Microwave Circuit Design Research Articles

Electromagnetic design of high‐temperature superconducting microwave filters

AbstractWe present novel approaches to electromagnetic design of high‐temperature superconducting (HTS) quarter‐wave parallel coupled‐line microstrip filters. The desired narrow bandwidths (less than 2%) coupled with the large dielectric constant of substrate materials used in the HTS technology (εr ≈ 24) make the design problems difficult to treat accurately for many traditional microwave circuit design software packages with analytical/empirical models. We have successfully performed an HTS filter design with accurate electromagnetic field simulations. We discuss problems related to electromagnetic design of such filters. We describe a look‐up table method and a powerful space mapping optimization technique, which dramatically reduce the CPU time needed in the design process. Finally, we address the issue of improved modeling of the HTS filter using analytical/empirical models. © 1995 John Wiley & Sons, Inc.

Microwave circuit analysis and design by a massively distributed computing network

The advances in microelectronic engineering have rendered massively distributed computing networks practical and affordable. This paper describes one application of this distributed computing paradigm to the analysis and design of microwave circuits. A distributed computing network, constructed in the form of a neural network, is developed to automate the operations typically performed on a normalized Smith chart. Examples showing the use of this computing network for impedance matching and stabilizing are provided. >

Temperature-dependent kinetic inductance of YBa2Cu3O7−δ thin films predicted by the coupled grain model in the strong-coupling limit

The introduction of a temperature dependence to the effective penetration depth as calculated in the strong-coupling limit of the coupled grain model is discussed. Assuming a phenomenological Gorter–Casimir behavior for the intrinsic penetration depth of YBa2Cu3O7−δ (YBCO) and a simple model for the temperature-dependent intergrain critical current density, the coupled grain model is found to predict a kinetic inductance which accurately fits the relative phase velocity, vφ(T)/vφ(T0), measured on coplanar YBCO transmission lines. This indicates that the coupled grain model provides an adequate physical interpretation of the empirical penetration depth proposed by, e.g., Rauch et al. [J. Appl. Phys. 73, 1866 (1993)] and suggests that the kinetic inductance is strongly influenced by boundaries between grains with minor relative misalignment. The average grain size and critical current density of the grain boundaries were estimated at a=140–240 nm and Jgc(0)=3.5×1010–1×1011 A m−2, respectively. We argue that the coupled grain model may prove suitable for implementation in microwave circuit design software, as thin film preparation techniques mature in the sense of providing samples with highly reproducible properties.

Optimum design of nonlinear microwave circuits

This paper reports a direct optimization method of nonlinear circuits. The procedure consists in determining in the power space, a surface including all the extremum allowed powers at terminal ports of each nonlinear component of the circuit. According to the required nonlinear function, an appropriate choice of the tangent planes to this surface allows to calculate the optimum loads for the nonlinear components. This method optimizes the parameters of nonlinear devices without any constraint on the circuit. A small signal analysis is then taken in order to deduce the optimum performance of the nonlinear designed circuit. The realization of a single balanced diode mixer has shown good agreement between the calculated values and the experimental results. >

Computationally efficient and accurate capacitance model for the GaAs MESFET for microwave nonlinear circuit design

A new equation for simulating the bias dependency of the gate-source and gate-drain capacitances of the GaAs MESFET is presented and compared with existing techniques. It provides increased accuracy for microwave circuit design applications and substantial savings in CPU execution speed over existing techniques. The new empirical relation is applied successfully to a wide range of silicon and GaAs devices.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Nonreciprocal coupling structure of dielectric wave guides

M-type hexagonal ferrites have been incorporated in a coupled dielectric image guides structure for nonreciprocal microwave circuits design. Two different field configurations have been considered in this paper: for case I the c axis of the ferrite materials was aligned along the direction of propagation; for case II the c axis was aligned in the transverse direction. Electromagnetic wave scattering S parameters of the device were measured for an external biasing magnetic field applied parallel and perpendicular to the c axis of the ferrite slab. We have observed nonreciprocal microwave effects in the ferromagnetic resonance regime as a result of a nonuniform external biasing magnetic field along the propagation direction. We believe that ferrite devices operating at millimeter-wavelength frequencies, such as isolators, filters, modulators, switches, phase shifter, etc., can be implemented from our device design.

Artifical intelligence techniques applied to microwave circuit design

(1993). Artifical intelligence techniques applied to microwave circuit design. The Irish Journal of Psychology: Vol. 14, Psychology, Artificial Intelligence and Cognitive Science, pp. 530-531.

Improved junction capacitance model for the GaAs MESFET

An empirical equation for simulating the bias dependency of the junction capacitances of the GaAs MESFET is presented and compared with existing techniques. It provides increased accuracy over a wide range of silicon and GaAs devices for microwave circuit design applications and up to 72% savings in CPU execution speed over existing techniques. >

Physical methods for microwave circuit design

GaAs Code Ltd was formed in 1988 as a software company dealing in device physical methods for FET and HEMT design, GaAs IC process design and MMIC design. The company develops and sells commercial software packages for these purposes, and undertakes contract work on both sole contractor basis, and as a collaborating partner in large consortia projects.

Finite difference time‐domain simulation of electromagnetic fields and microwave circuits

AbstractAn overview is given on the application of finite difference time‐domain analysis techniques to the simulation of electromagnetic wave phenomena and the design of planar microwave integrated circuits. In particular the application to the analysis of three‐dimensional discontinuities in coplanar microwave circuits is described and numerical and experimental results are presented. Finally the design of planar microwave circuits containing non‐linear active components using the finite difference time‐domain method in combination with a harmonic balance technique is demonstrated using an example of a LUFET circuit.

Computer-aided microwave circuit analysis by a computerized numerical Smith chart

The Smith chart, while being a very useful graphical tool for the manual analysis and design of microwave circuits, is not suitable for computer manipulation. A computerized Smith chart represented by a numerical matrix is developed. In addition to the fact that this numerical matrix is very convenient for computer storage and efficient for algorithmic operations, it retains the locality relationships between impedances and reflection coefficients on a graphical Smith chart. >

A simplified means for computation for interconnect distributed capacitances and inductances

A simplified, approximate means for computing the distributed capacitance and inductance matrices for TEM-mode (or quasi-TEM-mode) single or multiple transmission lines is presented. Cases with multiple dielectrics and/or ground planes are included. The conductors used may be either rectangular or planar. Simplicity is achieved by use of the method of moments along with two physically meaningful charge basis functions per conductor face. The techniques utilized are relatively easy to program and result in fast programs which are accurate for many important geometries. Such programs should be suitable for inclusion as subroutines in larger CAD programs for analysis and design of high-speed digital or microwave circuits. >

Optimum networks for simultaneous multiple beam antennas

The design of passive microwave circuits for the formation of simultaneous multiple beams with arbitrary but specified shapes is considered. The maximum possible efficiency is derived from energy conservation and is determined from a Hermitian matrix whose elements are the correlation coefficients between all beam pairs. The eigenfunctions of the correlation matrix are the basis of a synthesis procedure for a practical network that will achieve the maximum efficiency. Several practical examples are given where unavoidable losses are typically 1 dB or more.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Introduction to Computer Methods for Microwave Circuit Analysis and Design

Introduction to Computer Methods for Microwave Circuit Analysis and Design

Direct synthesis of distributed lossless networks with application to microwave amplifier design

The Simplified Real-Frequency Method, initiated by Carlin and Yarman in 1982, has rapidly become the most powerful one among the available numerical methods for solving singleor double-matching problems. So far it has been applied successfully to the synthesis of multistage microwave amplifiers, but the equalizers contained inductors and capacitors only. This article describes the extension of that technique to the direct synthesis of low-pass and high-pass distributed matching networks. The main interest of such an extension is to avoid using equivalences between lumped and distributed elements which are not valid in a wide frequency range. In addition, technological constraints are taken into account earlier in the synthesis. Examples are given of bipolar or field-effect transistor amplifiers which show that LIMDSYN, our in-house software, is an efficient tool for linear microwave circuit design with distributed elements.

High-frequency output characteristics of AlGaAs/GaAs heterojunction bipolar transistors for large-signal applications

High-frequency i c- v ce output characteristics of bipolar transistors, derived from calculated device cutoff frequencies, are reported. The generation of high-frequency output characteristics from device design specifications represents a novel bridge between microwave circuit design and device design: the microwave performance of simulated device structures can be analyzed, or tailored transistor device structures can be designed to fit specific circuit applications. The details of our compact transistor model are presented, highlighting the high-current base-widening (Kirk) effect. The derivation of the output characteristics from the modeled cutoff frequencies are then presented, and the computed characteristics of an AlGaAs/GaAs heterojunction bipolar transistor operating at 10 GHz are analyzed. Applying the derived output characteristics to microwave circuit design, we examine large-signal class A and class B amplification.

Preparation of thin films of Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-x/ by magnetron sputtering techniques

Three variations of sputtering for growing thin films of Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7-x/ are examined: a three-metal cosputtering technique requiring a postanneal at high temperatures, an in situ process using a inverted cylindrical magnetron sputter gun, and another in situ process using an planar target in an off-axis geometry. The films are grown primarily on a magnesium oxide substrate because it is readily available, inexpensive, and its low dielectric constant permits convenient microwave circuit design. It is found that the cosputter process with postanneal produces films with depressed T/sub c/'s and J/sub c/'s. The inverted cylindrical magnetron sputtering has yielded the best films, showing complete transitions as high as 87 K and J/sub c/=4*10/sup 6/ A/cm/sup 2/ at 4 K. The off-axis results are not quite as good, with 79 K complete transitions. By lowering the substrates further out of the plasma in the off-axis system, films can be improved by avoiding damage from negative ions.

Microwave circuit design using linear and nonlinear techniques

Foreword by David Leeson. Preface. 1. RF/Microwave Systems. 2. Lumped and Distributed Elements. 3. Active Devices. 4. Two-Port Networks. 5. Impedance Matching. 6. Microwave Filters. 7. Noise in Linear Two-Ports. 8. Small- and Large-Signal Amplifier Design. 9. Power Amplifier Design. 10. Oscillator Design. 11. Microwave Mixer Design. 12. RF Switches and Attenuators. 13. Microwave Computer-Aided Workstations foor MMIC Requirements. Appendix A: BIP: Gummel-Poon Bipolar Transistor Model. Appendix B: Level 3 MOSFET. Appendix C: Noise Parameters of GaAs MESFETs. Appendix D: Derivations for Unilateral Gain Section. Appendix E: Vector Representation of Two-Tone Intermodulation Products. Appendix F: Passive Microwave Elements. Index.

CAD for statistical analysis and design of microwave circuits

AbstractStatistical circuit design is essentially a method of design for reliability and high yield. For all but the smallest circuits, this is a CAD problem. Within this problem there are three subproblems: design centering, tolerance assignment, and variability reduction. This paper concentrates on design centering. Yield optimization is inherently a difficult problem because yield cannot, in general, be calculated exactly; only estimates of the yield are available. Furthermore, yield gradients are not available when some yield estimation techniques are used. This paper presents a review of useful definitions using parameter space concepts. Yield estimation techniques and some of their properties are also presented. The two distinct yield optimization strategies commercially available today, statistical and deterministic, are each discussed in detail. Examples of each are given.

Modern perspectives in supercomputer‐aided microwave circuit design

AbstractThe computer‐aided simulation and design of microwave integrated circuits often leads to large‐size numerical jobs, especially for modern multiple‐device MMIC subsystems such as distributed mixers and amplifiers. When this is the case, the use of large computer systems such as vector processors may become very attractive, because of the dramatic reduction of wall‐clock time and of the related improvement of cost‐to‐performance ratio. This paper discusses the application of supercomputers to the solution of a number of such advanced microwave circuit CAD problems. An overview of the performance of general‐purpose vectorized algorithms such as system solvers and Fast Fourier Transforms is first presented, in order to give a feeling of the potential of this class of machines in microwave CAD applications. Then a few typical microwave engineering problems are specifically addressed, including the statistical design (yield optimization) of linear circuits, the analysis of nonlinear circuits under multitone excitation, and the optimization of ultrabroadband nonlinear subsystems. In each case, a possible vectorization strategy is studied in depth, and the structure and performance of a specific highly vectorized algorithm are described in detail.