An analysis method for high-speed circuit systems

A new method for analyzing high-speed circuit systems is presented. The method adds transmission line end currents to the circuit variables of the classical modified nodal approach. Then the matrix equation describing high-speed circuit system can be formulated directly and analyzed conveniently for its normative form. A time-domain analysis method for transmission lines is also introduced. The two methods are combined together to efficiently analyze high-speed circuit systems having general transmission lines. Numerical experiment is presented and the results are compared with that calculated by Hspice.     

Time-domain analysis of multiple parallel transmission lines by means of equivalent circuits

Thévénin's equivalent circuit for a single transmission line is well known. The letter presents an application of Thévénin's equivalent circuit for multiple parallel transmission lines to the time-domain analysis of wave propagation over such lines. For purposes of illustration, a system of two coupled transmission lines is treated.     

耦合型漏泄同轴电缆传输和耦合特性研究

针对泄漏同轴电缆作为分布式传感器应用于物联网和智能家居的室内安防入侵检测时，运用全波仿真软件HFSS不能有效仿真长距离的耦合漏缆的问题，提出了一种等效电路模型.利用参数提取软件，先提取单个开槽的缝隙单元的等效电路模型，然后借助于传输线理论，利用四个传输矩阵级联得到整段漏泄同轴电缆的传输矩阵.并考虑两根漏缆缝隙间相互耦合，提出了表征耦合特性的等效电路模型.将等效电路模型利用商用软件高级设计系统（advanced design system，ADS）进行电路搭建与仿真.仿真结果表明，本文提出的两根漏缆的等效电路模型与全波仿真结果非常符合，可以快速地仿真长距离的耦合漏缆结构，并大大节约了仿真时间.     

A Dual Mode Tuning Circuit for Microwave Transistor Oscillators

A two-port circuit adjusting both even and odd mode fields, with orthogonal mode adjustment, can be used as an embedding circuit for a microwave transistor oscillator. The circuit, analyzed in TEM line, may also be realized in any other form of transmission line geometry, including two coexistent modes in a cavity. The resulting oscillator is stable, has low FM noise, and is readily tunable. Analyses of the tuning circuit and oscillator are presented, along with some experimental results and a discussion of methods using other than TEM transmission lines to produce the even and odd modes.     

关于传输线等效集总电路模型的拓展教学

传输线的等效集总电路模型有助于理解和掌握传输线的基本概念,并可用于电特性的仿真分析。本文分别探讨了在教学过程中需拓展的两个重要知识点。其一,在高频工作情况下,需要对含有频变分布参数的传输线进行准确建模,获取相应的等效集总电路模型;其二,在分析多导体构成的耦合传输线时,等效集总电路模型同样值得探究。     

Numerical techniques for planar and quasi-planar millimeter-wave passive components

The necessity for accurate characterizations of microwave circuits and components is well recognized. This is because of the use of higher frequencies and more complicated circuit configurations. This paper reviews two important numerical approaches to the analysis and design of printed circuit transmission lines, the planar circuit approach and the transverse resonance technique. The former is applicable basically to microstrip quasi-TEM circuits, and constitutes a considerable improvement compared to the conventional transmission line approach. It is, however, an approximate technique that cannot be expected to give extremely accurate results in all practical cases, particularly in the higher frequency spectrum. On the contrary, the transverse resonance technique, in a formulation generalized with respect to the conventional transverse resonance method, is a rigorous full wave technique that can be applied to the characterization of both planar and quasi-planar transmission lines. The extension of this method to the modeling of discontinuities is also illustrated.     

On controlled switching of high voltage unloaded transmission lines

The limitation of switching overvoltages on very high voltage transmission lines is traditionally carried out with the aid of circuit breakers — fitted with closing resistors. This widely used system has repeatedly shown itself to be highly efficient. Nevertheless, it is possible to envisage other methods, in particular, those giving control of the circuit breaker instant of closing. This paper examines the possibilities offered by controlled switching on UHV transmission lines and compares existing solutions. It takes into account the various network characteristics that may be encountered. It details the results in terms of overvoltage levels which could be attained, due to the performance of the circuit breaker. The paper also highlights the critical points relative to the application.     

LTCC微带传输线损耗特性研究

为了减小LTCC微带传输线损耗,提升电路传输性能,设计了一个LTCC50Ω标准匹配微带线实验。利用矢量网络分析仪测量了微带线损耗,并依据电子显微镜对电路的检测结果分析了损耗产生的原因。结果显示,在10GHz频率下,微带线损耗约为0.6dB。提出了减小微带线高频损耗的有效方法,如提高光绘膜精度和丝网精度等。     

Printed Circuit Transmission-Line Characteristic Impedance by Transverse Modal Analysis

Dispersion characteristics of printed circuit transmission lines such as finlines, shielded microstrips, slotlines, suspended striplines, coupled slotlines, and coupled striplines computed by the transverse modal analysis were reported in a previous paper. Application of the transverse modal analysis to compute the characteristic impedances of these printed circuit transmission lines is illustrated in this paper. Favorable comparison with various published data demonstrates the outstanding accuracy achieved by this technique. Combining the characteristic impedance computation with the dispersion results, the transverse modal analysis can be employed for solving various problems in printed circuit transmission lines.     

用NILT导出的传输线瞬态分析模型

K Singhal与J Vlach的NILT(数值Laplace反变换) 技术是端接线性负载传输线分析的一种有效方法.本文利用这一NILT技术,导出了传输线的时域离散模型,由此可进行端接任意负载传输线的瞬态分析.这一模型毋须象通常的频域方法那样对传输线作有理逼近,因而不存在由此带来的数值问题,而计算量与它们相当.文中分别给出了均匀与非均匀传输线的处理,并用实例作了验证.     

New N-way Hybrid Power Combiner to Improve the Graceful Degradation Performance

In this paper, a new N-way hybrid power combiner for improving the graceful degradation performance has been proposed. The proposed combiner has been configured with two dummy transmission lines per each section, where each dummy transmission line has a different characteristic impedance, of the standard combiner. Under this proposed configuration, a detailed theoretical analysis has been performed to show the general function of a power combiner. When any M amplifiers among N identical amplifiers are suffering the failure mode in a power combining circuit or system, the graceful degradation performance has been improved due to the separation of a transmission line and an internal resistor in every failed section from the proposed combiner by simultaneously operating two shorting devices. Simulation results for all the items which can be measured from the proposed combiner with an eight-way configuration have been presented.     

Time-domain analysis of lossy multiconductor transmission lines based on the Lax–Wendroff technique

Taking advantage of the hyperbolic characteristics of the telegrapher equations, this paper applies the Lax–Wendroff technique, usually used in fluid dynamics, to transmission line analysis. A second-order-accurate Lax–Wendroff difference scheme for the telegrapher equations for both uniform and nonuniform transmission lines is derived. Based on this scheme, a new method for analyzing lossy multiconductor transmission lines which do not need to be decoupled is presented by combining with matrix operations. Using numerical experiments, the proposed method is compared with the characteristic method, the fast Fourier transform (FFT) approach, and the Lax–Friedrichs technique. With the presented method, a circuit including lossy multiconductor transmission lines is analyzed and the results are consistent with those of PSPICE. The nonlinear circuit including nonuniform lossy multiconductor transmission lines is also computed and the results are verified by HSPICE. The proposed method can be conveniently applied to either linear or nonlinear circuits which include general transmission lines, and is proved to be efficient.     

人工传输线传输特性的分析与设计

人工传输线以其慢波效应可以使微波部件小型化,因而得到了广泛应用。首先介绍了人工传输线的基本原理,给出了一种简洁的等效电路模型,然后推导出了基于该模型的传输特性计算公式;在此基础上,根据仿真结果推算出各等效电路参数,从而得到了人工传输线传输特性与等效电路参数的关系;最后设计制作了人工传输线,测试结果与分析结果比较吻合,证明了提出的分析模型是有效的。为进一步简化设计平面型人工传输线奠定了基础。     

A diplexer based on transmission lines, implemented in LTCC

This paper presents a diplexer circuit based on transmission lines. In comparison with other diplexer circuits, the implementation of the proposed diplexer can be easily done on single- as well as multilayer substrates. An implementation example of the presented circuit will be discussed for a global system for mobile communications/digital cellular system (GSM/DCS) application. The diplexer is implemented in a multilayer substrate, using low-temperature cofired ceramics (LTCC) technology. Finally, the simulation results will be compared with the measurements, and it will be shown that they agree excellently. These results and the results out of a sensitivity and yield analysis confirm the excellent behavior of the proposed circuit.     

A new approach for closed-form transient analysis of multiconductor transmission lines

A novel closed-form model for multiconductor transmission lines is presented. The proposed model is derived from the analytical characterization of half-T ladder networks, which using closed-form polynomials (named DFF and DFFz), allow one to exactly extract poles and residues of the two-port representation of multiconductor transmission lines, thus, generating a time domain macromodel that can be incorporated in a circuit simulator. Since the model is derived from a stable and passive equivalent network, its stability and passivity are strictly preserved. Simulation results for one, two, and three-conductor transmission lines with linear and nonlinear terminations are presented, confirming the validity of the proposed model.     

Compact Rat-Race Coupler Using Shunt-Stub-Based Artificial Transmission Lines

In this letter, a compact rat-race coupler is developed using shunt-stub-based artificial transmission lines (SSB ATLs). A conventional quarter-wavelength microstrip can be equivalent to an SSB ATL realized by two series high-impedance microstrips with the high-impedance branch-type shunt stubs. The circuit configuration of the SSB ATL is beneficial to miniaturize the circuit size using the folding technique. By integrating six SSB ATLs, a compact rat-race coupler can be implemented with a 3.9% circuit size of the conventional one. The measured results of the developed rat-race coupler are in a good agreement with the simulated results by full-wave electromagnetic simulator.      

Network-analyser reflection measurements of microstrip circuits not requiring exactly reproducible coaxial-to-microstrip transitions

A measuring and correction procedure for network-analyser measurements of microstrip circuits is presented which does not need exactly reproducible coaxial-to-microstrip transitions. The transmission properties of the transitions and the parameters of the microstrip lines are determined by transmission measurements of two homogeneous lines; the input reflection coefficient of the coaxial-to-microstrip transition is measured directly at the microstrip circuit under test using sliding-load techniques. Assuming the transition to have low losses, its backward reflection coefficient can be calculated approximately. The measured scattering parameters of the microstrip circuit are corrected using these values, and a measurement example shows the results of this procedure.     

A Coupling Model for a Pair of Skewed Transmission Lines

A coupling model in the form of an equivalent circuit is developed for a pair of skewed transmission lines. The inductive coupling is evaluated in closed form and the capitances are obtained from the solution of a pair of coupled integral equations for the excess-charge distributions along the transmission lines. The coupled integral equations for the excess charges are solved by an approximate analytical method and also by employing the method of moments. The two solutions are seen to be in excelent agreement. The excess-charge distributions are then used in a parametric study of the capacitances in the coupling model. The results are presented in graphical form.     

An accurate experimental method for characterizing transmission lines embedded in multilayer printed circuit boards

We have developed an accurate method for measuring the complex propagation constant and characteristic impedance of transmission lines embedded in multilayer printed circuit boards. It is based on mathematical error-removal schemes using two different length transmission lines and an advanced via-hole structure that minimizes coupling. Consequently, associated errors, due to discontinuities and interference can be effectively eliminated, and the frequency dependencies of the transmission line parameters can be clarified in wide frequency bandwidths. We verified the validity of this method in frequency ranges up to at least 18 GHz, by comparing the determined values with the theory derived from transverse electromagnetic (TEM) approximations.