用控制量转移求解含受控源的戴维宁等效电路

在电路分析中,常需要求解含受控源的戴维宁等效电路,其核心是求等效电路端口的开路电压U_∞及等效电阻R_0 。通常要列方程,运算量较大,特别是对多网孔和多节点电路。另一种方法是用电路等效求解,要求在等效过程中控制量支路不能变动,这种要求对电路等效带来很多限制。本文提出先采用控制量转移,然后进行电路等效的方法。 如何进行控制量转移,控制量转移到何处合适呢?通过对电路的考察分析,含受控源的电路按控制量所在位置大致可分为下述三类。 第一类:受控电流源的控制量为该受控源两端电压,或受控电压源的控制量为该受控源所在支路的电流,这两种受控源可以用置换定理将受控源置换为电阻。含有这两种受控源的电路在置换定理使用后,电路中不再含受控源,用电路等效的方法可以得出戴维宁等效电路。     

电容器等效电路方式选择

电容器等效电路方式选择成都宏明电子实业总公司张泽厚电容器的测量实际上是一个阻抗测量的问题。众所周知，一个阻抗量可用电阻和电抗元件的串联或并联等效电路表示。只要适当地选择等效电路的元件值，采用同一类型的元件，在给定的条件下，两种等效电路具有相同的阻抗。...     

基于单π模型的RF螺旋电感模型及参数提取法

提出了一种基于单π模型的RF螺旋电感等效电路模型及参数提取方法。该模型在传统单π模型基础上,增加支路间的并联RC网络来表征衬底耦合。在串联支路,增加RL网络来模拟趋肤效应和邻近效应。采用分频段的方法来合理简化等效电路。采用直接解析法来获得等效电路网络中所有的模型参数,无需任何优化。验证结果表明,在0~40 GHz范围内,模型值与仿真值吻合较好。该模型及参数提取方法不仅能简化计算量,还能更好地解释电路行为,对RFIC设计有参考价值。     

含无伴电源电路的几种特殊解法探讨

电路中不与电阻串联的电压源和不与电阻并联的电流源称为无伴电源。当无伴电源出现在电路系统中时,电路分析变得比较复杂。最基本的做法是直接以支路电流或支路电压为电路变量,应用KCL,KVL和支路的伏安关系,通过列出独立方程求解;而这里则是从几种不同的新角度切入问题,对无伴电源电路的几种情况做了分析,并对几种特殊解法进行了探讨。     

普遍意义下介观RLC并联电路的量子化及在真空态下的量子涨落

对具有普遍意义的介观RLC并联电路进行量子化并对各支路电流与电压的量子涨落进行研究, 同时分析耗散电阻对两个支路的量子涨落所产生的影响. 结果表明:各支路的量子涨落均与电路元件的参数有关并且随时间而衰减; 而耗散电阻对电感支路和电容支路量子涨落的衰减因子及其系数均产生影响, 对两个支路电流与电压的量子涨落的衰减因子产生的影响相同, 而对其系数产生的影响不同.当电感支路与电容支路的耗散电阻相同时, 两个支路的电压涨落与耗散电阻有关, 而电流涨落不受耗散电阻的影响.     

基于正多边形的电阻网络研究

各支路电阻皆为 r 的正多边形电阻网络可以展开成两个完全相同的并联梯形电阻.当正多边形电阻网络边数 n 逐渐增大时,从网络中心到多边形顶点的等效电阻逐渐变小,当n >10时,等效电阻趋近于一个常数0.4472r,该常数与各支路的电阻 r 成正比     

改进型梯形谐振滤波器的带通滤波器设计

提出了一种改进型的梯形滤波器,串联支路由单端谐振器构成,并联支路由单端对谐振器与电容元件组成.以这种改进型梯形谐振滤波器为基本单元,进行了五级级联,同时并联了一个SAW谐振器,设计出一个带通滤波器.利用等效电路模型,得到了频率响应.与传统方法相比,通带内更加平稳,同时获得了一个陡峭的过渡带,带外抑制达30 dB以上.     

无线电基础知识讲座

无线电三大基本元件组成的电路(上) 电阻、电容、电感，称无线电三大基本元件。将它们每两种结合在一起可以有12种不同组合，即：电阻串、并联，电感串、并联，电容串、并联，电阻与电感串、并联，电阻与电容串、并联及电感与电容串、并联。这12种组合称基本无源电路，它们是搭建无线电电路的基础。     

并联晶体振荡器的振荡频率

关于并联晶体振荡器的振荡频率,在各种教材中,看法不尽相同。大多认为,并联晶体振荡器的振荡频率在石英谐振器的并联谐振频率附近;少数认为是在石英谐振器的串联谐振频率附近,本文将证明后一种说法是正确的。图1是石英谐振器的等效电路,在不考虑晶体的损耗时,它的串联谐振频率为     

基于高耦合分裂电抗器的短路发电机保护断路器TRV仿真与分析

基于高耦合分裂电抗器（HCSR）的保护断路器是大容量试验站发电机系统的重要保护装置,可以有效解决短路发电机系统短路故障的开断难题。本文通过研究短路发电机保护断路器在均流开断和限流开断两种工作模式下,计算过零开断后暂态恢复电压（TRV）特性的等效电路和边界条件,并以额定电压14kV、短路容量6500MVA短路发电机出口端短路故障为例,计算两台并联的真空断路器在两种开断模式下的TRV参数。结论表明,在均流开断模式下,断路器BK1、BK2的预期TRV基本不受高耦合分裂耦合电抗器的影响;在限流开断模式下,首先开断的断路器在第一和第二过零点的预期TRV均低于标准值。最后开断的断路器在第二个过零点的预期TRV上升率RRRV高于标准值,通过在分裂电抗器支路并联1000Ω电阻可以将RRRV降至合理的范围内。     

Generalized Analysis of Parallel Two-Post Mounting Structures in Waveguide

An analytical expression is obtained for the reactance of parallel two-post mounting structures having unsymmetrical strip and gap positions and different strip and gap widths. An equivalent circuit is derived and analytical expressions for its components established giving a physical insight into the problem of coupling between the two gaps. The analysis is based on deriving a variational expression for the structure reactance from the boundary conditions at the structure position. The theoretical results are experimentally verified for a wide range of coupling conditions. Exploitation of this model for the design of wide-band varactor-tuned negative resistance oscillators and multidiode parallel mounts in general is discussed.     

Equivalent circuit of a dipole antenna using frequency-independentlumped elements

A four-element lumped-parameter equivalent circuit, consisting of a resistance, an inductance, and two capacitances, has been found to represent the feed-point impedance of a dipole antenna. The values of these elements are related only to the physical dimensions of the antenna, not the frequency of operation. Empirical formulas are given for all the elements. The equivalent circuit gives negligible errors in radiation resistance and reactance for dipole half-lengths less than 0.1λ, rising to 1% for resistance and 6% for reactance at 0.25λ. It can be readily used in standard computer software packages such as SPICE, PSPICE, and MICROCAP     

The piezoelectric crystal unit—Definitions and methods of measurement

The properties of a piezoelectric crystal unit as a circuit element are characterized and defined, in terms of a general equivalent circuit that is valid at any frequency up to and including the lower UHF ranges but reduces to the conventional equivalent circuit if the parameters are properly redefined. The characteristic values such as resonance frequency and resistance, parallel resonance frequency and resistance, etc., for a crystal unit with or without other reactive elements in series and/or parallel are tabulated and their significance is illustrated with the aid of the crystal impedance and admittance diagrams. These diagrams are also used in deriving and describing the methods to be followed when determining the crystal equivalent circuit parameters by impedance bridge measurements. Techniques are developed for use with various types of impedance and admittance bridges and the relations required to determine the resonance resistance R1, resonance frequency fs, and quality factor Q0of the motional arm, and the reactance X^-0of the parallel capacitance from the measured quantitites are listed. The effects of transmission lines of various lengths between the plane of measurement in the bridge and the crystal unit are fully considered. The nature and magnitude of the sources of measurement errors, exclusive of errors in bridge calibration, are examined.     

Complex Radiation Impedance of Microstrip-Excited Magnetostatic-Interface Waves

A technique is described for computing the radiation reactance of microstrip-excited MSSW's from a Hilbert transform of a previously derived expression of the radiation resistance. The series combination of the radiation reactance, radiation resistance, and an inductive reactance corresponding to a shorted section of microstrip line forms an equivalent circuit characterizing the excitation process. Supporting impedance measurements are presented and limitations of the model are discussed.     

The detection of the onset of electrode-electrolyte interfaceimpedance nonlinearity: a theoretical study

The equivalent series resistance and reactance of the electrode-electrolyte interface impedance have both been used to detect the onset of signal amplitude induced nonlinearity. Using a theoretical model, it is shown that the choice of the most sensitive indicator depends on the phase angle of the “polarization” impedance and on the applied frequency     

The Design of a Bandpass Filter with Inductive Strip -- Planar Circuit Mounted in Waveguide

The equivalent circuit of an inductive strip inserted in the middle of a waveguide parallel to the E plane is analyzed theoretically by evaluating the inductive reactance of the equivalent T network which was obtained by the Rayleigh-Ritz variational technique. A design theory for the bandpass filter of this type is derived from this equivalent circuit. The confirmation between the design theory and the experimental resuIts is also shown.     

Pulse width modulated capacitor for series compensation

This paper presents a variable reactance type series compensator with pulse-width modulation (PWM) capability. On a per-phase basis, it can be represented by a bidirectional force-commutated switch in parallel with a combination of a capacitor in series with another bidirectional force-commutated switch. The equivalent reactance of the capacitor circuit can be continuously varied, with no risk of short-circuiting the capacitor or interrupting the line current. A simple and reliable PWM AC controller which requires only four force-commutated switches and a three-phase diode bridge is proposed for the implementation of the three-phase compensator. The degree of series compensation is controlled by duty cycle variation of a common train of pulses. No low order harmonics are generated since the force-commutated switches can operate at frequencies higher than that of the AC mains. The operating principles are presented and the theoretical analysis is verified by digital simulation and experimental results on a laboratory set-up     

矩形波导中小导体异物的影响

本文利用矩形谐振腔中的教扰公式结合准静态近似,导出了矩形波导中小导体异物的等效串联电抗和并联电纳。求出了反射系数,传输相移及功率容量降低的表示式.这种表示式在试验中表明是适合的。     

An analytic method for the design of a constant resistance multiplexer

The design of a constant resistance multiplexer composed of three reactance ladder networks connected either in series or in parallel is a very practical problem. In this paper, an improvement on Norton's method and a set of necessary and sufficient conditions on the realizability of a Butterworth or elliptic constant resistance multiplexer are presented. Two illustrative examples are given to show the design procedure.     

Wide-Band Network Modeling of Interacting Inductive Irises and Steps

Methods of field and network theory are jointly applied to the problem of deriving wide-band models for interacting inductive irises and steps in standard and oversize lossless rectangular guides. The resulting equivalent network is a cascade of lumped multiports, described by means of their reactance matrix, given in the canonical Foster's form, and of several parallel transmission lines, connecting the interacting discontinuities. The required frequency band and the accuracy of the model can be prescribed at will. The features of the approach are: the solution of the field problem yields a reactance matrix with monotonic convergence properties; small matrices only need be manipulated; the frequency dependence is explicit, so that the field analysis need not be repeated at each frequency point; a true network model (and not a "spot frequency" equivalent circuit) is produced, which is prerequisite for exact synthesis.