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Circuits and Systems II: Express Briefs, IEEE Transactions on

Issue 9 • Date Sept. 2005

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Displaying Results 1 - 25 of 28
  • Table of contents

    Page(s): c1
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  • IEEE Transactions on Circuits and Systems—II: Express Briefs publication information

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  • A mixed time-frequency-domain approach for the analysis of a hysteretic oscillator

    Page(s): 525 - 529
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (208 KB) |  | HTML iconHTML  

    The global dynamic behavior of a hysteretic oscillator is investigated. It is shown that the most significant bifurcation phenomena can be accurately detected through the joint application of two frequency-domain techniques, i.e., describing function and harmonic balance, and of a suitable time-domain method for computing limit-cycle Floquet's multipliers. The proposed approach can be effectively applied for investigating nonlinear oscillators and circuits that do not admit of a simple Lur'e representation and that exhibit a complex dynamic behavior. View full abstract»

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  • A trigonometric formulation of the LMS algorithm for realization on pipelined CORDIC

    Page(s): 530 - 534
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (248 KB) |  | HTML iconHTML  

    This paper presents an alternate formulation of the least mean square (LMS) algorithm by using a set of angle variables monotonically related to the filter coefficients. The algorithm updates the angles directly instead of the filter coefficients and relies on quantities that can be realized by simple CORDIC rotations. Two architectures based on pipelined CORDIC unit are proposed which achieve efficiency either in time or in area. Further simplifications result from extending the approach to the sign-sign LMS algorithm. An approximate convergence analysis of the proposed algorithm, along with simulation results showing its convergence characteristics are presented. View full abstract»

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  • Warped discrete cosine transform-based noisy speech enhancement

    Page(s): 535 - 539
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB) |  | HTML iconHTML  

    In this paper, a warped discrete cosine transform (WDCT)-based approach to enhance the degraded speech under background noise environments is proposed. For developing an effective expression of the frequency characteristics of the input speech, the variable frequency warping filter is applied to the conventional discrete cosine transform (DCT). The frequency warping control parameter is adjusted according to the analysis of spectral distribution in each frame. For a more accurate analysis of spectral characteristics, the split-band approach in which the global soft decision for speech presence is performed in each band separately is employed. A number of subjective and objective tests show that the WDCT-based enhancement method yields better performance than the conventional DCT-based algorithm. View full abstract»

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  • Control for stability and positivity: equivalent conditions and computation

    Page(s): 540 - 544
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (152 KB) |  | HTML iconHTML  

    This paper investigates the stabilizability of linear systems with closed-loop positivity. A necessary and sufficient condition for the existence of desired state-feedback controllers guaranteeing the resultant closed-loop system to be asymptotically stable and positive is obtained. Both continuous and discrete-time cases are considered, and all of the conditions are expressed as linear matrix inequalities which can be easily verified by using standard numerical software. Numerical examples are provided to illustrate the proposed conditions. View full abstract»

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  • Optimization of MOS amplifier performance through channel length and inversion level selection

    Page(s): 545 - 549
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB) |  | HTML iconHTML  

    The dependence of MOS amplifier performance on channel length and channel inversion is simulated and discussed. Suggestions are made regarding the optimization of voltage gain, nonlinear distortion and the gain-bandwidth product (GBW) through careful device length and inversion level selection. The midband voltage gain of the common-source amplifier is shown to remain relatively constant when biased for weak inversion operation, with short-channel devices continuing to amplify effectively at very low levels of inversion, allowing for extremely low power circuits. Total harmonic distortion is reduced through decreasing channel length and/or the level of channel inversion. The GBW is optimized through the use of minimum sized transistors biased to operate in the strong inversion region. View full abstract»

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  • On Brayton and Moser's missing stability theorem

    Page(s): 550 - 552
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (128 KB) |  | HTML iconHTML  

    In the early 1960s, Brayton and Moser proved three theorems concerning the stability of nonlinear electrical circuits. The applicability of each theorem depends on three different conditions on the type of admissible nonlinearities in circuit. Roughly speaking, this means that the theorems apply to either circuits that contain purely linear resistors or conductors-combined with linear or nonlinear inductors and capacitors or to circuits that contain purely linear inductors and capacitors-combined with linear or nonlinear resistors and conductors. This brief note presents a generalization of Brayton and Moser's stability theorems that also includes the analysis of circuits that contain nonlinear resistors, conductors, inductors, and/or capacitors at the same time. View full abstract»

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  • Multiple integration method for a high signal-to-noise ratio readout integrated circuit

    Page(s): 553 - 557
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (768 KB) |  | HTML iconHTML  

    A multiple integration method is reported that greatly improves the signal-to-noise ratio (SNR) for applications with a high-resolution infrared (IR) focal plane array. The signal from each pixel is repeatedly sampled into an integration capacitor and then output and summed into an outside memory that continues for n read cycles during each period of a frame. This method increases the effective capacity of the charge integration and improves sensitivity. Because a low-noise function block and high-speed operation of the readout circuit is required, a new concept is proposed that enables the readout circuit to perform digitization by a voltage skimming method. The readout circuit was fabricated using a 0.6-μm CMOS process for a 64×64 midwavelength IR HgCdTe detector array. The readout circuit effectively increases the charge storage capacity to 2.4×108 electrons and then provides a greatly improved SNR by a factor of approximately 3. View full abstract»

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  • Bio-inspired compact cell circuit for reaction-diffusion systems

    Page(s): 558 - 562
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (672 KB) |  | HTML iconHTML  

    A bio-inspired MOS cell design for reaction-diffusion systems with corresponding single-layer cellular neural network (CNN) implementation is presented. The resulting network layer is introduced and approximate theoretical analysis of its certain dc characteristics is given. A test chip which includes a two-dimensional array of 10 × 9 cells is fabricated. The test chip also houses stand-alone modified cells which employ thick-oxide poly2 gate MOSFETs where the inherent high threshold characteristic is used for the design. Both the cell circuit design and the resulting network are very compact and easily implementable with available technologies. The network layer is capable of trigger wave propagation and can also be used as a compact building block for more general and multilayer reaction-diffusion (RD)-CNN designs. The wave propagation across the network and nonlinear I-V characteristics of the separate cells with thick-oxide MOSFETs are demonstrated via measurement results. View full abstract»

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  • Design of low-power analog drivers based on slew-rate enhancement circuits for CMOS low-dropout regulators

    Page(s): 563 - 567
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (552 KB) |  | HTML iconHTML  

    Low-power analog driver based on a single-stage amplifier with an embedded current-detection slew-rate enhancement (SRE) circuit is presented. By developing a systematic way to design both the response time and optimal sizing of driving transistors in the SRE circuit, the SRE circuit can be controlled to turn on or turn off properly. In addition, the analog driver only dissipates low static power and its transient responses are significantly improved without transient overshoot when driving large capacitive loads. Implemented in a 0.6-μm CMOS process, a current-mirror amplifier with the current-detection SRE circuit has achieved over 43 times improvement in both slew rate and 1% settling time when driving a 470-pF load capacitor. When the proposed analog driver is employed in a 50-mA CMOS low-dropout regulator (LDO), the resultant load transient response of the LDO has 2-fold improvement for the maximum load-current change, while the total quiescent current is only increased by less than 3%. View full abstract»

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  • On minor prime factorizations for n-D polynomial matrices

    Page(s): 568 - 571
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (168 KB) |  | HTML iconHTML  

    A tractable criterion is presented for the existence of minor prime factorizations for a class of multidimensional (n-D) (n>2) polynomial matrices whose reduced minors and greatest common divisors have some common zeros. We also present a constructive method for carrying out the minor prime factorizations when they exist. The proposed method is further extended to a larger class of n-D polynomial matrices by an invertible variable transformation. Three illustrative examples are given to show the effectiveness of the proposed method. View full abstract»

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  • Design approach using tunnel diodes for lowering power in differential comparators

    Page(s): 572 - 575
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (152 KB) |  | HTML iconHTML  

    Adding two clocked tunnel diode pairs to the output ports of a differential amplifier enables high-speed current-mode switching at a lower tail current than in a transistor-only differential pair. The addition of the tunnel diodes also lowers the output open-circuit time constant of the differential pair leading to faster switching speed. As a design example, a return-to-zero D flip-flop is simulated for use as the decision circuit in a single-bit oversampling digital-to-analog converter. Indium phosphide-based heterojunction bipolar transistors and resonant tunneling diodes are used in the model simulation; both conventional and tunnel-diode-augmented circuits are compared. Power dissipation of 3.5 mW/latch at 100-GHz clock frequency with 60-dBc spur-free dynamic range (SFDR) is obtained in the tunnel diode/transistor flip-flop. In comparison with the transistor-only approach, power is reduced by approximately 1.6× at the same speed and SFDR. View full abstract»

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  • Quantization of FIR filters under a total integer cost constraint

    Page(s): 576 - 580
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB)  

    In this paper, we present computationally efficient algorithms for obtaining a particular class of optimal quantized representations of finite-impulse response (FIR) filters. We consider a scenario where each quantization level is associated with a certain integer cost and, given an FIR filter with real coefficients, our goal is to find the quantized representation that minimizes a certain error criterion under a constraint on the total cost of all quantization levels used to represent the filter coefficients. We first formulate the problem as a constrained shortest path problem and discuss how an efficient dynamic programming algorithm can be used to obtain the optimal quantized representation for arbitrary quantization sets. We then develop a greedy algorithm which has even lower computational complexity and is shown to be optimal when the quantization levels and their associated costs satisfy a certain, easily checkable criterion. For the special case of the quantization set that involves levels that are sums of signed powers-of-two and whose cost is captured by the number of powers of two used in their representation, the total integer cost relates to the cost of the very large-scale integration implementation of the given FIR filter and our analysis clarifies the optimality of previously proposed algorithms in this setting. View full abstract»

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  • Connecting border collision with saddle-node bifurcation in switched dynamical systems

    Page(s): 581 - 585
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB) |  | HTML iconHTML  

    Switched dynamical systems are known to exhibit border collision, in which a particular operation is terminated and a new operation is assumed as one or more parameters are varied. In this brief, we report a subtle relation between border collision and saddle-node bifurcation in such systems. Our main finding is that the border collision and the saddle-node bifurcation are actually linked together by unstable solutions which have been generated from the same saddle-node bifurcation. Since unstable solutions are not observable directly, such a subtle connection has not been known. This also explains why border collision manifests itself as a "jump" from an original stable operation to a new stable operation. Furthermore, as the saddle-node bifurcation and the border collision merge tangentially, the connection shortens and eventually vanishes, resulting in an apparently continuous transition at border collision in lieu of a "jump." In this brief, we describe an effective method to track solutions regardless of their stability, allowing the subtle phenomenon to be uncovered. View full abstract»

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  • Nash games for multiparameter singularly perturbed systems with uncertain small singular perturbation parameters

    Page(s): 586 - 590
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB) |  | HTML iconHTML  

    In this paper, the linear quadratic Nash games for infinite horizon multiparameter singularly perturbed systems with uncertain singular perturbation parameters are discussed. The main contribution is that a construction of high-order approximations to a strategy that guarantees a desired performance level on the basis of the successive approximation is proposed. It is newly shown that the proposed high-order approximate strategy improves the cost performance. View full abstract»

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  • High-performance error amplifier for fast transient DC-DC converters

    Page(s): 591 - 595
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (376 KB) |  | HTML iconHTML  

    A new error amplifier is presented for fast transient response of dc-dc converters. The amplifier has low quiescent current to achieve high power conversion efficiency, but it can supply sufficient current during large-signal operation. Two comparators detect large-signal variations, and turn on extra current supplier if necessary. The amount of extra current is well controlled, so that the system stability can be guaranteed in various operating conditions. The simulation results show that the new error amplifier achieves significant improvement in transient response than the conventional one. View full abstract»

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  • TSK-based decision feedback equalizer using an evolutionary algorithm applied to QAM communication systems

    Page(s): 596 - 600
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB) |  | HTML iconHTML  

    A Takagi-Sugeno-Kang (TSK) fuzzy-based decision feedback equalizer (DFE) applied to detecting a quadrature-amplitude-modulation (QAM) signal is presented. The structure of a TSK fuzzy system may produce many local minimum of involved cost functions for detecting received signals. An evolutionary algorithm is adopted for the proposed TSK fuzzy equalizer to overcome the difficulty for locating global minimum in weight space. Results showed that the performance of the newly designed equalizer is much improved for DFEs with multilayer perceptron or least mean square scheme. View full abstract»

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  • Design of FIR digital filters with prescribed flatness and peak error constraints using second-order cone programming

    Page(s): 601 - 605
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB) |  | HTML iconHTML  

    This paper studies the design of digital finite impulse response (FIR) filters with prescribed flatness and peak design error constraints using second-order cone programming (SOCP). SOCP is a powerful convex optimization method, where linear and convex quadratic inequality constraints can readily be incorporated. It is utilized in this study for the optimal minimax and least squares design of linear-phase and low-delay (LD) FIR filters with prescribed magnitude flatness and peak design error. The proposed approach offers more flexibility than traditional maximally-flat approach for the tradeoff between the approximation error and the degree of design freedom. Using these results, new LD specialized filters such as digital differentiators, Hilbert Transformers, Mth band filters and variable digital filters with prescribed magnitude flatness constraints can also be derived. View full abstract»

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  • Novel current-mode background suppression for 2-D LWIR applications

    Page(s): 606 - 610
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (352 KB) |  | HTML iconHTML  

    A new readout circuit involving two-step current-mode background suppression is studied for two-dimensional long-wavelength infrared focal plane arrays (2-D LWIR FPAs). Buffered direct injection (BDI) and a feedback amplifier are used for the input circuit and background suppression circuit, respectively. The readout circuit has been fabricated using a 0.6-μm 2-poly 3-metal CMOS process for a 64×64 LWIR HgCdTe IR array with a pixel size of 50 μm×50 μm. The simple pixel circuit has a very small skimming error of less than 0.3% and low noise characteristics for an adequate calibration range and integration time. View full abstract»

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  • A novel FPGA compliant micropipeline

    Page(s): 611 - 615
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (688 KB) |  | HTML iconHTML  

    In this paper, it has been demonstrated that the concept of micropipeline which is native to full custom design can be imported to a traditionally synchronous environment of field-programmable gate arrays (FPGAs) by introducing delay pads which are implemented with a special technology-independent circuit called single-inverter ring oscillator. The delay pad can be customized with the help of a dividing counter to suit the requirements of various stages of the micropipeline. To implement FPGA compliant micropipeline unbundled data strategy has been adopted by incorporating special event controlled registers as opposed to traditional bundled data approach of micropipeline. A 5-stage reconfigurable micropipeline based load-store machine has been developed to demonstrate the validity of the proposed idea. Furthermore, it has been shown that a particular micropipeline stage functioning at its own pace goes into the sleep mode whenever the following stage is not ready to accept the data hence reducing the overall power consumption of the system. View full abstract»

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  • Special issue on advances on life science systems and applications

    Page(s): 616
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    Freely Available from IEEE
  • Special issue on smart sensors

    Page(s): 617
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    Freely Available from IEEE
  • 2006 IEEE International Symposium on Circuits and Systems (ISCAS 2006)

    Page(s): 618
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    Freely Available from IEEE
  • 2006 IEEE International Conference on Multimedia and Expo (ICME)

    Page(s): 619
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    Freely Available from IEEE

Aims & Scope

TCAS II publishes brief papers in the field specified by the theory, analysis, design, and practical implementations of circuits, and the application of circuit techniques to systems and to signal processing. Included is the whole spectrum from basic scientific theory to industrial applications. The field of interest covered includes:

  • Circuits: Analog, Digital and Mixed Signal Circuits and Systems  
  • Nonlinear Circuits and Systems, Integrated Sensors, MEMS and Systems on Chip, Nanoscale Circuits and Systems, Optoelectronic
  • Circuits and Systems, Power Electronics and Systems
  • Software for Analog-and-Logic Circuits and Systems
  • Control aspects of Circuits and Systems. 

Full Aims & Scope