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Circuits and Systems I: Fundamental Theory and Applications, IEEE Transactions on

Issue 10 • Date Oct 1994

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Displaying Results 1 - 9 of 9
  • On equivalent forms of single op-amp sinusoidal RC oscillators

    Page(s): 617 - 624
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    It has been known that a given single op-amp RC sinusoidal oscillator has four distinctly different, equivalent, stable forms, This paper shows that with the op-amp replaced by a four terminal floating nullor, the number of such equivalent realizations of any given single op-amp oscillator are much more than four. Through some examples it is demonstrated that some of such additional realizations of a given op-amp oscillator, are likely to have some interesting properties not available in the usually derived four equivalent forms of the same oscillator, The theory is supplemented with examples and verified by SPICE simulations and experimental results View full abstract»

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  • A geometric approach to properties of the discrete-time cellular neural network

    Page(s): 625 - 634
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    Using the available theory on linear threshold logic, the Discrete-Time Cellular Neural Network (DTCNN) is studied from a geometrical point of view, Different modes of operation are specified. A bound on the number of possible mappings is given for the case of binary inputs. The mapping process in a cell of the network is interpreted in the input space and the parameter space. Worst-case and average-case accuracy conditions are given, and a sufficient worst-case bound on the number of bits required to store the network parameters for the case of binary input signals is derived. Methods for optimizing the robustness of DTCNN parameters for certain regions of the parameter space are discussed View full abstract»

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  • Rate optimal scheduling of recursive DSP algorithms by unfolding

    Page(s): 672 - 675
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    We propose a novel criterion called modified generalized perfect rate graph (MGPRG) to facilitate efficient synthesis of recurrent digital signal processing (RDSP) algorithms on application specific multiprocessor systems. We prove that a rate optimal schedule, which is a multiprocessor realization with maximum throughput rate, exists if and only if the dependence graph of the corresponding RDSP algorithm is unfolded sufficient number of times to satisfy the MGPRG condition. We show that MGPRG is a more general and unified criterion compared to earlier proposed criteria. An advantage of MGPRG is that the original algorithm needs not to be unfolded too many times before it can be guaranteed to have a rate optimal schedule. Consequently, the resulting MGPRG will consist of fewer nodes and edges, making it easier to find the rate optimal schedule View full abstract»

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  • An energy function method for determining voltage collapse during a power system transient

    Page(s): 635 - 651
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    The occurrence of a voltage collapse is often described as a small-signal stability problem resulting from a bifurcation of the equilibrium load flow equations as the bus loads and generator power injections incur small changes. However, during a transient period, a voltage collapse may occur as a bifurcation of the transient load flow equations as the generator rotor angles vary. The purpose of this paper is to address voltage collapse in the general context of a transient stability problem for a differential algebraic equation (DAE) power system model. In particular, we define a stability region that guarantees both rotor angular stability and voltage stability. The stability region does not intersect the “impasse surface,” the surface on which the bus voltage variables are not defined as functions of the generator rotor angles. Bifurcation theory is used along with some recent results that characterize the stability boundary for DAE models, to show that an important component of the stability boundary is formed by the trajectories that are tangent to the impasse surface at a fold bifurcation point. An energy function transient stability method is developed that uses a sustained fault trajectory to find the first point of intersection with the impasse surface and then involves solving for the (stability) limiting trajectory that is tangent to the impasse surface at this point. This new transient stability method is somewhat similar in theory to the potential energy boundary surface method. Also, this method can be extended to develop stability estimates for power system models in which the stability region is more complex, possibly constrained by line power flow limits, voltage magnitude limits, etc View full abstract»

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  • Iterative solution of linear equations

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    The problem of iteratively solving linear equations of the form Ax = b, for a solution x, given b and an operator A, arises in several contexts in the circuits and systems area. The author presents a theorem for the iterative solution of such linear equations View full abstract»

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  • Interaction of low- and high-frequency oscillations in a nonlinear RLC circuit

    Page(s): 669 - 672
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    The interaction of low- and high-frequency oscillations in an RLC circuit with a nonlinear capacitance is studied from the point of the modern theory of dynamical systems. It is found that for a certain range of parameters such an interaction may cause chaotic instability, even under the weakly nonlinear excitation conditions. The scenarios and conditions that give rise to chaotic oscillations are investigated both numerically and analytically View full abstract»

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  • On a Lyapunov approach to stability analysis of 2-D digital filters

    Page(s): 665 - 669
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    This paper describes an approach to the stability analysis of two-dimensional (2-D) digital filters that are modeled in the Fornashni-Marchesini state space using a class of generalized 2-D Lyapunov equations, the generalization was made based on the constant 2-D Lyapunov equation proposed recently by Hinamoto (see ibid., vol. 40, no. 2, p. 102-10, 1993). It is shown that the use of the generalized Lyapunov equations narrows the gap between “sufficiency” and “necessity” for a state-space digital filter to be stable, which occurs in Hinamoto's Lyapunov theorem. Feasible methods for finding numerical solutions of the generalized 2-D Lyapunov equation are also proposed. An example is included to illustrate the main results of the paper View full abstract»

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  • Hybrid MOS-bipolar transistor switching with profiled drive signal

    Page(s): 662 - 665
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    A method for switching MOS-bipolar transistor hybrids has been developed, which improves the transition performance and minimises the base drive power requirements in a split Darlington configuration with low on-state voltage. The type of wave shaping of the input control signal, enables unusually small and high speed MOSFETs to drive exceptionally high base current pulses for fast turn-on of a bipolar power transistor. Since bipolar over-saturation is avoided, the turn-off is also improved View full abstract»

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  • Sliding mode control of DC-to-DC power converters via extended linearization

    Page(s): 652 - 661
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    The method of extended linearization is proposed for the systematic solution of sliding mode controller design in DC-to-DC power converters of the boost and the buck-boost type. A nonlinear sliding surface with suitable stabilizing properties is synthesized on the basis of the extension of a linear sliding design carried out for the parametrized average linear incremental model of the converter. The obtained feedback strategies lead to asymptotically stable sliding modes with remarkable self-scheduling properties. Simulation examples are presented for illustrative purposes View full abstract»

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