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Circuits and Systems, IEEE Transactions on

Issue 12 • Date December 1986

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Displaying Results 1 - 10 of 10
  • Sidney Darlington is 80 years old

    Publication Year: 1986 , Page(s): 1157 - 1158
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  • Eigenvalue spectra and bounds for certain classes of dynamic systems having tree bond graphs

    Publication Year: 1986 , Page(s): 1232 - 1240
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    For a class of linear, time-invariant dynamic systems, information about the eigenvalues of the system can be obtained directly from a graphical model of the system, namely the bond graph model. In contrast to the standard approach, which starts from the state matrix of the system, we use a canonical form of the bond graph, namely the gyrobondgraph, to estimate bounds on the eigenvalues of the associated system. For some special cases, the entire spectrum of the system can be obtained by comparing the graph structure to existing graphs with known spectra. For more general cases, bounds are obtained on the largest real and imaginary parts of the eigenvalues as functions of the system's gyrobondgraph topology and its parameters. For some classes of systems, we present a simple graph-based recurrence formula for deriving the characteristic polynomial of a system from a simplified form of its gyrobondgraph. These results, when suitably automated, can reduce the time required to estimate the system performance. View full abstract»

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  • Generalized approximation techniques for selective linear-phase digital and nonreciprocal lumped filters

    Publication Year: 1986 , Page(s): 1159 - 1169
    Cited by:  Papers (11)
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    The paper presents expressions for low-pass digital filter transfer functions with finite-band approximation to constant amplitude and delay in the passband, together with an arbitrary number of transmission zeros at half the sampling frequency. The corresponding high-pass filter transfer functions can be obtained by a transformation. The available degrees of freedom can be divided arbitrarily between the passband and stopband responses. The functions are of the nonminimum-phase type, and the corresponding nonreciprocal analog (continuous) filters are also covered; these can be realized in standard active RC structures. The zero-bandwidth cases are obtained, either directly or as limiting cases of the finite-band ones. It is also indicated that there is an upper bound on the number of transmission zeros which may be introduced while maintaining the stability of the filter for a given degree. The technique represents the most comprehensive one available for the solution of the combined amplitude and phase approximation problem, and leads to a large family of stable transfer functions. View full abstract»

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  • Theory and design of uniform DFT, parallel, quadrature mirror filter banks

    Publication Year: 1986 , Page(s): 1170 - 1191
    Cited by:  Papers (31)  |  Patents (1)
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    In this paper, the theory of uniform DFT, parallel, quadrature mirror filter (QMF) banks is developed. The QMF equations, i.e., equations that need to be satisfied for exact reconstruction of the input signal, are derived. The concept of decimated filters is introduced, and structures for both analysis and synthesis banks are derived using this concept. The QMF equations, as well as closed-form expressions for the synthesis filters needed for exact reconstruction of the input signal x(n) , are also derived using this concept. In general, the reconstructed. signal \hat{x}(n) suffers from three errors: aliasing, amplitude distortion, and phase distortion. Conditions for exact reconstruction (i.e., all three distortions are zero, and \hat{x}(n) is equal to a delayed version of x(n)) of the input signal are derived in terms of the decimated filters. Aliasing distortion can always be completely canceled. Once aliasing is canceled, it is possible to completely eliminate amplitude distortion (if suitable IIR filters are employed) and completely eliminate phase distortion (if suitable FIR filters are employed). However, complete elimination of all three errors is possible only with some simple, pathalogical stable filter transfer functions. In general, once aliasing is canceled, the other distortions can be minimized rather than completely eliminated. Algorithms for this are presented. The properties of FIR filter banks are then investigated. Several aspects of IIR filter banks are also studied using the same framework. View full abstract»

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  • On Complimentary and sensitivity of generalized wave digital filters

    Publication Year: 1986 , Page(s): 1244 - 1248
    Cited by:  Papers (1)
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    In recent literature, a general theory has been developed to design low-sensitivity digital filter structures in the z -domain. These structures are two-ports with two inputs and two outputs and wave digital filters belong to this general class. This paper explores the significance of the para-unitary or complementary condition on generalized wave digital filters. Satisfying this condition allows, for example, the simultaneous generation of low- and high-pass filter outputs. There is discussion too of sensitivity and its significance to those generalized wave digital filter structures that do not satisfy the para-unitary condition. View full abstract»

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  • System Semantics and formal circuit description

    Publication Year: 1986 , Page(s): 1219 - 1231
    Cited by:  Papers (5)
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    This paper introduces the concept of system semantics, an extension of the denotational theory of programming languages to the description of arbitrary systems. For a given formal description, different meaning functions describe different properties of interest concerning the system, e.g., structure, behavior, performance. The meaning functions can be made sufficiently simple to serve equally well as rules for formal reasoning and as an actual system description language (SDL) implementation. These principles are first demonstrated in the area of digital systems, which represent the class of systems with unidirectional information flow, and subsequently in the area of analog circuits, where information flow is bidirectional. It is shown how semantic functions can be used to derive properties, ranging from general theorems of circuit theory, expressed as conversion rules in the language, to special conditions for particular circuits, expressed as equations in the meta-language. View full abstract»

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  • Design of state-variable SC filters by means of polynomial transformation

    Publication Year: 1986 , Page(s): 1248 - 1251
    Cited by:  Papers (8)
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    A simple polynomial transformation is presented which permits efficient computation of SC state-variable coefficients directly from Z -domain specifications. The algorithm relies merely upon synthetic division. The technique is applied to synthesize a fourth-order elliptic filter using only forward difference integrators (FDI), or, alternatively, only backward difference integrators (BDI). A specific state-variable topology, the so-called observer canonical form, was chosen; the technique, however, is more generally applicable. The use of a single SC integrator topology permits a significant reduction in the number of switches. Experimental results are presented which demonstrate the practical utility of the method. View full abstract»

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  • Realizations of 2-D filters and time delay systems

    Publication Year: 1986 , Page(s): 1241 - 1244
    Cited by:  Papers (9)
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    Possible techniques for achieving an absolutely minimal realization of an input/output system described by a matrix of rational functions in two indeterminates are described. View full abstract»

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  • Floating-point error analysis of recursive least-squares and least-mean-squares adaptive filters

    Publication Year: 1986 , Page(s): 1192 - 1208
    Cited by:  Papers (20)
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    A floating-point error analysis of the Recursive LeastSquares (RLS) and Least-Mean-Squares (LMS) algorithms is presented. Both the prewindowed growing memory RLS algorithm (\lambda = 1) for stationary systems and the exponentially windowed RLS algorithm (\lambda < 1) for time-varying systems are studied. For both algorithms, the expression for the mean-square prediction error and the expected value of the weight error vector norm are derived in terms of the variance of the floating-point noise sources. The results point to a tradeoff in the choice of the forgetting factor \lambda . In order to reduce the effects of additive noise and the floatingpoint noise due to the inner product calculation of the desired signal, \lambda must be chosen close to one. On the other hand, the floating-point noise due to floating-point addition in the weight vector update recursion increases as \lambda \rightarrow 1 . Floating point errors in the calculation of the weight vector correction term, however, do not affect the steady-state error and have a transient effect. For the prewindowed growing memory RLS algorithm, exponential divergence may occur due to errors in the floatingpoint addition in the weight vector update recursion. Conditions for weight vector updating termination are also presented for stationary systems. The results for the LMS algorithm show that the excess mean-square error due to floating-point arithmetic increases inversely to loop gain for errors introduced by the summation in the weight vector recursion. The calculation of the desired signal prediction and prediction error lead to an additive noise term as in the RLS algorithm. Simulations are presented which confirm the theoretical findings of the paper. View full abstract»

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  • Idealized Operation of Class E Frequency Multipliers

    Publication Year: 1986 , Page(s): 1209 - 1218
    Cited by:  Papers (33)
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    The theoretical performance of class E frequency multipliers described by Kozyrev bears little resemblance to the observed performance of such circuits. This paper provides a new analysis of idealized class E frequency multipliers similar to that used by Raab in his description of class E amplifiers, in that the equations describing multiplier operation are obtained from Fourier series methods and the assumption of an infinite output network Q . The equations so obtained are used to determine 1) optimum operation (maximum power output capability at 100-percent efficiency) at any harmonic, and 2) design equations that yield the requisite component values for optimum operation. The equations provide an easily used design method for optimum class E multipliers but allow the implementation of nonoptimum multipliers to suit any design objective. Class E multipliers with moderate values of output network Q were constructed and tested. The measured performance of these experimental circuits shows excellent agreement to the theoretical performance predicted by the equations. View full abstract»

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