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Circuits and Systems I: Regular Papers, IEEE Transactions on

Issue 3 • Date March 2005

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Displaying Results 1 - 25 of 25
  • Table of contents

    Page(s): c1 - c4
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  • IEEE Transactions on Circuits and Systems–I: Regular Papers publication information

    Page(s): c2
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  • Analysis of mismatch effects in a randomly interleaved A/D converter system

    Page(s): 465 - 476
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (552 KB) |  | HTML iconHTML  

    Time interleaving can be used to significantly increase the sampling rate of an ADC system. However, the problem with time interleaving is that the ADCs are not exactly identical. This means that time, gain and offset mismatch errors are introduced in the ADC system, which cause nonharmonic distortion in the sampled signal. One way to decrease the impact of the mismatch errors is to spread the distortion over a wider frequency range by randomizing the order in which the ADCs are used in the interleaved structure. In this paper we analyze how the spectrum is affected by mismatch errors in a randomly interleaved ADC system. We also discuss how the mismatch errors can be estimated. View full abstract»

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  • A bio-physically inspired silicon neuron

    Page(s): 477 - 488
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    The physical principles governing ion flow in biological neurons share interesting similarities to electron flow through the channels of MOSFET transistors. Here, is described a circuit which exploits the similarities better than previous approaches to build an elegant circuit with electrical properties similar to real biological neurons. A two-channel model is discussed including sodium (Na+) and potassium (K+). The Na+ channel uses four transistors and two capacitors. The K+ channel uses two transistors and one capacitor. One more capacitor simulates the neuron membrane capacitance yielding a total circuit of four capacitors and six transistors. This circuit operates in real-time, is fabricated on standard CMOS processes, runs in subthreshold, and has a power supply similar to that of real biology. Voltage and current responses of this circuit correspond well with biology in terms of shape, magnitude, and time. View full abstract»

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  • Analog VLSI implementation of spatio-temporal frequency tuned visual motion algorithms

    Page(s): 489 - 502
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1168 KB) |  | HTML iconHTML  

    The computation of local visual motion can be accomplished very efficiently in the focal plane with custom very large-scale integration (VLSI) hardware. Algorithms based on measurement of the spatial and temporal frequency content of the visual motion signal, since they incorporate no thresholding operation, allow highly sensitive responses to low contrast and low-speed visual motion stimuli. We describe analog VLSI implementations of the three most prominent spatio-temporal frequency-based visual motion algorithms, present characterizations of their performance, and compare the advantages of each on an equal basis. This comparison highlights important issues in the design of analog VLSI sensors, including the effects of circuit design on power consumption, the tradeoffs of subthreshold versus above-threshold MOSFET biasing, and methods of layout for focal plane vision processing arrays. The presented sensors are capable of distinguishing the direction of motion of visual stimuli to less than 5% contrast, while consuming as little as 1 μW of electrical power. These visual motion sensors are useful in embedded applications where minimum power consumption, size, and weight are crucial. View full abstract»

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  • Multistep optimal analog-to-digital conversion

    Page(s): 503 - 515
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    An important aspect of analog-to-digital conversion is the impact of quantization errors. This paper outlines how finite horizon constrained optimization methods can be utilized to design converters which minimize a weighted measure of the quantization distortion. We propose a novel converter, which can be implemented as a feedback loop. It embeds ΣΔ conversion in a more general setting and typically provides better performance. We also examine the role played by the associated design parameters in ensuring error convergence. View full abstract»

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  • Efficient time-recursive implementation of matched filterbank spectral estimators

    Page(s): 516 - 521
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    In this paper, we present a computationally efficient sliding window time updating of the Capon and amplitude and phase estimation (APES) matched filterbank spectral estimators based on the time-variant displacement structure of the data covariance matrix. The presented algorithm forms a natural extension of the most computationally efficient algorithm to date, and offers a significant computational gain as compared to the computational complexity associated with the batch re-evaluation of the spectral estimates for each time-update. Furthermore, through simulations, the algorithm is found to be numerically superior to the time-updated spectral estimate formed from directly updating the data covariance matrix. View full abstract»

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  • Recasting modified nodal analysis to improve reliability in numerical circuit Simulation

    Page(s): 522 - 534
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    Modified nodal analysis (MNA) can be considered as the most adopted method in circuit simulation programs. Once node equations were written and complemented with those from the current controlled branches, a nonlinear system of algebraic and/or differential equations is obtained. In general, by using linear multistep integration methods, differential equations are recast as nonlinear algebraic ones, which are solved through the Newton method at each integration time step. While computer precision is not an issue in most situations, some specific but frequent cases yield ill-conditioned or singular matrices even in originally well posed circuits. This drawback can occur in different situations namely in presence of strongly nonlinear elements and/or when very small integration time steps are used. In the second case, very large conductances in the companion model of capacitors can introduce roundoff errors. In this paper, a transformation of the MNA that overcomes these problems is proposed. It is based on a suitable recombination of equations and electrical variables of the conventional MNA and it can be easily implemented in a circuit simulator. View full abstract»

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  • Elitist nondominated sorting genetic algorithm based RF IC optimizer

    Page(s): 535 - 545
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (992 KB) |  | HTML iconHTML  

    An optimization tool for radio frequency integrated circuits (RFICs) based on an elitist nondominated sorting genetic algorithm is introduced. It casts RF circuit synthesis as a multi-objective optimization problem and produces multiple solutions along the Pareto optimal front. Optimization is followed by sensitivity assessment wherein Monte Carlo simulations are performed for the Pareto points with respect to process, voltage, and temperature variations. The tool is validated in the synthesis of a 5.2-GHz direct-conversion receiver front-end that includes a common-gate differential low-noise amplifier, I/Q down-conversion mixers, and a quadrature voltage-controlled oscillator in a 250-nm SiGe BiCMOS process. View full abstract»

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  • A prewhitening-induced bound on the identification error in independent component analysis

    Page(s): 546 - 554
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    In this paper, we derive a prewhitening-induced lowerbound on the Frobenius norm of the difference between the true mixing matrix and its estimate in independent component analysis. This bound applies to all algorithms that employ a prewhitening. Our analysis allows one to assess the contribution to the overall error of the partial estimation errors on the components of the singular value decomposition of the mixing matrix. The bound indicates the performance that can theoretically be achieved. It is actually reached for sufficiently high signal-to-noise ratios by good algorithms. This is illustrated by means of a numerical experiment. A small-error analysis allows to express the bound on the average precision in terms of the second-order statistics of the estimator of the signal covariance. View full abstract»

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  • Performance bounds of forgetting factor least-squares algorithms for time-varying systems with finite measurement data

    Page(s): 555 - 566
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    This paper on performance analysis of parameter estimation is motivated by a practical consideration that the data length is finite. In particular, for time-varying systems, we study the properties of the well-known forgetting factor least-squares (FFLS) algorithm in detail in the stochastic framework, and derive upperbounds and lowerbounds of the parameter estimation errors (PEE), using directly the finite input-output data. The analysis indicates that the mean square PEE upperbounds and lowerbounds of the FFLS algorithm approach two finite positive constants, respectively, as the data length increases, and that these PEE upperbounds can be minimized by choosing appropriate forgetting factors. We further show that for time-invariant systems, the PEE upperbounds and lowerbounds of the ordinary least-squares algorithm both tend to zero as the data length increases. Finally, we illustrate and verify the theoretical findings with several example systems, including an experimental water-level system. View full abstract»

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  • Input and output coupled nonlinear systems

    Page(s): 567 - 575
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    In this paper, a class of input and output coupled nonlinear systems with multiple equilibria are studied. These kinds of systems can also be viewed as interconnected systems composed of single-input and single-output systems through some linear and nonlinear interconnections. Frequency-domain conditions are established for global convergence and convergence of bounded solutions for such systems. The effects of nonlinear input and output interconnections can be studied through a nonsingular matrix. The design method based on linear matrix inequality for the interconnected matrix is presented. In addition, the relation between input and output coupling here and input transformation in control theory is established. The coupling method is illustrated through a coupled Chua's circuit. The nonexistence of chaotic attractors or limit cycles in the coupled Chua's circuit can be analyzed by convergence of bounded solutions. View full abstract»

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  • Controllability and reachability of 2-D positive systems: a graph theoretic approach

    Page(s): 576 - 585
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    When dealing with two-dimensional (2-D) discrete state-space models, controllability properties are introduced in two different forms: a local form, which refers to single local states, and a global form, which instead pertains the infinite set of local states lying on a separation set. In this paper, these concepts are investigated in the context of 2-D positive systems by means of a graph theoretic approach. For all these properties, necessary and sufficient conditions, which refer to the structure of the digraph, are provided. While the global reachability index is bounded by the system dimension n, the local reachability index may far exceed the system dimension. Upper bounds on the local reachability index for some special classes of positive systems are finally derived. View full abstract»

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  • Generation of wave digital structures for networks containing multiport elements

    Page(s): 586 - 596
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    Most standard wave digital filters are derived from passive reference circuits, where only parallel and serial connections between one-port elements occur. In this paper, a framework for the automated generation of the wave digital structures is presented, where the reference circuit is assumed to comprise arbitrary connection types. It is shown how the representation of the underlying graph by its so-called SPQR-tree is related to a suitable adaptor structure and how this concept can be generalized to also cope with networks containing certain multiport elements. We propose two different novel approaches to finding a valid tree representation from a given reference circuit. The first approach relies on the usage of apt replacement graphs for the multiport elements. The second one is based on searches for circles on suitably constructed graph representations and generates wave digital structures with minimum implementation effort even in presence of nonreciprocal elements. In both approaches, standard separation algorithms with known efficient implementations can be applied. View full abstract»

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  • Numerically efficient optimal design of cosine-modulated filter banks with peak-constrained least-squares behavior

    Page(s): 597 - 608
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    Several current applications related to signal compression and representation and high-speed transmission require very selective filter banks/transmultiplexers. A possible solution is to employ the cosine-modulated filter banks/transmultiplexers (CMFBTs) where the prototype filters satisfy demanding constraints with respect to both the total stopband energy and maximum stopband ripple. This work proposes an efficient procedure to design nearly-perfect reconstruction CMFBT prototype filters with peak-constrained least-squares characteristics using a modified weighted least-squares algorithm. Substantial flexibility is added in the design of the magnitude response of the prototype filter, ranging from minimum stopband energy to minimum stopband ripple, which may be required in many applications. Some constraints are imposed to the CMFBTs in order to control the direct transfer and aliasing distortion functions, related to the intercarrier and intersymbol interferences. Algebraic simplifications are also provided on the overall objective function and associated constraints, leading to substantial reduction on the computational burden of the optimization process. The procedure is proven to be very powerful in designing CMFBT systems satisfying multiple constraints as indicated by numerical examples. View full abstract»

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  • Robust controller for a full-bridge rectifier using the IDA approach and GSSA modeling

    Page(s): 609 - 616
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    An interconnection-and-damping assignment passivity-based control (IDA-PBC) for a full-bridge rectifier is presented in this paper. The closed-loop system performance fulfils unity power factor in the ac mains and output dc voltage regulation. The controller design takes advantage of the generalized state space averaging (GSSA) modeling technique to convert the quoted nonstandard problem (in actual variables) into a standard regulation one (in GSSA variables). In this approach, the output current is the measured signal instead of the line current; therefore, the number of sensors does not increase in comparison with traditional approaches. The whole system is robust with respect to load variations. View full abstract»

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  • Nonlinear adaptive bilinear filters for active noise control systems

    Page(s): 617 - 624
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (440 KB) |  | HTML iconHTML  

    The reference and error channels of active noise control (ANC) systems may be saturated in real-world applications if the noise level exceeds the dynamic range of the electronic devices. This nonlinear saturation degrades the performance of ANC systems that use linear adaptive filters with the filtered-X least-mean-square (FXLMS) algorithm. This paper derives a bilinear FXLMS algorithm for nonlinear adaptive filters to solve the problems of signal saturation and other nonlinear distortions that occur in ANC systems used for practical applications. The performance of this bilinear adaptive filter is evaluated in terms of convergence speed, residual noise in steady state, and the computational complexity for different filter lengths. Computer simulations verify that the nonlinear adaptive filter with the associated bilinear FXLMS algorithm is more effective in reducing saturation effects in ANC systems than a linear filter and a nonlinear Volterra filter with the FXLMS algorithm. View full abstract»

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  • Toward a CPFLOW-based algorithm to compute all the type-1 load-flow solutions in electric power systems

    Page(s): 625 - 630
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    This paper presents a potential algorithm based on continuation power flow (CPFLOW) to compute all the Type-1 load-flow solutions. Type-1 solutions are of a single positive real-part eigenvalue associated with Jacobian of load-flow equations and are used in conjunction with techniques such as energy methods and the voltage instability proximity index (VIPI) for assessing system voltage stability. The benefits of the proposed algorithm are the following. The algorithm has the potential to find all the Type-1 load-flow solutions by tracing a small number of homotopy curves. Traditional methods, which can locate some of the Type-1 solutions, suffer from the uncertainty that there might be another Type-1 solution that might be more suitable for voltage stability assessment. This uncertainty is eliminated if all the Type-1 solutions are located. The proposed algorithm has been tested for two example systems, and encouraging results have been obtained. View full abstract»

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  • Generalized noise analysis technique for four-port linear networks

    Page(s): 631 - 640
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    In this paper, we present and discuss a general and modular semi-analytical analysis method for the electrical and the noise characterization of noisy linear four-port circuits. The analysis method presented builds upon the concept of noise correlation matrices and is valid for both two-port and four-port electrical networks. We also consider a four-port active transversal filter case study for which we compare the measured results with those obtained from the analysis presented here. The analytical results are in very good agreement with measured results. View full abstract»

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  • Analysis of error in the fixed-point implementation of two-dimensional discrete wavelet transforms

    Page(s): 641 - 655
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    Computational error due to the fixed-point implementation of two-dimensional (2-D) discrete wavelet transform (DWT) is analyzed. This analysis is based on the exact knowledge of the DWT analysis and synthesis filters and the word length of the original image. In the fixed-point implementation, it is crucial to understand and analyze effects of finite precision in filters coefficients as well as rounding of intermediate calculations for the purpose of storage and/or transmission. Analyses and formulations are presented for both convolution and lifting approaches and they are validated by Monte Carlo simulations. The specific example used throughout this work is the lossy wavelet transformation used in the JPEG2000 compression standard. View full abstract»

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  • Complete characterization of systems for simultaneous Lagrangian upsampling and fractional-sample delaying

    Page(s): 656 - 667
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (536 KB) |  | HTML iconHTML  

    We present a complete formulation and an exact solution to the problem of designing systems for simultaneous sampling rate increase and fractional-sample delay in the Lagrangian sense. The problem may be regarded as that of a linear transformation, i.e., scaling, and/or shifting, of the uniform sampling grid of a discrete-time signal having a Newton series representation. It is proved that the solution forms a three-parameter family of maximally flat finite impulse response digital filters with a variable group-delay at the zero frequency. Various properties of the solution, including Nyquist properties and conditions for a linear phase response are analyzed. The solution, obtained in the closed form, is exact for polynomial inputs. We show that it is also suited for processing discrete-time versions of certain continuous-time bandlimited signals and signals having a rational Laplace transform. We then derive a generalization of the solution by augmenting the family with a fourth parameter that controls the number of multiple zeros at the roots of unity. This four-parameter family contains various types of maximally flat filters including those due to Herrmann and Baher. We list specific conditions on the four parameters to obtain many of the maximally flat filters reported in the literature. A significant part of the family of systems characterized by the solutions has been hitherto unknown. Examples are provided to elucidate this part as well. View full abstract»

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  • The L(2,1)-labeling and operations of graphs

    Page(s): 668 - 671
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    Motivated by a variation of the channel assignment problem, a graph labeling analogous to the graph vertex coloring has been presented and is called an L(2,1)-labeling. More precisely, an L(2,1)-labeling of a graph G is a function f from the vertex set V(G) to the set of all nonnegative integers such that |f(x)-f(y)| ≥ 2 if d(x,y)=1 and |f(x)-f(y)| ≥ 1 if d(x,y) = 2. The L(2,1)-labeling number λ(G) of G is the smallest number k such that G has an L(2,1)-labeling with max{f(v):v∈V(G)}=k. A conjecture states that λ(G) ≤ Δ2 for any simple graph with the maximum degree Δ≥2. This paper considers the graphs formed by the Cartesian product and the composition of two graphs. The new graph satisfies the conjecture above in both cases(with minor exceptions). View full abstract»

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  • Additive mixing modulation for public key encryption based on distributed dynamics

    Page(s): 672 - 679
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (312 KB) |  | HTML iconHTML  

    We introduce a public key encryption scheme that is based on additive mixing of a message with chaotic nonlinear dynamics. A high-dimensional dissipative nonlinear dynamical system is distributed between transmitter and receiver. The transmitter dynamics is public (known to all) and the receiver dynamics is private (known only to the authorized receiver). Bidirectional signals that couple transmitter and receiver are transmitted over a public channel. Once the chaotic dynamics which is initialized with a random state converges to the attractor, a message is mixed with the chaotic dynamics at the transmitter. The authorized receiver who knows the entire dynamics can use a simple algorithm to decode the message. An unauthorized receiver does not know the receiver dynamics and needs to use computationally unfeasible algorithms in order to decode the message. Security is maintained by altering the private receiver dynamics during transmission. We show that using additive mixing modulation is more efficient than the attractor position modulation distributed dynamics encryption scheme. We demonstrate the concept of this new scheme by simulating a simple coupled map lattice. View full abstract»

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  • The Fourth International Workshop on Multidimensional (nD) Systems NDS 2005

    Page(s): 680
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    Freely Available from IEEE
  • IEEE Circuits and Systems Society Information

    Page(s): c3
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    Freely Available from IEEE

Aims & Scope

The theory, analysis, design, and practical implementations of circuits, and the application of circuit techniques to systems and to signal processing.

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Meet Our Editors

Editor-in-Chief
Shanthi Pavan
Indian Institute of Technology, Madras