Hybrid-mode analysis of planar transmission lines with arbitrarymetallization cross sections

The problem of planar transmission lines of arbitrary metallization cross sections is solved by using the generalized transverse resonance technique combined with the mode-matching procedure. Analyses are carried out on the dispersion characteristics of microstrip lines, finlines and coplanar waveguides with trapezoidal strip cross sections. Numerical results verify the versatility and accuracy of this method, and show that the profiles of the metallizations in miniaturized MMIC guiding structures have marked effects on the transmission properties     

Analysis of lossy planar transmission lines by using a vectorfinite element method

The vector finite element method with hybrid edge/nodal triangular elements is extended for the analysis of lossy planar transmission lines. In order to handle lossy conductor transmission lines, the present approach includes the effect of finite conductivity of a lossy area, and the dissipations in metallic conductors and dielectrics are calculated directly by considering a complex permittivity for the lossy region of interest. A propagation constant formulation is used in the FEM, which avoids spurious solutions absolutely and can handle sharp metal edges in inhomogeneous electromagnetic waveguides. Numerical examples are computed for microstrip lines, finlines, and triplate strip lines. The results obtained agree well with the earlier theoretical and experimental results, and thus show the validity of the method. Also, the current distributions on the lossy microstrip lines with finite strip thickness and isotropic substrates are presented     

Effects of the Thin-Film Metal Ground Embedded in On-Chip Microstrip Lines

This letter studies the influence of embedded thin-film metallization layers, normally designed as ground planes, upon the dispersive characteristics of multilayer microstrip lines. The spectral domain approach is used to analyze the effects of the metallization thickness as a design parameter in two structures: the thin-film microstrip line and metal-insulator-metal-insulator line. Numerical results indicate that the thin metallization layer can excite the slow-wave mode and change significantly the dispersive characteristics. Moreover, at low frequencies a local minimal attenuation can be achieved with certain metallization thickness. Thus, it is necessary to take into account this thin-film metal ground to achieve reliable numerical simulation from dc to millimeter-wave frequencies     

超薄微带线信号完整性的矩量法分析

超薄（或说零厚度）微带线是微波电路设计的重要组成部分。基于矩量法,推导了零厚度微带线电磁参量的公式,计算了微带线的特性阻抗和相应的等效介电常数,探讨了微带线的准静电边缘效应和两条微带线间的近端串扰问题。计算结果与已有结果相比较,一致性良好。     

Hybrid-mode analysis of multilayered and multiconductortransmission lines

Hybrid-mode propagation properties of multilayered and multiconductor transmission lines are studied by using an efficient vector finite element method (FEM) with high-order hybrid edge/nodal triangular elements, which can give frequency-dependent propagation constants directly. Characteristic impedances are also calculated from the FEM field solutions employing a reciprocity-related definition and taking the modal orthogonality into account. The numerical results of a coupled microstrip line are compared with those of the boundary integral equation technique, and good agreement is obtained. Also, a dual-plane triple microstrip line is analyzed. The approach is found to be very general and able to simultaneously handle different thicknesses and widths of strip conductors. The flexibility of the approach is also shown by including anisotropy in the dielectric substrates of such lines     

Characterization of V-groove coupled microshield line

A new membrane supported air-filled V-groove coupled microshield has been investigated using finite element method. The even- and odd-mode characteristic impedances and the effective dielectric constants have been computed. The dependence on various dimensions has been studied. The crosstalk levels between adjacent lines have been compared with that in coupled microstrip lines, coupled microstrip lines with lateral ground planes, and V-groove structures with and without metallization in the groove.     

Finite-element analysis of generalized V- and W-shaped edge andbroadside-edge-coupled shielded microstrip lines on anisotropic medium

This paper presents detailed finite-element analysis of generalized V- and W-shaped shielded microstrip lines in an anisotropic medium. The computed results show detailed quasistatic characteristics of the effective dielectric constant, characteristic impedance, and conductor loss of the lines. The broadside edge coupled lines are proposed for the first time in this paper. Unlike the previous analysis based on the conformal mapping method, this analysis takes into account the top walls and sidewalls, finite metallization thickness, and dielectric anisotropy. The results presented in this paper will considerable advance microwave-integrated-circuit technology using V- and W-shaped shielded microstrip lines     

Slow-Wave Propagation Along Variable Schottky-Contact Microstrip Line

Schottky-contact microstrip lines (SCML) are a special type of transmission line on the semiconducting substrate: the metallic-strip conductor is specially selected to form a rectifying metal-semiconductor transition while the ground plane exhibits an ohmic metallization. Thus the cross section of SCML is similar to that of a Schottky-barrier diode. The resulting voltage-dependent capacitance per unit length causes the nonlinear behavior of such lines. In this paper a detailed analysis of the, slow-wave propagation on SCML is presented, including the effect of metallic losses. Formulas for the propagation constant and characteristic impedance are derived and an equivalent circuit is presented. Conditions for slow-mode behavior are given, particularly taking into account the influence of imperfect conductors and defining the range of many interesting applications. Experimental results performed on Si-SCML are compared with theory.     

The influence of finite conductor thickness and conductivity onfundamental and higher-order modes in miniature hybrid MIC's (MHMIC's)and MMIC's

The effect of finite metallization thickness and finite conductivity on the propagation characteristics of conductor-backed CPW on thin substrate is rigorously analyzed. A self-consistent approach is used together with the method of lines (MoL) to determine the propagation constant, losses and field distribution of the fundamental and first two higher-order modes in coplanar waveguides (CPWs) with finite metallization thickness and lossy backmetallization. The method used is general and can be applied to miniature MHMICs and MMICs including lossy semiconductor substrate. It is shown that the onset of higher-order modes limits the usable frequency range of conductor-backed CPWs. The analysis also includes microstrip transmission lines on thin substrate material. It is demonstrated that a resistive strip embedded into the microstrip ground plane may potentially be useful in the design of integrated planar attenuators     

Dice‐Five Polarization‐Agile Corner‐Fed Patch Array Antenna

A novel planar polarization‐agile microstrip subarray is proposed and its performance assessed by a thorough numerical investigation. The subarray consists of five square patches with a central element, directly coupled to a pair of microstrip feed lines by a cross‐shaped aperture, which spreads the power outwards to the other patches through a network of suitable connections. By properly exciting the antenna at its input ports, any kind of polarization of the radiated field can be accomplished with fairly low cross‐polarization levels. Moreover, since only two feed lines are required to drive the whole subarray, polarization agility is simply and attractively achieved by a single phase‐shift circuit. The design concept is described and the results of the analyses and simulations performed by two completely independent full‐wave approaches are presented and discussed.     

A simple metal-semiconductor substructure for the advanced thermo-mechanical numerical modeling of the power integrated circuits

The metallization of double-diffused metal-oxide semiconductor (DMOS) power devices, which operate under fast thermal cycling (FTC), undergoes thermal induced plastic metal deformation (TPMD). The design of the metallization has a significant impact on the device lifetime and thus requires a thorough understanding of the temperature, stress and strain distribution. A simple three-dimensional (3D) transistor substructure which is commonly found in various high integration Bipolar-CMOS-DMOS (BCD) technologies is analysed. The thermomechanical behaviour is studied with the finite element method (FEM) for investigation of two potential failure mechanisms: delamination of power metal and accumulation of plastic deformation in signal metallization layer (which leads to inter-metal dielectric cracking). These failure mechanisms are analysed on two versions of the structure: the first one has only signal and power metal lines and the second one has vias, in addition to the signal and power metal lines. The target of the paper is to propose an efficient finite element analysis (FEA) model that can be used for a qualitative assessment of thermo-mechanical phenomena in the metal system of high integration BCD technologies.     

Characterization of microstrip lines near a substrate edge anddesign formulas of edge-compensated microstrip lines [MMICs]

The proximity effects of microstrip lines near a substrate's edge present a problem for effectively designing high-packing-density MMICs (monolithic microwave integrated circuits). Proximity effects of this type are analyzed using the rectangular boundary division method. It is assumed that the cross-sectional dimensions of transmission lines in the MMICs are small compared with the wavelengths to allow the use of the quasi-TEM-wave approximation. Then, the concept of edge-compensated microstrip lines to keep the characteristic impedance constant near a substrate edge is introduced to circumvent the proximity effects and to expand the interconnection flexibility of microstrip lines on MMIC substrates. The practical design parameters of edge-compensated 50-Ω microstrip lines are given in the form of numerical data and simple polynomials for CASD (computer-aided design) work with a curve-fitting procedure. Results of capacitance measurements are compared with this theory with errors of about 1% resulting     

Hybrid Electrodes Used in Polymer Electro-Optic Modulator with Ultra-Broadband

Hybrid electrode combined coplanar waveguide (CPW) and microstrip lines in ultra-broadband electro-optic modulators. The characteristics of the modulators with hybrid electrode is like that of the modulator with the microstrip lines, in which the microstrip electrode is loaded above only one arm of Mach-Zehnder (M-Z) optical waveguide, besides the problem of microstrip line to coaxial transition and corona polarization in polymer modulators have been best solved at the same time. By using finite element method (FEM), the characteristic parameters such as half-wave voltage, modulation bandwidth characteristic impedance, effective microwave refractive index of polymer modulators with microstrip line and hybrid electrode are analysed and compared in this paper. The results present that velocity match, impendence match and lower microwave propagating loss is easily realized in modulators with hybrid electrode.     

微带传输线特性的数值分析

本文应用混合模有限元方法分析和计算了微带传输线的各种特性,包括特性阻抗、速度比、色散特性以及带厚的影响,并与有关文献结果作了比较。结果表明,有限元法是对微带传输线进行数值分析的有效方法。     

An analysis of microstrip with rectangular and trapezoidalconductor cross sections

The finite-difference time-domain (FDTD) technique is used to analyze boxed microstrip with both rectangular and trapezoidal cross sections. It is confirmed that the exact shape of the conductor has a marked effect on the effective permittivity of the microstrip. Results using this method are compared to the findings of K.A. Michalski et al. (1989) using the analytically more complicated boundary element method; very good agreement is observed. The effect of adding a thin passivation layer is also calculated and it is found that such an addition noticeably reduces the effective permittivity of the microstrip. It is shown that the FDTD technique is capable of treating microstrip with a general cross section and producing accurate results     

Accurate quasi-TEM spectral domain analysis of single and multiplecoupled microstrip lines of arbitrary metallization thickness

The quasi-TEM spectral domain approach (SDA) is extended to rigorously and efficiently analyze single and multiple coupled microstrip lines of arbitrary metallization thickness. The charge distributions on both the horizontal and vertical conductor surfaces are modeled by global basis functions. This results in a relatively small matrix for accurate determination of the line parameters of coupled thick microstrips. A convergence study is performed for the results of a pair of coupled lines with crucial structural parameters to explore the conditions for obtaining reliable solutions using the technique. Results for thick microstrips are validated through comparison with those from available measurements and another theoretical technique. The soundness of the technique is further demonstrated by looking into the trend of the results obtained by a simplified model in which the structural parameters are pushed, step by step, to the numerical extremities. Variations of circuit parameters of a four-line coupled microstrip structure due to the change of finite metallization thickness are presented and discussed     

EM Modeling of Microstrip Conductor Losses Including Surface Roughness Effect

This letter presents a method to model conductor losses in transmission lines utilizing a commercial full wave solver. The lines consist of multilayered metallization with inherent surface roughness. Metal thickness is assumed to be larger than skin depth. To validate accuracy of the modeling, the measurements of a 50-Omega microstrip line and edge-coupled microstrip filter are provided, with random errors taken into account. Good correlation between the modeled results and measurements has been demonstrated from this comparison     

Hybrid-mode computation of propagation and attenuationcharacteristics of parallel coupled microstrips with finitemetallization thickness

The hybrid-mode mixed spectral domain approach (MSDA) is formulated to investigate the dispersion nature of multiple coupled microstrip lines with arbitrary metallization thickness. Incorporated into the solution procedure, a new set of basis functions with δ ^-1/3 field singularity near conductor edges is found to be effective in calculating both the phase and attenuation constants. The computation of conductor loss is based on the perturbation procedure. Over a broad band of frequency spectrum, excellent agreement is obtained between the calculated results and existing experiment data for the metallic losses of a single microstrip and effective dielectric constants of coupled lines. The influence of finite metallization thickness on the frequency dependent modal propagation and attenuation characteristics is presented for both a three-line and four-line structure     

DESIGN OF A NEW TYPE OF ELECTRO-OPTIC POLYMER WAVEGUIDE MODULATOR WITH ULTRAHIGH BANDWIDTH

In this article, rectangle, trapezoidal and T type microstrip lines embedded into up cladding of the waveguide are designed. By the analysis of the finite element method (FEM), this embedded microstrip line has perfect velocity matching between the electric signal and lightwave carrier and at the same time, conductor loss of the trapezoidal and T type microstrip lines also reduce. Thus the modulator’s bandwidth increases greatly. Calculations show that, comparing with one of non-embedded rectangle microstrip line which is the most familiar configuration of polymer modulator, the optical 3-dB bandwidths of embedded trapezoidal and T type microstrip increase 264% and 339% respectively under the condition of impedance matching.     

Quasi-static analysis of shielded microstrip transmission lineswith thick electrodes

An extended point-matching method for analyzing the shielded microstrip transmission lines with thick electrodes has been developed based on the method by Marcuse (1989). This method provides a simple and fast approach to the quasi-static analysis of the structures. The calculated fields are used to estimate the characteristic impedance and effective dielectric constant of the structures. The results agree well with available theoretical results obtained using other methods, such as the finite element method and the boundary element method. This method can be further applied to other microstrip lines widely used in monolithic microwave integrated circuits (MMICs) applications