Representation of the SiGe HBT's thermal impedance by linear and recursive networks

In this paper, new methods for approximating the thermal spreading impedance of SiGe HBT devices with electrical equivalent circuits are presented. The electrical equivalent circuits permit an accurate representation of the fractional behavior of the thermal impedance. Using these equivalent circuits, the thermal model can be implemented in electrical SPICE type simulators.     

Characterisation and simulation of digital device electromagnetic noise under non-ambient temperature conditions

Presented is a new approach to the evaluation of electromagnetic emissions of electronics circuits under thermal stress. Near-field radiations, of essentially magnetic-type owing to the current switching of CMOS chips, have been measured in different external temperature conditions. Electrical equivalent models are proposed to investigate thermal influences on the electromagnetic compatibility characteristics of a printed circuit board excited by digital sources.     

Limitations of the Thevenin and Norton equivalent circuits for a receiving antenna

The investigation carried out in this paper was stimulated by a recent paper published by Love (2002), in which the appropriateness of the use of the Thevenin and Norton equivalent circuits for a receiving antenna was questioned. A review of the available literature led to the conclusion that the limitations inherent in the Thevenin and Norton equivalent circuits had not been adequately examined, and this led to the investigation that is reported on in this paper. The Thevenin and Norton equivalent circuits are useful in the reduction of the equivalent circuit for a transmitting-receiving antenna system to simpler networks that facilitate the evaluation of the received power. One finds in the literature that the calculated power dissipation within these equivalent circuits is often equated to the reradiated and scattered power from the receiving antenna. Such calculations are not correct, because power dissipation in the network from which the Thevenin and Norton equivalent circuits were obtained cannot be made using the Thevenin and Norton equivalent circuits. However, as we will show, the Thevenin and Norton equivalent circuits can be used to find a reradiated electromagnetic field that is a part of the total field scattered by a receiving antenna. As part of the derivation of this new result, we develop a derivation of the Thevenin and Norton equivalent circuits from the basic principles of uniqueness and superposition applied to electromagnetic fields.     

Two-Port Equivalent Circuits of Two-Wire Parabolic Tapered Coupled Transmission Lines

Two-port equivalent circuits of two-wire parabolic tapered coupled transmission lines (PTCTL) with open or short terminal conditions on the remaining two ports are presented. First, two-port equivalent circuits of PTCTL, whose characteristic admittances increase along the lines, are shown. Second, two-port equivalent circuits of PTCTL, whose characteristic impedances increase along the lines, the dual of the previous circuits, are shown. These two-port circuits of PTCTL are expressed in terms of two equivalent representations, one having mixed, lumped and uniform distributed circuits, and the other consisting of uncoupled nonuniform distributed circuits.     

Equivalent Transformations for Mixed-Lumped and Multiconductor Coupled Circuits

Distributed circuits consisting of a cascade connection of m -port stab circuits and multiconductor coupled transmission lines are equivalent to ones consisting of cascade connections of multiconductor coupled transmission lines whose characteristic impedances are different from original ones, m-port stub circuits, and an m-port ideal transformer bank. Because of the reciprocity of the circuit, values of transformer ratio must be identified. In the special case of a one conductor transmission line, these equivalent transformations are equivalent to Kuroda's identities. These extended equivalent transformations may be applied to mixed-lumped and multiconductor coupled circuits. By using these equivalent transformations, equivalent circuits and exact network functions of multiconductor nonuniform coupled transmission lines can be obtained.     

Equivalent Representations of Lossy Nonuniform Transmission Lines

Equivalent transformations, which were recently derived for mixed lumped and distributed circuits, may be extended to circuits consisting of lumped reactance, resistors, and Iossy transmission lines. It is shown that circuits consisting of a cascade connection of lumped element sections and Iossy uniform transmission lines are equivalent to circuits consisting of a cascade connection of lossy nonuniform transmission lines, lumped elements, and ideal transformers. Furthermore, by considering the limiting case of these transformations, equivalent transformations for circuits consisting of a cascade connection of lumped reactance, resistors, and nonuniform transmission lines are obtained. Exact equivalent circuits of Iossy even-order binomial form transmission lines are derived from these equivalent transformations.     

含源T形电路和含源Ⅱ形电路的等效变换

本文讨论了含源T形电路和含源Ⅱ形电路的等效变换,扩展了T形电路和Ⅱ形电路等效变换的内容。根据含独立电源二端口网络的特性方程,推导了含源T形电路和含源Ⅱ形电路等效变换的条件。含源T形电路和含源Ⅱ形电路等效变换的结果不具有唯一性,但可通过附加一些条件使变换结果唯一,本文给出了这些附加条件。并通过实例说明了推导结果的正确性。本文的分析对电路教学具有一定的价值,可供教学参考。     

Developing a Simplified Analytical Thermal Model of Multi-chip Power Module

The study of the thermal behavior of power modules has become a necessity regarding the known rapid development in modern power electronics, and the prediction of temperature variation has generally been performed using transient thermal equivalent circuits. In this paper we have developed a simplified analytical thermal model of a power hybrid module. This analytical method is used to evaluate the thermal parameters of a device. The model takes into account the thermal mutual influence between the different module chips based on the analytical method. The thermal interaction between components is dependent on the boundary condition, the dissipated power value in the different components and the number of operating chips constituting the module. This effect is modelled as a source energy and a thermal resistance simply computed tanks to reasonably low measurement applied on the module. The derived thermal models offer an excellent trade-off between accuracy, efficiency and CPU-cost.     

Fast thermal profiling of power semiconductor devices using Fourier techniques

Accurate prediction of temperature variation of power semiconductor devices in power electronic circuits is important to obtain optimum designs and estimate reliability levels. Temperature estimation of power electronic devices has generally been performed using transient thermal equivalent circuits. In the presence of varying load cycles, it has been typical to resort to a time-domain electrical simulation tool such as P-Spice or SABER to obtain a time series of the temperature profiles. However, for complex and periodic load cycles, time-series simulation is time consuming. In this paper, a fast Fourier analysis-based approach is presented for obtaining temperature profiles for power semiconductors. The model can be implemented readily into a spreadsheet or simple mathematical algebraic calculation software. The technique can be used for predicting lifetime and reliability level of power circuits easily. Details of the analytical approach and illustrative examples are presented in this paper.     

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。     

高压LDMOS I—V特性宏模型的建立

目前LDMOS已经广泛应用于功率集成电路和微波集成电路中,建立LDMOS的SPICE等效电路变得很重要。以往的模型都是将LDMOS分为线性区和饱和区两段来分析,公式复杂而且计算量大。因此在数值模拟的基础上提出了全导通区域的伏安特性方程,建立了LDMOSI-V特性的宏模型。该模型的特点是参数少,易于提取,得到的SPICE等效电路简单,仿真容易收敛。     

Analysis of SC networks using continuous-time equivalent circuits without frequency-dependent elements

Continuous-time equivalent circuits for the analysis of SC networks are derived by using the mixed bilinear and LDI transformation, the developed equivalent circuits contain no frequency-dependent elements.     

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.     

晶体管混合π型参数与Y参数的关系

晶体管高频小信号等效电路模型可用两种方法得到:一是把晶体管视为一个二端口网络,列出电流、电压方程式,拟定满足方程的网络模型,常采用Y参数模型;二是根据晶体管内部发生的物理过程来拟定的模型,即π型参数模型;同一个晶体管应用在不同场合可用不同的等效电路表示,同一晶体管的各种等效电路之间又应该是互相等效的,各等效电路中的参数可互相转换。     

基于Pspice光发射机驱动电路的仿真分析

根据发光二极管（LED）和双异质结激光器（DH-LD）的Pspice等效子电路程序,将它们做成新的元件嵌入Pspice A/D 8.0电路仿真平台中。利用该平台对各种光发射机的光驱动回路进行模拟,证明用光电子器件的等效电路模型来模拟光电集成回路的可行性和便利性。     

Tapped-Line Coupled Transmission Lines with Applications to Interdigital and Combline Filters

Exact, general, open-wire-line equivalent circuits for tapped-line combline and interdigital arrays are derived using a combination of graph transformations and induction. A significant feature of the equivalent circuits is that they do not require commensurate length sections. The equivalent circuit for tapped-line interdigital arrays is utilzed to develop design equations for tapped-line interdigital filters.     

基于矢量拟合的过孔等效电路提取方法

提出了一种用于提取过孔的等效电路模型的方法,该方法通过使用矢量拟合法对散射参数或者导纳参数进行有理函数形式的拟合,建立起与有理函数相对应的等效电路模型.该电路模型既保存了实际印刷电路板过孔的物理结构信息,又很好地解决了信号完整性仿真速度的问题.文章还对单个过孔和差分对过孔进行了等效电路的建模分析,为解决包含过孔的信号完整性仿真问题提供了一种有效的解决方案,并通过与电磁场分析软件Ansoft HFSS 仿真结果的对比很好地验证了所建电路模型的有效性和正确性.     

Kuroda's Identity for Mixed Lumped and Distributed Circuits and Their Application to Nonuniform Transmission Lines

Kuroda's identities, which are used in analysis and synthesis of distributed transmision line circuits, may be applied to mixed lumped and distributed circuits. It is shown that circuits consisting of cascade connections of lumped reactances and uniform transmission lines are equivalent to circuits consisting of a cascade connection of nonuniform transmission lines, lumped reactances, and ideal transformers. Moreover, by using these equivalent transformations, network functions of some nonuniform transmisssion lines can be derived exactly.     

An improved GaAs MESFET equivalent circuit model for analog integrated circuit applications

An improved equivalent circuit model of a gallium-arsenide (GaAs) MESFET that is optimized for the design and analysis of precision analog integrated circuits is described. These circuits entail different modeling requirements from digital or microwave circuits, for which existing equivalent circuit models are optimized. Improved techniques are presented to model the drain-to-source conductance, device capacitance, and the functional dependence of drain-to-source current.     

压电微悬臂梁微弱压电信号检测

压电微悬臂梁是一种利用压电元件的逆压电效应驱动微悬臂梁使其振动，并利用压电元件的压电效应来检测梁的变形量的集成微驱动器和微传感器。文中讨论了压电微悬臂梁中的压电元件的两种等效电路模型，并且提出了检测微压电信号的检测系统以及两种前放电路。在检测微悬臂梁频率响应特性的实验中得到了较好的结果。