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

Issue 9 • Date Sep 1996

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Displaying Results 1 - 18 of 18
  • Globally optimal floorplanning for a layout problem

    Page(s): 713 - 720
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (760 KB)  

    In this paper, the floorplanning problem for a layout problem is formulated as a global optimization problem. The area of each building block is assumed to be fixed. However, its width and height are allowed to vary subject to aspect ratio constraints. Also, a block may be arbitrarily oriented in parallel to the xy orthogonal axes, subject to partition constraints with associated adjacency relationships. The objective is to minimize the rectangular area of the entire layout. By formulating the problem appropriately, it becomes a geometric programming problem. Its global minimum can then be found by using standard convex optimization techniques. The problem formulation and its conversion to a convex optimization problem are first illustrated through a simple example. The general procedure is then described and the effectiveness of the approach demonstrated through numerical examples View full abstract»

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  • Coprime factorizations of parallel, cascade, feedback interconnections

    Page(s): 813 - 814
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    Doubly coprime factorizations of the transfer-functions of parallel, cascade, and feedback system interconnections are derived algebraically, extending the results of previous work on parallel interconnections. The factors of these doubly coprime representations derived here are important in characterizing all stabilizing controllers for these interconnections View full abstract»

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  • Linear conjugacy of vector fields in Lur'e form

    Page(s): 782 - 785
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (368 KB)  

    We show that the behavior of a class of n-dimensional systems having vector fields in Lur'e form is uniquely determined by their eigenvalue patterns. The construction of a canonical system that retains almost all features of vector fields in Lur'e form having the same eigenvalue pattern is given View full abstract»

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  • Buck converter with a new driving circuit in a TV power system

    Page(s): 811 - 813
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (276 KB)  

    In this letter, a new buck converter of a TV power system is presented. First, we devised a driving circuit for an emitter-coupled type buck converter, by which it is possible to reduce the material cost of transformers and voltage stress of power device. Second, we adopted a hybrid oscillation technique. After self-oscillating mode feeds initial standby power, main power is provided by a forced oscillating mode and switching frequency is synchronized to that of horizontal deflection, which results in reducing picture noises and the size of power transformer. Third, a simple error amplifier is added in the feed-back loop to keep the output voltage constant. Finally, we showed that experimental values of our proposed converter agree well with the theoretical values View full abstract»

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  • Analysis and design of a current-driven two-inductor ZCS low diD/dt full-wave rectifier

    Page(s): 745 - 759
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1164 KB)  

    An analysis and experimental verification of a current-driven two-inductor zero-current-switching (ZCS) low diD/dt full-wave rectifier are given. The design equations are derived using the time-domain analysis and Fourier series technique. The rectifier operates as a full-wave rectifier with two diodes and a one-secondary winding transformer overcoming the limitations of class D current-driven full-bridge and center-tapped rectifiers and preserving their advantages. The rectifier operates with lower conduction losses than the center tapped rectifier. Moreover, the diodes turn on at zero diD /dt, low dνD/dt, and turn off at low diD/dt. As a consequence, switching losses are reduced and this rectifier is suitable for a high-frequency and high-efficiency operation. Integrated inductors can be used to reduce the size, volume, and cost of the circuit. A breadboard of the rectifier was designed and tested for a constant output voltage V0=12 V, and an output current I0 ranging from no-load to 12 A. The rectifier was driven by an off-line AC-AC converter operated at an input r.m.s. voltage varying from 176-270 V and a minimum frequency of 550 kHz. The predicted results are in good agreement with those measured. A full-load efficiency of 89.4% was achieved for the entire AC-DC converter View full abstract»

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  • Limitation of delayed feedback control in nonlinear discrete-time systems

    Page(s): 815 - 816
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    Recently, Pyragas [1993] proposed a control method called delayed feedback control to stabilize unstable periodic orbits in nonlinear continuous-time systems. In this letter, we consider delayed state-feedback control in discrete-time systems. We show that a fixed point can not be stabilized by the delayed state-feedback control if the linearized system around the fixed point has an odd number of real eigenvalues greater than one. Moreover, in one- and two-dimensional systems, we show necessary and sufficient conditions for the local stabilization by the delayed state-feedback control View full abstract»

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  • 1.5 V full-swing BiCMOS dynamic logic circuits

    Page(s): 760 - 768
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (728 KB)  

    This paper presents the design of BiCMOS dynamic logic circuits that are capable of full-swing operation from low supply voltages down to 1.5 V. Basic full-swing low-voltage BiCMOS cells are introduced. These include emitter-follower complementary n-type cell, quasi-complementary n-type cell and a p-type cell based on the transiently saturated full-swing technique. The propagation delay, power consumption and the full-swing capability of such cells have been studied both at the cell level and in a 4 b CLA design. The results clearly show the validity of the proposed circuits for high-speed low-voltage operation View full abstract»

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  • A continuously variable tuning technique for switched capacitor filters

    Page(s): 798 - 800
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    A new tuning technique for SC filters is described which allows separate, continuous tuning of centre frequency and Q. Feedforward control is used with this arrangement and so the complexities and hence cost of feedback control are largely avoided. Measured results from a discrete component model are provided View full abstract»

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  • Secure communication via chaotic parameter modulation

    Page(s): 817 - 819
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    In this letter, we extend chaotic switching to general chaotic parameter modulation. By using adaptive controller, synchronization between transmitter and receiver is maintained and message signal is recovered. Computer simulation results are given View full abstract»

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  • A rational formulation of thermal circuit models for electrothermal simulation. II. Model reduction techniques [power electronic systems]

    Page(s): 733 - 744
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (912 KB)  

    For pt. I see ibid., vol. 43, no. 9, p. 721-32 (1996). To increase the efficiency of the electrothermal simulation of power electronic circuits and devices, model reduction techniques are applied to develop reduced thermal circuit models of Si chips, thermal packages, and heat sinks. Both the Modal Superposition method and a Component Mode Synthesis method are presented together with a model error estimation and a Ritz vector method. An alternative method for substructuring is also included. The reduced thermal circuit models are verified and implemented in the SABER circuit simulator. The electrothermal model of a full-bridge converter is simulated employing the proposed approach, and the results discussed View full abstract»

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  • A precision control circuit for variable-gain amplifiers

    Page(s): 779 - 782
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (348 KB)  

    The author describes a circuit that precisely controls the gain of one or more single-ended amplifiers by means of a corresponding number of Gilbert quads. The circuit employs a configuration consisting of a differential pair with two negative feedback loops and is used in conjunction with a precision potentiometer to generate a DC gain-control voltage as a function of its setting. The gain-control characteristic accurately mimics the potentiometer's function of resistance versus wiper position to achieve a control range in excess of 55 dB. Experimental results are provided for the frequency response and the gain-control characteristic of the amplifiers View full abstract»

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  • Stability analysis of Hill systems

    Page(s): 794 - 797
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (300 KB)  

    The author shows that the (α, β)-plane stability boundaries of the Hill equation, x¨+[α+βf(t)]x=0, f(t)=f(t+T), (which governs the behavior of many physical and engineering systems) can be obtained in a simple fashion by first evaluating a series of constants that depend only on f(t). Definite integral expressions of order k, k=1,2,..., are given that allow one to evaluate the kth constants explicitly for a given f(t). For square, triangular and cisoidal f(t)'s, these constants have been evaluated upto k=6, and the corresponding stability boundaries drawn View full abstract»

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  • A rational formulation of thermal circuit models for electrothermal simulation. I. Finite element method [power electronic systems]

    Page(s): 721 - 732
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (872 KB)  

    As the size of the semiconductor devices is getting smaller with advanced technology, self-heating effects in power semiconductor devices are becoming important. An electrothermal simulation of complete power electronic systems that include Si chips, thermal packages, and heat sinks is essential for an accurate analysis of the behavior of these systems. This paper presents a rational approach to construct thermal circuit networks equivalent to a discretization of the heat equation by the finite element method. Elemental thermal circuit networks are developed, which correspond to the linear and cubic Hermite elements in the 1-D case, to the triangular and rectangular elements in the 2-D case, and to the tetrahedral and cube elements in the 3-D case. These thermal circuit networks are to be connected to the electrical networks of power electronic systems to provide complete electrothermal models that can be conveniently used in any circuit simulator package. Verification examples are presented to demonstrate the accuracy of the proposed formulation View full abstract»

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  • Energy recovery circuits using reversible and partially reversible logic

    Page(s): 769 - 778
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (948 KB)  

    This paper presents a new family of logic gates for low energy computing using pulsed power CMOS logic. The logic gates use the principles of adiabatic-switching and results show that in typical cases 90% of the energy can be recovered with operating frequency around 1 MHz. Constant capacitance condition is enforced in our designs so that signals' energy can be efficiently recycled in the chip. We also present a detailed analysis and modeling of energy dissipation in adiabatic circuits. The models were experimentally validated using the circuit simulator SPICE. A simplified version of adiabatic logic with simplicity comparable to static CMOS circuits is also presented. For a 2×2 multiplier using this type of logic, 60% of energy can be saved over static CMOS case at 20 MHz and there is 35% less energy consumption at 100 MHz View full abstract»

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  • Factorization of high degree polynomials-a numerical solution

    Page(s): 792 - 794
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (276 KB)  

    An algorithm based on the least-squares solution for overdetermined linear equations is presented. It is shown that a general polynomial of 2M° can almost always be factored into two halves each with a degree M. Polynomials with odd degrees can be factored by introducing one extra zero root View full abstract»

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  • A new approach for the design of digital integrators

    Page(s): 785 - 791
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (432 KB)  

    A new method is proposed for the design of digital integrators. The new method is based upon the formulation of an appropriate linear programming problem which assures a satisfactory minimax approximation error for the magnitude response in a predefined frequency range. In comparison with existing methods the new design approach constructs a novel class of digital integrators by optimal determining more than one independent coefficients. Their capability to approximate in the minimax sense the ideal integrator with a good accuracy is shown. Well-known integrators can be obtained as special cases of the proposed methodology. Appropriate constraints can be introduced to accommodate signals with low frequencies View full abstract»

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  • Risk-sensitive maximum likelihood sequence estimation

    Page(s): 805 - 810
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    In this brief, we consider risk-sensitive Maximum Likelihood sequence estimation for hidden Markov models with finite-discrete states. An algorithm is proposed which is essentially a risk-sensitive variation of the Viterbi algorithm. Simulation studies show that the risk-sensitive algorithm is more robust to uncertainties in the transition probability matrix of the Markov chain. Similar estimation results are also obtained for continuous-range state models View full abstract»

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  • Optimal reduced-order models for unstable and nonminimum-phase systems

    Page(s): 800 - 805
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    A technique is presented for optimally approximating an unstable and/or nonminimum-phase high-order transfer function by a low-order one which has the same numbers of right half-plane (RHP) poles and zeros as the original system. It is based on representing the denominator and numerator polynomials of a reduced-order transfer function in products of quadratic factors with/without a linear factor. The Routh γ stability parameters of the linear and quadratic factors are determined such that a frequency-domain L2-norm is minimized. The main feature of the proposed approach to finding optimal reduced models is that the stability constraints on the decision parameters become simple bounds. As a result, the numbers of RHP zeros and poles of a reduced model are easily controlled by specifying the numbers of negative Routh γ parameters for the numerator and denominator polynomials. Moreover, it allows for using a gradient-based optimization technique to find the optimal parameters View full abstract»

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