Lumped-circuit model for inductor-capacitor hybrid

The inductor-capacitor hybrid described by Reeves is analysed by a lumped-circuit model, in which the metal foils in the device have finite resistance. The earlier theory appears as a special case of the model, and some difficulties at the principal resonance are removed.     

Plating of small blind vias [multilayer PCBs]

Metallization of laminates with blind vias on the dielectric side was performed by electroless copper plating with subsequent copper electroplating. The vertical cross section of blind vias with diameters between 125 and 75 μm were analyzed by reflective microscopy. Results indicate that ultrasonic vibration during the pretreatment processes of metallization enables complete electroless copper deposition of the inside wall of the small blind vias without any voids. Furthermore, the introduction of periodic pulse reversal current for the subsequent copper electroplating process resulted in high throwing power deposition. By employing these two protocols, it has been demonstrated that high throwing power deposition can be readily achieved for blind vias as small as 75 μm in diameter with an aspect ratio of 3:1     

A coaxial-to-microstrip transition for multilayer substrates

Described is a right-angle coaxial-to-microstrip transition suitable for multilayer substrates. Electrically, it transforms the transmission mode from coaxial (TEM) to microstrip (quasi-TEM). Physically, this transformation occurs in two ways. First, strips of the ground plane are incrementally removed from each metal layer. At the same time, the coaxial line is gradually shifted off-center (i.e., made eccentric) toward the microstrip line. The theory supporting the technique is briefly discussed. To demonstrate, a coaxial transition is designed on a six-metal-layer laminate board. Measurements are compared to a conventional coaxial transition design.     

Packaging of MMICs in multilayer LCP substrates

A 13-25-GHz GaAs bare die low noise amplifier is embedded inside a multilayer liquid crystal polymer (LCP) package made from seven layers of thin-film LCP. This new packaging topology has inherently unique properties that could make it an attractive alternative in some instances to traditional metal and ceramic hermetic packages. LCP is a near-hermetic material and its lamination process is at a relatively low temperature (285/spl deg/C versus >800/spl deg/C for ceramics). The active device is enclosed in a package consisting of several laminated C0/sub 2/ laser machined LCP superstrate layers. Measurements demonstrate that the LCP package and the 285/spl deg/C packaging process have minimal effects on the monolithic microwave integrated circuit radio frequency (RF) performance. These findings show that both active and passive devices can be integrated together in a homogeneous laminated multilayer LCP package. This active/passive compatibility demonstrates a unique capability of LCP to form compact, vertically integrated (3-D) RF system-on-a-package modules.     

CPW-fed slot antennas on multilayer dielectric substrates

Coplanar wave (CPW)-fed slot antennas printed on multilayer dielectric substrates are numerically analyzed using a full-wave integral equation technique and the method of moments. The Green's function is derived with an iterative formulation. Results obtained with a simplified and a rigorous model of the feeding CPW lines are compared. The mutual coupling between the slot antennas in an array environment is calculated for a three-layer high-low-high permittivity combination. The theoretical results are verified with measurements     

A full-wave electromagnetic model for the waveguide-to-strip-linecoupler using vias for confinement of parallel-plate modes

This paper presents a practical waveguide-to-strip-line coupler. An accurate integral-equation model satisfying all boundary conditions for the electromagnetic fields and all edge conditions for the currents are described. The integral equations are solved using the method of moments. An experimental -5-dB coupler has been built. Measured and computed scattering parameters are in excellent agreement. The waveguide-to-strip-line coupling terms agree within 0.1 dB at the resonance frequency. The discussion and the presented data provides physical insight to the operation of the coupler itself     

Lumped-circuit representation of Gunn diodes in domain mode

It is shown that the lumped circuit that has been used to date to represent a Gunn diode with a steadily propagating domain cannot and does not properly account for the transient, and therefore, high-frequency behavior of a Gunn diode. We have derived the nodal equations that must be obeyed by any circuit that is to represent a Gunn diode with a steadily propagating domain under all conditions --small signal and large signal, sinusoidal steady state, and transient. The validity of the new circuit and the fact that the conventional circuit would give erroneous results under transient conditions have been checked by transient experiments on the computer simulated Gunn diode. It is also shown that the domain differential capacitance is approximately half of what is given by zero diffusion theory, a result first predicted by Kuru, Robson, and Kino, and the discrepency is accounted for by the nonzero width of the accumulation layer, and incomplete depletion in the depletion layer.     

Radar backscattering model for multilayer mixed-species forests

A multilayer canopy scattering model is developed for mixed-species forests. The multilayer model provides a significantly enhanced representation of actual complex forest structures compared to the conventional canopy-trunk layer models. Multilayer Michigan Microwave Canopy Scattering model (Multi-MIMICS) allows overlapping layer configuration and a tapered trunk model applicable to forests of mixed species and/or mixed growth stages. The model is the first-order solution to a set of radiative transfer equations and includes layer interactions between overlapping layers. It simulates SAR backscattering coefficients based on input dimensional, geometrical, and dielectric variables of forest canopies. The Multi-MIMICS is an efficient realization of actual forest structures and can be shaped for specific interest of forest parameters. We present the model's application and validation in the paper. The model is parameterized using data collected from a 220,000-ha area of forests in central Queensland, Australia. Fifteen 50/spl times/50 m test sites representing the general forest diversity and growth stages are chosen as ground truth. Polarimetric backscattering airborne SAR (AIRSAR) data of the same area are acquired to validate the model simulations. The model predicts SAR backscattering coefficients of the test areas. Simulation results show a good agreement with AIRSAR data at most frequencies and polarizations. The simulated backscattering coefficient from the multilayer model and the standard MIMICS are also compared and significant improvements are observed.     

A multilayer exponential model for spreading resistance calculations

A new multilayer approach to spreading-resistance correction-factor calculations is proposed, based on the approximation of the graded resistivity profile by a series of exponential functions. The existence of a recurrence formula for the integration factor in the correction factor integral makes the proposed model a practical alternative to Schumann and Gardner's staircase model. Although a factor of 3 slower in terms of computation time, the exponential model yields results much closer to the true profile than the staircase model, particularly in cases where the profile has very steep gradient but where the available measurement data points are sparse.     

A multilayer recognition model for twitter user geolocation

Wireless Networks - Geolocation is important for many emerging applications such as disaster management and recommendation system. In this paper, we propose a multilayer recognition model (MRM) to...     

A substrate-dependent CAD model for ceramic multilayer capacitors

In this paper, a substrate-dependent lumped-element model for ceramic multilayer capacitors is presented. The height and dielectric constant of a substrate have a significant impact on the frequency response of a chip capacitor, and these effects cannot be treated independently from the capacitor model. Rather, the equivalent-circuit parameters in the model must be made to vary in accordance with changes in the substrate. The model presented in this paper is suitable for microstrip-mounted components, and has been applied up to 10 GHz for values from 0.5 pF to 0.47 μF, and for FR-4 substrates ranging in height from 5 to 62 mil. The modeling and extraction procedure is demonstrated for 0805- and 1206-style capacitors     

Equivalent circuit for multiple vias in parallel plate environment

An equivalent one-dimensional circuit has been developed to model the loading effects of vias (through or buried) in a parallel plate environment. Owing to the one-dimensional nature of the model, the simulation time is dramatically reduced, compared to either two-dimensional inductance-capacitance ladder network or full-wave numerical electromagnetic simulations. This model can be easily included in available commercial circuit simulators and accounts for multiple via interactions as well as for substrate edge reflections     

硅基平面螺旋电感的等效电路模型和参数提取

针对螺旋电感传统等效电路模型的不足,提出了一种改进形式的集总参数等效电路模型.该等效电路模型能很好地反映出电感参数随频率变化的实际效应,可适用于从低频到自谐振频率的宽频带范围.同时,应用电磁场全波分析方法对CMOS工艺下平面螺旋电感进行仿真分析.从得到的散射参数中提取电感L、Q值及自谐振频率.基于参数优化和曲线拟合技术,给出了等效电路模型中各个元件值的多变量闭合表达式.这些表达式可方便地用于集成电路的设计和优化,从而提高电路设计的性能和效率.     

Dispersion analysis of multilayer cylindrical transmission linescontaining magnetized ferrite substrates

Recently, there has been a growing interest in using cylindrical transmission lines that contain magnetized ferrite material in a variety of applications. In this paper, the finite-difference time-domain (FDTD) method (in cylindrical coordinates) and the spectral-domain analysis (SDA) are used to calculate the propagation characteristics of cylindrical transmission lines that contain magnetized ferrite material. The magnetization can be either in the longitudinal or azimuthal directions. Specifically, the cylindrical microstrip line, and the cylindrical coplanar waveguide printed on magnetized ferrite substrate are analyzed. Both the FDTD and SDA results are in very good agreement. In addition, the results are compared to those of planar structures by taking the radius of the substrate to be large enough such that the curvature effect is negligible     

银基多层氮化铝陶瓷基板低温共烧的工艺研究

从低温共烧的工艺角度来研究氮化铝坯片和银浆的排胶,从而确立排胶的温度及烧结气氛的控制.结果表明,二次排胶法与在氮气气氛中加入微量氧进行烧结,获得了综合性能优良的银布线多层陶瓷基板.     

A quantitative analysis of the stress relaxation effect ofthermoplastics in multilayer substrates

All plastics can be divided into two groups called thermoplastics and thermosets, and each group exhibits very different behaviors. Unlike thermosets, thermoplastics are empirically known by the viscoelastic behavior of the thermoplastic layers; the stress generated by building subsequent layers can be significantly relieved in a multilayer structure. In this study, we quantitatively investigated the stress relaxation effect of thermoplastics in lamination-based multilayer substrates. As an increasing number of layers were laminated using either thermoplastic or thermoset adhesives, the maximum bow values were measured layer-by-layer using a laser profilometry during thermal cycling. When analyzed through an analytical model, the measured thermal behavior of thermoplastics exhibited as much as 70% stress relaxation in the multilayer structures, and highly contrasted with that of thermoset adhesives. The result provides an important design guideline that thermoplastics can be used as a stress relaxation layer in lamination-based multilayer substrates     

Microwave circuits in multilayer inorganic-organic polymer thin film technology on laminate substrates

Requirements of higher performance, reduced size, weight and cost of high-frequency (HF) devices has led to the search for new: materials, material combinations, methods, processes and production equipment. Efficient technologies for producing HF-circuits and integral passives are looked for. Also of interest are integrated packaging solutions for high frequency electrical packaging and optical interconnects and packaging. Sequentially build up multi-layers have been deposited on a low cost FR-4 epoxy substrate. The dielectric layers consist of a photo-patternable inorganic-organic hybrid polymer (ORMOCER) and the metallization is Cu. An UV-exposure equipment enabling projection patterning with 5 /spl mu/m resolution have been used. The produced microstrip lines, ring resonators, vias, stacked capacitors and filters have been characterized at frequencies from 1 to 40 GHz showing the potential of the new dielectric materials and processing technologies for microwave applications.     

Closed-form expressions for the series impedance parameters of on-chip interconnects on multilayer silicon substrates

This paper presents accurate closed-form expressions for the frequency-dependent series impedance parameters of on-chip interconnects over general multilayer conductive silicon substrates. The closed-form expressions are obtained from a generalized complex image approach combined with a surface impedance formulation that takes into account the effects of the distributed eddy currents in the multilayer conductive substrate. Results for single and coupled microstrips on multilayer conductive substrates are shown over a broadband frequency range of 20 GHz and compared with full-wave electromagnetic solutions. It is demonstrated that a thin, heavily-doped channel-stop layer may contribute significantly to the series resistance at higher frequencies. The new approach is further validated for a coplanar waveguide interconnect by comparison with measurement data.     

Conductive adhesives for through holes and blind vias metallization

In the paper we propose the idea of “metallization” of the mechanically drilled through holes and the laser drilled blind holes by isotropic conductive adhesives in PCB manufacturing. Such processes can be used instead of electrochemical plating processes and are environmentally friendly. The investigations show that the filled through holes have the average resistance of about 100 mΩ while filled blind vias have average resistance of about 1 Ω in the case of PCBs with pure Cu pads. Better results were obtained if the Au pads metallization was applied onto the Cu layer. In that case the average fill resistance for through holes diameter 0.5 mm and 0.8 mm are about 50 mΩ and for vias 0.3 mm about 150 mΩ. The results are very promising for practical application.     

Laser chemical etching of vias in GaAs

Rapid drilling of vias in thick wafers (381 µm) of GaAs has been achieved by a laser assisted etching process. The technique utilized a cw visible argon ion laser and an etchant gas of low pressure Cl2. Data on the dependence of the etch rate on the laser power, wavelength, and Cl2gas pressure are presented.