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。     

基于受控源转移和分裂节点的去耦等效法

目前,对互感电路进行去耦等效,一般只解决接在节点上不多于三条含互感支路的去耦等效问题。本文提出的受控源转移概念,利用受控源转移和分裂节点的方法,深入研究了接在节点上多于三条含互感支路的去耦等效问题。本文提出的方法通过对电路图等效变换,获得去耦等效电路。     

等效变换的推广应用

提出了利用等效变换把受控源的受控支路等效为电路或电阻与电压源串联组合的方法来求解含受控源的线性电路,推广了等效变换在含受控源线性电路中的应用。     

预设控制量法求含受控源一端口网络的输入电阻

在电路理论中,除了独立电源外,还引进了“受控源”。受控源的源电压或源电流的值受电路中其它支路或元件上电压或电流的控制,本身不独立地起“激励”作用。在分析具有晶体管元件的电路时,受控源的概念是很有用的,并且经常遇到的是只含有一个受控源和线性电阻的电路模型。 在电路分析中,求不含独立源,仅含线性电阻和一个受控源的一端口网络的输入电阻,是一个比较常见的问题。一般可采用在欲求端口外接电压(电流)源,求端口的响应电流(电压),从而得出输入电阻。本文在这一方法的基础上,介绍一个比较简单而又实用的方法,即预设控量法。     

电路课程中含受控源电路教学的探讨

含受控源的电路在“电路”课程教学中既是难点又是重点。本文根据该课程的实际教学经验总结了含受控源电路的分析方法——基本分析方法（支路法、回路法、节点法和戴维南定理）和受控源等效变换法（受控源等效为电阻或电压源与电阻的串联组合）,结合一些具体实例对每一种方法做了详细的分析,总结了含受控源电路的教学特点,并对这两种分析法进行了比较,为含受控源电路的教学提供了有益的建议。     

含受控源电路等效化简时控制量支路的一种处理方法

在电路的等效变换中,含受控源电路的化简往往是一个难点,通常的做法是保留控制量支路。本文介绍一种不用保留控制量支路的处理方法,可在处理某些类型问题时显得更为简便。     

含受控源电路的改进分析方法

含受控源电路的分析是电路分析课程中的一个难点,受控源的存在增加了线性电路分析的难度。本文运用了电路的等效概念,首先对于几种特殊结构类型的含受控源支路采用线性电阻进行等效替代,从而简化了求解过程。然后在含受控源电路中运用戴维宁定理进行电路分析时,对于戴维宁定理的等效电阻的求解,本文又提出了一种有效的电路等效替代方法。最后通过举例,说明利用该方法可使复杂的计算变得简单。     

含受控源电路的等效含源支路的求解方法

本文根据受控电源在电阻电路中所表现出的电源和电阻的二重特性,就如何在含受控电源电路中利用戴维南定理求等效含源支路的方法进行了较为详细的讨论。文章对利用戴维南定理求解含受控源电阻电路时可能出现的情况分别提出了相应的求解方法,并对各种方法在不同情况下应用的优、缺点进行了比较,可以帮助我们加深对受控电源特性的理解和掌握,提高对含受控源电路问题的分析能力。     

含受控源电路等效化简时控制量支路的一种处理方法

在电路的等效变换中，当电路中含受控电源时，电路的化简往往是一个难点，通常的做法是保留控制量支路。本文介绍一种不用保留控制量支路的处理方法，可在处理某些类似问题时显得更简便、灵活。文中给出了算例以及用谊方法求解电路的过程。     

互易性一端口网络等效阻抗的灵敏度分析

本文研究了互易性一端口网络等效阻抗对元件参数的灵敏度分析.利用互易二端口的T形等效电路,建立了等效阻抗对电阻、电感和电容的灵敏度公式.只需计算在单位电流源相量激励下的元件电流或电压,再计算这些相量的平方或乘积,便可得到严格的灵敏度.由此也为相量的平方,以及电压相量与电流相量之积找到了理论价值.     

替代定理在含受控源电路中的应用

本文对电路理论中的替代定理能否应用于含有受控电源的电路问题进行了讨论,指出当被替代网络中含有电路其它部分受控电源的控制量时,在保留控制量的情况下同样可以应用替代定理;本文还提出替代定理应用于含受控源电路时为了保持受控源概念的完整,可以采用控制量的转移的处理方法。     

A functional GaAs FET noise model

It is the purpose of this paper to develop a theory upon which the design of low noise FET amplifiers can be based. This is not a fundamenta model of the noise mechanisms in GaAs FET's, but rather, an endeavor to relate physically measurable device capacitances and resistances to the device noise figure and optimum noise source impedance. I will be shown that the noise performance of an FET can be adequately described by two uncorrelated noise sources. One, at the input of the FET, is the thermal noise generated in the various resis, tances in the gate-source loop. This noise source is frequency dependent and it can be calculated from the equivalent circuit of the FET. The second noise source, in the Output of the FET, is frequency independent, and not recognizably related to any measured parameters. This output nise is a function of drain current and voltage. The decomposition of the FET noise into two uncorrelated sources simplifies the design of broad-band low noise amplifiers. Once the equivalent circuit of a device and its noise figure at one frequency are known, the optimum noise source impedance and noise figure over a broad range of frequencies may be calculated. For the device designer this model also may be helpful in balancing input-output noise tradeoffs.     

Internal thermal feedback in four–poles especially in transistors

Thermal-electric interaction or "internal thermal feedback" occurs in temperature dependent devices and four-poles at low frequencies, if the thermal time constants are small. An electrical equivalent circuit which describes this thermal effect is generally derived and applied to transistors in common base and common emitter configuration. It consists of current sources and of resistance-inductance circuits which can be directly related to the thermal equivalent circuit of the device. It is shown that this thermal feedback should not be neglected in the measurement of high-frequency transistors, in the design of dc or video amplifiers and voltage or current regulators. Some measurements are reported and discussed. For instance, a strong frequency dependence of some four-pole parameters, especially of the forward trans-conductance y21and the short circuit output admittance y22eof high frequency transistors was found at frequencies below 1 Mc. These effects can be explained by the new equivalent circuit. Possible application of this thermal-electric interaction may include the realization of large low Q inductances for low frequency integrated circuitry, and perhaps the investigation of pinch-in and second breakdown effects. It appears that the low frequency noise figure of transistors may also be affected by this effect.     

A Small-Signal and Noise Equivalent Circuit for IMPATT Diodes (Short Papers)

A frequency-independent small-signal equivalent circuit for an IMPATT diode is proposed. It incorporates five circuit elements, including a negative resistance, and is valid over an octave range of frequency. With the addition of two white noise sources it also serves as a noise equivalent circuit.     

独立源和受控源的异同点

“电路基础”对于高等学校电类专业学生来说,是一门重要的学科基础课,其中受控源是基础知识部分的一个难点,本文从受控源和独立源的定义出发,结合思维导图,在是否为激励源、端口情况、等效电路和在叠加定理的应用四个方面深入分析了受控源和独立源的不同之处,从“源”的角度阐述受控源和独立源的相同点,同时分别给出了四种受控源的原型电路实例,分析了受控源供出能量的来源,旨在为学习者深刻理解受控源提供帮助。     

回路电流矩阵方程的一种直观列写方法

给出一种直观列写电路回路电流矩阵方程的方法,通过直观建立独立源,受控源和控制变量等向量的KCL、KVL方程,使回路电流方程直观写出。该法可适用于含有各类受控源的电路,进行矩阵运算便可得到的回路电流解向量和任意输出解向量。     

Consistent modeling of capacitances and transit times of GaAs-based HBTs

This paper investigates how time delays and capacitances observed under small-signal conditions can be consistently accounted for in heterojunction bipolar transistor (HBT) large-signal models. The approach starts at the circuit level by mapping the large-signal equivalent circuit (which consists of charge and current sources) to the well-known small-signal circuit (which consists of capacitances, transit-time, and resistances). It is shown that and how bias dependent charge sources at either pn-junction impact transit-time, base-collector capacitance, and their mutual dependence. It is demonstrated for the example of a GaAs-based HBT that the interrelation of the elements is observed in measurements as predicted. The results of the investigation enhance understanding of HBT model characteristics and provide a criterion to check model consistency.     

Essential-coupling-path models for non-contact EMI in switching power converters using lumped circuit elements

This paper proposes a simple lumped circuit modeling approach for describing noncontact EMI coupling mechanisms in switching power converters. The resulting model assumes a minimum number of noise sources and contains essential coupling paths that allow easy physical interpretations. Essentially, all capacitive couplings are represented by an equivalent noise voltage source and six coupling impedances, whereas all inductive couplings are represented by an equivalent noise current source and three coupling impedances. The resulting coupled noise appears as currents flowing into the terminals of the line-impedance-stabilization-network (LISN). The equivalent voltage source can be conveniently approximated as the switching-node-to-zero voltage, which is typically a rectangular pulse of a few hundred volts. The equivalent current source can be modeled as the current flowing around a loop containing the equivalent voltage source and parasitics such as winding capacitance of the power transformer, the snubber capacitance and connection inductances. Also, the coupling impedances can be estimated by making simplifying assumptions about the geometry of the components and tracks, or by direct measurements. Simulations and experiments verify how inductive and capacitive couplings through each path may produce substantial EMI measured by the LISN. Being based on a lumped circuit approach, the proposed model is easy to apply in practice for understanding, diagnosing and approximating EMI behaviors.     

交流通路中理想直流电压源的短路处理

利用等效电路分析法分离交流通路时,理想直流电压源要作短路处理。对这一问题进行比较全面的分析阐述,对含非线性元件的放大电路转化为线性电路的前提进行了分析。得到了在放大电路工作点确定、输入信号为小信号的前提下,可将非线性的放大电路转化为线性电路,从而利用叠加原理进行分析计算,在处理方法上,理想直流电压源在交流通路中要做短路处理的结论。