0.22THz折叠波导行波管放大器理论分析与数值模拟

为了解折叠波导行波管放大器的性能影响因素,在理论分析的基础上,对0.22 THz折叠波导行波管放大器进行系统的数值模拟与分析,重点讨论电子束压、束流、输入信号功率、结构周期数、材料电导率、引导磁场大小、电子能散度以及发射度对器件输出功率水平的影响.发现束压存在最佳工作范围,增加束流可以有效提高器件增益;输入信号不宜过强...     

折叠腔He-Ne激光器中角锥棱镜直角误差分析

首次研究了应用空心角锥棱镜的折叠腔免调试He-Ne激光器系统.根据矩阵光学理论分析了角锥棱镜的直角误差对其光路反射特性的影响,并应用于折叠腔免调试He-Ne激光器系统,定量给出了返回光线偏角误差与棱镜直角误差的线性关系,计算了免调试激光器系统中角锥棱镜直角误差的临界值.这一结果对控制折叠腔免调试激光器中的角锥棱镜加工误差具有指导意义.     

太赫兹折叠波导慢波结构的设计与微加工

从行波管工作的物理特性提出了一种获得折叠波导慢波结构参数的简单方法,给定工作频率和电压,能够获得折叠波导慢波结构的初始参数.设计了D波段的折叠波导结构来验证该方法,对其冷测特性如色散、耦合阻抗进行了分析.仿真结果表明,设计的折叠波导慢波结构在中心频率处具有较平缓的色散关系,在中心频率处耦合阻抗为3.5欧姆.在电子注电压为20.6 kV,电流为15 mA时,27 mm(50个周期)的折叠波导慢波结构在220 GHz具有13.5 dB的增益,3 dB带宽为11 GHz(213~224 GHz).同时讨论了折叠波导慢波结构的微加工工艺,并通过UV-LIGA工艺获得了实验样品.     

两级运放中共模反馈电路的分析与设计

在两级共源共栅CMOS运算放大器中,设计了一种新的共模反馈电路。这种电路克服了一般共模反馈电路存在的限制输出摆幅的缺点,在稳定电路直流工作点的同时,能有效提高电路的输出摆幅。通过对共模电路结构的分析,证明了其功能原理的正确性。基于0.18μm(3V)CMOS工艺库,用Hspice软件对电路结构进行了仿真验证。结果显示,电路低频增益达到120dB,功耗不到0.24mW。     

小型LTCC折叠线带通滤波器的设计

移动通信的发展使得滤波器趋于小型化,相应地就需要对传统的滤波器设计方法加以改进.LTCC(Low Temperature Co-fired Ceramic)为滤波器小型化提供了良好的材料平台.此外,更为新颖的电路结构同样是解决小型化的重要因素.这里提出了三层折叠线,并给出了适于工程应用的设计公式.以此为基础设计了适用于GSM、Bluetooth、802.11a频段的带通滤波器.最后加工生产了一个实物样品.     

小型折叠腔自由振荡TEA CO2激光器实验研究

分析了TEA CO2激光器和差分吸收雷达的工作原理,研制了一种新型双通道放电激励折叠腔TEA CO2激光器.详细分析了折叠腔TEA CO2激光器的结构及其设计特点.对影响气体快放电过程的各种因素,如储能电容与峰值电容的比值、工作气压、充放电电感及输入电压的范围等进行了实验研究,确定了充放电谐振回路的最佳参数,实现了双通道的稳定辉光放电.对激光器输出能量与激励电压、混合气体工作气压等参数的关系进行了实验研究,得到最大输出能量约为722 mJ.     

扩频数字接收机匹配滤波器的设计与实现

介绍了扩频数字接收机中利用匹配滤波器捕获伪码的原理。就某型号接收机对匹配滤波器的原理进行了理论分析．给出了在FPGA中匹配滤波器的软、硬件设计与算法实现。通过对设计电路的实时仿真表明：该匹配滤波器具有设计合理、捕获精度高、使用灵活方便等特点，可应用于其他扩频系统的数字接收机中。     

Material and geometric nonlinear isoparametric spline finite strip analysis of perforated thin-walled steel structures—Analytical developments

This paper presents the analytical developments of the application of the Isoparametric Spline Finite Strip Method (ISFSM) to the material inelastic and geometric nonlinear analysis of perforated thin-walled steel structures. The general theory of the ISFSM is briefly introduced. The formulations of the kinematics, strain–displacement and constitutive assumptions are presented, and the tangential stiffness matrix is derived by applying the incremental equilibrium condition. The requirements for strip continuity and boundary conditions are also discussed. In particular, the plasticity theory and the methods to integrate the ‘rate equations’ are emphasized, and the related ‘backward Euler return method’ and use of a ‘consistent material modulus’ are highlighted. The present isoparametric spline finite strip analysis is verified against a number of analyses of perforated and non-perforated plates and plate assemblages, as described in the companion paper (Yao and Rasmussen, submitted for publication) [1], demonstrating its accuracy and efficiency for the predictions of the inelastic post-buckling behavior of perforated thin-walled steel structures.     

A novel feed-forward compensation technique for single-stage fully-differential CMOS folded cascode rail-to-rail amplifier

This paper presents a novel active and passive mixed feed-forward compensation technique for single-stage CMOS folded-cascode rail-to-rail operational trans-conductance amplifiers (OTA). Simulations using 0.5 μm Agilent CMOS process parameters indicate a phase margin of around 82° with an unity gain bandwidth of 320 MHz (@1.17 pF capacitive load including the device parasitics). Also, the compensated OTA provided over 60 dB DC-gain with rail-to-rail output voltage swing as well as wide input common-mode range. This ensures optimum step response (fast and accurate settling without ringing) for the feedback amplifier in switched-capacitor signal processing applications. An improved ``fast sensing' common-mode feedback circuit with high common-mode gain is also used for the single-stage cascode OTA.     

On f-fault tolerant arc-forwarding and optical indices of all-optical folded hypercubes

We construct a leveled f-fault tolerant routing for a class of the folded hypercube networks. This routing achieves a lower bound established by Gupta in [A. Gupta, J. Man?uch, L. Stacho, Fault tolerant forwarding and optical indices: A design theory approach, J. Combin. Designs 14 (2006) 25-40] and therefore, yields the exact value of the f-fault tolerant arc-forwarding index for this class. In addition, again by applying this routing together with the Brook's Theorem [J.A. Bondy, U.S.R. Murty, Graph Theory with Applications, The Macmillan Press Ltd., 1976], an upper bound for the f-fault tolerant optical index is also established.