柴油发电机组机房的低噪声工程设计

柴油发电机组机房的低噪声工程设计主要是针对柴油发电机组工作时的排气噪声，机械噪声及燃烧噪声，冷却风扇运转噪声和排风通道噪声、进气噪声等声源，采取减震和隔声措施，限制震动和噪声传播的途径，达到使柴油机低噪声工作的目的。     

Noise measurements in charge-coupled devices

Measurements of the noise levels at the output of surface and bulk channel charge-coupled devices with three-phase overlapping polysilicon electrodes are presented. Pulser noise, correlated transfer noise, shot noise, dark current noise, and electrical insertion noise at the input have been measured and studied. The dependences of the electrical insertion noise and the transfer noise on charge packet size and clock frequency are discussed in detail and the latter related to interface state densities. New schemes and input circuits for low-noise electrical insertion of the signal charge are discussed. Our measurements indicate that the noise levels due to the intrinsic noise sources (transfer and storage noise) agree with our physical understanding of the device operation. The noise levels due to the extrinsic noise sources (pulser noise and electrical insertion noise) are above the expected theoretical values.     

Compact Noise Models for MOSFETs

A physical understanding of both intrinsic and extrinsic noise mechanisms in a MOSFET is developed. Intrinsic noise mechanisms fundamental to device operation include channel thermal noise, induced gate noise, and induced substrate noise. While the effect of channel thermal noise is observable at zero drain-to-source voltage, the induced gate and substrate noise do not manifest themselves under these conditions. However, the attendant fluctuations in the channel charge are observable by the passage of electric current through the device. Extrinsic noise mechanisms manifested due to structural evolution of the MOSFET include the distributed gate resistance noise, distributed substrate resistance noise, bulk charge effects, substrate current supershot noise, gate current noise, excess channel noise, and$hbox1/f$noise. Where available, compact noise models covering these noise mechanisms are explained. Also, where possible, methods of suppression of these mechanisms are highlighted. A survey of current public domain MOS models is presented, and a lack of comprehensive coverage of noise models is noted. Open areas of MOSFET noise research in the sub-hundred-nanometer regime are also highlighted. With suitable adaptation, noise concepts elucidated in the context of MOS transistors have a much wider applicability to the operation of HEMTs, JFETs, MESFETs, and other field-effect devices.     

A unified approach to RF and microwave noise parameter modeling inbipolar transistors

A unified approach to RF and microwave noise parameter modeling in bipolar transistors is presented. Circuit level noise parameters including the minimum noise figure, the optimum generator admittance, and the noise resistance are analytically linked to the fundamental noise sources and the y-parameters of the transistor through circuit analysis of the chain noisy two-port representation. Comparisons of circuit level noise parameters from different physical models of noise sources in the transistor were made against measurements in UHV/CVD SiGe HBTs. A new model for the collector shot noise is then proposed which produces better noise parameter agreement with measured data than the SPICE noise model and the thermodynamic noise model, the two most recent Y-parameter based noise models     

防离子反馈MCP噪声因子测试与分析

噪声因子是输入信噪比和输出信噪比的比值,能够反映微通道板的噪声特性,是影响微光像增强器信噪比的主要因素。为探寻降低微光像增强器中防离子反馈微通道板噪声因子的技术途径,根据微通道板噪声因子定义和测试原理,构建了防离子反馈微通道板噪声因子测试系统。由于防离子反馈微通道板的输入面镀覆有一层薄膜,其对微通道板的噪声因子有较大影响。因此,利用噪声因子测试系统重点测试了有、无防离子反馈膜以及不同材料、不同孔径、不同输入电子能量、不同微通道板作电压条件下的微通道板噪声因子,获得了微通道板噪声因子与输入电子能量、微通道板电压之间的关系,为降低防离子反馈微通道板噪声提供了有效的技术指导。     

基于小波神经网络的非线性噪声对消

利用小波神经网络作为噪声对消滤波器,实现了参考噪声与干扰噪声呈非线性相关条件下的噪声对消。在参考噪声与干扰噪声非线性相关时,传统的横向滤波器效果不理想,利用小波神经网络的非线性特性,可更好的解决非线性噪声条件下的噪声对消问题。计算机仿真结果证明,小波神经网络噪声对消在非线性噪声条件可有效提高信噪比增益。     

Analysis of noise up-conversion in microwave field-effecttransistor oscillators

The conversion process of the low frequency noise into phase noise in field-effect transistors (FET) oscillators is investigated. First, an evaluation of the baseband noise contribution to the oscillator phase noise is provided from the analysis of the baseband noise and the frequency noise spectra. A distinction is made within the different components of the low frequency noise contributions to close-in carrier phase noise. Next, the frequency noise of the oscillator circuit is analyzed in terms of the FET's low frequency noise multiplied by the oscillator's pushing factor. Though this product usually provides a good evaluation of the phase noise, experimental results presented here show the inaccuracy of this method at particular gate bias voltages where the pushing factor decreases to zero. To account for these observations, a new nonlinear FET model involving at least two noise sources distributed along the channel is proposed     

基于电子元器件低频噪声特性和相关测试技术

基于电子元器件低频噪声特性测试中,针对影响低频噪声测量系统准确性的因素,提出了一种改进型的低频噪声测量方法,优化设计电子元器件低频电噪声测试系统,放大噪声测试部分噪声,并可以分析电子元器件低频噪声测试过程中的低频噪声特性,从而可以有效证实通过测试低频噪声,就能够验证电子元器件质量是否缺陷,分析电子元器件的使用可靠性.在...     

Noise in solid-state devices and lasers

A survey is given of the most important noise problems in solid-state devices. Section II discusses shot noise in metal-semiconductor diodes, p-n junctions, and transistors at low injection; noise due to recombination and generation in the junction space-charge region; high-level injection effects; noise in photodiodes, avalanche diodes, and diode particle detectors, and shot noise in the leakage currents in field-effect transistors (FETs). Section III discusses thermal noise and induced gate noise in FETs; generation-recombination noise in FETs and transistors at low temperatures; noise due to recombination centers in the space-charge region(s) of FETs, and noise in space-charge-limited solid-state diodes. Section IV attempts to give a unified account of 1/f noise in solid-state devices in terms of the fluctuating occupancy of traps in the surface oxide; discusses the kinetics of these traps; applies this to flicker noise in junction diodes, transistors, and FETs, and briefly discusses flicker noise in Gunn diodes and burst noise in junction diodes and transistors. Section V discusses shot noise in the light emission of luminescent diodes and lasers, and noise in optical heterodyning. Section VI discusses circuit applications. It deals with the noise figure of negative conductance amplifiers (tunnel diodes and parametric amplifiers), and of FET, transistor, and mixer circuits. In the latter discussion capacitive up-converters, and diode, FET, and transistor mixers are dealt with.     

Phase Noise Model of Single Loop Frequency Synthesizer

The phase noise spectrum of a single loop frequency synthesizer for S-band, which can be utilized in broadcasting terminals, was predicted based on the analyses for phase noise contributions of noise sources. The proposed phase noise model in this paper more accurately predicts the phase noise spectrum of a frequency synthesizer. To accurately model the phase noise contributions of noise sources in the frequency synthesizer, the phase noise sources were analyzed via modeling of the frequency divider and phase noise components using Leeson model for the reference signal source and VCO. The phase noise transfer functions to VCO from noise sources were analyzed by superposition theory and linear operation of the phase-locked loop. The frequency synthesizers were fabricated and the phase noise prediction model was evaluated by measured data and prediction data.     

Partition noise in CCD signal detection

Reset noise in CCD signal charge detection is analyzed experimentally and theoretically. From a reset noise measurement experiment, it has been inferred that reset noise consists of two parts: the sensing capacitance (Cs) dependent part and the effective reset channel length (L) dependent part. Conventional reset noise theory, where the Johnson noise in the reset MOS channel was regarded as the only noise source, agrees with the Csdependent part of measured reset noise. However, it cannot explain the L dependent part. To explain theLdependence, the authors propose "partition noise" caused by carrier partition in the reset MOS channel. Partition noise is analyzed by the unique technique of solving the one-dimensional diffusion equation. As a result, a reset channel capacitance dependent characteristic for partition noise has been derived, which agrees with theLdependent part for measured reset noise. Consequently, in addition to Johnson noise, partition noise is found to be a noise source in CCD signal detection.     

Noise in phototransistor optical isolators

Noise measurements were performed on several commercially available phototransistor optical isolators in order to examine the signal detection limits of typical devices. It was found that, in general, phototransistor optical isolators are very noisy devices exhibiting all of the common types of noise usually found in bipolar junction transistors. A large number of devices exhibited burst noise which dominated their low-frequency noise performance. The noise performance of devices without burst noise was dominated by 1/f noise or flicker noise at low frequencies and by shot noise at high frequencies. Experimental data indicates that in most cases the electrical noise contribution of the LED is negligible and that the dominant source of noise is the phototransistor.     

噪声鲁棒的动态范围压扩算法

结合基于递归平均的噪声估计算法和动态范围压扩算法,提出了一种动态调整噪声抑制临界点的动态范围压扩算法。通过对噪声水平的动态估计,实时调整噪声抑制阈值,在进行听力补偿的同时进一步提高信噪比,避免了动态范围压扩算法在放大语音的同时,噪声也被放大的问题。试验结果表明,该方法在4种不同的噪声环境下,进行听力补偿之后,相对于典型的动态范围压扩算法,信噪比平均提高约9．7dB。     

A functional GaAs FET noise model

It is the purpose of this paper to develop a theory upon which the design of low noise FET amplifiers can be based. This is not a fundamenta model of the noise mechanisms in GaAs FET's, but rather, an endeavor to relate physically measurable device capacitances and resistances to the device noise figure and optimum noise source impedance. I will be shown that the noise performance of an FET can be adequately described by two uncorrelated noise sources. One, at the input of the FET, is the thermal noise generated in the various resis, tances in the gate-source loop. This noise source is frequency dependent and it can be calculated from the equivalent circuit of the FET. The second noise source, in the Output of the FET, is frequency independent, and not recognizably related to any measured parameters. This output nise is a function of drain current and voltage. The decomposition of the FET noise into two uncorrelated sources simplifies the design of broad-band low noise amplifiers. Once the equivalent circuit of a device and its noise figure at one frequency are known, the optimum noise source impedance and noise figure over a broad range of frequencies may be calculated. For the device designer this model also may be helpful in balancing input-output noise tradeoffs.     

Measurement of white and 1/f noise within burst noise

A measurement method is described which enables the separate measurement of the power spectra of the normal noise (white and l/f) superimposed on burst noise. With this method the power spectra of normal noise can be determined for each burst noise level. It is found that the clean burst noise and the superimposed normal noise are generated by statistically independent processes. The fact that burst noise devices have a higher 1/f noise power content than devices without burst noise indicates that there exists a common condition for the generation of burst noise and 1/f noise.     

Realistic scalability of noise in dynamic circuits

The usage of noise-sensitive dynamic circuits has become commonplace due to speed and area requirements, making the noise issue even more prominent. This paper focuses on the trends of coupling and its effects on dynamic circuits. It presents closed form analytical solutions for noise, as well as noise tolerance metrics for dynamic circuits. These solutions are within 5% of dynamic simulations. It is shown that not all scaling trends are negative for noise, and that the scaling down of supply voltage and increasing frequency, help improve certain aspects of the noise immunity of dynamic circuits. Most of the works treated the noise immunity and the noise content separately. This paper introduces an analysis of noise scalability by looking at the noise immunity and the noise content simultaneously.     

GaAlAs红外发光二极管低频噪声检测方法

通过分析GaAlAs红外发光二极管(IRED)的低频噪声产生机理及特性,建立了GaAlAs IRED的噪声模型,设计了一套低频噪声测试系统,通过该系统测量得到了GaAlAs IRED的低频噪声。实验表明,该方法能准确的测量GaAlAs IRED的低频噪声,发现其低频噪声主要表现为1/f噪声,得到与噪声模型一致的结果。该研究为GaAlAs IRLED可靠性的噪声表征提供了实验基础与理论依据。     

AM and FM Noise of BARITT Oscillators

AM, FM, and baseband noise of a BARITT diode oscillator in the range 100 Hz-50 kHz off the carrier has been measured under various operating conditions. A simple calculation has been made, relating the baseband noise to the oscillator AM and FM noise via measured amplitude and frequency modulation sensitivities and the results have been compared with the noise measured. It is shown that, depending on the bias current applied, both AM and FM noise performance can be degraded by up-conversion. Complete removal of up-converted noise requires a high-impedance low-noise bias supply since both the diode noise and bias supply noise at baseband frequencies may be significant when up-converted. Even with all modulation suppressed, the AM and FM noise has a flicker component almost completely correlated with the diode flicker noise at baseband frequencies. The RF power dependence of the AM and FM noise has also been investigated. It is shown that the BARITT oscillator noise compares very favorably with that of IMPATT's and TEO's. Values of -142 dB/100 Hz (AM noise) and 3.5 Hz/(100 Hz)/sup 1/2/ for Q/sub ext/ = 200 (FM noise) have been measured at 30 kHz off the carrier.     

On quantization of noisy signals

Quantized noise distributions derived from continuous signals with additive noise are studied. Two noise sources are considered, quantized image noise derived from the continuous input noise source and noise due to quantization roundoff error. These are treated as statistically independent sources. An analytic solution for the quantized noise probability density is obtained. The analytic solution is estimated by two expressions valid for normally distributed noise over different ranges of variance. The estimates have excellent agreement in the region of overlapping validity. Quantized noise variance is related to the continuous noise variance from normally distributed noise using these expressions. A table and plots of useful values are included. These results are helpful in choosing a quantization interval for a particular application. They can also be used to determine quantizer output noise level and signal-to-noise ratio in digital applications     

Design concept for a low-noise CCD image sensor based on subjectiveevaluation

To achieve a high-performance image sensor for a broadcast TV camera, several studies of the noise characteristics of a CCD image sensor are described. The noise perception limit and the dependence of random noise and fixed pattern noise (FPN) on signal charge in a CCD imager were measured to obtain a correlation between measured noise and subjective noise. A method has been devised to measure FPN and random noise separately. Using this method, it has been confirmed that noise can be reduced to less than the perception limit using new noise-suppression techniques