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Circuits and Systems, IEEE Transactions on

Issue 2 • Date Feb. 1989

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Displaying Results 1 - 25 of 25
  • Comments on "The analog median filter" by J.P. Fitch et al

    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (127 KB)  

    It is pointed out that in the above-mentioned paper (see ibid., vol.33, no.1, p.94-102, 1986), the necessary and sufficient conditions (if any exist) under which the properties of the discrete median filter also apply to the analog median filter remain unclear.<> View full abstract»

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  • Comments on "Calculation of L norms for scaling second-order state-space digital filters sections" by B.W. Bomar and R.D. Joseph

    Page(s): 310 - 311
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (211 KB)  

    In a previously published paper (see ibid., vol.34, no.8, p.983-4, 1987), an expression for L/sub infinity / norms was derived for a particular second-order digital transfer function. It is shown that closed-form expressions for L/sub infinity / norms for any general biquadratic digital transfer function ar available in the literature.<> View full abstract»

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  • Design of an efficient VLSI inner-product processor for real-time DSP applications

    Page(s): 324 - 329
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    A technique for the design of an efficient word-level inner-product processor based on a parallel array multiplier is described. This processor cell forms the fundamental computing module of the systolic array architectures that are increasingly used to solve many computationally intensive DSP functions. These functions are characterized by linear recurrences involving multiply-add/subtract operations. The use of the present scheme results in the total elimination of the separate-adder module that is usually required along with a multiplier unit in conventional designs. Simulation results of a linear bidirectional systolic array are presented for a test-case example of a convolution problem. A reduction of 32-50% in the computation time is achieved. Besides, it results in reducing the number of basic cells used, making it highly attractive for VLSI implementation. View full abstract»

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  • Accurate representation of time-varying signals using mixed transforms with applications to speech

    Page(s): 329 - 331
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB)  

    Basis functions from two transforms, the discrete Fourier transform (DFT) and the Walsh-Hadamard transform are used. An iterative algorithm to implement the mixed representation is developed. A finite number of DFT components, either fixed or variable, is used to represent the selective (narrowband) dominant spectrum of the signal on a frame-by-frame basis. The whitened (broadband) residual signal is represented using a small number of Walsh components. The mixed partial sets are applied to speech representation. Preliminary results and informal listening using this model produced good quality speech View full abstract»

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  • Efficient modeling of dominant transform components representing time-varying signals

    Page(s): 331 - 334
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    The mixed transform representation of time-varying signals uses partial sets of basis functions from the discrete Fourier transform (DFT) and the Walsh-Hadamard transform. The location, magnitude, and phase of the transform components have to be specified for proper signal reconstruction. A least-squares IIR (infinite impulse response) algorithm, in the transformed domains, which fits each of the retained subsets of the complex transform components accurately, is presented. The IIR function, while characterized by real coefficients about twice the number of the retained complex transform components, carries enough location, magnitude, and phase information for accurate signal reconstruction. To illustrate the technique's accuracy and efficiency, its application to model the DFT part of a voice speech segment is given View full abstract»

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  • Floating output VMOS amplifier

    Page(s): 307 - 309
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    A differential input-differential output floating amplifier is described. The essential characteristics of the system are defined by three feature-of-merit parameters. A practical design using VMOS power transistors is also presented and the experimental measured parameters are compared to the theoretical estimates View full abstract»

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  • Performance analysis of frequency-domain block LMS adaptive digital filters

    Page(s): 173 - 189
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    The performance of the frequency-domain block least-mean-square (FBLMS) adaptive digital filters, whose filter weights are updated efficiently using the fast Fourier transform, is investigated. In particular, the convergence of the unconstrained FBLMS algorithm with reduced complexity, which is obtained by removing the constraint that has been known to be required in adjusting the frequency-domain weights based on overlap-save sectioning, is analyzed. The performance of the self-orthogonalizing FBLMS algorithm with improved convergence speed, in which different convergence factors normalized by frequency-domain power estimates are used for different frequency components of the weights, is also studied View full abstract»

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  • Stability and noise performance of constant transimpedance amplifier with inductive source

    Page(s): 264 - 271
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    The design of a low-noise wideband transimpedance amplifier which matches an inductive source is considered. The presence of an inductive source makes it difficult to design such an amplifier to meet both low-noise and stability requirements. A novel feedback configuration is proposed. The use of this configuration gives good noise performance and at the same time realizes a constant transimpedance. The stability and signal transfer conditions for four different cases are derived. Noise analysis and optimization performed for each case yield amplifiers with optimal noise performance. Four amplifiers have been designed to verify the analytical results. The amplifier is suitable to be implemented in bipolar junction transistor technology and can be used as the preamplifier in an upconversion radio receiver. A transimpedance of 220 kΩ and total equivalent input noise current density between 0.35 to 0.75 pA/√Hz have been achieved in the whole AM band. A reduction of two in noise current has been measured when a JFET (junction field-effect-transistor) is used as input instead of a bipolar transistor View full abstract»

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  • A ten-channel equalizer for digital audio-applications

    Page(s): 276 - 280
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    The design and implementation of a high-quality digital audio equalizer set composed of 10 equalizer sections with a worst-case overall signal-to-noise ratio greater than 90 dB, which is suitable for CD (compact-disc) applications is discussed. The implementation of the equalizer sections has been realized with wave digital filters. Each equalizer section consists of a resistively terminated bandpass or bandstop filter, respectively, i.e. a simple second-order section. This simple structure makes possible a hardware implementation of the equalizer set with digital signal processors or a custom design implementation View full abstract»

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  • MOD-CHAR: an implementation of Char's spanning tree enumeration algorithm and its complexity analysis

    Page(s): 219 - 228
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    Two complexity analyses of MOD-CHAR are presented. It is shown that MOD-CHAR leads to better complexity results for J.P. Char's algorithm than what could be obtained using the straightforward implementation implied in Char's original presentation (see IEEE Trans. Circuit Theory, Vol.15, p.228-38, 1968). The class of graphs for which MOD-CHAR and, hence, Char's algorithm, has linear time complexity per spanning tree generated is identified. This class is more general than the corresponding one identified in R. Jayakumar et al. (see ibid., vol.31, no.10, p.853-60, 1984). Using a result on random graphs, it is proved that for almost all graphs MOD-CHAR has linear worst-case time complexity per spanning tree generated. It is also shown that for any complete graph MOD-CHAR requires, on the average, at most seven computational steps to generate a spanning tree. This result and computational experiences provide evidence to believe that for dense graphs of any order the time complexity of MOD-CHAR is O(t), where t is the number of spanning trees generated. On the other hand, there is enough evidence to conclude that for sparse graphs, Char's original implementation is superior to MOD-CHAR View full abstract»

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  • Limit-cycle free complex biquad recursive digital filters

    Page(s): 280 - 285
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (388 KB)  

    A novel type of complex biquad recursive digital structure, based on the concept of a generalized immittance converter, is discussed. Orthogonal filters which are widely used in time-division multiplexing-frequency-division multiplexing (TDM-FDM) transmultiplexers can be obtained as a special class of these complex biquads. It is shown that the proposed structure is completely free from zero-input limit cycles under linear conditions, and further, that the stability under finite arithmetic conditions can be achieved using the technique of magnitude truncation. It is also shown that for this structure, the stability of the forced response can be ensured for certain types of overflow nonlinearities View full abstract»

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  • A novel efficient algorithm for stability test by continued fraction expansion with application to 2-D digital filters

    Page(s): 315 - 317
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    Based on a theorem on a continued fraction expansion of complex discrete reactance functions, an algorithm for the stability test of digital filters directly in the z-domain is derived. The algorithm is formulated in a table form which is similar to the Marden-Jury table but shows some more interesting numerical aspects. Finally, the application of the algorithm to the 2-D stability test is briefly discussed View full abstract»

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  • Overflow analysis of a fixed-point implementation of the Goertzel algorithm

    Page(s): 322 - 324
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    It is shown that the second-order Goertzel algorithm, though favored over the first-order Goertzel algorithm for its reduced computational complexity, is in fact prone to overflows when implemented in hardware with only fixed-point arithmetic. An overflow analysis reveals that the second-order Goertzel algorithm requires a different scaling factor at each frequency sample to systematically eliminate the possibilities of overflow View full abstract»

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  • Calculation of signal delay in integrated interconnections

    Page(s): 272 - 276
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    A procedure for calculating the signal delay in integrated interconnections modeled by RC networks is presented. This method is based on the elimination of all the internal nodes of the RC network, using a first-order approximation. The method is valid for calculating the approximate transient response of RC mesh networks, not only for a step input, but also for inputs of many different waveforms View full abstract»

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  • Qualitative analysis of neural networks

    Page(s): 229 - 243
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    Results from the qualitative theory of large-scale interconnected dynamical systems are surveyed and utilized to develop a qualitative theory for the Hopfield model of neural networks. Such networks are viewed as an interconnection of many single neurons. The results are phrased in terms of the qualitative properties of the individual neurons and in terms of the properties of the interconnecting structure of the neural networks. This method of analysis makes it frequently possible to circumvent difficulties usually encountered in the analysis of complex systems with high dimension. Aspects of neural networks which are addressed include asymptotic stability, exponential stability, and instability of an equilibrium; estimates of trajectory bounds; estimates of the domain of attraction of an asymptotically stable equilibrium: and stability of neural networks under structural perturbations (arising, e.g. during adaptive learning schemes). The results are not overly conservative. Furthermore, they are in a form which will make them highly useful as constraints in synthesis or design procedures View full abstract»

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  • Stability robustness of two-dimensional discrete systems and its computation

    Page(s): 285 - 288
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    Using the stability criterion of R.A. DeCarlo et al. (1977), a previously proposed measure of stability robustness is extended to the two-dimensional case. An easy-to-use linear algebra type algorithm is developed to accomplish the numerical computation of the proposed robustness measure. In the Roesser's local state-space setting, the measure provides a least conservative upper bound for system's stable perturbations View full abstract»

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  • Self-reconstructing technique for expert system-based analog IC designs

    Page(s): 318 - 321
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    The flexible-architecture approach to expert-system-based analog IC designs is presented. The self-reconstructing technique which uses circuit primitives as replacement parts in a design is described. The expert system used is capable of making an intelligent initial choice among circuits of fixed architecture as well as reconstructing the selected circuit to better satisfy a given set of performance specifications. Software implementation and experimental results are shown to demonstrate the power of the approach View full abstract»

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  • Modifications to the Liang, McClellan and Parks computer program for designing optimal recursive multirate digital filters

    Page(s): 311 - 315
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    A class of recursive digital filters of the form H(z )=A(z)/B(zD) for sampling rate conversion is designed with an iterative Remez exchange algorithm. Simple modifications are made to the Liang, McClellan, and Parks computer program for designing these multirate digital filters. The resulting filters can greatly reduce the multiplication rate and the coefficients memory storage. Some design examples are presented to show the effectiveness of this approach View full abstract»

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  • BIBO stability of inverse 2-D digital filters in the presence of nonessential singularities of the second kind

    Page(s): 244 - 254
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    It is shown that there exist bounded-input bounded-output (BIBO) stable 2-D filter transfer functions having simple nonessential singularities of the second kind on T2, that also admit BIBO stable inverses. A class of such functions is obtained. Another class of BIBO stable 2-D functions that cannot have BIBO stable inverses is also characterized View full abstract»

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  • Simulating general-parameter LC-ladder filters for monolithic realizations with only transconductance elements and grounded capacitors

    Page(s): 299 - 307
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    A generalized approach based on signal flow graph methods for designing continuous-time active signal processing circuits with only transconductance elements and grounded capacitors is presented. For generating active simulations of LC-ladder filters, the methods result in circuits where all transconductors except possibly one are identical, making the approach extremely convenient for monolithic realization with systematic design and dense layout. Although derived for single-ended devices, it is shown how the methods can be extended to designs based on differential input or even fully balanced transconductors. SPICE simulations demonstrate the validity of the approach and practical design aspects are discussed View full abstract»

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  • On network partitioning algorithm of large-scale CMOS circuits

    Page(s): 294 - 299
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    A topological partitioning algorithm which decouples the large-scale CMOS circuits into numerous small-scale subcircuits, in which each subcircuit can be individually analyzed with better overall efficiency, is discussed. The parasitic couplings between the partitioned subcircuits are shown to be negligible in most digital circuits. Bidirectional coupling between cross-coupled subcircuits is studied and a decoupling criterion is derived. The flexibility offered by the decoupled structure can be fully taken advantage of by using: (1) the latency; (2) the event-driven operation; and (3) the regular structure of the partitioned subcircuits. An experimental program, as a result from the partitioning algorithm, demonstrates a three-order-of-magnitude speed improvement over the SPICE program View full abstract»

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  • Chaos from phase-locked loops. High-dissipation case

    Page(s): 255 - 263
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    For pt.I see ibid., vol.35, no.8, p.987-1003, 1988. The numerical calculations of theorem 2 of pt.I which gives the homoclinicity condition for the non-Hamiltonian, i.e. dissipative, unperturbed case, are performed. In particular, many boundary curves which identify the homoclinic tangency and show that there exists a homoclinic orbit above the curves but no homoclinic orbit below them are obtained. Moreover, the associated Poincare maps (obtained by Runge-Kutta-Gill simulation) confirm that the homoclinicity condition predicted from these diagrams is correct. Finally, computer simulation is used to obtain the actual chaotic attractors observed from a very small external sinusoidal force. This corresponds exactly to the experimental results reported in pt.I that the chaotic phenomena observed from actual experiments in pt.I is indeed a horseshoe chaos based on a homoclinic orbit View full abstract»

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  • A generalized expression for the impulse responses of recursive linear time-variant digital filters

    Page(s): 205 - 218
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    Digital filters described by linear time-variant (LTV) difference equations, especially for the general case of time-variant order, are considered. Three notions, i.e. the linearly dependent length for a group of sequences, the lowest time-variant order and the standard form for LTV difference equations, are presented. It is shown that the lowest time-variant order of an LTV difference equation is equal to the linearly dependent length of its linearly independent homogeneous solutions. The properties of an LTV homogeneous difference equation and its homogeneous solutions are investigated. A method to determine one from the other is given. Based on this, LTV homogeneous difference equations have been studied and the general expression for the impulse responses of all the forward recursive LTV digital filters with a finite time-variant order has been determined View full abstract»

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  • Electronic `neural' net algorithm for maximum entropy solutions of ill-posed problems

    Page(s): 288 - 294
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    An ill-posed problem does not provide sufficient information to obtain a unique solution. In such cases, a predetermined strategy must be used to choose a particular solution. A powerful and widely used technique is to select the solution with the maximum informational entropy. Here an algorithm suitable for solving ill-posed problems using the entropy of the solution as a regularizer is described. The algorithm has been simulated on a microcomputer as if implemented in a `neural', i.e. multiply connected, net-type electronic circuit. Two types of problem are considered. First, where the constraints on the solution are hard, as in the loaded-dice problem, the maximum-entropy solution is shown to be achieved in the high gain limit of the net. Second, where the constraints are soft, as in the deconvolution of data corrupted by noise, a maximum-entropy solution is obtained directly. Prior knowledge of the solution is not required but can be introduced to the net so that the cross entropy is used as the regularizer. Finally, issues pertinent to the building of an actual circuit are discussed View full abstract»

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  • A unified approach to the via minimization problem

    Page(s): 190 - 204
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    A unified via minimization approach for two-layer routing of printed circuit boards and VLSI chips is presented. A topological routing strategy for the unconstrained via minimization (UVM) problem is proposed. Both the constrained via minimization (CVM) and the UVM problems are treated under a unified {0,1} linear programming formulation. The proposed practical algorithm can handle both grid-based and grid-less routing. Also, an arbitrary number of wires is allowed to intersect at a via and both Manhattan and knock-knee routings are included in the treatment. Compared with existing algorithms, the proposed algorithm is a unified one and computationally efficient. The time and space complexities of the algorithm are O(nlog n+k) and O(n+k), respectively, where n is the number of layout objects and k is the total number of cross points, knock-knee points and via candidates View full abstract»

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