By Topic

Microwave Theory and Techniques, IEEE Transactions on

Issue 6 • Date Jun 1999

Filter Results

Displaying Results 1 - 18 of 18
  • Microstrip directional couplers with ideal performance via single-element compensation

    Page(s): 956 - 964
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (228 KB)  

    Microstrip directional couplers suffer from poor directivity because of inhomogeneous dielectric, i.e., partly dielectric substrate, partly air. It is possible to compensate for this poor performance by introducing a single lumped capacitor or inductor at the edges or center of the coupled region. No attempt at a theoretical design of these couplers has been made in the literature. This paper fills the void by presenting an accurate approach to the design of microstrip directional couplers with ideal match or high directivity of both, using a single capacitive of inductive compensation. The method is valid for tight and loosely coupled structures. The method is validated via design and experimental results View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Extrapolation of a measurement-based millimeter-wave nonlinear model of pHEMT to arbitrary-shaped transistors through electromagnetic simulations

    Page(s): 908 - 914
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (192 KB)  

    In this paper, a new method for nonlinear modeling of a millimeter-wave pseudomorphic high electron-mobility transistor is proposed. The method relies upon the measurements of a particular transistor sample from a given process. Deembedding of measured multibias S-parameters is performed using electromagnetic simulations of metallic parts of the transistor and leads to the determination of a distributed nonlinear model for a unit finger. This elementary model combined with electromagnetic simulations can be used to extrapolate the nonlinear model to arbitrary-shaped devices with any number of fingers. The accuracy of the method is demonstrated by predicting nonlinear models of T-shaped devices starting from a U-shaped measured transistor View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Linear and nonlinear FET modeling applying an electromagnetic and electrical hybrid software

    Page(s): 915 - 918
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (88 KB)  

    A new approach is presented in this paper to help the modeling of complex active microwave devices like field-effect transistors. This hybrid method couples an electromagnetic three-dimensional simulator to characterize the extrinsic part and a circuit software to introduce the contribution of the component intrinsic part. The interests of such approach are diverse and are discussed in this paper. Theoretical linear and nonlinear results are compared with measurements and show good agreements View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • State-variable-based transient analysis using convolution

    Page(s): 882 - 889
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (196 KB)  

    A state-variable-based approach to the impulse response and convolution analysis of distributed microwave circuits is developed. The state-variable approach minimizes computation time and memory requirements. It allows the use of parameterized nonlinear device models, thus improving robustness. Soliton generation on a nonlinear transmission line is considered as an example View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A new approach to FET model scaling and MMIC design based on electromagnetic analysis

    Page(s): 900 - 907
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (252 KB)  

    A new approach, using electromagnetic analysis, is proposed for field-effect transistor model scaling and monolithic-microwave integrated-circuit (MMIC) design. It is based on an empirical distributed modeling technique where the active device is described in terms of an external passive structure connected to a suitable number of internal active sections. On this basis, an equivalent admittance matrix per gate unit width is obtained which, as confirmed by experimental results provided in this paper, is consistent with simple scaling rules. The same technique can also be adopted for a “global approach” to MMIC design where complex electromagnetic phenomena are also taken into account. An example of application concerning this aspect is presented View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Air-bridged gate MESFET: a new structure to reduce wave propagation effects in high-frequency transistors

    Page(s): 890 - 899
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (172 KB)  

    In conventional microwave transistors, the gain and output power are significantly reduced by gate ohmic resistance and phase cancellation. The air-bridged gate (ABG) transistors overcomes both problems by providing larger gate cross section along the propagation direction of the signal, and keeping both the input and output signals in phase along the device width. The performance of the air-bridged and conventional transistor is evaluated from both dc and radio-frequency (RF) points-of-view. A full hydrodynamic transport model, which accurately describes the electron dynamics in short channel devices, is used in the dc analysis. For RF analysis, a full-wave model, capable of capturing all important high-frequency effects, such as wave-particle interactions and traveling-wave effects, is implemented. This model is based on the coupling of the hydrodynamic transport equations with Maxwell's equations. Results related to the traveling-wave effects in conventional and ABG devices, such as phase mismatch and gain reduction at high frequencies, are illustrated, From these results, we show that the ABG metal-semiconductor field-effect transistor (MESFET) has superior performance at very high frequency as compared to conventional planar MESFETs View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A review of global modeling of charge transport in semiconductors and full-wave electromagnetics

    Page(s): 817 - 829
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (196 KB)  

    Models of semiconductor devices that combine complex transport models with full-wave solutions of Maxwell's equations are reviewed. Both hydrodynamic and ensemble Monte Carlo transport models are studied. The coupling of such transport models with electrodynamics is discussed and sample results are presented. The physical consistency of the models is considered and some open computational challenges are reviewed View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Global modeling of microwave applications by combining the FDTD method and a general semiconductor device and circuit simulator

    Page(s): 919 - 928
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB)  

    This paper presents the coupling of two commercially available simulation codes: DESSIS-ISE, a multidimensional semiconductor device and circuit simulator, and EMLAB-ISE, an electromagnetic-field solver based on the finite-difference time-domain (FDTD) method. Full-wave electromagnetics and nonlinear devices are simulated in a coupled self-consistent way using the lumped-element approach. The active region of the device is represented as a lumped element within the FDTD grid, while the packaging and waveguiding structures are modeled in their physical dimensions. For the nonlinear device, multidimensional semiconductor device simulation, as well as standard SPICE models, may be applied. Several examples show the capability of comprehensive analysis of microwave applications and the versatility in the simulation of the active elements. The coupling formalism is explained in detail, including time-step adjustment and biasing of active devices View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Transient simulation of millimeter-wave circuits incorporating numerical device modeling

    Page(s): 877 - 881
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (128 KB)  

    A fast convolution-based computational approach is employed to integrate numerical solid-state device simulation with nonlinear millimeter-wave circuit simulation. Unlike previous combined harmonic-balance/device approaches, the high-frequency circuit/physical device response is allowed to evolve in time to its natural steady-state mode of operation, permitting insight into harmonic and parametric energy exchange, stability, load pulling, and frequency tuning effects. To demonstrate this computationally efficient approach, a second-harmonic 150-GHz transferred electron oscillator is simulated using both conventional Gunn and novel stable-depletion-layer InP devices. The integrated device/circuit simulations in the time domain enable us to investigate the formation and buildup of the oscillation modes in detail View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Global modeling of spatially distributed microwave and millimeter-wave systems

    Page(s): 830 - 839
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (284 KB)  

    Microwave and millimeter-wave systems have generally been developed from a circuit perspective with the effect of the electromagnetic (EM) environment modeled using lumped elements or N-port scattering parameters. The recent development of the local reference node concept coupled with steady-state and transient analyses using state variables allows the incorporation of unrestrained EM modeling of microwave structures in a circuit simulator. A strategy implementing global modeling of electrically large microwave systems using the circuit abstraction is presented. This is applied to the modeling of a quasi-optical power-combining amplifier View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A new algorithm for the incorporation of arbitrary linear lumped networks into FDTD simulators

    Page(s): 943 - 949
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB)  

    The inclusion of lumped elements, both linear and nonlinear, into the finite-difference time-domain (FDTD) algorithm has been recently made possible by the introduction of the lumped element FDTD method. Such a method, however, cannot efficiently and accurately account for two-terminal networks made of several lumped elements, arbitrarily connected together. This limitation can be removed as proposed in this paper by describing the network in terms of its impedance in the Laplace domain and by using appropriate digital signal-processing methodologies to fit the resulting description to Yee's algorithm. The resulting difference equations allow an arbitrary two-terminal network to be inserted into one FDTD cell, preserving the full explicit nature of the conventional FDTD scheme and requiring a minimum number of additional storage variables. The new approach has been validated by comparison with the exact solution of a parallel-plate waveguide loaded with lumped networks in the transverse plane View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Waveguide bandpass filter analysis and design using multimode parallel FDTD diakoptics

    Page(s): 867 - 876
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB)  

    This paper presents an analysis and design method based on finite-difference time-domain diakoptics. A complex structure is divided into several smaller subsections. The characteristics of the subsections are analyzed entirely in the time domain using mode-type discrete time-domain Green's functions. A multimode parallel algorithm is proposed to connect the subsections. Several filter analysis and design examples are presented. The effectiveness and accuracy of this method is demonstrated by comparison with other computational methods and measurements View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Millimeter-wave pulsed oscillator global modeling by means of electromagnetic, thermal, electrical, and carrier transport physical coupled models

    Page(s): 929 - 934
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (128 KB)  

    The time domain modeling of the operation of a 94-GHz pulsed silicon IMPATT oscillator, based on a physical approach, is described in this paper. It relies on the coupling of electrical, thermal, electromagnetic, and carrier transport physical models. The model has been used to study the high-power stable operation of a 94-GHz oscillator. The results of a comparison between simulations, using two different types of passive radio-frequency load circuits, including experimental measurements, are presented and discussed. They tend to demonstrate that it is now possible to develop accurate millimeterwave-circuit predictive models even for application based on a nonlinear thermal and electrical transient operation such as IMPATT oscillators View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Electromagnetic model order reduction for system-level modeling

    Page(s): 840 - 850
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (192 KB)  

    Reduced-order modeling of an electromagnetic system is understood as the approximation of a continuous or discrete model of the system by one of substantially lower order, yet capable of capturing the electromagnetic behavior of the original one with sufficient engineering accuracy. Specific methodologies for model order reduction of distributed electromagnetic systems are discussed in this paper. It is shown that electromagnetic model order reduction enhances computational efficiency and, thus, facilitates system-level modeling and computer simulation of multifunctional systems. The proposed methodologies are demonstrated through applications to the reduced-order modeling of high-speed interconnects, electromagnetic waveguides, and microstrip antennas View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Global modeling strategies for the analysis of high-frequency integrated circuits

    Page(s): 950 - 955
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (108 KB)  

    In this paper, a simulator based on a global electromagnetic model is presented, suited for the analysis of HF integrated and hybrid electronic circuits. The model is based on the self-consistent solution of Maxwell's equation and of semiconductor transport equations, exploiting a generalized finite-difference time-domain (FDTD) scheme. The tool is, therefore, capable of accounting, on a distributed basis, for actual interactions between wave propagation and charge transport, anti is capable of providing a physically based picture of traveling-wave semiconductor devices. The implementation is such that more conventional algorithms (e.g. lumped-element FDTD or plain FDTD) can be regarded as a subset of the global scheme itself. This makes it possible to intermix different physical models, featuring different degrees of physical accuracy and computational efficiency, within the same simulation environment. Main features of such an environment are described by means of the simulation of a simple 76-GHz distributed switch View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A 38-GHz integrated uniplanar subsystem for high-speed wireless broad-band multimedia systems

    Page(s): 935 - 942
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (364 KB)  

    This paper outlines the high flexibility of the uniplanar technology to design complex multifunction subsystems. Furthermore, a design procedure based on a subsystem repartition into elementary blocks and a very simple electrical modeling is proposed and applied to a uniplanar biphase (0°-180°) modulator/mixer, which is intended to be used as building block for wideband digital communication systems at 38 GHz. This subsystem is implemented on a high dielectric-constant substrate (εr=9.9), which is close to the dielectric constant of GaAs and demonstrates the feasibility of integration of such a device structure into monolithic circuits. This approach has been initially validated with experiments on a subsystem up to 20 GHz and preliminary results demonstrate the validity of this subsystem design procedure at millimeter-wave frequencies. Theoretical field calculation methods are combined with conventional transmission-line and computer-aided design calculations to analysis the critical parts of the subsystem and the integral-equation approach is used for efficiency design View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Global time-domain full-wave analysis of microwave circuits involving highly nonlinear phenomena and EMC effects

    Page(s): 859 - 866
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (248 KB)  

    The global time-domain analysis of microwave circuits involving highly nonlinear phenomena such as injection locking and intermodulation, along with parasitic effects and electromagnetic compatibility (EMC) issues is presented in this paper. Employing the concept of equivalent sources, the device-wave interaction is characterized and incorporated into the finite-difference time-domain method. The investigation of nonlinear phenomena is accomplished by utilizing a large-signal device circuit model. Measured results are also provided for comparisons with simulated results. The applicability of this equivalent-source algorithm for investigating EMC effects is also demonstrated. A correspondence between simulated and measured EMC phenomenon indicates the usefulness of this algorithm in providing an effective tool for real world radio-frequency front-end circuit designs View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Full-wave modeling and automatic equivalent-circuit generation of millimeter-wave planar and multilayer structures

    Page(s): 851 - 858
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB)  

    A general method for the automated extraction of lumped-element equivalent circuits for linear passive reciprocal distributed microwave circuits from time-domain scattering signals is presented. The proposed method autonomously generates network topology as well as parameter values while preserving circuit properties like reciprocity and passivity. Modeling examples for a two- and three-port structure are given View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

The IEEE Transactions on Microwave Theory and Techniques focuses on that part of engineering and theory associated with microwave/millimeter-wave components, devices, circuits, and systems involving the generation, modulation, demodulation, control, transmission, and detection of microwave signals. This includes scientific, technical, and industrial, activities. Microwave theory and techniques relates to electromagnetic waves usually in the frequency region between a few MHz and a THz; other spectral regions and wave types are included within the scope of the Society whenever basic microwave theory and techniques can yield useful results. Generally, this occurs in the theory of wave propagation in structures with dimensions comparable to a wavelength, and in the related techniques for analysis and design..

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Dominique Schreurs
Dominique.Schreurs@ieee.org

Editor-in-Chief
Jenshan Lin
jenshan@ieee.org