排序方式: 共有14条查询结果,搜索用时 15 毫秒
1.
对Cl/HN3/I2产生NCl(a)/I激光的过程进行了化学动力学计算,主要考察了Cl,HN3和I2的初始粒子数密度及其配比对小信号增益系数的影响。结果发现,当温度为400K, 初始Cl粒子数密度为1×1015,1×1016和1×1017cm-3时,小信号增益系数分别达到1.6×10-4,1.1×10-3和1.1×10-2cm-1,获得最佳小信号增益系数的HN3和I2的初始粒子数密度分别为初始Cl粒子数密度的1~2倍和2%~4%。同时,对Cl,HN3和I2配比对小信号增益系数和增益持续时间的影响进行了讨论。 相似文献
2.
Measurement of small-signal and large-signal responses of packaged laser modules at high temperature
Ning Hua Zhu Ji Min Wen Hai Peng Song Shang Jian Zhang Liang Xie 《Optical and Quantum Electronics》2006,38(15):1245-1257
In this paper, the pulsed injection method is extended to measure the chip temperature of various packaged laser modules,
such as the DFB laser modules, the FP laser modules, and the EML laser modules. An optimal injection condition is obtained
by investigating the dependence of the lasing wavelength on the width and period of the injection pulse in a relatively wide
temperature range. The small-signal frequency responses and large-signal performances of packaged laser modules at different
chip temperature are measured. The adiabatic small-signal modulation characteristics of packaged LD are first extracted. In
the large-signal measurement, the effects of chip temperature, bias current and driving signal on the performances of the
laser modules are discussed. It has been found that the large-signal performances of the EML modules depend on the different
red-shift speeds of the DFB and EAM sections as chip temperature varying, and the optimal characteristics may be achieved
at higher temperature. 相似文献
3.
Mohamed Kameche Mohamed Feham 《International Journal of Infrared and Millimeter Waves》2006,27(5):687-705
Simple techniques for determining the broadband small signal equivalent circuit (SSEC) of MESFETs are presented in this paper.
The intrinsic elements are calculated using two-dimensional method from the Y parameters, which are obtained from the Fourier
analysis of the device transient response to voltage-step perturbations at the drain and gate electrodes. Whereas, the parasitic
external elements are determined by simple approximations used in transmission line modeling. In addition, a new technique
is also proposed to determine the source and drain series resistances. A comparison of the SSEC of three different MESFETs
technologies shows that the MESFETs on GaN and 4H-SiC are suitable for high power applications. The method used to determine
the intrinsic elements is validated with simulated data obtained by Monte Carlo method. 相似文献
4.
Based on the rate equations and the power propagation equations, the amplified model is obtained which considers the cross-phase modulation (XPM)-induced intensity fluctuation between pump power and signal power in erbium-doped fiber amplifier (EDFA). Simulation results show: a higher nonlinear coefficient and a stronger pump power cause a stronger XPM in EDFA. Before the optimal length of EDF, the intensity caused by XPM increases with the increasing length, but after the optimal length, the XPM presents saturation. A bigger nonlinear coefficient γ corresponds to a smaller optimal length and gain, and makes gain saturation more easy. XPM effect will decrease EDFA’s amplified efficiency. 相似文献
5.
Lei Wang Rui-Min Xu Bo Yan 《International Journal of Infrared and Millimeter Waves》2007,28(12):1133-1141
An accurate small-signal modeling approach applied to GaAs-based pHEMT devices is presented. The procedure for extracting
equivalent-circuit model parameters is illustrated in detail. A genetic algorithm (GA) program is developed to optimize the
model parameters in order to improve the modeling accuracy. The validity of modeling approach is verified by comparing the
simulated and measured result of two pHEMTs and a fabricated ka-band power amplifier. The conclusion can be drawn that the
proposed modeling method is rather accurate and efficient. 相似文献
6.
Under the condition of magnetic confinement, the paper analyzes the following discharge processes from CO gas: (1) the variation of electron energy distribution; (2) the impact excitation rates of electron for the vibrational CO molecules; and (3) the vibrational-state population of CO molecule and small-signal gain. Our results show that, by adding magnetic field, the electron density increases greatly in the energy region corresponding to the maximum electron cross sections of CO molecule, while the electron impact on excitation rates also increases. At the same time, the vibrational-state population of CO molecule and the laser small-signal gain of every vibrational level are also higher than that without magnetic field. 相似文献
7.
This paper presents a small-signal model for graphene barristor, a promising device for the future nanoelectronics industry. Because of the functional similarities to the conventional FET transistors, the same configuration and parameters, as those of FETs, are assumed for the model. Transconductance, output resistance, and parasitic capacitances are the main parameters of the small signal equivalent circuit modeled in this work. Recognizing the importance of physical modeling of novel semiconductor devices, we develop physical compact expressions for the device radio-frequency characteristics. Furthermore, we clarify the physics behind the variation of the characteristics as the device parameters change. We also validate our model results with available simulation results. Impact of equilibrium Schottky barrier height of the graphene–silicon junction on the radio frequency performance of barristor is investigated, too. 相似文献
8.
Impact of Channel Length and Width for Charge Transportation of Graphene Field Effect Transistor
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The effect of channel length and width on the large and small-signal parameters of the graphene field effect transistor have been explored using an analytical approach. In the case of faster saturation as well as extremely high transit frequency, the graphene field effect transistor shows outstanding performance. From the transfer curve, it is observed that there is a positive shift of Dirac point from the voltage of 0.15 V to 0.35 V because of reducing channel length from 440 nm to 20 nm and this curve depicts that graphene shows ambipolar behavior. Besides, it is found that because of widening channel the drain current increases and the maximum current is found approximately 2.4 mA and 6 mA for channel width 2 μm and 5 μm respectively. Furthermore, an approximate symmetrical capacitance-voltage (\begin{document}$C-V$\end{document} ) characteristic of the graphene field effect transistor is obtained and the capacitance reduces when the channel length decreases but the capacitance can be increased by raising the channel width. In addition, a high transconductance, that demands high-speed radio frequency (RF) applications, of 6.4 mS at channel length 20 nm and 4.45 mS at channel width 5 μm along with a high transit frequency of 3.95 THz have been found that demands high-speed radio frequency applications. 相似文献
9.
Small-signal modeling approach to 0.1-μm metamorphic HEMTs for W-band coplanar MMIC amplifier design
Sung-Woon MoonByoung-Chul Jun Sung-Ho JungDeok-Soo Park Jin-Koo RheeSam-Dong Kim 《Current Applied Physics》2012,12(1):81-88
We present an accurate and reliable modeling method for designing the W-band (75-110 GHz) small-signal millimeter-wave monolithic integrated circuit (MMIC) amplifiers with the GaAs-based 0.1-μm metamorphic high electron-mobility transistors (MHEMTs). For this, we propose an improved process control monitoring (PCM) pattern layout for the MHEMT modeling and a small-signal equivalent circuit model of 17 elements accounting for the feedback capacitance (Cpgd) and output conductance time delay (τds). The modeling technique adopts a gradient optimizer with the initial values of the extrinsic parameter set determined from the cold-FET measurement avoiding the forward gate-biasing in a frequency range of 0.5-65 GHz and the intrinsic parameter set obtained at an operating hot-FET condition in our W-band design frequency range. On the basis of the proposed small-signal equivalent circuit model, we design and fabricate 1- and 2-stage W-band MMIC amplifiers using the MHEMTs (30-μm gate width, 2 gate fingers) and a coplanar waveguide-based MMIC process. The measurements of the fabricated MMIC amplifiers show an excellent agreement with simulation data in the design frequency range. 相似文献
10.
Yanyu Wei Hongtao Liu Jun He Yubin Gong Lingna Yue Wenxiang Wang Gun-Sik Park 《International Journal of Infrared and Millimeter Waves》2007,28(12):1051-1062
Properties of traveling wave-beam interaction in a centered dielectric-rod loaded, arbitrarily-shaped helical groove slow-wave
structure (SWS) are investigated for a thin annular electron beam. The “hot” dispersion equation is obtained by means of the
self-consistent field theory, and the small signal analysis is carried out including the effects of the dielectric-rod parameters
and the groove shapes. The numerical results show that the bandwidth of the helical groove TWT is expanded by loading dielectric-rod,
however, the small-signal gain is reduced; and when the groove shape changes from the swallow-tail shape to the triangle shape,
the working frequency increases , while the peak gain decreases.
Project supported by the National Nature Science Foundation of China (Granted NO.60401005 and 60532010). 相似文献