Design of microwave devices with adjoining positions of the source and loads

A new approach to formation of analysis and parametric-synthesis algorithms for microwave devices with adjoining positions of the source and one or several loads is proposed. The specific feature of this approach is the block notation of circuit transmission matrices formed in the course of decomposition of fragments and subsequent use of the corresponding block matrices in combination with impedance and/or admittance matrices of equivalent two-port or multiport circuits. The proposed algorithm is tested analytically with the use of the Richards theorem by considering two previously solved analysis problems. The results of solution of a synthesis problem for differential phase shifters are presented.     

Incorporation of Multiport Lumped Networks Into the Hybrid Time-Domain Finite-Element Analysis

A systematic and efficient algorithm is presented for incorporating multiport lumped networks in terms of admittance matrices into a hybrid field-circuit solver based on the extended time-domain finite-element method. The Laplace-domain admittance matrices are cast into the time-domain stepping equations for port voltages and currents to form a lumped-network subsystem, which is then interfaced with the finite-element and circuit subsystems through shared ports. While the port voltages of the lumped-network subsystem are determined by the finite-element and circuit subsystems, its port currents are treated as external current excitations for the finite-element and circuit subsystems. All the lumped-network port variables are then eliminated from the final expressions to form a global system for only the finite-element and circuit unknowns. The proposed algorithm further extends the capability of the existing field-circuit solver to model more complex and mixed-scale hybrid circuits, and the algorithm is validated and demonstrated through numerical examples.      

Dynamics, stability, and control of multivariable piezoelectric shunts

This paper is concerned with the dynamics and stability of piezoelectric laminate structures, where several piezoelectric elements are shunted by a multiinput impedance. The problem is shown to be equivalent to a multivariable feedback control problem for a square plant. A parameterization of stabilizing admittance transfer function matrices is given together with a specific class of controllers capable of reducing structural vibrations and guaranteeing closed-loop stability. An efficient method for implementation of a multiport admittance transfer function is introduced and applied experimentally to demonstrate the effectiveness of the proposed methodology.     

Multiport through-resistor (TR) numerical calibration

A multiport through-resistor (TR) numerical calibration technique is proposed and presented. The multiport TR calibration is used to remove the effects of port discontinuities in a deterministic method-of-moments (MOM) algorithm and can be easily combined with commercial full-wave MOM simulators. Analytical equations for multiport TR calibration are derived in this work. Three-dimensional characteristic impedance of a microstrip coupled line is calculated and showcased as an example by using the proposed scheme and its validity is verified.     

波导阻抗带宽与缝隙导纳关系研究

本文从谐振阵等效网络出发,探索了缝隙波导谐振阵实现理想阻抗匹配的导纳特性,为波导谐振阵的超宽带设计提供了新思路.改进了波导并联缝隙的等效电路,首次实现缝隙导纳特性的单参数表征,创新提出了不同单元间距与单元数缝隙波导阵实现最大带宽的导纳特性分析方法,为波导缝隙阵带宽的优化设计提供了理论依据,建立了传统谐振阵非过载时的最大...     

An adjoint variable method for sensitivity calculations of multiport devices

Recently, an adjoint variable method (AVM) for sensitivity calculations has been proposed for use with the method of moments solvers. In this paper, we extend this method to be suitable for application to multiport devices. The target objective function is usually represented in terms of the device's S-parameters. Our AVM obtains the sensitivities of the S-parameters with respect to all design variables using only one full simulation with additional overhead. This overhead is usually less than the computation time of a full simulation. An analytical expression for the adjoint excitation is derived, leading to stable sensitivities. The potential of the proposed technique is demonstrated by analyzing low-pass and bandpass filters. The results show very good agreement between the proposed AVM and the conventional finite-difference approach (FDA). Moreover, the AVM is always faster than the FDA. The speed-up factor increases as the size of the problem increases.     

Scalable Compact Circuit Model for Differential Spiral Transformers in CMOS RFICs

A new compact circuit model for differential spiral transformers in CMOS radio frequency integrated circuits (RFICs) is developed in this paper. The model consists of two coupled “$hbox2-pi$” subcircuits for each inductor coil in the transformer. All the values of the circuit elements can be analytically calculated according to the process parameters and the device's geometric dimensions, making the model highly scalable and predictive. The model has very good accuracy as validated by comparison to a 2.5-dimensional full-wave numerical electromagnetic field solver.     

MCM多层导体板频率响应的平面电路分析方法

MCM电源分配系统设计要求全频带目标阻抗维持在较小的范围内,使得瞬变电流不会引发过大的电压噪声。本文利用平面电路分析方法建立了MCM叠层多端口等效电路,并在此基础上推导了MCM多层导体板多端口阻抗频率响应,该方法在满足趋肤效应假设前提下对于高速数字系统是行之有效的。分别利用平面电路分析方法与传输矩阵方法计算了多层导体板MCM叠层端口自阻抗与互阻抗,计算结果得到了较为一致的吻合,从而验证了该方法的合理性。     

On the synthesis of equivalent-circuit models for multiports characterized by frequency-dependent parameters

The synthesis of lumped-element equivalent circuits for time-domain analysis of problems with frequency-dependent parameters is of great interest in microwave theory. This paper presents a systematic approach to generate minimal-order realizations for passive microwave circuits characterized by either admittance, impedance, or scattering-parameter data. In addition, a very efficient method to ensure inherent system properties such as stability and passivity is described. The proposed method is suitable for simulating frequency-response-based linear subnetworks in a general circuit environment consisting of lumped/distributed elements and nonlinear devices. Modeling examples for a two-, four-, and ten-port system with nonlinear and linear terminations, respectively, are given.     

Design of an interdigital hairpin bandpass filter utilizing a modelof coupled slots

A design methodology of an interdigital hairpin filter based on a full-wave model of coupled slots is developed and discussed. It is applied to design a five-pole bandpass filter centered at 1.7 GHz; with 1.75% relative bandwidth. A low level of in-band insertion loss is achieved using high-temperature superconductor electrodes. Experimental data are presented and compared with the simulated response. A model of coupled slots embedded in a layered lossy media is developed on the basis of the spectral-domain approach. The multiport admittance (impedance) matrix of the coupled slots is formulated using the E-H duality principle. It is successfully applied in the design of the filter     

Fast multipole method for time domain PEEC analysis

High-speed electronic circuits are becoming more and more important in modern communication systems, thus leading to an increasing interest in printed circuit boards, interconnect, and packaging. Nowadays, full-wave numerical methods are widely used in order to investigate both signal integrity and electromagnetic compatibility issues arising in PCBs design. When broadband information is desired and transient effects dominate, it is more efficient using time domain numerical techniques, which may scale better than corresponding frequency-domain methods. This paper presents the derivation of the time domain partial element equivalent circuit (PEEC) method enhanced by the three-dimensional (3D) fast multipole method (FMM). It is shown that combining the full-wave time domain PEEC method with the FMM allows performing the analysis of electrically large electronic systems, which reduces both memory and CPU-time requirements. Several examples are presented confirming the capability of the proposed approach to provide a significant reduction of the computational complexity associated with the transient analysis of large systems.     

On deembedding of port discontinuities in full-wave CAD models of multiport circuits

A systematic numerical methodology is proposed for the accurate deembedding of multiport discontinuities in full-wave numerical models of multiconductor microwave and millimeter-wave passive structures and high-speed digital interconnects. The discussed methodology is based on the earlier-proposed short-open calibration (SOC) procedure. The latter being a numerical analog of the experimental transmission-thru-reflection technique provides a consistent removal of the feed networks of the device-under-test over a wide range of frequencies. The treatment of multiport topologies is achieved through the continuation of the original scalar SOC method into the vector space. The new vector SOC method is easily combined with integral-equation-based method-of-moments electromagnetic-field solvers and allows for substantial flexibility in the choice of excitation mechanisms. Such commonly used method-of-moments driving schemes as ports locally backed up by a vertical conducting wall, ungrounded-internal differential ports, and via-mounted ports can be accurately deembedded within the framework of the vector SOC. Several numerical experiments are provided to validate the proposed multiport deembedding methodology and demonstrate its application.     

An efficient systematic approach to model extraction for passivemicrowave circuits

This paper introduces a new systematic approach to equivalent circuit model extraction for linear microwave passive circuits directly from full-wave frequency domain simulation. The devices being modeled may be either lossless or lossy. Adaptive frequency sampling is used to minimize the computational effort of EM simulation while critically assisting in determining the pole locations of an RF circuit. A simple circuit model for lossy RF circuits along with a determined starting point of optimization of lumped element component values is also presented in detail. The overall result is an efficient and accurate means to produce a complete equivalent lumped element model for RF circuits that is suitable for use in conventional SPICE-like simulation software     

Large signal circuit characterization of solid-state microwave oscillator devices

A method of direct measurement of the admittance in X band seen by an encapsulated solid-state oscillator embedded in microwave hardware is described. It is applicable to many two-terminal devices in waveguide, coaxial line or microstrip circuit configurations. The criterion for oscillation in negative conductance oscillators is used in conjunction with these admittance measurements to determine the complete frequency-dependent 'device-plane' of Gunn and IMPATT devices in S4 (pill-prong) encapsulations, and the forms of negative conductance and susceptance variation with RF voltage amplitude and frequency have been extracted for each of these devices. It is found that for transferred-electron devices in particular, the frequency dependence of these parameters over X band is very marked. The use of the admittance measuring technique to characterize the microwave circuit is discussed with reference to the improvement of AM and FM noise by the controlled insertion of perturbations in the admittance locus, and an example is given of its use in fault-finding in a mechanically tunable waveguide oscillator.     

Multiport network approach for modeling the mutual coupling effectsin microstrip patch antennas and arrays

A method is described for representing the mutual coupling between edges of a microstrip patch (or the edges of two different patches in an array) in form of a mutual admittance matrix. Coefficients of the mutual admittance matrix are evaluated by modelling the edge fields by equivalent magnetic current line sources. The formulation is an extension of the multiport network modeling of microstrip patches and the segmentation method of analysis. Results are found to be in good agreement with the measured data on mutual coupling available in the literature. Relative contributions of various edges of rectangular patches to the mutual coupling are discussed     

Frequency Notched UWB Planar Monopole Antenna Optimization Using a Finite Element Method-Based Approach

The objective of this work is the design and optimization of an ultrawideband (UWB) planar monopole antenna with frequency-notched behavior intended to get rid of the 5–6 GHz frequency band for WLAN compatibility purposes. An optimized profile UWB planar monopole designed by means of a Simulated Annealing algorithm and full three-dimensional finite element method, detailed in a companion paper, was considered as the design starting point. In order to design the band-notched rejection no full finite element analysis is carried out on each profile modification as is usual. The procedure is based on a genetic algorithm and a multipurpose admittance matrix approach instead. Artificial ports are allowed in the computational domain and an admittance-type matrix comes up. As a result, a multiport network describes the electromagnetics within the analysis domain. Circuit manipulations of this network efficiently outperform full-wave analyses for different monopole modifications, thus making it possible to use this strategy in a computer aided-design scheme.      

An efficient approach for power delivery network design with closed-form expressions for parasitic interconnect inductances

Investigation of a dc power delivery network, consisting of a multilayer PCB using area fills for power and return, involves the distributed behavior of the power/ground planes and the parasitics associated with the lumped components mounted on it. Full-wave methods are often employed to study the power integrity problem. While full-wave methods can be accurate, they are time and memory consuming. The cavity model of a rectangular structure has previously been employed to efficiently analyze the simultaneous switching noise (SSN) in the power distribution network. However, a large number of modes in the cavity model are needed to accurately simulate the impedance associated with the vias, leading to computational inefficiency. A fast approach is detailed herein to accelerate calculation of the summation associated with the higher-order modes. Closed-form expressions for the parasitics associated with the interconnects of the decoupling capacitors are also introduced. Combining the fast calculation of the cavity models of regularly shaped planar circuits, a segmentation method, and closed-form expressions for the parasitics, an efficient approach is proposed herein to analyze an arbitrary shaped power distribution network. While it may take many hours for a full-wave method to do a single simulation, the proposed method can generally perform the simulation with good accuracy in several minutes. Another advantage of the proposed method is that a SPICE equivalent circuit of the power distribution network can be derived. This allows both frequency and transient responses to be done with SPICE simulation.     

Multiport scattering analysis of general multilayered printedantennas fed by multiple feed ports. I. Theory

A general solution is given for a class of printed antenna geometries composed of multiple dielectric layers or ground planes, radiating patches, dipoles, or slots, and an arbitrary configuration of multiple transmission lines proximity-coupled or aperture-coupled to the radiating elements. The solution uses a full-wave spectral-domain moment method approach, and a new generalized multiport scattering formulation to model the excitation from the multiple feed lines. This method treats infinite phased arrays as well as isolated elements. The general theory using the new multiport scattering formulation is elaborated, with details of the key analytical and numerical aspects. Considering the unified nature of the multiport scattering analysis, and its simplicity, this analysis is appropriate for computer simulation of a large variety of multilayered microstrip antennas involving radome layers, dual polarized feeds, proximity-coupled or aperture-coupled elements, multifeed stacked or parasitic patches, and several related configurations for integrated phased array applications     

A coupled efficient and systematic full-wave time-domain macromodeling and circuit Simulation method for signal integrity analysis of high-speed interconnects

This paper presents an accurate and systematic approach for analysis of the signal integrity of the high-speed interconnects, which couples the full-wave finite difference time domain (FDTD) method with scattering (S) parameter based macromodeling by using rational function approximation and the circuit simulator. Firstly, the full-wave FDTD method is applied to characterize the interconnect subsystems, which is dedicated to extract the S parameters of the subnetwork consisting of interconnects with fairly complex geometry. Once the frequency-domain discrete data of the S parameters of the interconnect subnetwork is constructed, the rational function approximation is carried out to establish the macromodel of the interconnect subnetwork by employing the vector fitting method, which provides a more robust and accurate solution for the overall problem. Finally, the analysis of the signal integrity of the hybrid circuit can be fulfilled by using the S parameters based macromodel synthesis and simulation program with integrated circuits emphasis (SPICE) circuit simulator. Numerical experiments demonstrate that the proposed approach is accurate and efficient to address the hybrid electromagnetic (interconnect part) and circuit problems, in which the electromagnetic field effects are fully considered and the strength of SPICE circuit simulator is also exploited.