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

Issue 8 • Date Aug. 2001

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Displaying Results 1 - 16 of 16
  • Comments on "Breaking the 2n-bit carry-propagation barrier in residue to binary conversion for the [2/sup n/-1, 2/sup n/, 2/sup n/+1] moduli set" and author's reply

    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (24 KB)  

    In the above paper [see ibid., vol. 45, p. 998-1002, 1998] Bharadwaj et al, have suggested two changes for Piestrak's technique [1995]. It may be recalled that the first stage in Piestrak's converter contains two levels of 2n bit carry-save adders each comprising of 2n full adders since four inputs need to be added. Interestingly, Dhurkadas's modification [1998] of Pieshak' s technique reduces the four addends to three, thus needing one level of carry-save adders only. We would like to make some observations on this modification. The authors' reply is included. View full abstract»

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  • Author's reply

    Page(s): 1031
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (24 KB)  

    First Page of the Article
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  • Robust stabilization of singular-impulsive-delayed systems with nonlinear perturbations

    Page(s): 1011 - 1019
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (312 KB) |  | HTML iconHTML  

    Many dynamic systems in physics, chemistry, biology, engineering, and information science have impulsive dynamical behaviors due to abrupt jumps at certain instants during the dynamical process, and these complex dynamic behaviors can be modeled by singular impulsive differential systems. This paper formulates and studies a model for singular impulsive delayed systems with uncertainty from nonlinear perturbations. Several fundamental issues such as global exponential robust stabilization of such systems are established. A simple approach to the design of a robust impulsive controller is then presented. A numerical example is given for illustration of the theoretical results. Meanwhile, some new results and refined properties associated with the M-matrices and time-delay dynamic systems are derived and discussed View full abstract»

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  • Hierarchical fault diagnosis of analog integrated circuits

    Page(s): 921 - 929
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (144 KB) |  | HTML iconHTML  

    This paper introduces a hierarchical-fault-diagnosis algorithm as an aid to testing analog and mixed signal circuits. The diagnosis approach is based on that introduced by Wey and others and makes use of the self-test algorithm, and the component-connection model. The main extension to these techniques is the use of a hierarchical approach whereby blocks of circuitry are grouped together leading to a reduction in matrix size, so making even large scale circuits diagnosable. Other improvements from this approach include a novel test-point selection procedure and the fact that hard faults can also be diagnosed, provided they lie completely within a hierarchical block. The overall algorithm is described and the results from example circuits show good functionality of the diagnosis algorithm. Fault masking and sensitivity to the simulation/measurement resolution of test point values are examined and are highlighted as future activities to further improve the approach View full abstract»

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  • A deterministic nonlinear-capacitor model for single-electron tunneling junctions

    Page(s): 1019 - 1022
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (124 KB) |  | HTML iconHTML  

    Single-electron tunneling junctions (SETJs) have intriguing properties which make them a primary nanoelectronic device for highly compact, fast, and low-power circuits. However, standard models for SETJs are based on a quantum mechanical approach which is very impractical for the analysis and design of SETJ-based circuitry, where a simple, preferably deterministic model is a prerequisite. We verify by physics-based Monte Carlo simulations that the tunneling junction can in fact be modeled by a piecewise linear voltage charge relation, which, from the circuit-theoretic perspective, is a nonlinear capacitor View full abstract»

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  • An invariant-manifold-based method for chaos control

    Page(s): 930 - 937
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (196 KB) |  | HTML iconHTML  

    In this paper, we extend the OGY chaos-control method to be one based on the invariant manifold theory and the sliding mode control concept. This extended-control method not only can deal with higher order chaotic systems in the same spirit of the OGY method, but also can remove the reliance of the control on eigenvalues and eigenvectors of the system Jacobians, resulting in an even simpler but more effective controller. The novelty of the new design lies in the construction of suitable invariant manifolds according to the desired dynamic properties. The controller is then forcing the system state to lie on the intersection of the selected invariant manifolds, so that once the invariant manifolds are reached,the chaotic system will be guided toward a desired fixed point that corresponds to an originally targeted unstable periodic orbit of the given system. Such an idea is directly relevant to the sliding mode control approach. This new method is particularly useful for controlling higher order chaotic systems, especially in the case where some of the eigenvalues of the system Jacobian are complex conjugates. The effectiveness of the proposed method is tested by numerical examples of the third-order continuous-time Lorenz system and the fourth-order discrete-time double rotor map View full abstract»

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  • A low-noise, low-power CMOS SOI readout front-end for silicon detector leakage current compensation with capability

    Page(s): 1022 - 1030
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB) |  | HTML iconHTML  

    A low-noise, low-power CMOS semiconductor on insulator (SOI) readout front-end aiming at dc coupling to silicon radiation detectors is presented in this paper. It is able to compensate the leakage current of detectors within a wide range up to 10 μA. While the presented solution does not significantly deteriorate the amplifier noise performance it complies with demands for low-noise readout system for silicon detectors. This front-end system includes a charge-sensitive amplifier, a semi-Gaussian CR-RC shaping amplifier and an output buffer. It has been simulated and implemented in a CMOS SOI-SIMOX process. For no leakage current, an input referred equivalent noise charge (ENC) of 426 electrons (rms) for 0 pF of detector capacitance with a noise slope of 40 electrons/pF, a peaking time of 50 ns, and a conversion gain of 23.4 mV/fC have been obtained View full abstract»

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  • Chaotic dynamics in Josephson junction

    Page(s): 990 - 996
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (172 KB)  

    In this paper, different models of superconducting Josephson junction, particularly, the shunted inductive model have been discussed to understand its chaotic dynamics so that it could be used as a high-frequency chaos generator for communications. Some interesting results on modulation of chaotic oscillation in such devices by external sinusoidal signal as information signal have also been reported View full abstract»

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  • Controlling chaotic oscillations in delay-differential systems via peak-to-peak maps

    Page(s): 1032 - 1037
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (212 KB) |  | HTML iconHTML  

    A method for controlling chaotic oscillations in delay differential systems is presented. The method, which is intrinsically heuristic, relies on the capability of predicting the peak (relative maximum) of an output variable from the knowledge of the previous peak. This property, called peak-to-peak dynamics, is owned by several finite-dimensional systems, and crucially relies on the low-dimensionality of the chaotic attractor. In this paper it is shown that even delay-differential systems may display peak-to-peak dynamics, and the conditions giving rise to this property are analyzed. Then, a reduced model (a first-order map) derived via peak-to-peak dynamics is exploited to suppress chaos in favor of a periodic regime View full abstract»

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  • Quasi-periodic route to chaos in a PWM voltage-controlled DC-DC boost converter

    Page(s): 967 - 978
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (396 KB) |  | HTML iconHTML  

    A quasi-periodic route to chaos is studied both numerically and experimentally in a DC-DC boost switching regulator. After undergoing a Neimark-Sacker bifurcation of a one-periodic orbit, quasi-periodic behavior is obtained and the corresponding attractor is a T2 torus, Under parameter changes, such a torus may breakdown to give chaotic behavior. Two different scenarios are possible for the destruction of the torus. One is obtained by means of period doubling of a phase-locking orbit while the other is achieved by losing the torus smoothness. An approximated two-dimensional mapping is built up to predict the nonlinear phenomena detected in this system View full abstract»

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  • Low-frequency differentiators and integrators for biomedical and seismic signals

    Page(s): 1006 - 1011
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (136 KB) |  | HTML iconHTML  

    A general active-network synthesis approach to inverse system design is introduced. The approach is applied to a passive RC differentiator and a passive RC integrator to obtain, respectively, a very low-frequency differential integrator and a very low-frequency differential differentiator. The frequency ranges of the proposed circuits, from dc to a few hundred hertz, are particularly suitable to the frequency ranges of biomedical and seismic signals. The advantages of the proposed circuits are delineated and include single time constants, dc stable integrators, and resistive input differentiators. Noninverting and inverting differentiators and integrators could be obtained by grounding one of the input terminals in the differential configurations View full abstract»

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  • Rigorous event-driven (RED) analysis of large-scale nonlinear RC circuits

    Page(s): 938 - 946
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (172 KB) |  | HTML iconHTML  

    Event-driven methods are very promising for simulating large-scale linear and nonlinear circuits but they may suffer some drawbacks, such as spurious numerical oscillations and have difficulties in convergence to equilibrium points. To overcome these drawbacks a pseudoanalytical method is presented that is based on the staircase approximation of v-i characteristics of linear and nonlinear resistors, on the piecewise-linear approximation of v-q characteristics of nonlinear capacitors and t-v characteristics of time-varying voltage sources. At a generic time instant, these approximations allow us to represent the original circuit with a very simple model composed of only linear capacitors, voltage and current sources. The solution of this circuit model is straightforward but, when the operating point meets some pathological situations, the model does no longer hold and then a rigorous and in general more complex analysis is needed. Even if this analysis yields a conceptual effort, its computational execution is not complex. This algorithm works successfully on circuits composed of linear and nonlinear resistors and capacitors, time-varying voltage and time-invariant current sources. Some applications of this method to the analysis of interconnects and power-grids in VLSI circuits are presented View full abstract»

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  • Electrothermal dynamics of circuits: analysis and simulations

    Page(s): 997 - 1005
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (224 KB) |  | HTML iconHTML  

    The electrothermal dynamics of electronic circuits is investigated. In the design of circuits, the thermal effects are, in general, analyzed only from a static point of view. These approaches are, in many cases, inadequate. Thermal and electrical quantities may have a strong nonlinear dynamic interaction that, for instance, generates “unexpected” oscillations. In this paper, some of these phenomena are analyzed by means of a mixed state-variable approach for commonly used semiconductor devices embedded in simple circuits. Simulation results show how these effects may be significant in the analysis and design of many circuits View full abstract»

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  • Adaptive blind equalization for chaotic communication systems using extended-Kalman filter

    Page(s): 979 - 989
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (192 KB) |  | HTML iconHTML  

    In this paper, a blind-channel equalization technique for chaotic communications based on extended Kalman filtering (EKF) is proposed. Assuming that the channel coefficients of a fading and multipath channel can be described by an autoregressive (AR) model, blind-channel equalization is formulated as a mixed nonlinear parameter and state estimation problem. Nonlinear filters such as EKF can then be used to estimate the state of the mixed system which represents the original signal without channel distortion. The stability problem of the proposed EKF equalization technique is also addressed. Simulations show that the proposed EKF equalization method has improved performance in terms of design, convergence speed, and demodulation quality compared to the standard synchronization-based technique for chaotic communications View full abstract»

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  • Global and local stability of circuits containing MOS transistors

    Page(s): 957 - 966
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (260 KB) |  | HTML iconHTML  

    The paper deals with nonlinear dynamic circuits containing MOS transistors. The problem of global and local stability of a class of these circuits is considered in detail. It is shown that any circuit belonging to this class is Lagrange stable. In a special case where no independent sources act in the circuit, it is proved that the origin is the only equilibrium point and the circuit is globally asymptotically stable. Special attention has been paid to the circuits driven by dc sources, having multiple equilibrium points. A simple tool for proving asymptotic stability of equilibrium points is developed and illustrated by numerical examples View full abstract»

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  • Efficient optimization by modifying the objective function: applications to timing-driven VLSI layout

    Page(s): 947 - 956
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB)  

    When minimizing a given objective function is challenging because of, for example, combinatorial complexity or points of nondifferentiability, one can apply more efficient and easier-to-implement algorithms to modified versions of the function. In the ideal case, one can employ known algorithms for the modified function that have a thorough theoretical and empirical record and for which public implementations are available. The main requirement here is that minimizers of the objective function do not change much through the modification, i.e., the modification must have a bounded effect on the quality of the solution. Review of classic and recent placement algorithms suggests a dichotomy between approaches that either: (a) heuristically minimize potentially irrelevant objective function (e.g., VLSI placement with quadratic wirelength) motivated by the simplicity and speed of a standard minimization algorithm; or (b) devise elaborate problem-specific minimization heuristics for more relevant objective functions (e.g., VLSI placement with linear wirelength). Smoothness and convexity of the objective functions typically enable efficient minimization. If either characteristic is not present in the objective function, one can modify and/or restrict the objective to special values of parameters to provide the missing properties. After the minimizers of the modified function are found, they can be further improved with respect to the original function by fast local search using only function evaluations. Thus, it is the modification step that deserves most attention. In this paper, we approximate convex nonsmooth continuous functions by convex differentiable functions which are parameterized by a scalar β>0 and have convenient limit behavior as β→0. This allows the use of Newton-type algorithms for minimization and, for standard numerical methods, translates into a tradeoff between solution quality and speed. We prove that our methods apply to arbitrary multivariate convex piecewise-linear functions that are widely used in synthesis and analysis of electrical networks. The utility of our approximations is particularly demonstrated for wirelength and nonlinear delay estimations used by analytical placers for VLSI layout, where they lead to more “solvable” problems than those resulting from earlier comparable approaches [29]. For a particular delay estimate, we show that, while convexity is not straightforward to prove, it holds for a certain range of parameters, which, luckily, are representative of “real-world” technologies View full abstract»

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