Fluctuations and noise of hot carriers in semiconductor materialsand devices

After recalling the definition of the noise temperature, the macroscopic expressions for noise sources are shown not to be specific to the hot carrier regime, though dependent on the electric field strength. Careful modeling allows one to obtain important information on transport parameters from noise measurements. The microscopic noise source expressions, via the transition rates, give a unified view of the noise sources. In particular, it is clarified that noise sources are intercorrelated, and that there is also space correlations over lengths of a few mean free paths. Recent developments are reviewed, concerning noise modeling using direct numerical methods for solution of the Boltzmann equation. Finally, impedance field methods for modeling noise of devices are briefly evoked     

Fluctuations of the wave amplitude level in a plane-layered medium with random irregularities

The spatial correlation properties of the amplitude (amplitude level) of a wave existing in a random medium and at the exit from it are determined. It is shown that, within the framework of geometric optics, the oblique incidence of a wave on a refractive medium accounts for the anisotropy of the spatial correlation characteristics of the medium in the case of the statistical isomerism of the medium’s permittivity. Special attention is focused on the investigation of the reflection region where the geometric optics method is invalid.     

基于统计噪声水平分析的图像拼接检测

图像拼接是最常用的图像篡改操作之一,针对篡改图像噪声水平不一致性的现象,本文提出了一种基于统计噪声水平分析的图像拼接检测方法。首先,将检测图像分割成大小相同的非重叠图像块,然后,利用一种非参数估计算法来估计每个图像块的噪声值,并且采取聚类法对图像块的噪声值进行聚类,聚类结果分为可疑部分和非可疑部分两大类。最后,通过一个由粗到细的两阶段策略对篡改区域进行定位。哥伦比亚未压缩图像拼接检测评估图像库的实验结果表明,本文方法能够准确地估计图像块的噪声和定位出拼接区域,性能优于现有方法。     

Variation of atmospheric radio noise level with sunspot number

Analysis of atmospheric radio noise data collected during 20-24-h periods at Delhi, India, shows that the noise levels decrease linearly with sunspot number. This result may be useful in reducing prediction uncertainties. It also suggests that residual absorption in the nighttime is significant.     

基于模糊度和噪声水平的图像质量评价方法

针对图像质量评价的重要性,提出了一种新的无参考图像质量客观评价方式。算法考虑了模糊度与噪声水平两方面,用平均边缘宽度衡量图像的模糊度,通过比较去噪前后的图像预测图像受噪声污染的程度,最后通过两者的综合作为无参考图像质量评价指标。实验结果表明:将模糊度和噪声评价相结合,具有很强的抗噪性和广泛的适用范围;与峰值信噪比(PSNR)和结构类似性(SSIM)等算法比较,本文算法可以很好地区分各种失真类型图像的质量好坏,其结果接近人眼的主观感受。     

Removal of impulse noise from color images based on the localized image characteristics and noise level

The proposed method is a switching vector median filter that utilizes suitable noise detection and restoration algorithms for different impulse noise densities. It works in a multistage manner with an enhancing accuracy of noise detection in each successive stage. The processing window is initially categorized into a non-edge-window and an edge-window, depending on the scale of abrupt transitions. The non-edge-window is further verified to be a smooth-window or a disorder-window, whereas the edge-window is again confirmed to be noise-free or a noisy edge-window. The proposed method is simulated on a variety of medical images and other standard test images to prove its efficiency in detection of noise and restoration.     

Selective removal of impulse noise based on homogeneity level information

We propose a decision-based, signal-adaptive median filtering algorithm for removal of impulse noise. Our algorithm achieves accurate noise detection and high SNR measures without smearing the fine details and edges in the image. The notion of homogeneity level is defined for pixel values based on their global and local statistical properties. The cooccurrence matrix technique is used to represent the correlations between a pixel and its neighbors, and to derive the upper and lower bound of the homogeneity level. Noise detection is performed at two stages: noise candidates are first selected using the homogeneity level, and then a refining process follows to eliminate false detections. The noise detection scheme does not use a quantitative decision measure, but uses qualitative structural information, and it is not subject to burdensome computations for optimization of the threshold values. Empirical results indicate that our scheme performs significantly better than other median filters, in terms of noise suppression and detail preservation.     

Quantum Fluctuations in Microwave Radiometry

This paper assesses the possible significance of the quantum nature of electromagnetic radiation in limiting the measurement accuracy attainable with a microwave radiometer. Analogies are shown to exist between the form of a formula describing fluctuations in the radiometer output, and both a formula describing the radiometer input signal, and also, a formula describing the output of a photocell detector. Detailed quantum mechanical consideration of the processes of amplification and detection are circumvented by considering how the formula for fluctuations in the radiometer output might be modfied so as to make it consistent with the measurement precision implied by these other formulas. A modified formula is suggested which includes a quantum fluctuation whose magnitude depends on signal power.     

600V HVIC高噪声抑制电平移位电路

A novel level shift circuit featuring with high dV/dt noise immunity and improved negative V_S capacity is proposed in this paper.Compared with the conventional structure,the proposed circuit adopting two cross-coupled PMOS transistors realizes the selective filtering ability by exploiting the path which filters out the noise introduced by the dV/dt.In addition,a differential noise cancellation circuit is proposed to enhance the noise immunity further.Meanwhile,the negative V_S capacity is improved by unifying the detected reference voltage and the logic block’s threshold voltage.A high voltage half bridge gate drive IC adopting the presented structure is experimentally realized by using a usual 600 V BCD process and achieves the stable operation up to 65 V/ns of the dV/dt characteristics.     

基于噪声估计的自适应块匹配和三维滤波降噪算法

针对经典的块匹配和三维滤波(BM3D)降噪算法中最 为核心的噪声水平(方差)参数在使用中需要 人工手动设置极大影响了降噪效果并限制了它的应用,提出了一种新的基于自然场景 统计(NSS)的噪声水平特征矢量和支持向量回归(SVR)技术的快速噪声水平估计算法并应用于 经典BM3D算法 中,使之转变为自适应降噪算法(Adaptive BM3D)。本文算法首先利用小波变换对图像进行 不 同尺度和不同方向的分解,提取各子带滤波系数并用通用高斯分布模型(GGD)建模,以模型 参数构成反映噪 声图像噪声水平的特征矢量;然后用SVR方法在大量噪声图像样本上进行训练获得图像噪声 水平预测模型。 实验表明:改进后的ABM3D算法实际图像降噪效果比BM3D算法获得进一步提升,并且仍然 保持了非常高的执行效率,相对于当前各主流算法具有明显的竞争力。     

Spontaneous Voltage Fluctuations in Glass Microelectrodes

The spontaneous fluctuations of voltage across a glass microelectrode have been studied as a function of the average difference in voltage (V) across the electrode and the concentration of internal (n2) and external (n1) salt solutions. A stationary fluctuation was observed, with a mean square value many times greater than that calculated from the Nyquist formula for noise due to the thermal agitation of charge, for all states of the electrode except n2=n1, V=0. Here the fluctuations equal the Johnson level. The spectral density of the fluctuation and its dependence on (n1, n2, V) are given in the range 3-0.003 MKCl and V = ±200 mV. The dependence on the species of cation (potassium and sodium) was also determined. The work has practical implications for users of microelectrodes who wish to minimize noise. It also serves as a model for studying noise generated when ions move through a micropore.     

Pattern-dependent noise prediction in signal-dependent noise

Maximum and near-maximum likelihood sequence detectors in signal-dependent noise are discussed. It is shown that the linear prediction viewpoint allows a very simple derivation of the branch metric expression that has previously been shown as optimum for signal-dependent Markov noise. The resulting detector architecture is viewed as a noise predictive maximum likelihood detector that operates on an expanded trellis and relies on computation of branch-specific, pattern-dependent noise predictor taps and predictor error variances. Comparison is made on the performance of various low-complexity structures using the positional-jitter/width-variation model for transition noise. It is shown that when medium noise dominates, a reasonably low complexity detector that incorporates pattern-dependent noise prediction achieves a significant signal-to-noise ratio gain relative to the extended class 4 partial response maximum likelihood detector. Soft-output detectors as well as the use of soft decision feedback are discussed in the context of signal-dependent noise     

EMI conducted emission in the differential mode emanating from anSCR: phenomena and noise level prediction

This paper deals with an EMC analysis of a power converter. In particular, the phenomena and modeling of conducted noise emission caused by an SCR (silicon controlled rectifier) are described. Theoretical results in the time as well as frequency domain are discussed and compared to the time signal measured and its spectrum     

介观电感耦合电路的量子涨落

提出了电感耦合电路的一种量子化方案,研究了电路中电荷和电流在相干态下的量子涨落,结果表明两个回路中的量子涨落是相互关联的,并对结果进行了讨论。     

Fluctuations in millimeter-wave signals propagated throughinclement weather

Results are presented from measurements of the effects of inclement weather on the fluctuations in amplitude and phase of millimeter-wave (MMW) signals propagated through the atmosphere. These measurements were made at frequencies near 116, 140, 173, and 230 GHz at a site near Champaign-Urbana, Illinois, in a community chosen for its exceptional flatness and lack of terrain features that might perturb the atmosphere. It was found that this inclement weather fluctuations are generally smaller than those observed in clear air under sunny conditions, and are also smaller than the corresponding effects observed at visible and near-infrared wavelengths. Rain has the greatest effect on MMW transmission, causing large, slow changes in received signal strength as a function of rain rate. It should also be noted that rain caused the only observed loss of the propagation link, during a thunderstorm in which the rain rate was as high as 60 mm/h. It is concluded that, in general, millimeter-wave radiation propagates well in adverse weather, with rain causing the major problems     

Role of Electromagnetic Fluctuations in Organic Electronics

Thin organic films find expanding applications in electronic and optoelectronic devices, biotechnology, food packing, and for many other purposes. Among other factors, the stability of films with a thickness below a micrometer is determined by the zero-point and thermal fluctuations of the electromagnetic field. These fluctuations result in the van der Waals and Casimir free energy and forces between a film and a substrate. The fluctuation-induced force may be both attractive and repulsive making the film either more or less stable, respectively. Here, we review recently obtained results for the Casimir free energy of both freestanding and deposited on the metallic and dielectric substrates peptide films. We also perform computations for the free energy of the peptide films deposited on a silica glass substrate in the region of parameters where this free energy vanishes. Possible applications of the obtained results are discussed.     

Device and circuit level suppression techniques for random-dopant-induced static noise margin fluctuation in 16-nm-gate SRAM cell

In this study, a three-dimensional “atomistic” coupled device-circuit simulation is performed to explore the impact of process-variation-effect (PVE) and random-dopant-fluctuation (RDF) on static noise margin (SNM) of 16-nm complementary metal-oxide-semiconductor (CMOS) static random access memory (SRAM) cells. Fluctuation suppression approaches, based on circuit and device viewpoints, are further implemented to examine the associated characteristics in 16-nm-gate SRAM cells. From the circuit viewpoint, the SNM of 8T planar SRAM is enlarged to 230 mV and the variation of SNM (σ_SNM) is reduced to 22 mV at a cost of 30% extra chip area. As for device level improvement, silicon-on-insulator (SOI) FinFETs replaced the planar MOSFETs in 6T SRAM is further examined. The SNM of 6T SOI FinFETs SRAM is 125 mV and the σ_SNM is suppressed significantly to 5.4 mV. However, development of fabrication process for SOI FinFET SRAM is crucial for sub-22 nm technology era.     

Fluctuations of Human Tapping Intervals

Spectral analysis of fluctuations in tapping intervals has been performed when a subject listened to and did not listen to a metronome ticking. The power spectral density for metronome tapping is white above 0.1 Hz, and still white or decreasing toward the lower frequency; this means that memory of interval fluctuations within the subject is cleared by referring to metronome ticking. On the other hand, the spectrum for free tapping is white above 0.1 Hz, below which it increases so that the spectral density is inversely proportional to frequency (the 1/f spectrum). Furthermore, the white spectral level in free tapping is lower than that for metronome tapping. Subjects with Zen training showed a 1/f2 spectrum.     

抑制电子电路中空间干扰噪音的措施

在进行电子产品开发过程中,必然会遇到各种各样的噪音。为了揭示空间噪音的根源、传输途径及抑制方法.在实验中,反复采用系统接地和电磁屏蔽有效结合的手段,对电路信号中的空间噪音波形进行观察、比较与分析。实践中,使用这些措施去抑制电子产品的空间噪音,都达到了事半功倍的效果。