Nonlinear circuit analysis of harmonic and intermodulationdistortions in laser diodes under microwave direct modulation

A microwave nonlinear circuit analysis technique which can account for all known steady-state responses has been developed and applied to the large-signal characterization of directly modulation laser diodes. An equivalent circuit derived from the rate equations is used to model the laser diode. The proposed technique is based on a harmonic balance algorithm which represents two-tone inputs by describing frequencies. Second-harmonic and third-order intermodulation distortion results for a single-mode GaAlAs diode have been compared with corresponding measured data to validate the method. Aperiodic responses are detected by means of bifurcation theory prior to the harmonic balance analysis and are simulated in the time domain. Simulated results are shown to agree well with published measurements, and indicate the capability of using this approach for the computer-aided design of microwave fiber-optic transmitters     

On the Use of Describing Functions in the Study of Nonlinear Active Microwave Circuits

It is shown that a nonlinear microwave circuit can easily be represented by a feedback model. This formalistic identity with nonlinear control systems suggests that methods and results can be borrowed from nonlinear control theory. The describing function technique, a concept that has been developed to a high degree of sophistication in control theory, is applied to the problem of phase-locking of microwave oscillators. The use of describing functions in the study of nonlinear microwave circuits may give a simple conceptual understanding of locking phenomena, for example, and thereby reduce computational efforts.     

A GaAs FET Model for Large-Signal Applications

The use of GaAs FET's under large-signal conditions requires a knowledge of the nonlinear behavior of these devices. A computer program, based on a circuit model with nonlinear elements, has been developed which provides this information. Results from the computer model and examples of its use in microwave circuit design are given.     

Complete Stability Analysis of Multifunction MMIC Circuits

This paper describes a systematic methodology for complete stability analysis of nonlinear microwave multifunction circuits. The proposed strategy has two different stages: the stability analysis of a nominal steady-state solution and the use of continuation techniques to efficiently determine the unstable operation ranges. The stability analysis is demanding due to the multiple loops contained in the large multifunction circuit. The first step is to check the possible fulfillment of the oscillation startup conditions at different circuit nodes followed by pole-zero identification. Given the complexity of the circuit topology, a systematic technique is necessary for the selection of the observation nodes. This has been applied at both the lumped-element schematic and the layout levels. These stability analyses have been carried out at small-signal (linear) and large-signal (nonlinear) since the multifunction circuit includes a nonlinear mixer. In the case of instability, the origin of the oscillation and its characteristics are analyzed versus the critical circuit parameters through the application of continuation techniques to the steady-state oscillatory solution. Moreover, sensitivity yield analysis and variations of environmental conditions combined with the stability techniques have also been taken into account and integrated into the design cycle. The proposed systematic approach has been successfully applied to determine and correct an oscillation of a multifunction monolithic-microwave integrated-circuit converter. It has also been proven in other multifunction circuits in the same way.     

High-frequency periodic time-domain waveform measurement system

A system is presented for the accurate measurement of high-frequency periodic time-domain voltage and current waveforms of a nonlinear microwave device. The measurements are performed in the time domain using a high-speed sampling oscilloscope. The results are Fourier-transformed into the frequency domain for error correction and then back into the time domain. An error-correction algorithm is presented that makes it possible to obtain accurate waveforms in spite of nonideal system components. Practical difficulties in measurement-system characterization are also discussed. An accurate circuit model for the measurement fixture is developed and its element values are determined. Measurement results are given showing the waveforms in a microwave transistor operated in the nonlinear region. The errors caused by signal processing are discussed     

A Microwave Compatible MIC Temperature Electrode for Use in Biological Dielectrics

A microwave compatible four-terminal electrode design based on hybrid microwave integrated circuit (MIC) construction is presented. The concept of electrothermal matching is employed to prevent artifact in either of two directions: heat sourcing and heat sinking. The electrode system includes a temperature-encoding electronic package. The electrode is designed for use in the brain at a specific insertion depth. It has been tested by thermographic methods for electromagnetic properties at 2450 MHz and a power density of ~250 mW/cm/sup 2/. The system has been thermometrically evaluated for calibration stability and freedom from hysteresis. Stability and artifact has been shown to be within /spl plusmn/15/spl deg/C independent of temperature cycling and/or thermal history.     

A novel temperature-dependent large-signal model of heterojunction bipolar transistor with a unified approach for self-heating and ambient temperature effects

A large-signal modeling of power heterojunction bipolar transistor (HBT) is demonstrated for an accurate simulation of self-heating and ambient temperature effects and nonlinear behaviors such as output power, gain expansion, intermodulation distortion (IMD), and adjacent channel power ratio (ACPR). The physical relationship between the device current and the rate of change in the built-in potential with respect to the device temperature has been utilized for a fully electrothermal modeling. To enable an immediate use for a circuit design, the model extraction was done for in-situ output-stage device from two-stage power amplifier (PA) circuit. In each parameter extraction step, measurement data obtained under a consistent environment, which are current-voltage (I-V) at various temperatures and small-signal S-parameters under various bias conditions, have been carefully examined and utilized to relate the meaning of each parameter to the physical principle of the device. Measurements and simulations are compared for the verification of the model under dc condition at various temperatures.     

High linearity 5.2-GHz power amplifier MMIC using CPW structure technology with a linearizer circuit

A built-in linearizer was applied to improve the linearity in a 5.2-GHz power amplifier microwave monolithic integrated circuit (MMIC), which was undertaken with 0.15-μm AlGaAs/InGaAs D-mode PHEMT technology.The power amplifier (PA) was studied taking into account the linearizer circuit and the coplanar waveguide (CPW) structures. Based on these technologies, the power amplifier, which has a chip size of 1.44 × 1.10 mm~2, obtained an output power of 13.3 dBm and a power gain of 14 dB in the saturation region. An input third-order intercept point (IIP_3) of-3 dBm, an output third-order intercept point (OIP_3) of 21.1 dBm and a power added efficiency (PAE) of 22% were attained, respectively. Finally, the overall power characterization exhibited high gain and high linearity, which illustrates that the power amplifier has a compact circuit size and exhibits favorable RF characteristics. This power circuit demonstrated high RF characterization and could be used for microwave power circuit applications at 5.2 GHz.     

A survey of the present state of microwave transistor modeling and simulation as applied to circuit design

A comprehensive overview of recent approaches to microwave transistor modeling and simulation is presented. Three basic approaches to semiconductor device modeling are compared: the linear two-port model, the device-physics model, and the equivalent circuit model. Equivalent circuit models are discussed in detail with examples. Good solutions to the problem of linear modeling have been found and several authors have been able to predict the noise and gain of microwave transistors in the linear operating regions. However solutions for nonlinear operation of transistors at microwave frequencies have only recently been implemented and much room for improvement remains.     

Characterization of integrated logic circuits

The characterization of integrated logic circuits must be accomplished in a manner which fully accounts for the circuit's nonlinear behavior and is amenable to experimental verification. The approach taken in this paper is to describe both the dc and the transient performance of the circuit by developing nonlinear equivalents of the 2-port "black box" parameters used in specifying linear networks. Such terminal parameter characterization has the obvious advantage of eliminating the need to probe the integrated circuit for testing purposes. In addition, knowledge of terminal performance is a necessity when the circuit is studied from a system point of view. In this paper an emitter-coupled logic circuit is used as an example to illustrate the analysis techniques. After accomplishing the terminal parameter characterization of this circuit, attention is directed towards using these results to establish a design procedure. To this end the relationship that exists between power consumption and the circuit safety margins is explored, and the minimum power-delay time product is derived. The analysis accounts for the parasitics which are present in a monolithic integrated circuit and illustrates the use of the nonlinear transistor model.     

Microwave electrothermal propulsion for space

The microwave electrothermal thruster (MET) is attractive for medium- or high-power spacecraft propulsion. A propellant gas is heated by passing it through a microwave plasma discharge created in a resonant cavity by tuning either the TM(011) or the TM(012) mode for impedance-matched operation. The MET is electrodeless, synergistically combines high pressure and high power capability, provides external control over the energy-conversion discharge, and operates on hydrogen propellant. Upwards of 95% efficiency has been reported. Calculations of potential MET performance are reported. Apparatus for testing the MET to power levels of 30 kW at 915 MHz is described. The low-ripple operation of the microwave generator has been verified, as has a procedure for starting the microwave discharge and raising the power applied to the cavity. Impedance-matched resonant operation of the microwave cavity has been achieved     

金属接触非线性引起的无源互调效应的数值分析

针对时域物理光学方法求解无源互调问题的局限性,提出基于"场路结合"的数值分析方法,建立非线性金属结的等效电路模型并将其引入到全波方法中,通过全波方法与等效电路相结合的方式来分析系统的无源互调干扰.计算实例表明,该方法可以精确地计算由于金属接触非线性引起的无源互调及其作为二次辐射源所激发的电磁场,避免了时域方法在电大尺寸问题上计算的积累误差以及只能对处于远场区的简单微波结构的无源互调效应进行求解的问题.本文提出的场路结合数值分析方法为微波部件无源互调效应的研究提供了新的思路与方法.     

Hybrid S-Parameters for Transmission Line Networks With Linear/Nonlinear Load Terminations Subject to Arbitrary Excitations

We propose a generalized S-parameter analysis for transmission lines (TLs) with linear/nonlinear load terminations subject to arbitrary plane-wave and port excitations. S-parameters are prevalently used to model TLs such as cable bundles and interconnects on printed circuit boards (PCBs) subject to port excitations. The conventional S-parameter approach is well suited to characterize interactions among ports. However, nontraditional port excitations associated with plane-wave coupling to physical ports at TL terminals lead to forced, as well as propagating, modal waves, necessitating a modification of the standard S-parameter characterization. In this paper, we consider external plane-wave excitations, as well as port (internal) sources, and propose a hybrid S-parameter matrix for characterization of the associated microwave network and systems. A key aspect of the approach is to treat the forced waves at the ports as constant voltage sources and induced propagating modal waves as additional entries (hybrid S-parameters) in the S-parameter matrix. The resulting hybrid S-matrix and voltage sources can be subsequently exported to any circuit solver such as HSPICE and Agilent's Advanced Design System for the analysis of combined linear and nonlinear circuit terminations at ports. The proposed method is particularly suited for susceptibility analysis of cable bundles and PCBs for electromagnetic interference evaluations. It also exploits numerical techniques for structural and circuit domain characterization and allows for circuit design optimization without a need to perform any further computational electromagnetic analysis     

GaAs MESFET非线性CAD模型综述

介绍了ＧａＡｓＭＥＳＦＥＴ应用在商业软件中的四种非线性ＣＡＤ模型、ＰＳＰＩＣＥ程序中的ＳＴＡＴＺ模型、ＥＥｓｏｆ微波电路模拟程序中的Ｃｕｒｔｉｃｅ对称和不对称模型以及ＱＵＡＳＩ程序中改进的ＳＴＡＴＺ模型。在给出多种模型ＤＣ方程和源漏电容公式的同时，对三种电路模拟程序的应用范围进行了分析。     

Electrothermal model for an SOI-based LIGBT

Several vertical insulated gate bipolar transistor (IGBT) electrothermal models are currently available on circuit simulators. However, no reliable electrothermal models have been proposed for the lateral IGBT (LIGBT). In this paper, for the first time, an electrothermal model for an LIGBT structure based on a novel concept recently reported by Udrea (IEDM, p. 451, 2004), and here termed silicon-on-membrane, is presented. The model relies on a systematic study of both the isothermal and self-heating behaviors of the device. The model is further implemented in the SPICE circuit simulator language and validated against extensive Medici numerical simulations and experimental data.     

Dynamic SPICE-simulation of the electrothermal behavior of SOIMOSFET's

A nonlinear dynamic electrothermal model of the SOI MOSFET is implemented and used in SPICE3. This model is formulated as a set of algebraic and (partial) differential equations which is converted into a SPICE3 netlist automatically by a model translator. Neither is the simulator rewritten nor are SPICE device models implemented or changed. In this way, the presented approach supports effective model development. To show the electrothermal interaction, the SOI MOSFET model is applied to several static and dynamic simulations. The SPICE-simulation results of the thermal model are verified with the commercial finite-element simulator ANSYS     

Systematic DC/small-signal/large-signal analysis of heterojunctionbipolar transistors using a new consistent nonlinear model

In this paper, a new systematic approach to heterojunction bipolar transistors (HBT's) characterization and modeling is presented. The proposed approach is based on a new compact HBT nonlinear circuit model which accounts for both self-heating and the temperature dependence effects. The model's parameters are extracted from measured dc-IV characteristics and S-parameters. The power characteristics of the device are then predicted using the extracted model without any further optimizations. The same model is also used for intermodulation distortion analysis. The model has been implemented in a number of commercial nonlinear simulators and in an in-house computer code. Results are presented for two different size devices showing good agreement with measurements     

Circuit simulations combined with the electromagnetic fieldanalysis

In order to provide a means of rigorous simulation for wideband nonlinear microwave integrated circuits, the concept of a lumped device model is introduced into a three-dimensional, time-domain electromagnetic field analysis method. This makes it possible to perform both a circuit simulation including nonlinear lumped devices and an electromagnetic field analysis for distributed microwave components at the same time. As an example, the generation of picosecond pulses from a nonlinear transmission line circuit is simulated. Based on the results, the features and the validity of the method are discussed in comparison with conventional circuit simulations