偏置电阻对放大电路频率响应调节数值仿真研究

首先利用matlab编程仿真分析偏置电阻对共发射极三极管放大电路的频率响应调节作用,然后利用仿真实验软件multisim对分析结果进行数值验证分析。对现行教材频率特性部分内容了做一些扩充。     

蔡氏电路数值仿真图像与实测图像的对比研究

三阶自治电路—蔡氏电路在特定的条件下可以产生混沌现象。本文基于MATLAB软件对建立的电路模型进行了数值仿真,并将结果与真实实验测得的图像进行了对比分析。结果表明,蔡氏电路的数值仿真图像与实测图像基本吻合;而基于MATLAB的数值仿真能够更精确的调节模型参数,更清晰地表现混沌现象的行为变化。     

品质因数的多重内涵及其教学探讨

从正弦激励下线性二阶系统的微分方程出发,结合阻尼振子的受迫振动以及RLC串联、并联谐振电路等具体物理情境,剖析了品质因数Q在频率特性、能量转换以及系统各物理参数等多个层次上的内涵,进而探讨如何更好地为工科各专业学生讲授品质因数这一概念.     

一种模拟滤波器电路的故障诊断方法

针对模拟滤波器电路,提出了一种基于测前仿真和测后仿真相结合的故障诊断方法。在测前仿真环节,通过仿真获取电路正常状态及故障状态的幅频响应曲线,引入“区别度”计算电路故障状态和正常状态的区分程度,从而确定电路的可测故障集,并通过频率选择建立可测故障集的故障字典。在测后仿真环节,通过不同频率的激励获得电路故障状态的测试数据,再利用“区别度”计算测试数据与故障字典中各故障特征的区分程度,通过最小“区别度”实现故障检测及故障元件的定位。最后通过一个滤波器电路仿真实例,基于PSpice仿真和Matlab程序计算实现了基于测前仿真的可测故障集确定和故障字典建立,以及基于测后仿真的故障检测和故障元件定位,验证了本文提出方法的实用性。     

一个新的恒Lyapunov指数谱混沌吸引子与电路实现

通过对改进恒Lyapunov指数谱混沌系统进行进一步演变,并引入新的绝对值项,发现了一种新的混沌吸引子.首先,通过相图、Poincar映射、Lyapunov指数以及功率谱,证明该混沌吸引子的存在性.接着,分析研究了这种新型混沌吸引子的基本动力学行为.Lyapunov指数谱、分岔图和状态变量幅值演变的数值仿真说明,该系统存在全局线性调幅参数,在该参数的调整下,系统输出三维信号的幅度皆能得到线性调整,而系统保持相同的混沌吸引子与Lyapunov指数谱.最后,通过构建电路实现了该混沌系统,观察到相应的混沌吸引子,也验证了全局线性调幅参数的调幅作用,数值仿真与电路实现有很好的一致性.     

SOI SiGe HBT电学性能研究

研究了SOI衬底上SiGe npn异质结晶体管的设计优化.给出了器件基本直流交流特性曲线,分析了与常规SiGeHBT的不同.由于SOI衬底的引入使SOI SiGe HBT成为四端器件,重点研究了衬底偏压对Gummel曲线、输出特性曲线以及雪崩电流的影响.最后仿真实现材料物理参数和几何物理参数对频率特性的改变.结果表明SOI SiGeHBT与常规器件相比具有更大的设计自由度.SOI SiGe HBT的系统分析为毫米波SOI SiGe BiCMOS电路的设计提供了有价值的参考.     

含有单相铁芯变压器的铁磁混沌电路的分析及控制

对一个含有单相铁芯变压器的三阶非自治铁磁混沌电路进行了理论研究和计算机仿真分析.研究表明,仅含由磁通链控制的非线性电感器件的三阶非自治电路可以作为一个四阶自治改进系统来分析.数值仿真和电路实验证实了此系统确实存在混沌动力学行为.同时,还提出了一种通过改变线性电容参数控制混沌的方法.     

基于随机共振原理的分段线性模型的理论分析与实验研究

提出了一种分段线性双稳态模型, 推导了模型的解析关系及其输出信噪比, 通过对该模型与连续双稳态模型的对比分析和仿真实验, 证明了该模型的优越性.该模型具有参数之间相互独立、易于调节的特点. 在对模型分析与数值仿真的基础上, 通过电路对强噪声背景下的微弱周期信号检测进行了实验研究. 结果表明分段线性随机共振模型能够有效实现对微弱周期信号的检测, 并能显著增强输出信噪比.     

改进恒Lyapunov指数谱混沌系统的广义投影同步研究

对改进恒Lyapunov指数谱混沌系统的广义投影同步进行了研究.用主动控制同步法设计合适的非线性反馈控制器,通过单向耦合,实现恒指数谱混沌系统的同结构广义投影同步与异结构广义投影同步.在指出广义投影同步体系中比例因子调节作用的同时,也分析了改进恒指数谱混沌系统的全局线性调幅参数对同步体系中两个系统的作用.基于模块与复用的设计思想,详细分析并构建了广义投影同步体系中的驱动系统、控制系统与响应系统.数值仿真与电路实验仿真一致显示：调节比例因子能够获得任意比例于原驱动混沌系统输出的混沌信号;调节全局线性调幅参数,能够同时线性调整同步体系中两个系统输出的状态变量的幅值,而不影响两个系统之间的广义投影同步. 关键词： 改进恒Lyapunov指数谱混沌系统 广义投影同步 比例因子 全局线性调幅参数     

一种二次型忆阻器四阶混沌电路

由HP实验室研制的无源忆阻器得到的荷控二次型忆阻器模型,与有源磁控分段线性和三次光滑忆阻器模型相比,更符合实际.利用此模型并基于蔡氏混沌电路演化而来的拓扑对偶结构设计了一种新型忆阻器四阶混沌电路.理论分析、仿真及电路实现表明,该电路具有依赖于忆阻器初始状态的复杂动力学行为,也会产生随时间和系统参数变化的状态转移等非线性动力学现象,在相轨图中出现"涡眼"和"环眼".     

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A wideband optical coupling isolation amplifier is presented. Experimental results showed that the presented isolation amplifier can transmit an analog signal from dc to 2.7MHz with good linearity and low propagation delay. Effects of the compensation capacitor on the frequency characteristics of the isolation amplifier was studied by simulation analysis. Meanwhile the mathematical model of the circuit was established with parts of the parasitic parameters taken into consideration. The linearity and frequency characteristics of the circuit was studied, combining theoretical analysis, simulation and test. At last, the availability of the presented isolation amplifier was verified in the Langmuir probe floating potential measurement system on J-TEXT tokamak.     

基于CMOS工艺的自动增益控制电路研究

在无线接收机中,天线接收的信号强度往往变化很大,自动增益控制环路(Automatic Gain Control,AGC)根据这个信号强度来动态调节控制放大器的增益,向后级基带电路(如ADC)提供幅度恒定的信号,使得接受到的不同强度信号均能被正确接收和解调。鉴于此,本文基于TSMC90nm CMOS工艺着重论述了针对70MHz中频信号的AGC电路设计过程。包括系统指标设定、系统模型建立、具体电路设计及仿真结果分析等,并对版图布局进行了探讨。     

半导体激光放大器的电路模型及噪声特性分析

给出了半导体激光（ＬＤ）放大器的电路模型，使得对半导体激光放大器的特性可以用通用电路分析软件进行分析。用该模型对谐振型光放大器光功率输出特性与失谐关系进行了模拟分析，模型的分析结果与已报道的理论和实验基本一致；用该模型还对谐振光放大器的噪声进行了分析。     

A KIND OF NEW AMPLIFIER

Chaotic characteristics in the iteration of logistic map(one-dimensional discrete dynamic system) are simulated and analyzed. The circuit implementation of a kind of chaotic amplifier model is based on the chaotic characteristics that chaos is sensitively dependent on its initial conditions, and the circuit simulation result is given using simulation program with integrated circuit emphasis for personal computer (PSPICE), and is compared with linear amplifier. Advantages and disadvantages of such a model are indicated.     

Analysis of chirp characteristics of DFB lasers and integrated laser-modulators

A new method of analyzing the chirp characteristics of directly modulated lasers and integrated laser-modulators is presented in this paper. Phase-circuit has been introduced into the circuit model of distributed feedback (DFB) lasers in the analysis. Therefore, the chirp characteristics of the device can be obtained by simulating the modified circuit model. The simulation results agree well with the published data. Furthermore, this modified model is combined with the circuit model of electroabsorption (EA) modulators to simulate the chirp characteristics of the monolithic integration of a DFB laser and an EA modulator. The simulation is focused on the dependence of the frequency chirp of the integrated device on the isolation resistance between laser and modulator. Much lower chirp can be seen in the integrated lightwave source compared to the directly modulated laser.     

长周期扫描电路的设计与应用

本文鉴于常用的基于电容充放电的运算放大器积分式长周期扫描电路输出电压线性差,设计了基于计数器和D／A转换的数字式线性功率扫描电路。     

Broadband Amplifier Module Used in 3MM IF-Switch Radiometer

This paper introduced the design procedure of a low-noise broadband amplifier module used in 3mm IF-Switch radiometer. We first analyzed the impact of IF amplifier on the overall performance of the radiometer and then illustrated the techniques used in broadband amplifier design. CAD software was used in the procedure of simulation and the circuit was implemented in hybrid microstrip format. The final amplifier module matched well with the simulation result.     

光学特征点亮度控制方法研究

针对用于空间大尺寸测量的单机视觉三维坐标测量系统的光学测棒的特征点亮度远程控制问题,提出了一种通过PC机的RS485串行接口控制的具有良好线性的光学测棒特征点亮度控制方案。介绍了方案的工作原理,根据光学特征点———红外发光二极管的光学特性,运用新型D/A转换器、运算放大器及三极管等构成可程序控制的恒流源电路,解决了发光二极管控制过程中的电流调整困难、工作过程中发热、管耗高等问题。实验证明该方法具有线性好,灵敏度高,反映速度快等优点,完全可以满足实际应用的要求。     

Optimization of the two-stage common-emitter transistor amplifier for equalization circuit in visible light communication system

The equalization circuit in the visible light communication (VLC) system has large impacts on the frequency response and can greatly improve the 3-dB modulation bandwidth. The optimization of the two-stage common-emitter transistor amplifier for equalization circuit is presented in detail and the design rules are disclosed. At first, the frequency response of the single-stage amplifier is derived and the simulated characteristic curves illustrated the changing regularity of four main factors are given. Subsequently, the frequency response of the two-stage amplifier is investigated by simulation. It is shown that the capacitors in the resistance–capacitance (RC) network has large impacts on the low-frequency range, while the resistors in the RC network can adjust the high-frequency, and the resistors in the emitter can adjust the low-frequency. Experimental measurements of the fabricated equalization circuit demonstrated the simulation results. Then, the two-stage amplifier is induced as post-equalization circuit (post-EQC) or pre-equalization circuit (pre-EQC) and the measured frequency response curves are given. The equalization circuit with proper sets of capacitors and resistors would flatten the frequency response curve of the VLC system. It is shown that the 3-dB modulation bandwidth of the VLC system equipped with post-EQC or pre-EQC can be expanded to 292 MHz or 304 MHz, respectively. Moreover, if the photoelectric receiver and the post-EQC are combined in the optimization, the 3-dB modulation bandwidth can be expanded to 375 MHz.     

Design of broadband hybrid fiber amplifier based on particle swarm optimization algorithm北大核心CSCD

基于铒/镱共掺光纤放大器（erbium-ytterbium doped fiber amplifier, EYDFA）的理论模型和受激拉曼散射效应的分析理论,利用EYDFA和拉曼光纤放大器（Raman fiber amplifier, RFA）的增益谱互补特性,研究并设计了EYDFA与二阶多泵浦RFA相结合的混合放大器结构。为了得到高增益和低平坦度的混合放大器,引入了粒子群算法优化泵浦光波长和功率。仿真结果表明:在不使用增益均衡器的条件下,所设计的混合光纤放大器在输出端得到了近似相等的输出光功率,在90 nm的带宽范围内平均增益为38.78 dB,增益平坦度为1.1 dB,为混合放大器的设计和优化提供了参考。