排序方式: 共有53条查询结果,搜索用时 15 毫秒
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An interfacing circuit for piezoresistive pressure sensors based on the CMOS operational floating amplifier in a current conveyor configuration is presented. The main advantages of the proposed circuit include the use of only two piezoresistors with high common-mode rejection ratio, using an instrumentation amplifier based on a second-generation current conveyor (CCII) and temperature compensation. The circuit has frequency output proportional to the applied pressure with high linearity and temperature dependence less than 150ppm°C?1. Experimental results, using the interfacing circuit and a commercial silicon pressure sensor, are included to demonstrate its performance. 相似文献
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A simple squarer based on floating-gate MOS transistors is presented. The squarer has rail-to-rail input range with less than 0.5% non-linearity error. Using this squarer single-ended and/or differential signals can be processed without additional circuitry. Also, a four quadrant analogue multiplier can be realised using the proposed squarer. Simulation results are given to verify the theoretical analysis 相似文献
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Vlassis S. Siskos S. 《IEEE transactions on circuits and systems. I, Regular papers》2004,51(2):329-341
In this paper, we present voltage-mode and current-mode computational circuits using floating-gate MOS (FGMOS) transistors, operating in saturation region. The circuits are designed using two FGMOS basic-cells, each one formed by three floating-gate transistors with common source. The first basic cell is connected in voltage mode, while the second one is connected in current-mode configuration in order to implement voltage and current-mode circuits, respectively. Using the basic FGMOS cells, voltage and current squarers, four-quadrant multipliers and a current square rooter are designed. Mismatches and distortion analysis for the proposed circuits have been elaborated. The most important advantages are, rail-to-rail dynamic input range, low distortion and ability for either differential or single-ended input signals. Simulation results demonstrate the feasibility and the accuracy of the circuits. 相似文献
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Vlassis N. Likas A. 《IEEE transactions on systems, man, and cybernetics. Part A, Systems and humans : a publication of the IEEE Systems, Man, and Cybernetics Society》1999,29(4):393-399
We address the problem of probability density function estimation using a Gaussian mixture model updated with the expectation-maximization (EM) algorithm. To deal with the case of an unknown number of mixing kernels, we define a new measure for Gaussian mixtures, called total kurtosis, which is based on the weighted sample kurtoses of the kernels. This measure provides an indication of how well the Gaussian mixture fits the data. Then we propose a new dynamic algorithm for Gaussian mixture density estimation which monitors the total kurtosis at each step of the EM algorithm in order to decide dynamically on the correct number of kernels and possibly escape from local maxima. We show the potential of our technique in approximating unknown densities through a series of examples with several density estimation problems 相似文献
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Vassileios Kalenteridis Spyridon Vlassis Stylianos Siskos 《Analog Integrated Circuits and Signal Processing》2012,72(2):333-341
A new low-voltage CMOS exponential current generator is proposed in this work. MOS transistors in weak-inversion region and a master?Cslave technique for the temperature compensation were used. The circuit was fabricated with standard CMOS 0.35???m process using a single supply voltage of 1.5?V. Experimental results validate the theoretical analysis and verify the effectiveness of the proposed structure. A 40?dB range linearly in dB controlled output current with less than 1.5?dB linearity error was achieved. The structure features ±1 and ±3?dB deviations for ±10% supply voltage and 80°C temperature variations, respectively. 相似文献
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Changseok Han Amos Doepke Wondong Cho Vlassis Likodimos Armah A. de la Cruz Tyson Back William R. Heineman H. Brian Halsall Vesselin N. Shanov Mark J. Schulz Polycarpos Falaras Dionysios D. Dionysiou 《Advanced functional materials》2013,23(14):1807-1816
A multiwalled carbon nanotube (MWCNT)‐based electrochemical biosensor is developed for monitoring microcystin‐LR (MC‐LR), a toxic cyanobacterial toxin, in sources of drinking water supplies. The biosensor electrodes are fabricated using vertically well‐aligned, dense, millimeter‐long MWCNT arrays with a narrow size distribution, grown on patterned Si substrates by water‐assisted chemical vapor deposition. High temperature thermal treatment (2500 °C) in an Ar atmosphere is used to enhance the crystallinity of the pristine materials, followed by electrochemical functionalization in alkaline solution to produce oxygen‐containing functional groups on the MWCNT surface, thus providing the anchoring sites for linking molecules that allow the immobilization of MC‐LR onto the MWCNT array electrodes. Addition of the monoclonal antibodies specific to MC‐LR in the incubation solutions offers the required sensor specificity for toxin detection. The performance of the MWCNT array biosensor is evaluated using micro‐Raman spectroscopy, including polarized Raman measurements, X‐ray photoelectron spectroscopy, cyclic voltammetry, optical microscopy, and Faradaic electrochemical impedance spectroscopy. A linear dependence of the electron‐transfer resistance on the MC‐LR concentration is observed in the range of 0.05 to 20 μg L?1, which enables cyanotoxin monitoring well below the World Health Organization (WHO) provisional concentration limit of 1 μg L?1 for MC‐LR in drinking water. 相似文献
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We address the problem of estimating an unknown probability density function from a sequence of input samples. We approximate the input density with a weighted mixture of a finite number of Gaussian kernels whose parameters and weights we estimate iteratively from the input samples using the Maximum Likelihood (ML) procedure. In order to decide on the correct total number of kernels we employ simple statistical tests involving the mean, variance, and the kurtosis, or fourth moment, of a particular kernel. We demonstrate the validity of our method in handling both pattern classification (stationary) and time series (nonstationary) problems. 相似文献