共查询到20条相似文献,搜索用时 15 毫秒
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Riccobene C. Wachutka G. Burgler J. Baltes H. 《Electron Devices, IEEE Transactions on》1994,41(7):1136-1148
Dual collector magnetotransistors are magnetic-field-sensitive devices currently developed in several laboratories. Optimized sensor design is often attempted by trial and error rather than by established design rules. This motivated the present comprehensive study of the operation of magnetotransistors by accurate two-dimensional numerical simulations. We model vertical and lateral transistors as obtained by industrial IC technology on the basis of data provided by the chip manufacturer. We consider the entire device structure with the full, complex device geometry, and the physically proper boundary conditions. Our simulations reveal the details, controversial hitherto, of the operating principle of these devices. In particular we find that, in the case of the vertical transistor, it is essentially the emitter injection modulation effect which dominates the sensor response. In the case of the lateral transistor, the magnetic sensitivity is predominantly determined by minority-carrier deflection, though side effects are involved as well. By variation of the doping profile and the device geometry we derive rules for optimized magnetotransistor design 相似文献
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首先介绍了PAL-D的图像分解力和均匀电子束屏迹计算方法,而后对VM的工作原理,VM电流速率的选择及人眼的清晰度感觉重点作了叙述。 相似文献
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《Electron Device Letters, IEEE》1983,4(3):51-53
An investigation of the magnetic-field sensitivity of lateral, double base contact p-n-p magnetotransistor is reported. At very low collector current levels the sensitivity is an exponential function of the base current and rises up to 30 A/A.T at 1 T. At larger collector currents sensitivity decreases drastically and approaches the usual value of less then 1.5 A/A.T. This behaviour is explained in terms of a Hall-type voltage, which is generated in the base region and causes a magnetic-field-modulated injection of carriers. 相似文献
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The two-dimensional theory of distributed feedback (DFB) lasers to take account of the planar waveguide structure which was presented in a previous paper (see ibid., vol.26, no.3, p.467-72, 1990) is applied to the analysis of the DFB laser threshold conditions with respect to the effects of the waveguide structure and the facet reflection. The asymmetric properties of the transverse functions of the coupled modes with respect to the Bragg frequency in the dispersion relations are found to be enhanced by the asymmetric index waveguide structure and by the asymmetric facet reflectivity. Therefore, the resulting confinement factor differences in the grating layer between the two adjacent lasing modes on both sides of the Bragg frequency give large threshold gain differences 相似文献
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NCP1601型功率因数校正控制器可工作在不连续传导模式(DCM)和临界传导模式(CRM)二种工作模式下.文中介绍NCP1601的结构和特点,详细叙述其工作原理并给出一种典型应用电路. 相似文献
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Fabrication imperfections cause offset in CMOS magnetotransistors (MTs). In this paper, MT offset is experimentally characterized and its causes are analyzed for two different commercial CMOS processes. For the MT structures chosen as references, the average absolute value of the offset in terms of a relative imbalance of two collector currents is up to 2.7%. The mean offset temperature drift between -40°C and +140°C is 0.25%. The offset exhibits a high degree of variation on a very small spatial scale. Additionally, variations on a large scale over the wafer are observed and, in some cases, systematic influences. The actual offset contributions of the various identified possible sources are investigated. Misalignment of the metal contact mask occurring during photolithography dominates large scale offset variations and can also have a systematic component. Another systematic influence arises from nonorthogonal dopant implantation. Doping inhomogeneities are a dominating contribution to local variations as indirect evidence suggests. Further, mismatch in emitter-collector spacing is critical. Suppressed sidewall injection magnetotransistors (SSIMTs) showing an enhanced sensitivity exhibit a quadrupling of the offset, which comes from a misalignment of the emitter guard ring. The obtained results are the basis for dedicated offset reduction in MTs as well as the development of MT-like test structures for processing tolerances 相似文献
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Arendt S. Umashankar K.R. Taflove A. Kriegsmann G.A. 《Antennas and Propagation, IEEE Transactions on》1990,38(10):1551-1558
A recent analytical formulation by G.A. Kriegsmann et al. (see ibid., vol.AP-35, p.153-61, Feb. 1987) of electromagnetic wave scattering by perfectly conducting two-dimensional objects using the on-surface radiation boundary condition approach is extended to the case of two-dimensional homogeneous convex dielectric objects. It is shown that a substantial simplification in the analysis can be obtained by applying the outgoing radiation boundary condition on the surface of the object. The analysis procedure decouples the fields in the two regions to yield explicitly a differential equation relationship between the external incident field excitation and the corresponding field distribution in the interior of the dielectric object. The interior fields can be obtained by solving the differential equation using either an analytical approach or a suitable numerical method. Two-dimensional scattering examples along with validations are reported, showing the near-surface field distributions for a homogeneous circular dielectric cylinder and an elliptic dielectric cylinder, with with transverse magnetic plane-wave excitation 相似文献
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基于条纹原理的阵列探测体制激光成像雷达由于其独特的技术优势在激光测绘中具有潜在的应用。介绍了扫帚扫描结合条纹原理阵列探测体制激光雷达的仿真及飞行实验研究结果。首先介绍新体制激光雷达仿真平台的建立及典型的仿真结果。利用该仿真平台可指导新体制激光雷达的设计,并对机载飞行实验参数的设定进行成像效果仿真,仿真的距离测量精度为0.5 m。最后开展了新体制激光雷达机载飞行实验,给出了典型地区的原始条纹图像及经过数据处理后的点云图。新体制激光雷达外场实验结果的测距精度优于1 m,机载飞行实验测距精度结果与仿真分析结果一致,验证了该仿真系统的正确性。通过与实际被动光学相机成像图像进行比较,验证了新体制激光雷达在航空测绘等方面的技术可行性。 相似文献
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MATLAB是一个很好的科研教学和工程应用仿真软件,它将可视化的方框图模型与编程形式的仿真模型综合起来加以利用。本文利用MATLAB实现对中波调幅发射机工作原理进行仿真。从系统建模原理和仿真的数值计算方法入手,对发射机理论研究、性能分析验证等方面为值机员提供深刻的从量到质的认识机会。 相似文献
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《Electron Device Letters, IEEE》1983,4(1):20-22
Heterojunctions in which both the conduction and the valence band edges of one semiconductor are shifted upward relative to those of the other, can exhibit adjacent dual quantum wells for electrons and holes on the two sides of the interface. Tunneling-assisted radiative recombination between the wells should be an efficient, bias-tunable source of radiation at below-gap quantum energies. Several semiconductor combinations that exhibit the proper lineup are available. 相似文献
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简述了红外场景产生的技术背景以及基于液晶光阀实现可见光到红外视频图像转换的模拟器的总体结构。重点介绍了一种适用于两种不同视场的红外光电系统测试与评估的动态红外场景模拟器光学系统的设计,其中包括变倍透镜的选择和准直投射光学系统的设计。从理论上分析了利用变倍透镜的变化写入不同放大倍率的可见光图像,来满足视场变化需要的方法;从光学指标的确定,结构、材料的选取到最终光学性能,阐述了准直投射光学系统的设计。此投射光学系统工作在8~ 12 μm , 焦距271.69 mm,视场为±4°,入瞳距150 mm,后工作距离139.2 mm,点列图和传递函数曲线表明此投射光学系统像质达到理想状态。最后分析了光学系统性能参数与指标要求的符合。在满足设计指标的前提下,和变焦系统相比,该光学系统结构简单、成本低、可行性高。 相似文献
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Experiments have been carried out on the 2N929 transistor to investigate the effect of collector voltage and collector current on junction temperature. The results indicate that at constant power dissipation increasing the collector voltage will increase the junction temperature and give the apparent effect of a higher thermal resistance. 相似文献
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《Electron Devices, IEEE Transactions on》1956,3(4):167-172
The collector capacity, C, of a junction transistor is known to vary as a nonlinear function of the voltage, V, across it. A calculation is made of the collector current rise time of a grounded emitter alloy junction transistor for which C = kV-1/2. A comparison is then made with linear analyses in which C is assumed to have one of the following constant values. 1) C = Ccc , where Ccc is the small signal capacity measured at the collector supply voltage, Vcc . 2) C = 1.52Ccc . This capacity is one which displaces the same charge as the nonlinear capacity as the voltage across it changes from 0-90 per cent of its final value. 3) C - 2Ccc . This capacity is one which displaces the same charge as the nonlinear capacity as the voltage across it changes from 0-100 per cent of its final value. The linear analysis using the latter two capacity values gives 0-90 per cent and 0-100 per cent rise times which are very close to those given by a numerical solution of the nonlinear circuit equation. The usual linear analysis using C = Ccc , on the other hand, is very much in error for predicting rise time. Experimental results show that the 2Ccc value, in a linear analysis, predicts the 0-100 per cent rise time almost exactly. In addition, analog computer solutions of the nonlinear circuit equation give results almost identical with the shape of the experimental curves. 相似文献
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This paper describes a technique for shaping the input current to a three-phase diode rectifier using a two-switch series-connected dual boost converter and a three-phase bidirectional switch circuit. Circuits are described for generating a single voltage DC output, “single DC-rail”, or a dual output DC voltage using center-tapped capacitors, “split DC-rail”. Both rectifier types can be operated with the boost inductors located either on the DC or the AC side of the rectifier. The resultant rectifier circuit configurations have an excellent immunity to the “shoot-through” fault condition and use active switching elements with low per-unit current ratings and low switching losses. These features increase the reliability factor and lower the cost penalty associated with unity fundamental power factor three-phase rectifiers. Test results are presented for the rectifiers using simulation and experimental results 相似文献
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为了突破传统时频测量技术的局限性,提高频率稳定度的精确程度,研究设计了一套数字式双混频时差测量系统,采用经典双混频时差测量原理,运用数字信号处理技术实现频标的比对测量。仿真结果证明,采用10 MHz信号进行测量时,得到相位噪声Allan方差优于3E-13/s,可对高精度频标进行实时测量和监控。 相似文献