Optimum Design of Stepped Transmission-Line Transformers

This paper describes the optimum stepped-transmission-line transformer structure for matching two unequal characteristic impedances. For any specified bandwidth, the steps are designed to yield a Tchebycheff-type (or equal-ripple) reflection-coefficient response. Over this band, the maximum vswr is less than that obtainable with any other stepped-transformer having the same number of steps. Design method and technique for eliminating discontinuity-capacitance effects are given. The measured results for a coaxial and a waveguide model are presented and found to verify the method.     

Transmission-Line Transformers

The radio-frequency transformers described in this paper consist of matched transmission lines of equal length and characteristic impedance. The lines are connected according to rules given in the text. These transformers exhibit a very broad frequency response which can be readily estimated; two methods of analysis are presented. The computations agree well with the test results.     

Analysis and Design of Planar, Spiral-Shaped, Transmission-Line Transformers

Coupled microstrip line theory is applied to analyze planar Ruthroff transmission-line transformers (TLTs). The results demonstrate that the TLT's low frequency response improves as the microstrip line's even-mode impedance increases, whereas the ratio of load impedance to the line's odd-mode impedance controls the high frequency response. Analysis of an approximate model of coupled microstrip lines formed into a spiral leads to a technique for predicting the performance of planar, spiral-shaped, Ruthroff TLTs. Microwave measurements up to 10 GHz are compared with predictions from the model for regular and suspended Ruthroff TLTs fabricated through a multichip-module deposited (MCM-D) process     

Some Notes on the Optimum Design of Stepped Transmission-Line Transformers

This paper describes an optimum design of monotonic stepped transmission-line transformers when the reflection coefficient and the bandwidth ratio are prescribed. For the analysis, discontinuity capacitances and reflection interactions are neglected and the validity of the conclusions is therefore restricted to small steps. The analysis is applicable to a multistep transmission line of which the quarter-wave transformer is a special case. In particular, it is shown that if the number of steps is increased from three to five a larger bandwidth may be obtained, but it is not possible to reduce the over-all length in this manner. For a given bandwidth, the shortest taper is always a stepped transmission line and never a continuous one.     

Synthetic Transmission-Line Impedance Transformers (Correspondence)

Somlo has presented a convenient procedure for obtaining the characteristic impedance and length of a single section of lossless transmission line to match two impedances. One impedance and the conjugate of the other are plotted on a circular transmission-line chart, i.e., Smith or Carter chart. A circle is drawn through the two points with its center on the X =0 axis. If the circle does not lie entirely within the R =0 circle, the two impedances cannot be matched with a single section of lossless transmission line with real characteristic impedance. However, if one does not require that the transmission line have a real characteristic impedance, it can be synthesized by a symmetrical T or /spl pi/ network consisting of either lossless inductances or capacitances.     

Analysis and Design of Singly Terminated Transmission-Line FIR Adaptive Equalizers

We present transmission-line-based finite-impulse response (FIR) filters built using singly terminated delay lines and compare their performance with respect to circuit nonidealities. New topologies for FIR filters called bi-transversal structures, which are electrically equivalent to transversal equalizers, are introduced. We show that resistive shunt compensation of transmission lines is a useful technique that results in dramatic improvements in the performance of singly terminated transversal filters, making them excellent candidates for LMS algorithm based adaptive equalization at gigabit speeds     

Design of Commensurate Transmission-Line Circuits

Digital computer techniques are developed for the approximation of the periodic frequency characteristics of commensurate transmission-line circuits. For a given periodic delay or loss-derivative function the system function is derived automatically rising a direct method. Any suitable synthesis program will complete the design.     

Simplified Analysis of Coupled Transmission-Line Networks

A relatively simple method is presented for analyzing coupled transmission-line networks by using network graphs and graph transformations. The network graph symbolism is easy to draw and to manipulate. All the graphs consist only of inductor, capacitor, and transformer symbols, and straight lines, which represent unit elements. The method of analysis is illustrated by several two-wire-line and multiwire-line examples. Also presented are several new useful transmission-line transformations and a graph equivalent for the general coupled transmission-line network. The graph-transformation method has four principal advantages: 1) explicit open-wire-line equivalent circuits of coupled line networks can be obtained relatively easily and without knowledge of network synthesis techniques; 2) the form of equivalent circuits can often be obtained without using any algebra; 3) at each step of the analysis, a positive-real network in graph form is available; consequently, in many analysis problems several equivalent circuits for the same network are derived; and 4) multiport networks are as easily dealt with as two-port networks.     

A General Design Procedure Inhomogeneous Impedance for Quarter-Wavelength Transformers Having Approximately Equal-Ripple Performance

A general design procedure for quarter-wavelength inhomogeneous impedance transformers having approximately equal-ripple performance is presented, based on the simplifying assumptions that the relative impedance of two waveguides of slightly different widths is a constant and that tan /spl Theta//sub i/= k/sub i/ tan /spl Theta//sub 0/ in the vicinity of /spl Theta//sub i/ and /spl Theta//sub 0/ = 90/spl deg/. The calculation of the design parameters depends on the fact that the insertion-loss function can be expressed, in closed form, in terms of the unknown parameters. When this is identified with the permissible equal-ripple function, a set of simultaneous equations in the unknown parameters results. The solution of these equations is approximated by the solution to the corresponding homogeneous transformer problem. Thus a set of simultaneous linear equations in the small differences can be obtained which provides an approximate solution to the problem. An experimental design is described and the resulting data are presented.     

An Alternate Derivation and Procedure for Cristal's Transformation for Transmission-Line Networks (Letters)

This letter gives an alternate derivation and procedure for Cristal's transformation which transforms commensurate transmission-line networks with unit elements from the frequency variable lambda to 1/lambda, where lambda = tanh(lambda L).     

微带线碳化硅E类功率放大器设计

SiC MESFET由于其高击穿电压和低输出电容,适合用于设计E类功率放大器.设计了一种结构简单的微带线拓扑E类负载网络,可以匹配至标准电阻,且抑制高至5阶的谐波.用ADS软件进行电路仿真,在2.14 GHz频率点下,峰值功率附加效率(PAE)为70.5%,漏极效率可达80%,功率增益约为10 dB.     

Design of Transmission-Line Reactance Networks for Equalizer Applications

Synthesis techniques are presented for realizing arbitrary transmission-line reactance functions in four common forms of arrays of coupled lines, together with minor variations of these forms. These are two types of interdigital lines and dual forms of half-wave parallel-coupled lines. Design examples are presented for each form of coupled-line network and variations. Although the synthesis procedures are developed from the point of view of applications to equalizers, the procedures are completely general.     

Boundary Integral Equation Analysis of Transmission-Line Singularities

The TEM line analysis of microstrips and coaxial lines generally involves boundary singularities which cause slow convergence of solutions computed by standard numencal techniques. In this study, the singularities occurring at the ends of the inner conductor in an unsymmetric closed microstrip containing a dielectric substrate, are treated by a modified boundary integral equation method. This method is shown to be successful in reducing the error due to the presence of the singularities.     

Three-Dimensional Transmission-Line Matrix Computer Analysis of Microstrip Resonators

A wide range of microwave resonators are analyzed using the same three-dimensional transmission-line-matrix (TLM) computer program. The paper demonstrates the ease of application, versatility, and accuracy of the TLM method. The results presented include the dispersion characteristics of microstrip on dielectric and magnetic substrates and an example of a microstrip discontinuity. The surface-mode phenomenon of microstrip is also investigated.     

A Transmission-Line Model for Full-Wave Analysis of Mixed-Mode Propagation

The paper presents a generalized transmission line model able to describe the high-frequency mixed-mode propagation along electrical interconnects. The model is derived from a full-wave formulation and extends the validity of the standard transmission line (TL) model to frequency ranges where the propagation is no longer of transmission electron microscopy (TEM)-type. This generalized TL model describes the high-frequency differential and common mode propagation and the mode conversion. Within its validity limits, the proposed model provides solutions in good agreement with those obtained through full-wave models. Case studies are carried out to evaluate the high-frequency mode conversion in asymmetric interconnects.     

Analysis of Certain Transmission-Line Networks in the Time Domain

Many linear components in nondispersive transmission line are made up solely of commensurate lengths of line of various characteristic impedances. Such components have impulse responses that are a series of equispaced impulses, and, as a result, their frequency responses can be written as a Fourier series. Given the period and coefficients of the Fourier series describing the frequency response, the time response of the circuit to any pulse can be written down immediately as a sum of replicas of the applied pulse, each replica having an amplitude given by the coefficient of a term in the series, and occurring at a time determined by the period of that term of the series. The pulse responses of stepped transmission-line transformers, backward-coupling hybrids, and branch-line hybrids are determined and, after assuming a simple applied-pulse shape, are plotted.     

The Analysis of Radial Transmission-Line in W-Band Circular Groove Guide

In this paper, finite-difference time-domain (FDTD) method is used to calculate the driving-point impedance of radial transmission-line in circular groove guide. A simple way is used to approximate the curvilinear metal boundary of circular groove guide. And perfectly matched layer (PML) is applied on the open boundary of circular groove guide. Fine-grid is used to calculate the EM fields in the radial transmission-line in which we are interest. Discretized wave equation is used to update the tangential electric field on the boundary of coarse- and fine-grid. At last, the driving-point impedances related to different diameter of the radial transmission-line are obtained from the ratio of the Fourier transform of the voltage to the Fourier transform of the current.     

Analysis and Exact Synthesis of Cascaded Commensurate Transmission-Line C-Section All-Pass Networks

An analysis of cascaded commensurate transmission-line C-section all-pass networks is presented. The analytical form of the transmission coefficient is found to have a very simple form, intimately related to the reflection coefficient of the stepped-impedance transformer prototype of the cascaded C-section. The phase function of cascaded commensurate transmission-line C-sections is investigated and found to be the arctangent of a reactance function in tan /spl theta/. Last, general, exact synthesis procedures for designing cascaded commensurate transmission-line C-section all-pass networks to have prescribed phase characteristics are presented, and two design examples are given. One of the examples is the exact design of a 3-section Schiffman 90/spl deg/ phase shifter, which has not been previously reported in the literature.