparator to generate a random digital bit stream. The INS generates 100 mV rms of analog output noise over a bandwidth of 3.2 MHz and operates from a single 5 V power supply with a quiescent current of 7.4 mA. The circuit has an area of 2.92 mm2. Potential applications of the INS include data encryption, mathematical simulation, and circuit test and measurement View full abstract»

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  • Nonparametric approach to Wiener system identification

    Page(s): 538 - 545
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    A Wiener system, i.e., a system consisting of a linear dynamic subsystem followed by a memoryless nonlinear one is identified. The system is driven by a stationary white Gaussian stochastic process and is disturbed by Gaussian noise. The characteristic of the nonlinear part can be of any form. The dynamic subsystem is asymptotically stable. The a priori information about both the impulse response of the dynamic part of the system and the nonlinear characteristics is nonparametric. Both subsystems are identified from observations taken at the input and output of the whole system. The kernel regression estimate is applied to estimate the invertible part of the nonlinearity. An estimate to recover the impulse response of the dynamic part is also given. Pointwise consistency of the first and consistency of the other estimate is shown. The results hold for any nonlinear characteristic, and any asymptotically dynamic subsystem. Convergence rates are also given View full abstract»

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