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Circuit Theory, IEEE Transactions on

Issue 3 • Date May 1972

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Displaying Results 1 - 25 of 25
  • Some properties of two series-connected synchronized van der Pol oscillators

    Publication Year: 1972 , Page(s): 292 - 294
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    The theory of synchronized oscillators which obey the van der Pol equation is extended to include the case of two series-connected oscillators, i.e., a situation where the phases of the oscillations are subject to constraint. A solution is found for the case of identical oscillators, and a perturbation method is used to find the modification required when the oscillators are not identical. Experimental results presented for an interesting special case show good agreement with theory in the range over which the perturbation theory can be expected to be valid. View full abstract»

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  • State equations for improper nonlinear time-varying networks using equivalent sources

    Publication Year: 1972 , Page(s): 294 - 296
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  • Comments on "Parasitics and the Stability of Equilibrium Points of Nonlinear Networks

    Publication Year: 1972 , Page(s): 296 - 297
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  • Synthesis of resistive n-port networks on linear 2-tree port structures

    Publication Year: 1972 , Page(s): 284 - 286
    Cited by:  Papers (2)
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    Some simple necessary conditions for the realizability of n+2 n -ports are given. View full abstract»

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  • Exploiting problem characteristics in the sparse matrix approach to frequency domain analysis

    Publication Year: 1972 , Page(s): 260 - 264
    Cited by:  Papers (8)
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    Most recent papers on sparse matrix methods in circuit analysis are written to describe large problem capability, but usually the illustrations given are for relatively small problems. In this paper a computer program for frequency domain analysis of large RLCM networks is described. It is regularly used on 3000-4000 node networks with many large sets of mutually coupled inductors. Timing and storage figures are given for a 3300 node problem. In the first part, the generation of the admittance description for networks with mutual inductors is described. Then the sparse matrix techniques are discussed. Some are standard, but the unique use of storage utilized in the construction of the LU factorization makes it possible to solve very large problems in a reasonable amount of core storage and time. View full abstract»

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  • Continuously equivalent state variable realizations

    Publication Year: 1972 , Page(s): 286 - 287
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    Suppose one is given two minimal realizations of the same transfer function matrix. The question is asked: When does there exist a family of coordinate transformations defined by a set of nonsingular matrices T(\lambda ) , continuously dependent on \lambda , with T(0) = I and with (1) mapping the state vector associated with one minimal realization into the state vector associated with the other? The quesion is answered, and a procedure is given for constructing the family when it exists. View full abstract»

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  • Characterizations of complete directed trees and two-trees

    Publication Year: 1972 , Page(s): 241 - 247
    Cited by:  Papers (1)
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    This paper presents necessary and sufficient conditions for a directed tree in the associated directed graph of a general network to be nonredundant. Based on these characterizations, new topological formulas for general network functions are presented that will not result in cancellations due to duplications. The relationships between the complete directed trees and two-trees and the complete trees and two-trees of the voltage and the current graphs of the Coates-Mayeda formulation are also discussed. An illustrative example is given. View full abstract»

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  • Bounds on the effective cutoff frequency of linear-phase filters

    Publication Year: 1972 , Page(s): 301 - 302
    Cited by:  Papers (3)
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    The effective cutoff frequency of a filter is defined in terms of the error it introduces. A Chebyshev norm is used to define this error. Easily applied bounds on the effective cutoff frequency are determined for several classes of filters. View full abstract»

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  • Electronically tunable analog active filters

    Publication Year: 1972 , Page(s): 299 - 301
    Cited by:  Papers (8)
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    Electronically tunable RC -active ladder filter transfer functions are realized by employing the four quadrant analogue multiplier as the basic nonlinear network element. All the frequency dependent branches of a conventional RC -active ladder structure realizations are simulated by means of impedance scaling networks. The scaling of these impedances allows the cutoff frequency of an elliptic low-pass or high-pass transfer function, of arbitrary order, to be varied by means of a tuning voltage. The method is strictly analogue and leads to practical filters that employ presently available integrated circuits; external timing signals or reference oscillators are not required in order to accomplish tuning. View full abstract»

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  • On tree graphs of directed graphs

    Publication Year: 1972 , Page(s): 282 - 283
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    A method is presented for the construction of a directed graph whose directed tree graph is an open-edge train of n edges. View full abstract»

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  • Simultaneous asynchronous oscillations in marginal oscillators

    Publication Year: 1972 , Page(s): 271 - 277
    Cited by:  Papers (6)
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    It is shown that a nonlinear active device is able to sustain simultaneous asynchronous oscillations in a linear network of two degrees of freedom. Coexisting oscillations are studied for soft buildup of oscillation and small amplitudes ("marginal oscillator"). In the case considered the even terms of the I-V nonlinear characteristics are to be taken into account, in addition to the usual odd terms. Such an oscillator gives a simple model for the multimode operation of a maser oscillator. View full abstract»

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  • Frequency Domain Stability Criteria for Large-Signal Tuned Common-Base Amplifiers

    Publication Year: 1972 , Page(s): 265 - 270
    Cited by:  Papers (1)
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    The purpose of this paper is to present a rigorous derivation of design criteria which ensure the stability of tuned large-signal common-base amplifiers. Utilization of the Sandberg-Zames circle criterion for stability investigations of nonlinear sytems coupled with an intertwining of the charge storage and excess phase models for a transistor, generates results which disclose the minimum and maximum rate of change of base-to-emitter voltage commensurate with unconditional stability. View full abstract»

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  • Theory of generalized least pth approximation

    Publication Year: 1972 , Page(s): 287 - 289
    Cited by:  Papers (14)
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    A unified discussion of least p th approximation as it relates to optimal computer-aided design of networks and systems is presented. General objective functions are proposed and their properties discussed. The main result is that a wider variety of design problems and a wider range of specifications than appear to have been considered previously from the least pth point of view should now be tractable. View full abstract»

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  • Network synthesis--A state-space approach

    Publication Year: 1972 , Page(s): 227 - 232
    Cited by:  Papers (4)
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    This paper presents the realization of the hybrid parameters of an RLCT network through state-space considerations. Two methods are given to obtain a state model from the hybrid parameters such that the state model is realizable by an RLCT network containing a minimum number of reactive elements and no gyrators. The first method is simpler when a particular matrix generated from the state model is positive semidefinite and the second method is simpler when the state model satisfies certain symmetry conditions. The methods use results obtained by Youla and Tissi, and Anderson and Newcomb. The techniques presented here are nonclassical in that they do not depend directly on the classical methods presented.by Darlington, Bayard, etc. View full abstract»

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  • Cut-set graph and systematic generation of separating sets

    Publication Year: 1972 , Page(s): 233 - 240
    Cited by:  Papers (3)
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    In this paper an efficient method of generating separating sets of a given graph with the use of a newly defined concept-a cutset graph-is discussed. The cut-set graph of a given graph G is defined such that each edge of the graph corresponds to a pair of basic branch cut-sets of G having the relation that the ring sum of these cut-sets coincides with an incident cut-set with respect to a vertex in G . The present paper shows that the cut-set graph is a useful tool for solution of the problem of generating all of the basic vertex cut-sets and the basic mixed cut-sets of a given graph. View full abstract»

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  • Active RC filters containing periodically operated switches

    Publication Year: 1972 , Page(s): 253 - 260
    Cited by:  Papers (6)
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    The state-variable approach to inductorless filters that utilize resistors, capacitors, gyrators, controlled sources or negativeimpedance converters (NIC), and switches suitable for integration is described. By using the state equations of active RC networks in the standard form, it is shown that multiplications of resistances, gyration conductances, transfer coefficients of controlled sources, and NIC in active RC network can be achieved by means of the switching technique. From these results, the relations between the input and the output at signal frequency of active RC filters containing periodically operated switches are derived at the steady state for the case where the switching frequency is much higher than the signal frequency. The results show that the cutoff and the center frequencies of active RC filters are adjustable by changing the ratio of the on duration in a period to the period of switching. The experimental results of low-pass, bandpass, and high-pass filters are shown along with the theoretical curves. View full abstract»

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  • Vulnerability of directed communication nets

    Publication Year: 1972 , Page(s): 283 - 284
    Cited by:  Papers (1)
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  • Steady-state solutions of certain types of differential equations by piecewise linearization

    Publication Year: 1972 , Page(s): 290 - 292
    Cited by:  Papers (1)
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    Two methods are presented for finding steady-state solutions of differential equations of any order governing certain systems that are acted upon by a harmonic force and have one nonlinear element with hysteresis represented by piecewise linearization. Both methods need the solution of a set of linear algebraic equations. In the first method, the unknowns are the Fourier coefficients of the steady-state solution, while in the second method, the unknowns are the values of the derivatives of the steady-state solution at a break point of the piecewise linearized characteristic. In both methods, the unknowns have to be calculated for different values of the time angle at the break point, yielding different corresponding values of the amplitude of the forcing term. The required solution is that consistent with the given amplitude of this forcing term. In the first method, the parameters involved in the multiple-input describing functions of the nonlinear element are unified by normalization. Comparison of the two methods is given, and the advantages of the piecewise linearization of characteristics is discussed. View full abstract»

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  • Spectral analysis of periodically time-varying linear networks

    Publication Year: 1972 , Page(s): 297 - 299
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    Spectral analysis of periodically time-varying lumped linear two-port networks is presented and a general form of the cascade spectral matrix is obtained. View full abstract»

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  • A lower bound for the minimum risetime of bandlimited systems

    Publication Year: 1972 , Page(s): 280 - 282
    Cited by:  Papers (2)
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    It is shown that the risetime T, bandwidth wo, and overshoot e of the step response of a bandlimited system are subject to the inequality \omega _{o} T > -\ln (\sqrt {2\epsilon}) . View full abstract»

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  • A note on equivalent networks

    Publication Year: 1972 , Page(s): 278
    Cited by:  Papers (1)
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    It is shown that the equivalent network in Fig. 1(b) can be derived from the network in Fig. 1(a) by establishing an equivalency transformation matrix T between these networks. View full abstract»

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  • Inductorless filter design using active elements and piezoelectric resonators

    Publication Year: 1972 , Page(s): 247 - 253
    Cited by:  Papers (2)
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    Inductorless active filters using piezoelectric resonators are described. Because of the excellent frequency stability of piezoelectric resonators (quartz crystals in particular), these filters are more suitable for realizing narrow bandwidth responses than are active RC filters which are restricted to relatively low Q applications by the limited tracking capability of the RC components. In addition, because the filters are active, the inductors and transformers which are often required in passive piezoelectric filters are eliminated. View full abstract»

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  • Uniform bounds on input-output difference for restricted systems

    Publication Year: 1972 , Page(s): 280
    Cited by:  Papers (2)
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    Simple bounds on the difference between the input signal and the output signal are given. This difference is uniformly bounded for all time. View full abstract»

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  • Effective bandwidth based on Lipschitz condition

    Publication Year: 1972 , Page(s): 279
    Cited by:  Papers (4)
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    The effective bandwidth of signals which are such that they and/or their derivatives satisfy a Lipschitz condition are obtained. View full abstract»

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  • Least-squares passband filters

    Publication Year: 1972 , Page(s): 302 - 304
    Cited by:  Papers (2)
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    The mathematical properties and design techniques of a novel low-pass filter type are described. A fifth-degree filter is designed, analyzed, and compared with its elliptic counterpart. This evaluation shows that the discrimination, phase, and delay properties of the two circuits are comparable; also, the time response of the proposed filter is substantially similar to that of an elliptic function filter. However, the loss responses are quite different: the loss of the least-squares filter is much less over the lower 90 percent of the passband. As a consequence, it is anticipated that the new circuit is best suited for the filtering of signals having most of their energies at lower frequencies. View full abstract»

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