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

Issue 3 • Date Mar 2003

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Displaying Results 1 - 17 of 17
  • Envelope-following method to compute steady-state solutions of electrical circuits

    Page(s): 407 - 417
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (791 KB) |  | HTML iconHTML  

    The paper deals with the determination of the steady-state solution of both autonomous and nonautonomous circuits. Only time-domain methods are considered, and, in particular, the shooting (SH) and multishooting (MSH) ones. It is well known that one of their main drawbacks is the lack of convergence if they are not started from an initial guess "close enough" to the steady-state solution. To overcome this problem, we present an envelope-following method that efficiently brings the operating point of the circuit into the convergence region of the shooting (SH) and multishooting (MSH) algorithms. View full abstract»

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  • The complete canonical piecewise-linear representation: functional form for minimal degenerate intersections

    Page(s): 387 - 396
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (827 KB) |  | HTML iconHTML  

    In this paper, we develop a functional form for canonical piecewise-linear (CPWL) functions defined over a minimal degenerate intersection of order k. This type of intersection is known to be the building block of CPWL representations. Accordingly, the representation proposed is the main component in a general CPWL representation and constitutes the first functional form that is valid in a domain that has arbitrary dimension and is subdivided by a generic partition. View full abstract»

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  • Observer-based output feedback controller design of piecewise discrete-time linear systems

    Page(s): 448 - 451
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (252 KB) |  | HTML iconHTML  

    This brief presents an output feedback controller design method for piecewise discrete-time linear systems based on a piecewise Lyapunov function and a state observer. It is shown that the resulting closed-loop system is globally stable and the controller can be obtained by solving a set of linear matrix inequalities that is numerically feasible with commercially available software. In other words, it is shown that the separation principle of the controller and observer design is still maintained when the piecewise Lyapunov function is used. A simulation example is also given to illustrate the advantage of the proposed approach. View full abstract»

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  • Current mode, low-power, on-chip signaling in deep-submicron CMOS technology

    Page(s): 397 - 406
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (618 KB) |  | HTML iconHTML  

    This paper reports an analogy between on-chip signaling and digital communication over a band-limited channel. This analogy has been used to design a scheme for low-power, on-chip signaling, robustly resistant to power-supply noise. The technique uses multilevel, current-mode signaling as its core. The number of levels is determined by estimating the bandwidth of the wire. A closed-form expression has been presented here describing the bandwidth of a wire modeled as a first-order RLC circuit. An algorithm is presented for computing the levels of the current given target bit rate, bit-error rate, and wire characteristics. Simulation results using HSPICE from Avant! show that the algorithm for computing the wire bandwidth presented here has an average error of less than 10%. Experimental results on a set of benchmark signaling problems implemented in a 0.25-μm 2.5-V CMOS process, show that using four levels of current instead of the standard two levels allows a two-fold reduction in the power and a reduction of 1.4 times the area. View full abstract»

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  • High-frequency harmonic distortion in feedback amplifiers: analysis and applications

    Page(s): 328 - 340
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (883 KB) |  | HTML iconHTML  

    An approach for the evaluation of high-frequency harmonic-distortion factors in feedback systems is proposed and the results obtained are applied to feedback amplifiers. Under the assumption that transistors are not driven out of their linear operating regions, small-signal analysis and conventional algebra are exploited to derive understandable and compact expressions highly improving the comprehension of harmonic-distortion generation. The impact of the frequency compensation utilized (namely, dominant-pole or Miller technique) on linearity performance is evaluated and the high-frequency distortion properties of closed-loop single-stage and two-stage amplifiers are analyzed and compared. The accuracy of the analysis, also in view of the given applications, is confirmed through extensive simulations with Spectre on idealized models as well as on CMOS transistor-level circuits. Despite the approximated nature of the analytical models, predicted data are found in very close agreement with simulations in nearly all the frequency range of interest. View full abstract»

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  • Application of impulsive synchronization to communication security

    Page(s): 341 - 351
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (843 KB) |  | HTML iconHTML  

    In this paper, criteria on uniform equi-boundedness and equi-Lagrange stability for impulsive systems are derived. These criteria are used to synchronize two nonidentical chaotic systems by impulsively controlling a nonautonomous second order system, which leads to the development of an induced-message scheme for communication system security. With the scheme, message signals are not transmitted across public channels, but induced at the receiver end. The scheme overcomes the transmission time-frame congestion in impulsive cryptosystems discussed in the literature and improves system security. Simulation results are given to demonstrate the performance of the proposed scheme. View full abstract»

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  • Fast parallel-frequency-sweeping algorithms for robust D-stability margin

    Page(s): 418 - 428
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (769 KB) |  | HTML iconHTML  

    This paper considers the robust D-stability margin problem under polynomic structured real parametric uncertainty. Based on the work of de Gaston and Safonov (1988), we have developed techniques such as, a parallel-frequency-sweeping strategy, different domain-splitting schemes, which significantly reduce the computational complexity and guarantee the convergence. View full abstract»

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  • Analog addition/subtraction on the CNN-UM chip with short-time superimposition of input signals

    Page(s): 429 - 432
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (555 KB) |  | HTML iconHTML  

    The cellular-neural-network universal machine (CNN-UM) technique which performs analog addition/subtraction between image frames has been developed. The equivalent circuit of the uncoupled CNN without self feedback is reduced to a simple RC circuit. If two inputs are presented to the circuit one after another during a very short time period, the voltages that are proportional to their input signals are superimposed on the state capacitor. The output of such superimposition is a reduced version of the addition/subtraction between the two signals. Simple amplification of the output can recover the actual output. The characteristics of analog addition/subtraction with the proposed algorithm are shown via on-chip experiment. Application of the proposed algorithm to moving target detection is also presented. View full abstract»

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  • The performance surface in filtered nonlinear mean-square estimation

    Page(s): 445 - 447
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (260 KB) |  | HTML iconHTML  

    This brief investigates the properties of the performance surface for the problem of linearly constrained nonlinear mean-square estimation of a random sequence. The problem studied has direct application to the study of active noise control systems when the transducers are driven into nonlinear behavior. A deterministic expression is derived for the mean-square error (MSE) surface as a function of the nonlinearity parameter for Gaussian inputs. It is demonstrated that the surface is unimodal, and expressions are determined for the optimum weight vector and for the minimum MSE. View full abstract»

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  • Behavioral modeling of switched-capacitor sigma-delta modulators

    Page(s): 352 - 364
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1261 KB) |  | HTML iconHTML  

    This paper presents a complete set of blocks implemented in the popular MATLAB SIMULINK environment, which allows designers to perform time-domain behavioral simulations of switched-capacitor (SC) sigma-delta (ΣΔ) modulators. The proposed set of blocks takes into account most of the SC ΣΔ modulator nonidealities, such as sampling jitter, kT/C noise, and operational amplifier parameters (white noise, finite DC gain, finite bandwidth, slew rate and saturation voltages). For each block, a description of the considered effect as well as all of the implementative details are provided. The proposed simulation environment is validated by comparing the simulated behavior with the experimental results obtained from two actual circuits, namely a second-order low-pass and a sixth-order bandpass SC ΣΔ modulator. View full abstract»

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  • Controllability of linear descriptor systems

    Page(s): 455 - 460
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (365 KB) |  | HTML iconHTML  

    This brief studies the controllability of linear descriptor systems with multiple time delays in control. Several controllability concepts are investigated. First, necessary and sufficient criteria for the controllability of the canonical system are established. Then, equivalent criteria for that of the general system are given. Finally, it is pointed out that the controllability is independent of the size of the time delays. View full abstract»

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  • On the computation of a minimum-phase spectral factor

    Page(s): 365 - 375
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (809 KB) |  | HTML iconHTML  

    The problem of finding the minimum-phase spectral factor of a linear-phase digital filter having double zeros on the unit circle is addressed. It is shown that a simple Newton-Raphson iterative algorithm can compute this factor quickly and accurately and a short Matlab program for doing the computation is given. The Newton-Raphson method is also compared to an alternative approach by finding the zeros of polynomials. The accuracy of solutions obtained is of major emphasis in the work. View full abstract»

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  • The quarter-state-sequence floorplan representation

    Page(s): 376 - 386
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (816 KB) |  | HTML iconHTML  

    A floorplan of a bounding box is its dissection into rectangles (rooms) by horizontal and vertical segments. This paper proposes a string data structure called the Quarter-state sequence (or Q sequence) to represent the floorplan. The Q sequence is a concatenation of the states of rooms along the Abe order and is related to the VH graph, which is the union of the vertical-constraint and horizontal-constraint graphs. It is proved that any floorplan of n rooms is uniquely encoded by a Q sequence and any Q sequence is uniquely decoded to a floorplan, both in O(n) time. An exact formula for counting distinct floorplans is given and compared with existing bounds. A linear time transformation of one Q sequence to another is defined. An n-room packing algorithm based on simulated annealing was implemented and found to compare favorably with existing packing algorithms. View full abstract»

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  • Fast generation of universal maximally flat FIR filters

    Page(s): 441 - 444
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (298 KB) |  | HTML iconHTML  

    The relation for impulse response coefficients of Baher's universal maximally flat filters is a threefold summation formula. The summand involves four binomial coefficients whose computation requires an extensive number of additions and multiplications. There are three main parameters that characterize the filters, the order N, the number of zeros K, and the group delay parameter d. With fixed values for these parameters, the total number of additions, multiplications, and divisions required to compute the impulse response coefficients hk are of the orders O(N4), O(N5) and O(N4), respectively. We present a recurrence for the computation of hk for all possible values of K under fixed values for N and d. The recurrence provides speedups of the orders O(N2), O(N3) and O(N2) for the number of additions, multiplications and divisions, respectively. View full abstract»

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  • Optimal linearity testing of analog-to-digital converters using a linear model

    Page(s): 317 - 327
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (623 KB) |  | HTML iconHTML  

    To maintain an acceptable level of quality in the production of analog-to-digital converters (ADCs), the linearity metrics of every ADC has to be measured and checked against performance specification limits. As ADCs continue to improve in resolution, their testing has becoming increasingly demanding in terms of test time. In this paper, we demonstrate a technique for reducing the test time for ADCs. The technique is shown to be significantly better than currently available techniques and can be easily integrated into current production test methodologies. Experimental results in simulation and on actual hardware are shown to demonstrate the technique. View full abstract»

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  • Observer-based iterative learning control for a class of time-varying nonlinear systems

    Page(s): 452 - 455
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (323 KB) |  | HTML iconHTML  

    In this brief, we propose an observer-based iterative learning control (ILC) scheme for the tracking problem of a class of time-varying nonlinear systems. First, a state observer is derived for the system under consideration, and sufficient conditions for the boundedness and the convergence to zero of the estimation error are given. Thereafter, an iterative learning rule - based on the proposed state observer - ensuring the boundedness of the tracking error is derived. Moreover, it is shown that if the initial state variables are known, it is possible to obtain a perfect convergence to zero, over a finite tracking horizon, when the number of iterations tends to infinity. By associating a state observer with the ILC scheme it is possible to avoid the use of state and output time-derivative measurements which are generally necessary in contraction mapping based ILC design for nonlinear systems without zero relative degree. View full abstract»

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  • Design of noncoherent receiver for analog spread-spectrum communication based on chaotic masking

    Page(s): 432 - 441
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1392 KB) |  | HTML iconHTML  

    A novel noncoherent receiver for chaotic masking (CM) is proposed for analog spread-spectrum (SS) communication. By exploiting the ergodic property of a chaotic signal, the proposed demodulator can recover information signal from the CM signal effectively. The communication performances of different information signals transmitted through this analog CM modulation SS system are investigated in terms of mean-square error. It is found that the proposed CM scheme is effective even in a very noisy additive white Gaussian channel. In addition, this new scheme has the potential advantage of a very simple hardware realization and it does not require the complicated synchronization process as in the conventional synchronization of chaos-based SS systems. View full abstract»

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