共查询到20条相似文献,搜索用时 15 毫秒
1.
The FM noise spectrum and the spectral width of semiconductor lasers are measured in the high-power state up to 20 mW. The FM noise spectrum consists of the white noise and the 1/f noise. The spectral density of the white noise is suppressed by the increase in the output power, whereas that of the 1/f noise is kept constant. This fact means that the residual linewidth in the high-power limit is caused by the 1/f noise rather than the white noise 相似文献
2.
The effects of a 1/f frequency noise on self-heterodyne detection are described, and the results are applied to the problem of laser diode linewidth measurement. The self-heterodyne autocorrelation function and power spectrum are evaluated for both the white and the 1/ f components of the frequency noise. From numerical analysis, the power spectrum resulting from the 1/f frequency noise is shown to be approximately Gaussian, and an empirical expression is given for its linewidth. These results are applied to the problem of self-heterodyne linewidth measurements for coherent optical communications, and the amount of broadening due to 1/f frequency noise is predicted 相似文献
3.
1/f noise experiments were performed for n-p-n GaAs/AlGaAs HBTs as a function of forward bias at room temperature. The experimental data are discussed with the help of new expressions for the 1/f noise in bipolar transistors where the influence of internal parasitic series resistances has been taken into account. At low forward currents the 1/f noise is determined by spontaneous fluctuations in the base and collector currents. At fixed bias, the collector current noise exceeds the base current noise. At higher forward currents the parasitic series resistances and their 1/f noise become important. Experimental results from the literature are compared with the results 相似文献
4.
Yiqi Zhuang Qing Sun 《Electron Devices, IEEE Transactions on》1991,38(11):2540-2547
Accelerated life tests with high-temperature storage and electric aging for n+-p-n silicon planar transistors were carried out. Current gain h FE increases monotonously with time during the tests, and the h FE drift is correlated with initial measured 1/f noise in the transistors, i.e. the drift amount significantly increases with the increase of noise level. The correlation coefficient of relative drift Δh FE /h FE and 1/f noise spectral density S iB(f ) is far larger than that of Δ h FE/h FE and initial DC parameters of the transistors. A quantitative theory model for the h FE drift has been developed and explains the h FE drift behavior in the tests, which suggests that the h FE drift and 1/f noise can be attributed to the same physical origin, and both are caused by the modulation of the oxide traps near the Si-SiO2 interface to Si surface recombination. 1/f noise measurement, therefore, may be used as a fast and nondestructive means to predict the long-term instability in bipolar transistors 相似文献
5.
A spectral linewidth of 56 kHz is achieved by a CPM-MQW-DFB (corrugation-pitch-modulated multiquantum-well distributed feedback) laser at an output power of 25 mW. To separate effects of the white noise and 1/f noise in limiting the linewidth, the authors measured the delayed-heterodyne lineshape by using a short delay-fiber. The minimum spectral linewidth is shown to be limited by white noise 相似文献
6.
New calculations are given for the 1/f noise in metal-oxide-semiconductor transistors (MOSTs) based on the McWhorter model (number fluctuations). Particular attention is paid to two regions of the drain current-voltage characteristic: weak inversion and near saturation. The results are at variance with previous theories, where some errors have been made. The gravest error was the violation of the physical law whereby the variance of the number of carriers N in the channel is ⩽N . The calculations do not give a divergent noise power at current saturation, as found by other authors. In the ohmic region, the relation between the spectral density of the drain current fluctuations and the number of carriers is determined. The Langevin method and the Klaassen-Prins method for calculating the 1/f noise in MOSTs are discussed and shown to have been used incorrectly when the mobility and the Hooge 1/f noise parameter depend on position in the channel 相似文献
7.
The optical power emitted by a monomode GaAlAs laser is filtered with a monochromator. The 1/f noise in the filtered emission is found to be directly dependent on the noncoherent emission, such as S pαP ncm. Here s p is the spectral density of the 1/f fluctuations, P nc is the average noncoherent power, m =3/2 under spontaneous emission, and m =4 in the superradiation and laser regions. Study of the 1/f noise in the optical power in a band centered at the laser wavelength and with variable bandwidth shows three operating regions. (1) LED region (at low currents): the fluctuations with a 1/f spectrum are uncorrelated in wavelength. (2) Superradiation region (at currents close to the threshold): the fluctuations are correlated. (3) Laser region: the 1/f noise apparently is dominated by noncoherent emission within a small optical band around the laser wavelength 相似文献
8.
Peransin J.-M. Vignaud P. Rigaud D. Vandamme L.K.J. 《Electron Devices, IEEE Transactions on》1990,37(10):2250-2253
The 1/f noise in normally-on MODFETs biased at low drain voltages is investigated. The experimentally observed relative noise in the drain current S I/I 2 versus the effective gate voltage V G=V GS-V off shows three regions which are explained. The observed dependencies are S I/I 2∝V G m with the exponents m =-1, -3, 0 with increasing values of V G. The model explains m =-1 as the region where the resistance and the 1/f noise stem from the 2-D electron gas under the gate electrode; the region with m =0 at large V G or V GS≅0 is due to the dominant contribution of the series resistance. In the region at intermediate V G , m =-3, the 1/f noise stems from the channel under the gate electrode, and the drain-source resistance is already dominated by the series resistance 相似文献
9.
The 1/f noise in the drain current of hot-carrier damaged MOSFETs biased in weak inversion has been studied. By the use of a biased annealing treatment to simultaneously decrease the density of oxide trapped charge (N ot) and increase the density of interface traps (D it), the authors have separated the contributions of these two kinds of defects. The results clearly indicate that, while the low-frequency 1/f noise is correlated with N ot, the high-frequency 1/f noise is correlated with D it 相似文献
10.
Quantum 1/f noise is given by a simple engineering formula. It affects photodetectors through mobility and recombination speed fluctuations. The former are also in the diffusion constant, and all affect the dark current. However, there is no quantum 1/f noise in the photogeneration of carriers, as is shown 相似文献
11.
A typical 1/f noise is excited in GaAs filament with the Hooge noise parameter of about αH=2×10-3 . The noise level increases in proportion to the square of the terminal voltage, and decreases approximately in inverse proportion to the total number of carriers within the device. A transition from the typical 1/f noise characteristics to the diffusion noise characteristics of MESFETs was observed when the electric field was increased above 1 kV/cm. The noise parameters were also investigated as a function of the device width between 2 and 200 μm. Deep levels within the n-GaAs active layer and the high electric field are the main factors of the nonideal 1/f characteristics 相似文献
12.
Measurements of the low-frequency spectral intensity of the current fluctuations in p-channel GaAs/AlGaAs heterostructure insulated-gate field-effect transistors are discussed. The measurements were performed at 77 K and a drain current of 1 μA. The spectra of two types of devices are compared, one grown directly on the substrate and the other embedded in an n-well. The latter type produced markedly less noise, its spectrum being almost perfect 1/f noise. The former type exhibited, in addition to the 1/f noise, a significant generation-recombination noise component in the spectrum 相似文献
13.
Wornell G.W. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1993,81(10):1428-1450
It is demonstrated that 1/f fractal processes are, in a broad sense, optimally represented in terms of orthonormal wavelet bases. Specifically, via a useful frequency-domain characterization for 1/f processes, the wavelet expansion's role as a Karhunen-Loeve-type expansion for 1/f processes is developed. As an illustration of potential, it is shown that wavelet-based representations naturally lead to highly efficient solutions to some fundamental detection and estimation problems involving 1/f processes 相似文献
14.
The 1/f noise of an n-type silicon MOSFET has been studied under conditions ranging from accumulation to depletion at 300 K. The experimental results are interpreted in terms of a bulk phenomenon and are characterized by Hooge's empirical 1/f noise parameter α with values between 10-7 and 10-5. The α value for surface conduction at strong accumulation can be at least one order of magnitude larger than the value for bulk conduction 相似文献
15.
Fang P. Hall J. Chen T.M. Dekker A.J. Van der Ziel A. 《Electron Device Letters, IEEE》1990,11(5):212-214
Experiments in which a normal-to-superconducting (NS) boundary is created in an originally superconducting bar of bulk YBa2Cu 3O7-x is described. The first noise measurements associated with such a boundary are presented. A high-density (5.20 g-cm -3) sample (sample A) and a low density (4.23 g-cm-3 ) sample (sample B) have been investigated. Common to both samples is 1/f 2 noise observed in the frequency region between about 15 and 50 Hz that can be associated with the NS boundary itself. Sample A also exhibits conventional 1/f noise as expected for the normal part of the boundary, below about 15 Hz. In contrast, sample B shows 1/f 1.5 noise in this region; since the sample contains considerably fewer small grains than sample A, any 1/f noise is presumably masked in B. It is suggested that the 1/f 2 noise might be associated with flux-flow noise 相似文献
16.
It is pointed out that a letter by Boukriss et al. (see ibid., vol.10, p.433-6, 1989) contains no reference to the actual value of the characteristic exponent of the noise spectrum (γ). This omission may result from the assumption that γ is equal to one. Similar measurements by the present author indicate that γ varies strongly following hot-carrier injection near the drain. The change in the characteristic component is caused by the injected carriers present in the oxide near the interface, rather than the increased number of traps. This injected charge has an effect on noise provided the channel is not pinched off. It is argued that to study only the amplitude of the noise and not γ misses critical information, the scaling properties, and that if one is to measure noise amplitude, one should measure the characteristic exponent as well. In a reply, the original authors state that the 1/f noise was studied for a nonhomogeneous MOSFET. The 1/f noise level was investigated from weak to strong inversion 相似文献
17.
The thermal and 1/f noise have been studied in MOSTs with side contacts along the channel. In difference biasing conditions, the distribution of the transversal noise in the channel has been explained in terms of the local values, including surface concentration, noise parameter, and mobility. Below saturation, the calculations are in good agreement with the observed experimental data. At saturation, the 1/f noise source strength seems to be nonuniform, along the channel, and the simple model deviates from experimental results. Possible reasons for this are discussed. The observed transversal noise and the coherence of longitudinal noise indicate that 1/f noise is uniformly generated through the channel in the ohmic region. However, there is no proof of the hypothesis that temperature fluctuation is the origin of the 1/f noise. A simple expression is derived to estimate the ratio of transversal to longitudinal noise in terms of channel geometric parameters. For MOSTs biased in the ohmic region at high gate voltage there is good agreement between experimental and calculated results 相似文献
18.
The usual approximate expression for measured f T =[g m/2π (C gs+C gd)] is inadequate. At low drain voltages just beyond the knee of the DC I -V curves, where intrinsic f t is a maximum for millimeter-wave MODFETs, the high values of C gd and G ds combine with the high g m to make terms involving the source and drain resistance significant. It is shown that these resistances can degrade the measured f T of a 0.30-μm GaAs-AlGaAs MODFET from an intrinsic maximum f T value of 73 GHz to a measured maximum value of 59 GHz. The correct extraction of maximum f T is essential for determining electron velocity and optimizing low-noise performance 相似文献
19.
Luo M.-Y. Bosman G. Van Der Ziel A. Hench L.L. 《Electron Devices, IEEE Transactions on》1988,35(8):1351-1356
A 1/f noise model for diodes operating in the thermionic-emission mode under forward-bias conditions has been developed. The model is based on mobility and diffusivity fluctuations occurring in the space-charge region and accounts for the current-limiting role of the metal-semiconductor interface The bias dependence of the 1/f noise spectral density calculated from this model is in excellent agreement with the results of the authors' experiments but is at variance with the predictions of a model developed by T.G.M. Kleinpenning (1979). From the experimental data, a value of 4.2×10-9 for the Hooge parameter is derived. This value is in good agreement with theoretical calculation for electrons in silicon 相似文献
20.
Oguchi K. Adachi H. Kusakabe T. Agu M. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1988,76(3):299-300
To produce a comfortable breeze similar to a natural one, a digital open-loop control system was utilized to control the speed of a small fan motor with 1/f fluctuation. The system was modeled as a first-order lag element with a time constant of 1.1 s. The output was controlled by commands and produced 1/f fluctuations, even though it was an open-loop system when the holding time of the data for 1/f fluctuation was set at more than 2 s 相似文献