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Circuits and Systems, IEEE Transactions on

Issue 8 • Date Aug. 1988

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Displaying Results 1 - 25 of 26
  • Comments on "An improved sufficient condition for absence of limit cycles in digital filters

    Publication Year: 1988
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (112 KB)  

    For the original article see ibid., vol.ASSP-26, P.334-8 (1978). The commenter states that the improved sufficient condition given by W.L. Mills et al., first suggested by K. Meerkotter (Proc. ISCAS p.295-8, 1976), was also explicitly shown by the commenter (Proc. Int. Conf. on Acoustics, Speech and Signal Processing, p.517-20, Apr. 1986), who applied it to the design of novel second-order structures, such as the modified Agarival-Burrus structure.<> View full abstract»

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  • Observability and reconstructibility of the 2-D Fornasini-Marchesini model

    Publication Year: 1988 , Page(s): 1011 - 1014
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (312 KB)  

    Notions of global and causal observability and reconstructibility of the model are presented. The necessary and sufficient condition for the existence of these properties are formulated. The conditions are given in terms of 1-D system observability and reconstructibility, so that well-known tests for those systems can be used to check the observability and reconstructibility of the 2-D systems. Some relations between these properties are also presented View full abstract»

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  • A time-domain solution approach to model reduction

    Publication Year: 1988 , Page(s): 1020 - 1024
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (468 KB)  

    Theoretical limitations for model reduction systems described by ordinary differential equations are investigated through use of the system solution rather than the system state equations. The general case is discussed first and the specialized to linear time-varying systems and finally to linear time-invariant systems. The distance between the original and reduced systems is measured by an error norm corresponding to energy. The reduction method is based on partition of the state space into two orthogonal subspaces. It is an effective procedure which works for both stable and unstable systems but requires knowledge of the system solution in order to be applied. In general the reduced-order model cannot be separated from the initial conditions, but this is possible for linear systems. If there is a driving function acting on the system, it will affect the reduced-order model in an essential way, and its order then cannot in general be reduced View full abstract»

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  • FIR switched-capacitor decimators with active-delayed block polyphase structures

    Publication Year: 1988 , Page(s): 1033 - 1037
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (400 KB)  

    Finite impulse-response (FIR) switched capacitor (SC) decimator circuits using previously proposed structures are not practical for applications requiring long impulse responses on account of a rather large (unrealistic) number of SC branches and switching waveforms. For such applications, polyphase structures are proposed that lead to FIR SC decimator circuits that use significantly fewer branches and switching waveforms, and are thus more attractive for integrated circuit implementation. The design of an FIR SC low-pass decimator with an amplitude response tailored for video interface applications is given as an example View full abstract»

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  • Timing-controlled fully programmable analogue signal processors using switched continuous-time filters

    Publication Year: 1988 , Page(s): 947 - 954
    Cited by:  Papers (3)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (704 KB)  

    Analog signal processors based on continuous-time emulation of sampled-data networks are presented. In these processors, continuous-time signal delay is realized using the phase shift of fixed-frequency, fixed-Q, continuous-time low-pass filters (LPFs), and analog multiplication is accomplished through signal switching using digitally programmable duty cycles. Each coefficient of the processor transfer function is dependently programmable, without requiring selectable capacitor (or resistor) arrays. Experiments verify that this method can be used to construct analog processors with arbitrarily programmable frequency responses. The results presented here are complementary to other results presented earlier by the authors, using sample-data delays View full abstract»

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  • A generalized on the study synthesis of 2-D state-space digital filters with minimum roundoff noise

    Publication Year: 1988 , Page(s): 1037 - 1042
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (460 KB)  

    The Fornasini-Marchesini local state-space (LSS) model is used as the basis for a novel expression for the output-noise variance due to roundoff together with an I2 scaling on the state variables. An optimal Fornasini-Marchesii LSS model structure is then synthesized that minimizes the output noise due to roundoff, subject to an l2 scaling constraint. The synthesis utilizes a 2-D similarity transformation matrix that is not block-diagonal, but general. This requires solving only one optimization problem. Some constraints imposed on the Fornasini-Marchesini LSS model and the 2-D similarity transformation yield the results obtained with the Roesser LSS model. The proposed synthesis theory is therefore quite general and simple. An example is given to illustrate its utility View full abstract»

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  • Spatial-domain design of three terms separable denominator two-dimensional digital filters

    Publication Year: 1988 , Page(s): 1027 - 1032
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (452 KB)  

    A two-dimensional (2-D) digital filter named a three-terms separable-denominator (3TSD) filter is considered and its spatial-domain design techniques are presented. The transfer function of the approximated filter is obtained by solving a set of bilinear equations iteratively. The 3TSD filter also offers some benefits as an SD filter. For example, the stability of the SD filter is easy to check and the filter is simple to implement. An example is presented to illustrate the utility of the proposed technique View full abstract»

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  • On the implementation of adaptive electronic hybrid for digital subscriber loops

    Publication Year: 1988 , Page(s): 1024 - 1027
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (332 KB)  

    An adaptive electronic hybrid is proposed to replace the conventional fixed hybrid in a digital subscriber loop and thus reduce the burden on the echo canceller. The theory of the adaptive hybrid is briefly reviewed. A simple method of hardware implementation is described in which the poles of the echo path transfer function are assumed to be constant. A three-residue adaptive electronic hybrid is realized by linear integrated circuits and shown experimentally to achieve at least 26-dB transhybrid loss View full abstract»

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  • Subharmonics and chaos in a controlled switched-mode power converter

    Publication Year: 1988 , Page(s): 1059 - 1061
    Cited by:  Papers (63)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (300 KB)  

    A difference equation is derived for the output current, at successive switch events, of a simple switching-regulator DC/DC converter using a pulsewidth modulator. Wideband feedback control of the nonlinear circuit leads to a one-dimensional return map of zigzag form from which a stability criterion is found. Operation in the unstable region is described and verified by numerical simulation. The system exhibits a noisy bifurcation, chaos and subharmonics View full abstract»

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  • Minimax sidelobe reduction filtering for Huffman sequence autocorrelation function type signals

    Publication Year: 1988 , Page(s): 1014 - 1019
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (472 KB)  

    A solution is presented for the impulse response of an FIR sidelobe reduction filter, intended for signals consisting of a main lobe and two symmetrically spaced side-lobes, i.e. for signals of the Huffman sequence autocorrelation function type. The filter minimizes the output main-lobe level subject to a constraint on the maximum sidelobe level. It is shown that for those input signals with sidelobe levels that do not exceed half of the main-lobe level, the filter required can be represented uniquely as a parallel combination of zero-forcing filters. The tradeoff between the reduction of sidelobe level and the degradation of signal-to-noise ratio is examined View full abstract»

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  • Multistage adaptive stochastic filters

    Publication Year: 1988 , Page(s): 929 - 935
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (528 KB)  

    A multistage stochastic adaptive recursive filter is introduced which uses a white noise dither signal at its second stage to avoid the strictly positive real condition existing algorithms used for convergence. In the first stage an autoregressive (AR) model fitted to estimate the first n parameters of the autoregressive portion of the filter. The second stage is used to compute the AR polynomial when the passivity condition is not satisfied. In the third stage, using the models obtained from the first and second stages, an improved autoregressive moving average (ARMA) model is generated. The proposed algorithm is used in two examples: detection and spectral estimation of a narrowband signal corrupted by white noise and identification of a second-order ARMA (autoregressive moving-average) model. Simulation results are compared with results for existing methods View full abstract»

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  • On the application of the no-gain property in nonlinear resistive networks

    Publication Year: 1988 , Page(s): 1061 - 1062
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (212 KB)  

    The necessary and sufficient topological conditions under which one can transfer all independent sources of a no-gain nonlinear resistive network to the branches with positive linear resistors are derived. Such a relocation of sources allows an estimate, practically without computation, of the greatest possible voltage and current in the circuit. The main theorem proved here shows that the simple localization of the solutions can, practically without computation, be made for a very large class of nonlinear circuits View full abstract»

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  • Qualitative analysis and synthesis of a class of neural networks

    Publication Year: 1988 , Page(s): 976 - 986
    Cited by:  Papers (112)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (776 KB)  

    The dynamic properties of a class of neural networks (which includes the Hopfield model as a special case) are investigated by studying the qualitative behavior of equilibrium points. The results fall into one of two categories: results pertaining to analysis (e.g., stability properties of an equilibrium, asymptotic behavior of solutions, etc.) and results pertaining to synthesis (e.g. the design of a neural network with prespecified equilibrium points which are asymptotically stable). Most (but not all) of the results presented are global, and their applicability is demonstrated by an example View full abstract»

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  • Systolic recursive filters

    Publication Year: 1988 , Page(s): 1067 - 1068
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (160 KB)  

    Two systolic arrays for recursive digital filtering are presented. Both have a rectangular structure and produce output for a particular computation in consecutive cycles. Their performance is analyzed and the design tradeoffs are discussed View full abstract»

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  • An adaptive algorithm for short-term multinode load forecasting in power systems

    Publication Year: 1988 , Page(s): 1004 - 1010
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (644 KB)  

    An online adaptive escalator lattice structure for orthogonalization of multiple-channel signals is used to predict load demands among loading nodes in a power system by an autoregressive multiple-channel mode. Since the escalator outputs are white and also uncorrelated with each channel or node, the parameters of the algorithm are updated adaptively using scalar operations. Because matrix or vector operations are not required in the updating procedures, the convergence speed is insensitive to the ratio of the largest to the smallest eigenvalues of the loads' covariance matrix. Thus the prediction filter has a faster convergence rate than common matrix-oriented gradient adaptive filters. Computer simulation shows that this algorithm has a faster convergence rate and better numerical properties in the adaptive process. This is very attractive for multinode load forecasting in a large power system, where each load model varies with time and has different statistical characteristics, or where loads are nonstationary and the ratio of eigenvalues in the load covariance matrix is large View full abstract»

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  • A new structure of sharp transition FIR filters using frequency-response masking

    Publication Year: 1988 , Page(s): 955 - 966
    Cited by:  Papers (21)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (716 KB)  

    A recently proposed frequency-response masking approach to implement linear phase FIR digital filters with very sharp transition band has resulted in saving in arithmetic operations as high as four to one. This approach is generalized to achieve additional savings of 20% or more. The discussion is presented in terms of low-pass filters, but the method can be applied to high-pass as well as some bandpass filters View full abstract»

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  • Analog implementation of median filter for real-time signal processing

    Publication Year: 1988 , Page(s): 1032 - 1033
    Cited by:  Papers (20)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (184 KB)  

    A novel median filter using analog tapped delay lines is designed for real-time signal processing. It requires only N+1 analog comparators for a window size of size N. As an extension, a general order-statistics filter can also be realized with moderate increase of circuit complexity. For current available fabrication technology for MOS switched-capacitor circuits, the filter can work at a clock rate up to 10 MHz. This development opens up possibilities for practical applications of nonlinear filtering in real-time signal processing, since the analog circuitry is far less complex than the corresponding digital circuitry View full abstract»

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  • Noise performance of SC-integrators assuming different operational transconductance amplifier (OTA) models

    Publication Year: 1988 , Page(s): 1042 - 1048
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (652 KB)  

    Analytic formulas describing the noise performance due to white noise of two SC-integrator structures using simple and more sophisticated OTA models are presented. It is shown that an oversimplified modeling can lead to underestimating as well as to overestimating the noise effects. The formulas suggest design rules for reducing the noise in the integrator structures. The numerical analysis of a second-order filter indicates that these design rules also hold for more complex structures using the mentioned integrators View full abstract»

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  • Interval mathematics algorithms for tolerance analysis

    Publication Year: 1988 , Page(s): 967 - 975
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (624 KB)  

    Two iterative algorithms for tolerance analysis of linear electrical circuits are suggested. They are based on the mean-value-form representation of the function considered and involve the internal computation of its first-order partial derivatives. Two modified mean-value forms for computing the interval extensions of multivariate functions are introduced. It is proved that under appropriate conditions these forms assure narrower interval enclosures of the range as compared with other known forms. Thus the use of the modified mean-value forms substantially improves the convergence speed of algorithms. The improved mechanical efficiency of the algorithms is illustrated by three examples, confirming that they require less computer time and memory volume than other first-order interval techniques View full abstract»

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  • A simplified viewpoint of two-dimensional continued fraction inversion based on matrix formulation

    Publication Year: 1988 , Page(s): 1066 - 1067
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (148 KB)  

    A computationally improved version of a recent method for the inversion of a two-dimensional continued fraction is pointed out. The number of multiplications and additions required is reduced, which will allow a more compact computer program to be obtained View full abstract»

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  • Chaos from phase-locked loops

    Publication Year: 1988 , Page(s): 987 - 1003
    Cited by:  Papers (46)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1116 KB)  

    The chaotic dynamics observed for the second-order phase-locked loop (PLL) operating as a frequency-modulated (FM) demodulator are studied theoretically as well as experimentally. The existence of horseshoe chaos in this circuit is proved using Melnikov's method. It is demonstrated that chaos can indeed occur in a practical FM demodulator circuit made of an integrated circuit module and using realistic parameter values. Explicit expressions that specify the possible region of chaos are derived View full abstract»

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  • The design of multiplierless FIR filters for compensating D/A converter frequency response distortion

    Publication Year: 1988 , Page(s): 1064 - 1066
    Cited by:  Papers (25)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (264 KB)  

    Designs are presented for multiplierless linear-phase FIR digital filters for compensating the sinc(x) frequency-response distortion resulting from D/A conversion. The filter coefficients are represented by a simple canonic single-digit code, and thus the filter can be implemented using only a few adders and delay registers. A 7-tap design is given which compensates the D/A distortion to within ±0.045 dB from DC through 0.41 fs and an 11-tap design is given which compensates the D/A distortion to within ±0.028 dB from DC through 0.045 fs View full abstract»

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  • Generation of continuous-time two integrator loop OTA filter structures

    Publication Year: 1988 , Page(s): 936 - 946
    Cited by:  Papers (112)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (696 KB)  

    Generation of two integrator loop filter structures using operational transconductance amplifiers (OTAs) and capacitors (TAC) is presented. A direct block diagram approach is used to generate the TAC filter structures. The basic filter building blocks consist of a lossless integrator, lossy integrators and the three types of summers. They are implemented using OTAs as the active components. The resulting TAC second-order filter structures, some previously reported and others new structures, are generated in an orderly way. It is shown that the selection of the best structure depends on the particular application or design specifications. The generated TAC biquadratic structures are only very suitable for monolithic filters since typically only OTAs and two capacitors are needed. A TAC filter structure homologous to the conventional KHN op amp filter structure is presented. Programmability of ωp, Qp and voltage gain is considered View full abstract»

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  • Edge-preserving noise filtering based on adaptive windowing

    Publication Year: 1988 , Page(s): 1048 - 1055
    Cited by:  Papers (11)  |  Patents (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (848 KB)  

    An adaptation procedure is introduced for determining in real-time the extent on the analysis window in point estimation of signals corrupted by additive noise. In the tasks of restoring a noisy one-dimensional test signal and a two-dimensional noisy image, mean, median and minimum-mean-square-error filters are compared with fixed and adaptive window implementations. The visual results of the signal and image restorations exhibit superior preservation of edge and detail and suppression of noise for the filters with adaptive windows View full abstract»

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  • On verification of limit cycle stability in autonomous nonlinear systems

    Publication Year: 1988 , Page(s): 1062 - 1064
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (264 KB)  

    A method for verification of limit-cycle stability in autonomous nonlinear systems is proposed. The method is applicable to systems with limit cycles described by a sinusoid (main oscillation) with small addition of harmonics. The main oscillation is represented in exponential form and is substituted into the nonlinear part of the initial differential equation. The nonlinear part is linearized with respect to the amplitude perturbations and the operator equation for the perturbations is obtained. Then the terms representing derivatives higher than first order are omitted in the corresponding operators and the real and imaginary parts of the simplified operator equation are separated. This results in two first-order linear differential equations for the increments of the main oscillation amplitudes. The differential equations are used for verification of the limit-cycle stability. The case of asynchronous perturbation is considered as well View full abstract»

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