SiGe HBT大信号等效电路模型

基于SiGe HBT(异质结双极晶体管)的物理模型，建立了描述SiGe HBT的大信号等效电路模型.该等效电路模型考虑了准饱和效应和自热效应等，模型分为本征和非本征两部分，物理意义清晰，拓扑结构相对简单.该模型嵌入了PSPICE软件的DEVEO(器件方程开发包)中.在PSPICE软件资源的支持下，利用该模型对SiGe HBT器件进行了交直流特性模拟分析，模拟结果与理论分析结果相一致，并且与文献报道的结果符合较好. 关键词： SiGe HBT 等效电路模型 PSPICE     

ACOUSTICAL TRANSMISSION LINE MODEL FOR ULTRASONIC TRANSDUCERS FOR WIDE-BANDWIDTH APPLICATION

An improved model for ultrasonic transducers is proposed.By considering only the first symmetric mode,each layer is represented as an acoustical transmission line in modeling of bulk wave transducers.In imaging applications,wide bandwidth and short time duration are required.The approach we have used consists of impedance matching the front face of the piezoelectric transducer to the propagating medium with a quarter wavelength impedance matching layer and inserting an unmatching quarter wavelength acoustical layer between the rear face and backing material.A heavy backing would degrade the wide-band phenomena,but show a time duration shorter than 0.5 μs for imaging applications.PSPICE code of the controlled source model is implemented to precisely predict the performance of the matched transducers such as impedance,insertion loss,bandwidth and duration of the impulse response.Good agreement between the simulation and experimental results has been achieved.     

Simulation of non-stationary electrodiffusion processes in charged membranes by the network approach

Single techniques of network approach have been used to obtain the numerical solution for a boundary value problem involving the Nernst-Planck and Poisson equations system. A network model has been proposed for a particular physical situation, namely, ionic transport in charged membranes including the Donnan equilibrium relations at the membrane/solution interfaces. With this network model and using the electrical circuit simulation program PSPICE, the ionic concentration profiles as well as electric potentials and ionic fluxes have been simulated as a function of time for the ternary systems HClKCl and NaClKCl.     

ECRH负高压电源的反馈控制

介绍一种利用大功率四极调整管的调整特性进行串联反馈调节,在反馈环节中采用新型预置值的积分器的高精度的负高压电源,解决了ECRH系统所要求的电压－80kV,脉宽10－100ms,电压稳定度为99．7％的负高压电源的关键技术问题,并通过PSPICE软件仿真,验证了方案的现实可行。     

TLCODE方法在多路传输线并联电路中的应用

 介绍了TLCODE方法对多路传输线并联电路的模拟情况。根据TLCODE方法的要求,在引入接地电阻的条件下推导了多路传输线并联时的界面电压公式,同时构建了一个多路传输线并联的PSPICE电路模型,将该模型计算得到的传输线输入端电压作为TLCODE方法的输入电压,通过比较发现两种方法计算的传输线任意处的电流、电压波形完全符合。这表明利用TLCODE方法模拟多路传输线并联问题取得了成功,标志着开发多路并联磁绝缘传输线电路模型取得了重要进展。     

间歇性正比于系统变量方法控制超混沌的实验

利用电子电路和PSPICE软件实现了间歇性正比于系统变量方法控制超混沌的实验，在实验中进一步拓展间歇性正比于系统变量方法，用一个微扰反馈信号作用到系统的其它变量，得到了较好的控制效果。     

一种四级传输线脉冲变压器的初步研究

 分析了四级传输线脉冲变压器的电路结构,采用等效电路方法简化了电路,推导了输出电压波形的表达式。开展了冷测实验,结果显示传输变压器变压比约为4,变压器上升时间约为48 ns。采用实验所测参数,利用PSPICE软件对全电路进行了数值模拟。结果表明:模拟和冷测结果基本一致。将各元件参数代入波形表达式,结果表明:传输变压器上升时间计算值为12 ns,与实验值(48 ns)有一定差距;而传输变压器变压比计算值为3.98,与实验结果基本吻合。     

CMOS电路的功耗分析及基于 PSPICE模拟的功耗估计

本文在分析传统直流供电 CMO S电路和新型交流供电 CMOS电路功耗的基础上 ,从系统电源 能耗的角度出发 ,结合 CM OS单元电路的 PSPICE模拟 ,提出了手段较为简便的针对于两类电路单元的 功耗估计方法 ,并具体对两个电路实例进行了功耗估计 . 模拟结果能直观地反映系统内部的开关动作和 能耗特性 .     

A study of the transport of ions against their concentration gradient across ion-exchange membranes using the network method

The network method has been used to analyze the conditions that favour the uphill transport across ion-exchange membranes. A model for the Nernst-Planck-Poisson equations describing the ionic transport in such system is proposed, including the Donnan equilibrium relations at the membrane/solution interfaces. With this model and the electric circuit simulation program PSPICE, the transient response of the system under open circuit conditions (I=0) and the response of the system subject to an applied potential difference are simulated. The ionic concentrations and electric potential profiles, as well as the electric current density, the ionic fluxes and the charge density, have been obtained as a function of time.     

PSPICE controlled-source models of analogous circuit for Langevin type piezoelectric transducer

The design and construction of wide-band and high efficiency acoustical projector has long been considered an art beyond the capabilities of many smaller groups. Langevin type piezoelectric transducers have been the most candidate of sonar array system applied in underwater communication. The transducers are fabricated, by bolting head mass and tail mass on both ends of stacked piezoelectric ceramic, to satisfy the multiple, conflicting design for high power transmitting capability. The aim of this research is to study the characteristics of Langevin type piezoelectric transducer that depend on different metal loading. First, the Mason equivalent circuit is used to model the segmented piezoelectric ceramic, then, the impedance network of tail and head masses is deduced by the Newton's theory. To obtain the optimal solution to a specific design formulation, PSPICE controlled-source programming techniques can be applied. A valid example of the application of PSPICE models for Langevin type transducer analysis is presented and the simulation results are in good agreement with the experimental measurements.