共查询到19条相似文献,搜索用时 375 毫秒
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效率是行波管(TWT)的重要技术指标,为提高某一0.22 THz折叠波导行波管的效率,需设计多级降压收集极。对注波互作用后的电子注信息进行分析,估算收集极效率最高时的电压设置。利用电磁仿真软件对三级降压收集极电极结构和电压设置进行仿真优化,得到效率大于87.5%,回流电流小于0.328 9 mA的轴对称三级降压收集极;在第二电极入口采用斜口结构进行仿真优化,得到回流电流小于0.075 mA的非轴对称三级降压收集极。结果表明,采用斜口结构可以有效降低0.22 THz行波管多级降压收集极的回流电流。 相似文献
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在美国空军(USAF)——国家航宇局(NASA)共同制定的规划中,Lewis研究中心正在进行电子对抗行波管效率的改进工作,它是通过采用多级降压收集极(MDC)以及在该中心所探索的对耗能电子注的再聚焦技术来实现的。在本规划的分析阶段,计算了整个行波管的三维电子注轨迹。轨迹计算一直到耗能电子注的再聚焦区和降压收集极。对收集极效率、收集极损耗和管子总效率进行了验证和计算。在实验工作方面,首先对不用多级降压收集极的管子性能进行估测,然后对耗能电子注的对称性、圆度和速度离散作了分析。最后,装上了多级降压收集极,使其性能最佳并进行了估测。对于理想的行波管,三维理论表明:具有对称、圆型并有最佳再聚焦电子注的2级多极降压收集极在中心频带有81%的效率(多级降压收集极),而4级多级降压收集极有85%的效率。实验结果所获得的数据表明:一个倍频程带宽——(4.8~9.6)千兆赫、功率为330~550瓦行波管的2级和4级降压收集极的最小多级降压收集极效率分别为81%和83%。 相似文献
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行波管多级降压收集极的计算和实验研究 总被引:3,自引:1,他引:3
采用多级降压收集极是提高行波管效率析有效途径之一。本文在SLAC-266程序的基础上对一支带有二级降压收集极的国外行波管进行了计算,并且将计算结果同实验结果进行了比较。同时用电子注分析仪对降压收集极区电子注和纵向速度分布进行了实验研究,获得了该二级降压收集极的部分工作曲线,并对实验结果进行了分析讨论。 相似文献
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为了提高真空管雷达发射机的效率、缩小整机的体积和重量,常使用多级降压收集极行波管作为功率射频放大器.为了保证多级降压收集极行波管高增益、高效率和良好线性等性能发挥的更好,就要在行波管每个电极上加合适的电压,确保行波管内建立稳定的电场.因此,根据行波管各电极的特性合理地选择各收集极的电压以及合理的设计高压电源显得尤其重要.文中结合多级降压收集极行波管的工作特性介绍了4种高压电源的设计方法及其特点. 相似文献
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为了确定回旋行波管收集极入口的初始条件,利用CST2009模拟回旋行波管静态电子的运动轨迹,以3D模型,更直观、形象的显示出电子在回旋行波管中的运动轨迹。模拟计算表明,在电子注电压为70kV,电子注电流为10.4A,工作磁场为l.5T时,回旋行波管的电子注发射出的电子最终降落在收集极的530~700mm处。模拟结果为回旋行波管的设计和收集极的热分析提供了有效的依据。 相似文献
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Q. J. Hartmann M. T. Fresina D. A. Ahmari G. E. Stillman 《Solid-state electronics》1995,38(12):2017-2021
InGaP/GaAs heterojunction bipolar transistors with various collector structures are compared. The dependence of d.c. device characteristics on the thickness of the n− GaAs spacer in the collector of composite collector devices is presented. Results indicate that the spacer thickness significantly affects the performance of the transistor. An n+ doping spike on the InGaP side of the collector heterojunction is included in the collector design of the composite collector devices. Standard single-heterojunction d.c. results are compared to abrupt double- and composite collector heterojunction devices. Optimization of the spacer thickness, in conjunction with the n+ doping spike, eliminates most of the detrimental effects associated with a double-heterojunction device while retaining the beneficial properties of a wide-gap collector. As expected, the composite collector structure produces devices with higher breakdown voltages and lower offset voltages than single heterojunction devices. In addition, optimizing the spacer thickness can reduce the collector current saturation voltage of the composite collector device below that of a single-heterojunction device. These characteristics make composite collector heterojunction bipolar transistors ideal candidates for high power microwave device applications. 相似文献
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Busta H.H. Zimmerman B.J. Tringides M.C. Spindt C.A. 《Electron Devices, IEEE Transactions on》1991,38(11):2558-2562
A simple model that is applicable to Spindt-type emitter triodes is presented. Experimentally, it has been observed that the gate current at zero collector voltage follows the same Fowler-Nordheim law as the collector current at high collector voltage, and that for low emission current densities, the sum of gate and collector currents is constant for any collector voltage and is given by the Fowler-Nordheim current I FN. Based on these observations, a simple model has been developed to calculate the I -V characteristics of a triode. By measuring the Fowler-Nordheim emission, emission area and field enhancement can be obtained assuming a value for the barrier height. Incorporating the gate current, the collector current can be calculated from I c=I FN-I g as a function of collector voltage. The model's accuracy is best at low current density. At higher emission currents, deviations occur at low collector voltages because the constancy of gate and collector currents is violated 相似文献
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Two-dimensional simulations of AlGaAs/GaAs HBTs with various collector structures were performed. The introduction of a semi-insulating external collector improves cutoff frequency fT in the low current region because the base-collector capacitance decreases. However, it leads to an earlier fall of fT in the high current region, because a high injection effect is enhanced. This high injection effect has two features: (1) expansion of the collector depletion layer is remarkable near the interface between the intrinsic collector and the semi-insulating external collector, resulting in a longer transit time in this region; and (2) the effective channel in the intrinsic collector becomes narrow by introducing the semi-insulating external collector and so the effective current density there becomes high, leading to an earlier appearance of the high injection situation. It is shown that to minimize these unfavourable high injection effects, the semi-insulating layer should be slightly away from the intrinsic collector region so that it may not affect electron transport in the intrinsic collector region. 相似文献
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The advanced bipolar transistor operating in the quasi-saturation region has been modeled, including collector current spreading effects. It is shown that the multidimensional collector current spreading, resulting from high carrier concentration gradient in the collector, ameliorates quasi-saturation effects in the d.c. and transient operation. The mechanism of collector spreading is investigated by physical device simulations. SPICE circuit simulations employing the collector spreading model are compared with measurements and are found to be in excellent agreement. 相似文献
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InAlAs/InGaAs heterojunction bipolar transistors with thin base and collector layers are fabricated. The maximum value of current gain cutoff frequency is as high as 96 GHz. It is shown that thinning of the base and collector is very effective not only for reducing the base and collector transit times but also for suppressing the space charge effect in the collector.<> 相似文献
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本文首次对新近提出的一种新结构的IGBT——内透明集电极IGBT进行了器件性能的仿真。这种IGBT是在传统非透明集电极IGBT结构基础上,通过在集电区内距离集电结很近处设置一个高复合层的方法,使器件在物理上实现了集电极对电子的透明,同时又避免了低压透明集电极IGBT制造过程中超薄片操作的技术难题。论文重点对器件的温度特性和关断特性进行了仿真研究,并与现行PT-IGBT和FS-IGBT进行了比较。仿真结果表明,通过合理调整内透明集电极IGBT的参数组合,可以使其具有通态压降正温度系数的同时,又具有较快的关断速度,实现透明集电极IGBT的优良性能。 相似文献
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Double-heterojunction bipolar transistors (DHBT) can exhibit a large collector/emitter offset voltage at zero collector current which will adversely affect digital switching circuits. It is shown that this effect results from insufficient grading at the base/collector heterojunction. A GaAlAs/GaAs DHBT grown by MBE having a 130 ? compositional grading at the emitter/base and base/collector junction showed no sign of the collector/emitter offset voltage. 相似文献
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Morizuka K. Katoh R. Asaka M. Iizuka N. Tsuda K. Obara M. 《Electron Device Letters, IEEE》1988,9(11):585-587
The effect of electron-velocity overshoot in a p-type GaAs collector on the transit-time reduction of AlGaAs/GaAs HBTs (heterojunction bipolar transistors) is investigated. A cutoff frequency improvement of about 30% over the conventional n-type GaAs collector was obtained in p-type collector HBTs for the same collector depletion-layer width. A significant increase in electron velocity in the p-type GaAs collector layer was confirmed by a simple analysis 相似文献