共查询到18条相似文献,搜索用时 78 毫秒
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外加磁场对含双δ势垒的铁磁/半导体/铁磁异质结中自旋输运和散粒噪声的影响 总被引:1,自引:1,他引:0
研究了外磁场存在时,含双δ势垒的铁磁/半导体/铁磁异质结中自旋相关的透射概率和散粒噪声,讨论了量子尺寸效应和Rashba自旋轨道耦合效应.研究结果表明:不同自旋取向的电子隧穿异质结时,透射概率和散粒噪声随半导体长度的变化特性是作等幅振荡;外加磁场和Rashba自旋轨道耦合强度的增强都会加大透射概率和散粒噪声的振荡频率;外加磁场角度的改变会改变散粒噪声的振荡频率;双δ势垒的存在增大了自旋电子透射概率的振幅. 相似文献
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应用Lamb的半经典激光理论,分析了散粒噪声和热噪声对激光特性的影响.推导了在散粒噪声和热噪声存在时激光场几率分布的Fokker-Planck方程,得到了计及噪声时聚束和反聚束的判据.并与单光子激光中噪声存在时相应的结果进行了比较. 相似文献
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在研究CMOS数字像素传感器(DPS)噪声特性的基础上,利用脉冲宽度调制(PWM)原理建立了关于PWM DPS完善的系统噪声数学模型。相比于传统CMOS图像传感器噪声研究,该模型考虑了系统中各像素单元积分时间不同和像素级模数转换的特点,推导出总噪声表达式。研究表明,低照度时噪声由暗电流散粒噪声主导,光强大时主要来源为光电二极管散粒噪声。模型中光电二极管散粒噪声与光照无关、暗电流散粒噪声与光照有关。研究结果表明针对PWM DPS系统,适当增大节点电容和比较器参考电压、改善比较器失配可有效降低噪声。 相似文献
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论述了纳米电子器件与结构中散粒噪声的产生机理和影响因素,表明散粒噪声与输运过程密切相关,按照噪声功率谱的幅值大小将散粒噪声分为泊松散粒噪声、亚泊松散粒噪声和超泊松散粒噪声四类。将散粒噪声的这些规律应用于纳米电子器件和结构,可表征不同器件与结构中的量子效应。利用散粒噪声已经成功检测到无序导线中的开放通道与量子点混沌腔中的波动性,测量出超导体与分数量子霍尔效应中的准粒子电荷。将散粒噪声用于检测纠缠态对量子计算具有重要的意义,自旋相干输运的检测是自旋电子学的重要研究课题。 相似文献
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凌云 《微电子学与计算机》2012,29(10):47-50
针对物联传感网络由于数据类型不一致造成散粒噪声.提出一种物联传感网络散粒噪声过滤的自适应线性权值算法.提取物联传感网络散粒噪声特征参数,对上述参数进行线性变换,获取噪声关联特征参数自适应线性权值,完成物联传感网络散粒噪声过滤.实验表明,该算法能够有效过滤物联传感网络中的散粒噪声,取得了令人满意的结果. 相似文献
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提出了一种自适应线性权值算法过滤传感网散粒噪声,算法首先提取散粒噪声的特征参数,然后对参数进行线性迭代变换,计算获得自适应权值参数,从而有效实现对散粒噪声的过滤。实验结果表明,该算法能过滤传感网中的散粒噪声,且效果良好。 相似文献
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噪声功率谱估计是语音增强算法中的关键技术之一.针对在非平稳噪声环境下噪声功率谱估计不够准确的问题,采用了基于后验语音存在概率的噪声功率谱估计算法,并对其中的语音存在概率估计算法进行了改进.利用语音信号的短时平稳性,在时域和频域上利用相邻帧和相邻频点的相关性估计当前帧的语音存在概率.仿真结果表明,该算法与原始算法及改进的最小值控制递归平均噪声估计(IMCRA)算法相比,能够有效提升非稳态噪声环境下噪声功率谱估计准确度和语音增强效果. 相似文献
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《Very Large Scale Integration (VLSI) Systems, IEEE Transactions on》2008,16(6):770-774
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掺铒光纤放大器噪声特性的全面分析 总被引:1,自引:1,他引:1
本文对掺铒光纤放大器(EDFA)的噪声特性进行了全面的分析。把光信号和EDFA中放大自发辐射(ASE)产生的量子噪声,以及信号-ASE拍频噪声和ASE-ASE拍频噪声一并加以考虑。通过数值模拟,给出了不同信号功率和泵浦功率下的EDFA噪声系数。这些结果对优化EDFA的工作参量及其工程制作具有一定的指导作用。 相似文献
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We have constructed a series of new code families for the spectral-amplitude-coding optical code-division multiple-access (CDMA) system, and proposed new transmitter and receiver structures based on tunable chirped fiber Bragg gratings (FBGs). The proposed system has been analyzed by taking into account the effects of phase-induced intensity noise, shot noise, and thermal noise. We have also compared the performance of this system with that of a former system where a Hadamard code is used. It has been shown that the new code families can suppress the intensity noise effectively and improve the system performance significantly. When the effective power is large (i.e., >-10 dBm), the intensity noise is the main factor that limits the system performance. When the effective power is not sufficiently large, thermal and shot noise sources become the main limiting factors and the effect of thermal noise is much larger than that of shot noise 相似文献
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Lowen S.B. Teich M.C. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1990,36(6):1302-1318
The behavior of power-law shot noise, for which the associated impulse response functions assume a decaying power-law form, is explored. Expressions are obtained for the moments, moment generating functions, amplitude probability density functions, autocorrelation functions, and power spectral densities for a variety of parameters of the process. For certain parameters the power spectral density exhibits 1/f -type behavior over a substantial range of frequencies, so that the process serves as a source of 1/f α shot noise for α in the range 0<α<2. For other parameters the amplitude probability density function is a Levy-stable random variable with dimension less than unity. This process then behaves as a fractal shot noise that does not converge to a Gaussian amplitude distribution as the driving rate increases without limit. Fractal shot noise is a stationary continuous-time process that is fundamentally different from fractional Brownian motion. Several physical processes that are well described by power-law noise in certain domains are considered: 1/f shot noise, Cherenkov radiation from a random stream of charged particles, diffusion of randomly injected concentration packets the electric field at the growing edge of a quantum wire, and the mass distribution of solid-particle aggregates 相似文献
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The power spectral densities of the current fluctuations through fresh and stressed thin oxide are investigated by means of a purposely designed ultra low noise measurement system. It is reported for the first time that the SILC noise spectrum exhibits partially suppressed shot noise down to about 70% with respect to the full shot noise observed for fresh oxide in Fowler-Nordheim regime. It is shown that a single trap assisted tunneling model with a uniform trap distribution in both energy and space is able to justify the observed noise behavior 相似文献
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提出了一种噪声功率谱估计算法,该算法对加权后的带噪语音进行递归平滑,可以持续更新噪声并可应用于非平稳噪声环境中。为了避免在强语音后的弱语音区域出现噪声过估计,本文提出了用于计算加权函数的投影平滑算法。本文噪声估计算法可以快速跟踪噪声的变化并且没有过估计。实验结果表明,本文噪声估计算法应用于一个语音增强系统时,取得了较小的噪声分段估计误差及较好的感知语音质量评价(PESQ)得分。 相似文献