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

Issue 4 • Date April 2003

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Displaying Results 1 - 16 of 16
  • Simplicial RTD-based cellular nonlinear networks

    Page(s): 500 - 509
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1704 KB) |  | HTML iconHTML  

    Recently, a novel structure called the simplicial cellular neural network (CNN) has been introduced , which permits one to implement any Boolean/Gray-level function of any number of variables. This paper is devoted to explore novel circuit architectures for the implementation of the simplicial CNN based on resonant tunneling diodes. The final objective is to implement a fully programmable CNN in a hardware platform based on nanoelectronic devices. View full abstract»

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  • Periodic waveform relaxation of nonlinear dynamic systems by quasi-linearization

    Page(s): 589 - 593
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (329 KB) |  | HTML iconHTML  

    In this brief, we provide an algorithm to treat periodic problems of nonlinear dynamic systems. Our approach is to apply quasi-linearization and waveform relaxation to a system of equations so as to produce a series of linear time-varying systems with periodicity constraints. We prove convergence of the algorithm and apply it to solutions of forced van der Pol equations as a further illustration. View full abstract»

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  • Step response of a second-order digital filter with two's complement arithmetic

    Page(s): 510 - 522
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2336 KB) |  | HTML iconHTML  

    It is well known that the autonomous response of a second-order digital filter with two's complement arithmetic may exhibit chaotic behavior. In this paper, results of the step-response case are presented. Despite the presence of the overflow nonlinearity, it is found that the step-response behaviors can be related to some corresponding autonomous-response behaviors by means of an appropriate affine transformation. Based on this method, some differences between the step response and the autonomous response are explored. The effects of the filter parameter and input step size on the trajectory behaviors are presented. Some previous necessary conditions for the trajectory behaviors, initial conditions and symbolic sequences are extended and strengthened to become necessary and sufficient conditions. Based on these necessary and sufficient conditions, some counter-intuitive results are reported. For example, it is found that for some sets of filter parameter values, the system may exhibit the type I trajectory even when a large input step size is applied and overflow occurs. On the other hand, for some sets of filter parameter values, the system will not give the type I trajectory for any small input step size, no matter what the initial conditions are. View full abstract»

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  • Synthesis of high dynamic range motion blur free image from multiple captures

    Page(s): 530 - 539
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (693 KB)  

    Advances in CMOS image sensors enable high-speed image readout, which makes it possible to capture multiple images within a normal exposure time. Earlier work has demonstrated the use of this capability to enhance sensor dynamic range. This paper presents an algorithm for synthesizing a high dynamic range, motion blur free, still image from multiple captures. The algorithm consists of two main procedures, photocurrent estimation and saturation and motion detection. Estimation is used to reduce read noise, and, thus, to enhance dynamic range at the low illumination end. Saturation detection is used to enhance dynamic range at the high illumination end as previously proposed, while motion blur detection ensures that the estimation is not corrupted by motion. Motion blur detection also makes it possible to extend exposure time and to capture more images, which can be used to further enhance dynamic range at the low illumination end. Our algorithm operates completely locally; each pixel's final value is computed using only its captured values, and recursively, requiring the storage of only a constant number of values per pixel independent of the number of images captured. Simulation and experimental results demonstrate the enhanced signal-to-noise ratio (SNR), dynamic range, and the motion blur prevention achieved using the algorithm. View full abstract»

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  • Robust L2-L filtering for uncertain systems with multiple time-varying state delays

    Page(s): 594 - 599
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (431 KB) |  | HTML iconHTML  

    This paper is concerned with the robust L2-L filtering problem for uncertain systems with multiple time-varying state delays. The uncertain parameters are supposed to reside in a polytope and the attention is focused on the design of robust full-order and reduced-order filters guaranteeing a prescribed energy-to-peak noise-attenuation level for all admissible uncertainties and time delays. The admissible filters can be obtained from the solution of convex optimization problems in terms of linear matrix inequalities, which can be solved via efficient interior-point algorithms. Both delay-independent and dependent approaches are presented, with an example illustrating the validity of the proposed designs. View full abstract»

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  • A simultaneous coefficient calculation method for sincN FIR filters

    Page(s): 523 - 529
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (526 KB) |  | HTML iconHTML  

    A novel simultaneous coefficient calculation method for sincN filter and its application to the filter design are described. This method can be applied to any (N) stages of sincN filters with no degradation of coefficient accuracy. Every coefficient can be calculated by Nth-order multiple-loop accumulation of N-scaled delayed impulses. The coefficient can be obtained every clock or operation cycle because these loops are not nested but merely chained together. SincN decimation filters based on this method are suitable for high-speed operation as well-known cascaded integrator-comb (CIC ) filters. If rounding or truncation is used at data-accumulation stages, they can operate faster than those in some cases. For example, the critical-path-length ratio of 32-tap single-bit-input (for delta-sigma analog-to-digital converters) sinc4 decimation filters by this and the CIC approach is 0.714 if their outputs are rounded to 8-bit words. Unfortunately, the gate count exponentially increases in proportion to the order N. However, in some special cases (single-bit-input sinc2 and sinc3 decimation filters), they are comparable to the equivalent CIC filters in size. View full abstract»

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  • Hilbert space techniques for modeling and compensation of reactive power in energy processing systems

    Page(s): 540 - 556
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1090 KB) |  | HTML iconHTML  

    The paper provides a unified exposition of various definitions of reactive (or inactive) power and of various compensation methods. In particular, it presents a comparative Hilbert space analysis of definitions used in power system studies and in electric drives (the so called instantaneous reactive power). The paper casts several compensation strategies (such as compensation without energy storage and compensation with linear shunt components) in a common framework, and utilizes the concept of orthogonal projections on suitable subspaces as the main analytical and computational tool. Various notions are illustrated on two examples. View full abstract»

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  • Laplace domain analysis of periodic noise modulation

    Page(s): 584 - 588
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (345 KB) |  | HTML iconHTML  

    Noise analysis of sampled-data circuits in the general framework of periodic noise modulation is discussed. The analysis relies on the Laplace transform instead of the more popular Fourier analysis. The approach leads to integral expressions that can be directly computed through numerical methods. Familiar Fourier domain expressions involving infinite series are shown to be special solutions to these integrals. The theory of the modified z transform is extended to the case of two-sided random signals to study the effect of correlated double sampling. The purpose of this analysis is to elaborate a basis for noise analysis of complex switched-capacitor (SC) circuits. View full abstract»

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  • Chaotic cryptosystem with high sensitivity to parameter mismatch

    Page(s): 579 - 583
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (349 KB) |  | HTML iconHTML  

    In this brief, we present a new sufficient condition for the stabilization and the synchronization of Chua's circuit. The Chua's circuit is used in our chaotic secure cryptosystem and the relaxed stability condition enables us to obtain a larger bound on the impulsive interval, which leads to a higher efficiency in bandwidth utilization. In the proposed system, we introduce the concept of a magnifying glass to enlarge and observe minor parameter mismatch and hence to increase the sensitivity and the security level of the cryptosystem. We use speech transmission as an example to illustrate that the proposed cryptosystem can achieve an excellent encryption effect and that it is sensitive to parameter mismatch. View full abstract»

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  • Object-oriented image analysis using the CNN universal machine: new analogic CNN algorithms for motion compensation, image synthesis, and consistency observation

    Page(s): 488 - 499
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1408 KB)  

    Image-analysis algorithms are of great interest in the context of object-oriented coding schemes. With reference to the utilization of the cellular neural network (CNN) universal machine for object-oriented image analysis, this paper presents new analogic CNN algorithms for obtaining motion compensation, image synthesis, and consistency observation. Along with the already developed segmentation and object labeling technique, the proposed method represents a framework for implementing CNN-based real-time image analysis. Simulation results, carried out for different video sequences, confirm the validity of the approach developed herein. View full abstract»

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  • Stable Laguerre-SVD reduced-order modeling

    Page(s): 576 - 579
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (281 KB) |  | HTML iconHTML  

    A provably stable reduced-order model, based on a projection onto a scaled orthonormal Laguerre basis, followed by a SVD step, is proposed. The method relies on the conformal mapping properties induced by the complete orthonormal scaled Laguerre basis, allowing a mapping from the discrete-stable case to the continuous-stable case and vice versa. View full abstract»

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  • A singular-value decomposition approach for ambiguity group determination in analog circuits

    Page(s): 477 - 487
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (526 KB) |  | HTML iconHTML  

    An efficient approach for ambiguity group determination in low-testability analog linear circuits is presented. It is based on the use of the singular-value decomposition of the testability matrix of the circuit under test, and permits us to determine canonical ambiguity groups also in the case of circuits of relatively large dimensions. The new approach is characterized by a numerical robustness not present in previous approaches, which give only an estimate of both testability and ambiguity groups. A program implementing the proposed method has been developed by exploiting symbolic analysis techniques. Examples of application of the new approach are considered through the use of this program. View full abstract»

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  • Propagation delay model of a current driven RC chain for an optimized design

    Page(s): 572 - 575
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (358 KB) |  | HTML iconHTML  

    This work presents models which evaluate the propagation delay of an RC chain driven by a step input current generator. Starting from a rule of thumb model, involving network parameter values, three different approximations have been devised. The approximated models are quite simple and can be adopted in finding the number of stages after which repeaters can be introduced. In particular, one of the models can be used to optimize the propagation delay when inserting repeaters in a chain of transmission gates. Results from the new approach were compared with the traditional one with optimization by Spice simulation using a 0.35-μm CMOS technology. The optimization based on the proposed model shows both a lower propagation delay and the need for a smaller number of repeaters compared with the traditional approach, hence, lower power consumption and silicon area. View full abstract»

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  • Compact modeling of electrical devices for electrothermal analysis

    Page(s): 465 - 476
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (672 KB) |  | HTML iconHTML  

    Discretization of diffusion-equation modeling heat conduction in electrical devices, as needed for accurate electrothermal simulations, tends to produce thermal networks of very large size. This paper investigates an effective method for thermal network complexity reduction preserving high accuracy in electrothermal analysis. The method is based on a suited port-like definition of thermal network and on the use of the truncated balanced-reduction method. The strategy is practically applied to the electrothermal simulation of a power vertical double diffused MOSFET. View full abstract»

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  • A new class of wide-band amplifiers with monotonic step response

    Page(s): 569 - 571
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (260 KB) |  | HTML iconHTML  

    This work describes the wide-band amplifiers that were designed using the first semi-period of the sink t function as an approximation to their impulse response. For this class of amplifiers with monotonic step response, one can establish a simple relationship between the delay-to-rise-time ratio and the required order of transfer function, and to derive the transfer function itself. To simplify the design, the corresponding transfer functions from the fourth to tenth order are tabulated. The delay-to-rise-time ratio for the proposed transfer functions is higher than that of Bessel or Gaussian filter functions. View full abstract»

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  • Optimal design of frequency-response-masking filters using semidefinite programming

    Page(s): 557 - 568
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (897 KB) |  | HTML iconHTML  

    Since Lim's paper (see IEEE Trans. Circuits Syst., vol.33, p. 357-364, Apr. 1986) on the frequency-response-masking (FRM) technique for the design of finite-impulse response digital filters with very small transition widths, the analysis and design of FRM filters has been a subject of study. In this paper, a new optimization technique for the design of various FRM filters is proposed. Central to the new design method is a sequence of linear updates for the design variables, with each update carried out by semidefinite programming. Algorithmic details for the design of basic and multistage FRM filters are presented to show that the proposed method offers a unified design framework for a variety of FRM filters. Design simulations are included to illustrate the proposed algorithms and to evaluate the design performance in comparison with that of several existing methods. View full abstract»

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