By Topic

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

Issue 6 • Date Jun 1998

Filter Results

Displaying Results 1 - 14 of 14
  • A class of relaxation algorithms for finding the periodic steady-state solution in nonlinear systems

    Page(s): 659 - 663
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (164 KB)  

    An improvement in the author's previous algorithm for computing periodic steady-state solutions in nonautonomous systems is proposed that enables efficient computation of the solutions in autonomous systems. In addition, the derivations more clearly demonstrate the impact that the s- to z-plane mapping has on the equation formulation, specifically in the computation of the “A” and “B” matrices. A class of relaxation algorithms is proposed for the efficient solution of both nonautonomous and autonomous systems. Finally, simulation results on a van der Pol oscillator are presented that demonstrate the potential of the proposed algorithms. In addition, these simulations show how the use of different mappings from the s- to z-plane effect the solution estimates, and how the use of different mappings may be exploited to improve the efficiency of finding solutions View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • New general immittance converter JFET voltage-controlled impedances and their applications to controlled biquads synthesis

    Page(s): 678 - 682
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (164 KB)  

    Two new general immittance converter (GIC) JFET configurations for the realization of voltage-controlled impedances (VCI's) are proposed. Compared with previously reported structures, the circuits exhibit wide dynamic range and low distortion properties that are frequency independent, even for nonresistive VCI's. We consider the influence of op-amp frequency dependent gain and derive conditions for obtaining high Q-factor inductances and capacitances. We also present computed and experimental results for several voltage-controlled GIC-type biquads that are built based on the proposed circuits View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Stability of characteristic curves of nonlinear resistive circuits

    Page(s): 634 - 643
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (440 KB)  

    In this paper, we discuss the stability of the characteristic curves for nonlinear resistive circuits including parasitic elements. Although the dc solution is determined by analyzing the nonlinear resistive circuit, its equilibrium point will be stable or unstable because every resistive element has a small parasitic component in practice. We consider here two parasitic elements: a capacitor between every resistor node and ground and an inductor in series with each resistor. Of course, the stability can be decided by solving the variational equation at each equilibrium point obtained by the dc analysis; however, this is very time consuming. We show here that the stability is mainly changed at the boundary of the presence of negative differential resistance (NDR) and the bifurcation points, such as turning and pitchfork points on the dc characteristic curves. The instability regions of the solution curve are easily found by both the locations of bifurcation points and NDR regions of the nonlinear resistors View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An iterative learning control method for continuous-time systems based on 2-D system theory

    Page(s): 683 - 689
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (220 KB)  

    This work presents a two-dimensional (2-D) system theory based iterative learning control (ILC) method for linear continuous-time multivariable systems. We demonstrate that a 2-D continuous-discrete model can be successfully applied to describe both the dynamics of the control system and the behavior of the learning process. We successfully exploited the 2-D continuous-discrete Roesser's linear model by extending the ILC technique from discrete control systems to continuous control systems. Three learning rules for ILC are derived. Necessary and sufficient conditions are given for convergence of the proposed learning rules. Compared to the learning rule suggested by Arimoto et al. (1984), our developed learning rules are less restrictive and have wider applications. The third learning rule proposed ensures the reference output trajectory can be accurately tracked after only one learning trial. Three numerical examples are used to illustrate the proposed control procedures View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Iteratively improved bounds for RC circuits

    Page(s): 663 - 666
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB)  

    For the waveform relaxation iterative process, the starting vectors can be found such that the iterations are globally monotonous, decreasing, or increasing. The method is new, and the class of RC circuits that we deal with is larger than in previous works View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • RNS-to-binary conversion for efficient VLSI implementation

    Page(s): 667 - 669
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (100 KB)  

    Conversion from a residue number system (RNS) to binary is a crucial point in the implementation of modular processors. The choice of the moduli is strictly related to conversion performance and influences the processor complexity. In this paper, a conversion method based on a class of couples of coprime moduli defined as (n-2k, n+2k) is presented. The method and the related architecture can easily be extended to a larger number of moduli. Since it is based on very small look-up tables, the proposed method can be implemented by fast and low complex architectures View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Control of chaos in DC-DC converters

    Page(s): 672 - 676
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB)  

    It has been demonstrated previously that DC-DC buck and boost converters with current or voltage feedback exhibit chaos for significantly large ranges of parameter values. In this paper, we present two methods for controlling chaos particularly suitable for switching circuits. The results of numerical investigation and experimental implementation are presented with reference to the duty cycle controlled buck converter View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A note on minimality of positive realizations

    Page(s): 676 - 677
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (84 KB)  

    A well-known result from linear system theory states that the minimal inner size of a factorization of the Hankel matrix H of a system gives the minimal order of a realization. In this work it is shown that when dealing with positive linear systems, the existence of a factorization of the Hankel matrix into two nonnegative matrices is only a necessary condition for the existence of a positive realization of order equal to the inner size of the factorization. Necessary and sufficient conditions for the minimality of a positive realization in terms of positive factorization of the Hankel matrix are then derived View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A new approach for parallel simulation of VLSI circuits on a transistor level

    Page(s): 601 - 613
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (352 KB)  

    In this paper, we present a new approach for parallel simulation of very large scale integration (VLSI) circuits on a transistor level. To achieve good parallel simulation performance on workstation clusters, low communication and coarse grain parallelization is crucial. Two main tasks have to be performed to obtain this target. First, the electronic circuit must be split into subcircuits. To do this, we present an efficient partitioning technique, which yields well-balanced partitions with few interconnects. Second, for minimizing communication between the partitions, sophisticated parallelization methods have to be applied. Therefore, we present our improved domain decomposition technique for parallel analog simulation. The excellent performance of our approach is demonstrated on several industrial VLSI designs. For the first time, good speedup results for parallel analog simulation of large industrial designs are presented View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Synchronizing hyperchaotic volume-preserving maps and circuits

    Page(s): 656 - 659
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (120 KB)  

    We show that it is possible to synthesize chaotic systems that have improved characteristics for use in communications. These include whiter spectrum, low-time correlation, hyperchaotic behavior, and little or no phase space structure. These systems are based on locally volume-preserving (or expanding) maps. We show how to construct a circuit that produces such characteristics View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The equivalence of twos-complement addition and the conversion of redundant-binary to twos-complement numbers

    Page(s): 669 - 671
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (84 KB)  

    The equivalence between redundant-binary (RB) to twos-complement number conversion and twos-complement addition is shown using a simple transform between the two number domains. As a consequence, all hardware architectures designed for either operation may be easily adapted to implement the other View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Signal flow graph in loop gain analysis of DC-DC PWM CCM switching converters

    Page(s): 644 - 655
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (384 KB)  

    A systematic and unified method using the signal flow graph (SFG) technique is presented in analyzing dc-dc pulsewidth modulated (PWM) switch mode power converters (SMPC's) operating in the continuous conduction mode (CCM). Loop gains for single and multiloop systems are reviewed. The SFG of the converter is then generated from the perturbed state-space averaged (SSA) equations, and the characteristic polynomial of the system is computed. By grouping terms associated with the gain of the error amplifier as the numerator, a unique definition of system loop gain is introduced, and locations for breaking the loop are discussed. System loop gains for both voltage- and current-programming converters with either trailing- or leading-edge modulation are derived. It is shown that for a SMPC, the loop gain measured by an analog injection method is the system loop gain, which determines the stability of the converter View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A new type of intermittency from a ring of four coupled phase-locked loops

    Page(s): 623 - 633
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (580 KB)  

    This paper investigates a new type of intermittency from a ring of four coupled phase-locked loops (PLL's). This system can be represented by a six-dimensional nonlinear autonomous differential equation that has a four-dimensional invariant manifold named H. With a quasi-attractive property, this invariant manifold causes a type of intermittency. Namely, long laminar phases in H and short bursts out of H alternate irregularly. Different from the well-known on-off intermittency, the core of this intermittency is not a chaotic set in H, but two kinds of semistable periodic orbits in H called the entrance set and the exit set. We try to clarify the mechanism of this intermittency by using bifurcation analysis of these periodic orbits View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Electromechanical wave propagation in large electric power systems

    Page(s): 614 - 622
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (348 KB)  

    An electrical power network consisting of generators and transmission lines is treated as a continuum system. The application of the limit of zero generator spacing, with finite rotor inertia and transmission line impedance per unit length, yields a nonlinear partial differential equation in time and two spatial dimensions for the rotor phase angle. The equation is a nonlinear version of the standard second-order wave equation which exhibits an explicit expression for the finite wave phase velocity. The electromechanical wave propagation characteristics, equilibrium solutions, and linear stability are investigated and some potentially important results are presented. Numerical simulations of the usual discrete generator model, based upon the swing equation, are presented and demonstrate the electromechanical wave propagation as having interesting properties. Numerical solutions of the analogous continuum model are compared to the discrete model and are found to be in excellent agreement. A numerical estimate of the wave phase velocity for the U.S. power grid is consistent with observations of the transient wave phenomena during staged fault events. The continuum model enables an array of alternative analytic and simulation methods to be applied to the study of global power system characteristics, such as stability and transient dynamics View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.