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

Issue 5 • Date May 1997

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Displaying Results 1 - 15 of 15
  • Early comparison and decision strategies for datapaths that recover from transient faults

    Publication Year: 1997 , Page(s): 435 - 438
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (100 KB)  

    Rollback and retry is a common approach used to achieve error recovery in datapaths that tolerate transient faults. In this approach, each segment of a computation is duplicated and the results are compared using fault-tolerant comparators. If the compared values are unequal, the segment is rolled back to the preceding correct state (rollback point) and retried from that state. We introduce early comparison and rollback strategies for use in such datapaths. These strategies utilize comparators during the computational portion of the segment and can initiate a rollback before the segment is completed. We illustrate through examples how these strategies can reduce hardware costs (number of comparators needed) and the delay in recovering from a transient fault compared to conventional strategies View full abstract»

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  • Mapping of one-dimensional Josephson junction arrays onto cellular neural networks and their dynamics

    Publication Year: 1997 , Page(s): 438 - 445
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (292 KB)  

    It is shown that one-dimensional Josephson junction arrays can be mapped onto sworks under some restrictions. Analytic expressions to the stability of equilibria of these arrays are derived and applied to the behavior of vortex solutions. Relations between these static solutions and a particular solution of a partial differential equation are shown. By means of the theory of Hamiltonian systems, a qualitative theory for Josephson junction arrays is derived and applied in numerical simulations View full abstract»

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  • Learning of periodic signals-an averaging analysis

    Publication Year: 1997 , Page(s): 402 - 411
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (480 KB)  

    This paper describes the concepts and background theory of the analysis of a neural-like network for the learning and replication of periodic signals containing a finite number of distinct frequency components. The approach is based on a two stage process consisting of a learning phase when the network is driven by the required signal followed by a replication phase where the network operates in an autonomous feedback mode while continuing to generate the required signal to a desired level of accuracy for a specified time. The analysis focusses on stability properties of a model reference adaptive control based learning scheme via the averaging method. The averaging analysis provides fast adaptive algorithms with proven convergence properties View full abstract»

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  • Cryptography based on chaotic systems

    Publication Year: 1997 , Page(s): 469 - 472
    Cited by:  Papers (122)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (168 KB)  

    In this letter, a new chaos-based secure communication scheme is proposed in an attempt to thwart the attacks proposed recently. Instead of encoding the message signal in a chaotic system directly, we use two chaotic signals in our scheme. One of the chaotic signals is used to synchronize the chaotic encrypter and the chaotic decrypter. The other is used to encrypt the plain signal by using a multishift cipher scheme. Thus the transmitted signal is not used to encrypt the message and a more complicated method of encryption is used View full abstract»

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  • Fast simulation and sensitivity analysis of lossy transmission lines by the method of characteristics

    Publication Year: 1997 , Page(s): 391 - 401
    Cited by:  Papers (31)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (396 KB)  

    In this paper we use the method of characteristics to derive a new simulation model of lossy transmission lines, and we present the sensitivity analysis in the time domain. The simulation model is as fast as the recursive convolution model based on moment matching and Pade' approximation, but does not have the stability problem. The sensitivity analysis model is particularly useful for transmission line circuits containing nonlinear elements, and is believed to be the first time domain model. Both the simulation and sensitivity analysis models are applicable to uniform and nonuniform transmission lines with arbitrary nonzero initial states. Also we show that any nonlinear circuit element has a very simple linear model in sensitivity analysis. Furthermore, we demonstrate that for any circuits, the modified nodal admittance (MNA) matrices in simulation and in sensitivity analysis equations are the same, therefore no LU decomposition is needed in sensitivity analysis. The contributions in this paper have been implemented into a general-purpose program CSSC (Circuit Simulation and Sensitivity Analysis with Characteristics) which shows excellent accuracy and efficiency in both simulation and sensitivity analysis of transmission line circuits View full abstract»

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  • A fundamental theorem for multiple-channel blind equalization

    Publication Year: 1997 , Page(s): 472 - 473
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (60 KB)  

    It is proved in this letter that, under mild conditions, the equalizer bank equalizes the channel bank if, and only if, its output is temporally uncorrelated. This result has applications to wireless communication View full abstract»

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  • Classification of units in H and an alternative proof Kharitonov's theorem

    Publication Year: 1997 , Page(s): 454 - 458
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (172 KB)  

    The authors present an alternative proof of Kharitonov's theorem, using the property of a ratio of odd and even parts of a Hurwitz polynomial and the Nyquist stability criterion. The ratio of Kharitonov's polynomials in the classification of units in H, along with its relation to the problem of simultaneous stabilization of one parameter family of plants is discussed. A new theorem on the existence of a Hurwitz polynomial such that its ratio with a Hurwitz interval polynomial family with either the same even or odd part, is a strictly positive real (SPR) function is proved. It is also proved that if the ratio of a polynomial β(s) with four Kharitonov's polynomials is an SPR function, then the ratio of β(s) with the interval family is an SPR function View full abstract»

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  • Digital communication method based on M-synchronized chaotic systems

    Publication Year: 1997 , Page(s): 383 - 390
    Cited by:  Papers (10)  |  Patents (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB)  

    Chaos shift keying (CSK) is a modulation method in digital communication systems which makes use of chaos synchronization to send binary signals. This paper extends the existent method of chaotic phase-shift keying (CPSK), a form of CSK which utilizes in-phase and antiphase synchronizations. As the method is based on M-synchronization, it will be called M-CPSK. We give an example of a quaternary wireless communication system and examine the effect of noise in transmission channels on the system by computer simulation View full abstract»

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  • On the structure of nonlinear polynomial models: higher order correlation functions, spectra, and term clusters

    Publication Year: 1997 , Page(s): 450 - 453
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (144 KB)  

    A framework is established which relates the structure of nonlinear polynomial models to the dynamical properties of the estimation data. Such a framework uses the concepts of term clusters, higher order correlation functions and higher order spectra. The results discussed offer a new way of understanding and interpreting term clusters in structure selection problems for nonlinear polynomial models. A numerical example which uses real data is included to illustrate the new results View full abstract»

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  • Identification of discontinuities in blurred noisy signals

    Publication Year: 1997 , Page(s): 422 - 434
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (520 KB)  

    In this paper we address the problem of estimating the locations of discontinuities in blurred and noisy signals. The discontinuity parameters (location and size) are embodied in a model describing the signal regular and singular components. First, the well-posedness of the estimation problem, i.e., uniqueness and robustness of the solution, is established. Then data are processed by a smoothing multiscale resolution technique that, besides providing some noise filtering, enhances the effect of the discontinuities. Hence, a maximum-likelihood method is used for parameter estimation. Numerical results are obtained both on simulated and real data View full abstract»

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  • Low voltage techniques for bias circuits

    Publication Year: 1997 , Page(s): 459 - 465
    Cited by:  Papers (7)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (204 KB)  

    Circuit design techniques for very low-voltage bias circuits are discussed. A Nagata current mirror is very suitable for battery operation because it provides current regulation. Also, it is very suitable for start-up circuitry. In this brief, an inverse Widlar current mirror is newly proposed as a nonlinear current mirror with a negative temperature coefficient (TC), a Nagata/inverse-Widlar current mirror is also proposed as a Nagata current mirror or an inverse-Widlar current mirror with an optionally programmed positive or negative TC, and a TC shifter with an offset voltage proportional to absolute temperature (PTAT) is also proposed. Furthermore, fundamental characteristics and temperature characteristics of the bias circuits discussed in this brief were verified with transistor-arrays and discrete components View full abstract»

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  • A smart CCD image sensor with real-time programmable parallel convolution capabilities

    Publication Year: 1997 , Page(s): 465 - 468
    Cited by:  Papers (2)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (100 KB)  

    A fully parallel focal plane charge-coupled device (CCD) array which performs image acquisition and convolution with arbitrary kernels is presented. The real-time programmable spatial convolution is generated for all pixels in parallel during the exposure. The 2-D convolution is performed by shifting a charge pattern in two dimensions and the exposure time is varied in proportion to the weight of each kernel coefficient. The problem of negative weights can be solved by taking the difference of two convolutions each with only positive weights. The CCD was fabricated using a standard CMOS/CCD process. Convolutions have been performed with a variety of linear filters that are commonly used in machine vision. Typical rms deviations from the ideal filter characteristics are between 1-2% of the largest kernel tap value. Results and practical applications of this work are discussed View full abstract»

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  • A new approach to communications using chaotic signals

    Publication Year: 1997 , Page(s): 373 - 382
    Cited by:  Papers (56)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (260 KB)  

    In this paper, a new approach for communication using chaotic signals is presented. In this approach, the transmitter contains a chaotic oscillator with a parameter that is modulated by an information signal. The receiver consists of a synchronous chaotic subsystem augmented with a nonlinear filter for recovering the information signal. The general architecture is demonstrated for Lorenz and Rossler systems using numerical simulations. An electronic circuit implementation using Chua's circuit is also reported, which demonstrates the practicality of the approach View full abstract»

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  • A state-constrained model for cellular nonlinear network optimization

    Publication Year: 1997 , Page(s): 445 - 449
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (196 KB)  

    A GmC-style state constrained neuron (SCN) model for the design of processors in analog recurrent neural networks such as Hopfield neural networks, cellular nonlinear networks for combinatorial optimization is described. The unconstrained neurons which have the free state variable, could be stable at any arbitrary point in the solution space or trapped by un-intentional effects. These may introduce errors. For the unconstrained network, the solution could be different from the expected one due to the discrepancy in the energy function of the network and the objective function to be optimized. In addition, if the state variable is limited by some neighboring saturated transistors, un-desirable results may be obtained. The GmC-style SCN model can ensure the convergence of the network and avoid discrepancy between the energy function of the network and the objective function. The state resistor is also eliminated in the GmC model so that high cell-density can be achieved. Simulation results show that the proposed model is effective in significantly reducing optimization error View full abstract»

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  • Dither in linear systems with memoryless nonlinearity and optimal control

    Publication Year: 1997 , Page(s): 412 - 421
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (564 KB)  

    The injection of a high-frequency signal, commonly called dither, into a nonlinear system may improve its performance. Stability of the dithered system is related to that of its corresponding model - the smoothed system, of which the nonlinear element Ns (smoothed nonlinearity) is the convolution of the dither distribution and the original nonlinearity N. The dither amplitude, but not its frequency affects the sector of Ns. The importance of dither frequency is found in its effect on the deviation of the smoothed system from the dithered system, and the deviation can be improved as dither frequency increases. The dither with a sufficiently high frequency may result in the smoothed system's output and the dithered system's output as close as desired. An optimal controller and a dither, as an auxiliary of the controller, are simultaneously introduced to make the stability more robust, no matter whether the controlled plant is stable or not. The main characteristic of this paper is that an algorithm is proposed to find a lower bound on dither amplitude to stabilize the nonlinear feedback system View full abstract»

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