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Circuits and Systems, IEEE Transactions on

Issue 3 • Date March 1989

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Displaying Results 1 - 24 of 24
  • Orthonormal ladder filters

    Page(s): 337 - 343
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    A state-space structure for the realization of arbitrary filter transfer-functions is presented. This structure should prove useful where integrators are the basic building blocks such as in transconductance-C, MOSFET-C, or active-RC filters. The structure is derived from a singly terminated LC ladder and has the characteristics that it is always scaled for optimum dynamic range and its integrator outputs are orthogonal. For this reason, the resulting realizations are called orthonormal ladder filters. Since dynamic range scaling is inherent to the proposed structure, it is felt that this design technique may be most useful in programmable or adaptive filters. The sensitivity and dynamic range properties of an orthonormal ladder filter are shown to be comparable in performance to the equivalent properties obtained from a cascade of biquads.<> View full abstract»

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  • An algorithm and a pipelined architecture for order-statistic determination and L-filtering

    Page(s): 344 - 352
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    An algorithm is presented for determination of order statistics, based on iterative adaptive thresholding of binary input data on a bit-row basis. It is shown that this algorithm lends itself very well to pipelined implementation and that a parallel pipelined device for L-filtering can be constructed from it, using the idea of a distributed arithmetic FIR (finite impulse response) digital filter. Such a device would be quite useful in image processing, since it would enable an operation which combines attributes of linear filtering with suppression of impulsive noise to be applied to data windows of useful size in real time.<> View full abstract»

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  • Pattern retrieval and learning in nets of asynchronous binary threshold elements

    Page(s): 353 - 364
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    A training algorithm for network of asynchronous learning-threshold elements is presented and analyzed. The algorithm is based on the Hebbian hypothesis, and it allows adaptation of the learning-network parameters to changing pattern environments. In particular, the network's properties can be quantified in environments where pattern occurrence is random, with nonequal, nonstationary probability distributions. The state reassessment probabilities of neurons during information retrieval can also be nonstationary and not equal for all neurons. The trained network is a content-addressable memory. The authors evaluate its stabilization properties with respect to a given set of patterns, using the theory of Markov processes. The results are applicable for the determination of efficient coding for information that has to be stored, and for prediction of actual pattern-retrieval capabilities of the trained network. The authors include the popular sum-of-outer-products assignment as an analyzable specific case of their training procedure, and allow the steady-state analysis of a large group of sigmoidal learning curves.<> View full abstract»

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  • Design of 3-D planar and beam recursive digital filters using spectral transformation

    Page(s): 365 - 374
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    A spectral transformation technique is proposed for the design of three-dimensional (3-D) recursive digital filters having planar and beam frequency responses. Circuit-theoretic concepts are used to generate stable 3-D continuous domain networks from a corresponding one-dimensional (1-D) prototype network. Implementation schemes are developed in the discrete domain that convert the 3-D analog network into a 3-D wave digital filter (WDF). The proposed 3-D discrete beam and planar filters offer significant advantages over direct-form realizations including the low-sensitivity properties of the WDF and simplicity of the structure.<> View full abstract»

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  • Design of N-D digital filters with finite wordlength coefficients

    Page(s): 375 - 382
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    A design technique for N-dimensional (N-D) IIR (infinite impulse response) digital filters is developed. Instead of using optimal step size in jth iteration of Fletcher-Powell algorithm, a suboptimal step size is used to increase the overall computation efficiency. Criteria are developed for the suboptimal step size to keep the mapping matrix D/sub j/ positive definite and to ensure the stability of the transfer function. The approach does not require checking the positive definiteness of the mapping matrix D/sub j/ or the stability of the filter. A optimization algorithm with finite-wordlength coefficients is developed. The algorithm minimizes the performance error caused by truncating the filter coefficients to a specified number of bits and provides a means for finding the smallest number of bits that results in an acceptable error. Two examples of 2-D digital filters are designed by the proposed technique.<> View full abstract»

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  • Stability testing of 2-D recursive digital filters based on a circuit-theoretic approach

    Page(s): 387 - 392
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    A procedure for checking the stability of 2-D digital filters is proposed. The key part of the test involves construction of related all-pass sections of reduced order, the stability of which is shown to be equivalent to the stability of the original function. This is a direct extension of a similar approach, developed recently (1987) by P.P. Vaidyanathan and S.K. Mitra, in detail for the 1-D case. The results are shown to be equivalent to some known stability testing methods in 2-D, but have the advantage of an additional insight gained from the circuit interpretation. Explicit formulas for checking the stability in terms of the filter coefficients are derived for some special cases, and numerical examples are included to clarify the application of the proposed approach.<> View full abstract»

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  • Integral manifold as a tool for reduced-order modeling of nonlinear systems: A synchronous machine case study

    Page(s): 403 - 410
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    A discussion is presented of the use of integral manifolds as a tool for reduced-order modeling in nonlinear systems. It specifically addresses its application to synchronous machine modeling. Not only does the integral manifold approach contribute to the understanding of the origin and validity of reduced-order models, but it also produces a systematic reduction procedure. While illustrated on a synchronous machine case study, the method has broad applications in a wide class of nonlinear dynamic systems.<> View full abstract»

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  • A method for obtaining a canonical Hamiltonian for nonlinear LC circuits

    Page(s): 411 - 420
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    A method is presented for obtaining the Hamiltonian and the proper canonical variables that is both very general and simple. A tree of capacitors is used to write the state equations for an LC circuit with independent sources, and transformations to canonical variables are generated from the circuit topology by considering an alternate tree (cotree) containing as many inductors (capacitors) as possible. A method is given to obtain these transformations by inspection, based on fundamental loops and cutsets of both the capacitor and alternate trees. When the nonlinearities in the capacitors and inductors are small, a change of coordinates is given to achieve complete separation of the canonical variables of the unperturbed (linear) system. These results should allow the application of techniques from Hamiltonian dynamics, such as canonical perturbation theory, to circuits.<> View full abstract»

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  • Class C-E high-efficiency tuned power amplifier

    Page(s): 421 - 428
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    A numerical analysis of a Class C-E tuned power amplifier is presented, along with a design procedure and experimental results. The efficiency and the maximum operating frequency of the amplifier are intermediate between those of the Class C and E amplifiers. The collector efficiency of the Class C amplifier is about 70%, whereas that of the Class E amplifier is about 96%. The maximum operating frequency of the optimum-efficiency Class E amplifier is, however, limited by the transistor output capacitance. The operating frequency of the Class C amplifier can be at least 16 times higher than that of the optimum-efficiency Class E amplifier at the same output power, DC supply voltage, and transistor output capacitance. The Class C, E, and C-E amplifiers can be obtained with the same circuit topology. The class of operation depends on the values of the load-network components. The tradeoff between the efficiency and the maximum operating frequency is evaluated for all three classes, using nonlinear time-domain simulation. The experimental and theoretical results are in good agreement.<> View full abstract»

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  • Frequency-domain modeling of continuous-time systems using the lattice algorithms

    Page(s): 429 - 433
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    Two frequency-domain methods for modeling continuous-time system using the lattice algorithms are presented. In one of the methods, the frequency-domain data are sampled at a nonuniformly spaced frequency grid. This method is suitable for applications where the frequency response of the continuous-time systems can be measured explicitly. In the other method, the frequency-domain data are sampled at a uniformly spaced frequency grid. This method is suitable for applications where the frequency spectrum of the input and output signals are computed from the input and output time-domain data using the FFT (fast Fourier transform).<> View full abstract»

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  • Constant-input stability and multiple-output realization of the GIC digital filters

    Page(s): 433 - 438
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    The constant-input stability of the generalized immitance converter (GIC) digital filter structures proposed by A. Antoniou and M.G. Rezk (1978) is investigated. This stability is essential for these structures since they are used in cascade form. It is shown that only one of the five sections previously proposed can be stabilized against constant-input limit cycles. It is also shown that each one of those five sections can be made to realize multiple transfer functions without any additional multiplier. A universal filter based on the GIC concept is proposed which realizes simultaneously all the five standard second-order transfer functions and which is also free from both zero- and constant-input limit cycles. The sensitivity and noise properties of the proposed universal filter are compared with those of other known universal structures for a specific example.<> View full abstract»

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  • Reduced sensitivities of direct form digital (sub) filter structures by increasing system order

    Page(s): 438 - 442
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    A reasonable coefficient sensitivity measure for state-space recursive, finite-wordlength digital filters is the sum of the L/sub 2/ norm of all first-order partials of the system function with respect to the system parameters. This measure is actually a lower-bound approximation to the output quantization noise power. The authors show that an important feature of this measure is that it can be broken down into evaluations of ARMA (autoregressive moving-average) auto-and cross-covariance sequences, all of which can be done efficiently and in closed form. The direct-form II sensitivity, which is shown to be approximately inversely proportional to the sum of products of system pole and zero distances, can usually be reduced by the judicious placement of added pole/zero cancellation pairs. These cancellation pairs provide extra degrees of freedom, which are used to minimize the sensitivity measure while not affecting the system function. The filter still has the direct-form II structure. A gradient-based method for sensitivity minimization is given. Some examples show its effectiveness.<> View full abstract»

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  • Parallel and pipeline architectures for 2-D block processing

    Page(s): 443 - 448
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    The authors are concerned with the development and design of parallel and pipeline architectures for 2-D recursive and nonrecursive block digital filters. In this regard, several high-speed structures using single-instruction multiple-data stream (SIMD) machines have been developed. The design of these structures is based on the specific nature of the block convolution processor, block recursive processor, and block state-space processor at both the block and scalar levels.<> View full abstract»

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  • Digital filters design by simulated annealing

    Page(s): 459 - 460
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    Presents preliminary results on the application of the simulated annealing (SA) algorithm to solve the general discrete coefficients filter design problem. The main characteristics of the approach taken with respect to optimal algorithms is that no particular assumptions are made on the filter structure or the cost function. With respect to heuristic methods, no particular starting point is needed, and no heuristics have to be invented for the design problem. The conclusion is that the approach is very versatile and have a very simple implementation: only the cost function and a few pieces of information need to be supplied. The main drawback is its high computational cost, which is one or two orders of magnitude more than conventional methods.<> View full abstract»

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  • Simplified pseudo-N-path cells for z to -z/sup N/ transformed SC active filters

    Page(s): 461 - 463
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    Two switched-capacitor (SC) cells for simple design of bandpass active filters from reference lowpass filters are presented. The pseudo-N-path approach used is based on the z to -z/sup N/ transformation. An elliptic sixth-order symmetric bandpass filter with center frequency of 200 kHz and 0.2 dB in-band ripple within a bandwidth of 2 kHz has been designed. The basic lowpass differential topology has been derived using flowgraph techniques from a C03 to 10 21 degrees passive prototype. Presently such a filter is under integration in a 3- mu m double poly CMOS technology.<> View full abstract»

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  • A further simplification to Jury's stability test

    Page(s): 463 - 464
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    Consideration is given to R.H. Raible's table (1974), which is a simplified version of E.I. Jury's discrete stability test. It is explicitly shown that Raible's table is none other than the classical Schur algorithm performed on a certain scattering function. This directly leads to an interpretation of Raible's table as a continued fraction expansion. The connection between Raible's table and the fast triangular factorization of the Schur-Cohn matrix is given.<> View full abstract»

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  • Matching properties of linear MOS capacitors

    Page(s): 465 - 467
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    Various random error mechanisms which affect the matching of MOS capacitors have been studied in a systematic manner. For the dimensions and technology considered, normalized random error in capacitor-ratio has been observed to have an inverse square-root dependence on the capacitor-area, a linear dependence on the perimeter-to-area ratio, and a very weak dependence, n/sup 16/, on the capacitor-ratio n. Increasing the intercapacitor gap slows down its dependence on n.<> View full abstract»

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  • Degree, ripple, and transition width of elliptic filters

    Page(s): 469 - 472
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    Simple analytic formulas inverting the degree education in both analog and digital equiripple filter approximations are presented. The inversion of the degree equation which is usually expressed as a ratio of theta functions, known in classical mathematics as a modular equation, is obtained in form of a finite product of Jacobian functions. From the numerical point of view it allows the recalculation of the parameters which control the optimization using an efficient arithmetic-geometric-mean procedure only. For the evaluation of k/sub 1/ from n and K (k', respectively) the zeros of the characteristic function are used and no additional computation is required.<> View full abstract»

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  • Lattice implementation of two-dimensional recursive digital filters

    Page(s): 383 - 386
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    The implementation of a quarter-plane autoregressive 2-D filter using a developed 2-D Levinson algorithm is presented. The resulting structure inherits most of the desirable characteristics of the 1-D lattice filter, such as high modularity, low coefficient sensitivities, low roundoff noise, and elimination of internal overflow. The low sensitivity of the structure is shown by numerical examples View full abstract»

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  • On the number of solutions of piecewise-linear resistive circuits

    Page(s): 393 - 402
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    Topological conditions are proved which allow an upper bound to be found for the number of DC operating points of a piecewise-linear circuit. The circuits may be nonreciprocal. The conditions amount to checking whether certain voltage and current orientations exist on the graph of the circuit. This can be implemented on a computer and it can be used for designing piecewise-linear circuits with prescribed DC operating points View full abstract»

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  • Effective bandwidth of 2-D functions that can be expressed as a linear combination of orthogonal functions

    Page(s): 452 - 454
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    The authors investigate bounds on the two-dimensional function f(x,y) that can be expressed as a linear combination of an orthogonal set of functions {qnm( x,y)} in the mean. Each function qnm (x,y) has the property of being separable. Each of these functions is bandlimited. Effective bandwidth expressions are derived on the basis of a given error criterion View full abstract»

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  • Roles of corners in matching of linear MOS capacitors

    Page(s): 467 - 469
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    Statistically highly significant improvement in matching MOS capacitors has been observed for a cornerless structure in which photolithographically defined corners are avoided. For the considered dimensions and technology, the improvement in matching is by a factor of two. This amounts to an economy of the silicon area by a factor of four in switched-capacitor, A/D (analog-to-digital), and D/A converter applications View full abstract»

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  • Synthesis of recursive LTV digital filters using the frozen-time approximation

    Page(s): 448 - 451
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    A reexamination is made of the frozen-time approximation (FTA) for the synthesis of recursive linear time-varying (LTV) digital filters. While the use of the FTA has been discouraged, analysis shows that this approach is still valuable. Improvements on the FTA are proposed that take advantage of the simplicity of the frozen-time approach, being based on the assumption that for any desired LTV filter there exists a related filter whose FTA produces a better realization of the desired filter than its own FTA. Methods of finding such a related filter are discussed. The resulting filters are superior in performance to those obtained by the currently available optimization techniques at a fraction of the computational load View full abstract»

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  • Boundary implications for interval positive rational functions

    Page(s): 454 - 458
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    Positive rational functions have provided the foundation supporting the realizability theory of electrical networks. In practice, it is meaningful to provide each coefficient value with a lower and an upper bound so that the interval rational functions set up be associated in parameter space by a multidimensional boxed domain. The boundary implications for the positive real (complex) property to hold for all rational functions associated with the box are formulated in terms of the validity of the same property on a small subset of the extreme functions associated with a correspondingly small subset of vertices of the box. The results, therefore, generalize recent contributions on boundary implications of stability properties and also strict positive realness View full abstract»

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