共查询到19条相似文献,搜索用时 125 毫秒
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主要研究了Koch岛分形天线的基模和高次模。研究表明,Koch岛分形天线高次模和基模都具有良好的辐射性能,且2种模式频比可达4.6∶1。基模的电流分布在天线的中间区域;高次模的电流分布在分形不规则的边界,形成强烈谐振。对Koch岛分形天线的基模和高次模的深入研究,为设计出性能优良的大频差天线打下了基础。 相似文献
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介绍了LVDS(低电压差分信号)的工作原理及电路结构。根据其工作原理和电路结构,结合LVDS的信号特征和数字信号的频域分析,分析LVDS抗电磁干扰的能力和辐射发射,举例估算LVDS的电流环的差模辐射、电流环的共模辐射和开路线的共模辐射。 LVDS的电磁兼容性分析表明LVDS能够适应复杂电磁环境。 相似文献
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一些学者对双绞线电磁干扰进行研究,建立了精确的干扰模型,但并不适合工程应用.为此根据电磁兼容优势效应理论,推导出双绞线传导干扰主要由差模电流引起,辐射干扰主要由共模电流引起.分别利用广义二端口网络模型和电流元分析方法建立双绞线串扰和辐射的简化模型,从而有效估算双绞线串扰电压和对外辐射场的大小,最后给出滤波连接器的选择方法,为工程人员采取有效措施抑制互连设备电磁干扰提供了理论帮助. 相似文献
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A turn-off failure mode in individual MOS-controlled thyristors (MCTs), initiated by a long gate voltage rise-time, is identified and analyzed. It is shown to be caused by turn-off current crowding in the MCT. In addition, a differential failure mode in paralleled devices is demonstrated in which the slower of the two MCTs fails to turn off. This is caused by the increase in anode current through the slower device and the decrease in gate voltage rise-time due to the MCTs Miller capacitance 相似文献
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S. O. Slipchenko Z. N. Sokolova N. A. Pikhtin K. S. Borschev D. A. Vinokurov I. S. Tarasov 《Semiconductors》2006,40(8):990-995
It is shown that the reason why the maximum attainable optical power in semiconductor lasers is limited is the finite time of carrier energy relaxation via scattering by nonequilibrium optical phonons in the quantum-well active region. The power and spectral characteristics of semiconductor lasers are studied experimentally at high excitation levels (up to 100 kA/cm2) in pulsed lasing mode (100 ns, 10 kHz). As the drive current increases, the maximum intensity of stimulated emission tends to a constant value (“saturates”), and the emitted power increases owing to extension of the spectrum to shorter wavelengths. The intensity saturation is due to limitation of the rate of stimulated recombination, caused by a finite time of the electron energy relaxation via scattering by polar optical phonons. It is found that the broadening of the stimulated emission spectrum is related to an increase in carrier concentration in the active region, which enhances the escape of electrons into the waveguide layers. As the drive current increases, the carrier concentration in the waveguide reaches its threshold value and there appears an effective channel of current leakage from the active region. The experiment shows that the appearance of a band of waveguide lasing correlates with a sharp drop in the differential quantum efficiency of a semiconductor laser. 相似文献
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《Microelectronics Reliability》2014,54(9-10):2142-2146
A 1300 nm InGaAsP laser diode, degraded after the application of high voltage ESD pulses in forward direction, showed after degradation a strong longitudinal mode suppression, resulting in a single mode emission spectrum identical to the one of a cleaved-coupled-cavity laser. The room temperature threshold current after ESD induced degradation increased by about 50% and the differential quantum efficiency dropped substantially. However, even after degradation in a wide temperature range stable single mode laser operation has been achieved. 相似文献
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开关负载在飞机交流电网的导线上产生的干扰主要是传导干扰.对使用射频电流探头和线性阻抗稳定网络测量开关负载传导干扰的方法进行了介绍,并用matlab对线性阻抗稳定网络测量方法进行了仿真.这两种方法能够容易地测出共模与差模干扰. 相似文献
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L. Ya. Karachinsky T. Kettler N. Yu. Gordeev I. I. Novikov M. V. Maximov Yu. M. Shernyakov N. V. Kryzhanovskaya A. E. Zhukov E. S. Semenova A. P. Vasil’ev V. M. Ustinov N. N. Ledentsov A. R. Kovsh V. A. Shchukin S. S. Mikhrin A. Lochmann O. Schulz L. Reissmann D. Bimberg 《Semiconductors》2005,39(12):1415-1419
Lasers based on InAs/InGaAs quantum dots grown on metamorphic (In,Ga,Al)As layers deposited by MBE on GaAs substrates exhibited emission near 1.5 μm with a differential quantum efficiency of about 50%. The narrow-stripe lasers operate in a single transverse mode and withstand continuous current density above 20 kA cm?2 without significant degradation. A maximum continuous-wave output power of 220 mW is obtained. Neither current nor beam filamentation was observed up to the highest pumping levels. 相似文献
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Knowledge of the propagation mode and the source impedance is necessary in order to predict the insertion loss of common-core powerline filters. If these quantities are standardized, the transition-band insertion loss corresponding to two test modes can be accurately calculated by use of only a programmable hand calculator, such as the Hewlett-Packard HP65 or Texas Instruments SR56. Such predictions of differential and common-mode insertion loss are of value in designing electronic equipment for conformance to world-wide specifications applying to powerline interference emission and filter leakage current. 相似文献
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S. A. Blokhin M. A. Bobrov A. A. Blokhin A. G. Kuzmenkov A. P. Vasil’ev Yu. M. Zadiranov E. A. Evropeytsev A. V. Sakharov N. N. Ledentsov L. Ya. Karachinsky A. M. Ospennikov N. A. Maleev V. M. Ustinov 《Semiconductors》2018,52(1):93-99
The emission-line width for 850-nm single-mode vertical-cavity surface-emitting lasers based on InGaAs/AlGaAs quantum wells is studied. The width of the emission line for a laser with a 2-μm oxide current aperture attains it minimum (~110 MHz) at an output power of 0.8 mW. As the optical output power is further increased, anomalous broadening of the emission line is observed; this is apparently caused by an increase in the α-factor as a result of a decrease in the differential gain in the active region under conditions of increased concentration of charge carriers and of high internal optical losses in the microcavity. The α-factor is estimated using two independent methods. 相似文献
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A. P. Danilova T. N. Danilova A. N. Imenkov N. M. Kolchanova M. V. Stepanov V. V. Sherstnev Yu. P. Yakovlev 《Semiconductors》1999,33(9):991-995
A reduction in the emission wavelength in the preferred mode of InAsSbP/InAsSb/InAsSbP heterostructure lasers by 50Å is observed when the current is raised from 1.8 to 5 times the threshold with dc and pulsed power. A comparison of the spectral and spatial distributions of the output as functions of current shows that this short-wavelength tuning is caused by a change in the distribution of the nonequilibrium charge carrier concentration over the strip width as the current is varied. This effect is modeled mathematically, taking into account the increase in the injection density and the drop in the output intensity from the middle to the sides of the waveguide. The results of the model calculation are in good agreement with experiment. 相似文献