共查询到20条相似文献,搜索用时 15 毫秒
1.
The noise parameter α=Rngm, where Rn is the noise resistance and gm the transconductance, was measured for n- and p-channel MOSFETs as a function of frequency with the temperature T as a parameter. At lower frequencies α varies as 1/f, as expected for flicker noise, whereas at higher frequencies α attains a limiting value α∞ that is larger than expected for thermal noise. Arguments are presented whether this high-frequency noise can be hot electron noise. The flicker noise resistance Rmf has a much stronger temperature dependence for n-channel than for p-channel devices; this is related to the energy dependence of the surface state distribution in the forbidden gap. 相似文献
2.
The authors analyze the performance of receivers that use envelope detection at an IF to detect optical signals with orthogonal modulation formats. Exact closed-form expressions for the error probability conditioned on the normalized envelope were obtained. The only information necessary for obtaining the unconditional error probability is a small set of tilted moments of the envelope. The authors then provide an approximation to this envelope which is not only accurate to the first order in phase noise strength, but also has the same range as the actual random envelope. This approximation was used to obtain the bit error performance of the three receiver models considered. A tight lower bound in closed form is given. The analysis is extended to the case of N -ary frequency-shift-keying (FSK) to provide very tight upper and lower bounds to the bit error probability 相似文献
3.
Measurements are reported of the excess gate leakage current IG in several n channel f.e.t.s, showing that IG varies exponentially with the inverse square root of the bias voltage between drain and gate. IG shows full shot noise, together with a component of the form Ign2?IG?/f? where values of 1.4 and 1.6 have been found for ? and ?, respectively. 相似文献
4.
The low-frequency noise spectra of partially annealed boron-implanted silicon resistors with various geometries are measured. The implantation energies are 50, 80 and 110 keV and the doses are 2·5 × 1012 cm?2, 1·0 × 1013 cm?2 and 1·0 × 1014 cm?2. The spectra exhibit thermal noise and (excess) noise exclusively. Investigations indicate that the contracts from the implanted layer to the electrode generally contribute small amounts to the total excess noise observed. The excess noise exhibits a strong dependence on the sheet resistance of the layers, while the dependence on substrate bias, implantation energy, and on temperature is relatively weak. A discussion of the results is given in terms of a volume effect. Noise measurements on implanted layers, produced under carefully controlled conditions, show promise as a tool to investigate excess noise. 相似文献
5.
The self-heterodyne detection Brillouin optical time domain reflectometer (BOTDR) system using broad-band laser is proposed to reduce coherent Rayleigh noise and improve the system performance. Compared with the system with narrow-band laser, the stimulated Brillouin scattering (SBS) threshold can be improved by about 3 dB. The experimental results of the narrow-band laser measurements for three times independently and the broad-band laser measurement for one time are compared. The root-mean-square (RMS) errors of Brillouin linewidth for two systems with narrow-band laser and broad-band laser are 6.9 MHz and 2.7 MHz, respectively, and the RMS errors of temperature for the heated fiber are about 1.3 °C and 0.7 °C. With the broad-band laser, signal-to-noise ratio (SNR) of the unheated fiber is approximately equivalent to that of the integrated three independent Brillouin signals for the narrowband laser, and the results are believed to be beneficial for performance improvement and measurement time reduction. 相似文献
6.
G. P. Zhigal’ski 《Journal of Communications Technology and Electronics》2010,55(3):241-255
Experimental results on the 1/f
γexcess noise and the nonlinearity of the I–V characteristics in nanosized semiconductors based on thin metal (Ni, Cu, and
Au) films at various current loads and temperatures are presented. It is demonstrated that relatively slow processes related
to the heat exchange of film and substrate serve as the reason for the nonlinearity of the I-V characteristic in low-dimensional
conductors. A method to determine the melting point of low-dimensional conductors based on the measurement of the positions
of the voltage fluctuation peaks on the temperature-time scale caused by the primary fluctuations of the film resistance in
the vicinity of the melting point in the presence of a low-density current flow in the sample and slow heating. The starting
temperature of melting of nanosized nickel and gold films on oxidized silicon is experimentally determined. 相似文献
7.
《Solid-state electronics》1988,31(12):1657-1661
Generation-recombination noise in reverse biased Schottky-barrier diodes (made on high resistivity n-type silicon) has been investigated theoretically and experimentally. It is shown that in the considered type of diodes generation-recombination noise can be larger than predicted by the common limit Ieq Ig-r. The measured spectral noise distribution is in good agreement with the theoretical predictions. 相似文献
8.
It has been known for some time that the bipolar transistor base region exhibits a noise in excess of that predicted by thermal noise associated with the base spreading resistance measured by large- or small-signal methods. This paper presents a relatively simple mechanism and model involving a transconductance gradient that accounts for the excess noise. 相似文献
9.
Ahmet Gokceoglu Yaning Zou Mikko Valkama Paschalis C. Sofotasios 《Mobile Networks and Applications》2014,19(4):473-486
For the development of highly integrated, flexible and low-cost cognitive radio (CR) devices, simple transceiver architectures, like direct-conversion receiver, are expected to be deployed and provide viable radio frequency (RF) spectrum sensing solutions for practical implementation. Yet, this can be very challenging task especially if spectrum sensing and down-conversion are conducted over multiple RF channels simultaneously for improved efficiency in channel scans. Then, the so-called dirty RF problem that degrades link performance of traditional transmission systems starts to be influential from spectrum sensing perspective as well. The unavoidable RF impairments, e.g., oscillator phase noise in direct-conversion receiver, could generate crosstalk between multiple channels that are down-converted simultaneously, and thus considerably limit the spectrum sensing capabilities. Most of the existing spectrum sensing studies in literature assume an ideal RF receiver and have not considered such practical RF hardware problem. In this article, we study the impact of oscillator phase noise on energy detection (ED) based spectrum sensing in multi-channel direct-conversion receiver scenario. With complex Gaussian primary user (PU) signal models, we first derive the detection and false alarm probabilities in closed-form expression. The analytical results, verified through extensive simulations, show that the wideband multi-channel sensing receiver is very sensitive to the neighboring channel crosstalk induced by oscillator phase noise. More specifically, it is shown that the false alarm probability of multi-channel energy detection increases significantly, compared to the ideal RF receiver case. The exact performance degradation depends on the power of neighboring channels as well as statistical characteristics of the phase noise in the deployed receiver. In order to prevent such performance degradation in spectrum identification, an enhanced energy detection technique is proposed. The proposed technique calculates the leakage power from neighboring channels for each channel and improves the sample energy statistics by subtracting this leakage power from the raw values. An analytical expression is derived for the leakage power which is shown to be a function of power spectral levels of neighboring channels and 3-dB bandwidth of phase noise process. Practical schemes for estimating these two quantities are discussed. Extensive computer simulations show that the proposed enhanced detection yields false alarm rates that are very close to those of an ideal RF receiver and hence clearly outperforms classical energy detection. 相似文献
10.
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
11.
基于光子在雪崩光电器件内吸收位置的差异,提出过剩噪声因子在器件垂直方向的分布模型,并基于TCAD 和Matlab 仿真,验证了模型的有效性。模型考虑了光子在硅雪崩器件内不同吸收位置的过剩噪声因子,结合光子在器件深度方向的吸收比例,计算器件(器件结构由TCAD构造)的平均噪声因子水平:233 @ E=34×105 V/cm 和534 @ E=36×105 V/cm,比单独考虑光子在N中性体区吸收(过剩噪声因子:288 @ E=34×105 V/cm 和1294 @ E=36×105 V/cm)或P中性体区吸收(过剩噪声因子:221 @ E=34×105 V/cm 和379 @E=36×105 V/cm),更能反映器件的真实工作情况。 相似文献
12.
Szczepanski P. Tyszka-Zawadzka A. Kujawski A. 《Quantum Electronics, IEEE Journal of》1995,31(12):2265-2268
The effect of the nonorthogonality of the longitudinal eigenmodes in laser with an extra cavity device described by the extra cavity distributed losses, is analyzed. An expression for the excess noise factor is derived. It is shown that the extra cavity devices changes remarkably the behaviour of the noise characteristics in comparison with conventional two-mirror laser 相似文献
13.
Hu C. Anselm K.A. Streetman B.G. Campbell J.C. 《Quantum Electronics, IEEE Journal of》1997,33(7):1089-1093
It is well known that the gain-bandwidth product of an avalanche photodiode can be increased by utilizing a thin multiplication region. Previously, measurements of the excess noise factor of InP-InGaAsP-InGaAs avalanche photodiodes with separate absorption and multiplication regions indicated that this approach could also be employed to reduce the multiplication noise. This paper presents a systematic study of the noise characteristics of GaAs homojunction avalanche photodiodes with different multiplication layer thicknesses. It is demonstrated that there is a definite “size effect” for multiplication regions less than approximately 0.5 μm. A good fit to the experimental data has been achieved using a discrete, nonlocalized model for the impact ionization process 相似文献
14.
Plana R. van Haaren B. Escotte L. Delage S.L. Blanck H. Graffeuil J. 《Electron Device Letters, IEEE》1997,18(3):108-110
In this paper an annealing procedure which gives an excess noise reduction both of heavily C-doped resistive structures and GaInP/GaAs Heterojunction Bipolar Transistors (HBTs) of 5 dB is proposed. The investigation of the correlation between the noise generators indicate that the annealing leads to a decrease of noise voltage attributed to a strain reduction both in the intrinsic and in the extrinsic base related to a site switching effect of carbon atoms. The reduction of noise current with annealing is attributed to the surface improvement related passivation process by hydrogen atoms 相似文献
15.
《Electron Devices, IEEE Transactions on》1977,24(12):1337-1341
The noise characteristics of semiconducting BaSrTiO3 were investigated as a function of frequency, bias current, and volume of the sample. It was found that the noise is approximately inversely proportional to the volume of the sample and the frequency dependence is a1/f behavior. This and other results have implications regarding an optimized use of this material for temperature-sensing applications. 相似文献
16.
The power spectrum for platinum silicide on p-type silicon Schottky diodes has been measured for the diodes available on an infrared focal plane array. A careful experimental technique is used to separate the mutual drift of the array as a whole from the drift of the individual diodes. The power spectrum of the noise associated with the diode appears to be white, even for frequencies below 3.0×10-5 Hz. This result is compared with recent models of 1/f noise. The measurements were made on an infrared camera that used a 160×244 PtSi infrared focal plane array. The data from each pixel were digitized to 12 b (0-4095 ADUs). The digital data were transferred to a Hewlett-Packard series 300 computer via the GPIO bus. The camera operated at 30 frames/s 相似文献
17.
G. Blasquez 《Solid-state electronics》1978,21(11-12)
In forward biased junctions crystallographic defects and impurities may be the cause of three different noise sources: (a) recombination noise, (b) flicker noise and (c) burst noise. Recombination noise is shown to be lower than the full shot noise of the recombination current and measurements at intermediate frequencies are shown to be very close to the theoretical value. For flicker noise at least two kinds of sources have been proposed: dislocations or surface traps. It is shown that the effects of dislocations on flicker noise can be explained by the surface model. Finally, the physical sources of burst noise are investigated. From statistical experiments carried out on several dozens of wafers it is concluded that crystallographic defects are the main source of burst noise. 相似文献
18.
The application of Golay pulse coding technique in spontaneous Brillouin-based distributed temperature sensor based on self-heterodyne detection of Rayleigh and Brillouin scattering is theoretically and experimentally analyzed. The enhancement of system signal to noise ratio (SNR) and reduction of temperature measurement error provided by coding are characterized. By using 16-bit Golay coding, SNR can be improved by about 2.77 dB, and temperature measurement error of the 100 m heated fiber is reduced from 1.4 °C to 0.5 °C with a spatial resolution of 13 m. The results are believed to be beneficial for the performance improvement of self-heterodyne detection Brillouin optical time domain reflectometer. 相似文献
19.
《Applied Superconductivity》1999,6(10-12):669-673
Thin-film HTS SQUIDs operated at 77 K and exposed to weak magnetic fields exhibit significant excess low-frequency noise arising from thermally-activated hopping of flux trapped in the superconducting film. We report an investigation of the dependence of this phenomenon on SQUID design and fabrication, measurement conditions and magnetic field history. The level of excess noise was directly related to the amount of flux penetrating the SQUID, and consequently was worse in large SQUIDs than in small SQUIDs due to the greater flux focussing of the larger SQUID. In SQUID fabrication, good film quality (high Jc) was found to be essential to minimize low frequency noise and careful patterning was required to avoid degrading the film. The method of cooling the SQUID was found to strongly affect the level of excess noise, with cooling in the magnetic field in which the SQUID was to be operated being preferable to zero-field cooling. The excess noise was typically 10 pTHz−1/2 at 1 Hz for 150 pH rf washer SQUIDs having a white noise floor of about 1 pTHz−1/2 operated in an applied field of 50 μT. 相似文献
20.
W. Schmid C. Jung B. Weigi G. Reiner R. Michalzik K.J. Ebeling 《Photonics Technology Letters, IEEE》1996,8(10):1288-1290
We report on high-resolution linewidth measurements of proton-implanted InGaAs-GaAs VCSELs employing the delayed self-heterodyne method. Devices with 16-/spl mu/m active diameter exhibit record low linewidths of 20 MHz and 4-MHz residual linewidth. The linewidth enhancement factor is accurately determined from the ratio of induced phase to amplitude modulation indexes. 相似文献