A sophisticated analysis procedure for an MMIC phase shifter

This paper describes a new analysis procedure for a highpass and lowpass (HP/LP) filter type MMIC phase shifter consisting of switching GaAs MESFETs. This paper reveals that a specially designed large signal model for a switching MESFET, described by a gate bias dependent equivalent circuit, is the key to realizing an accurate nonlinear simulation of the HP/LP filter type phase shifter. The new analysis procedure realizes a highly accurate phase shifter analysis for both linear and nonlinear simulations. A comparison between the analysis results and measurement results for the phase shifter shows excellent agreement     

Nonlinear models for the intermodulation analysis of FET mixers

An accurate, detailed analysis program has been developed for intermodulation distortion (IMD) simulation of FET mixers. This program is very efficient at calculating the IMD from multiple RF inputs. We have proposed a simplified nonlinear model for IMD analysis of FET gate mixers. The accuracy of the simplified model has been verified experimentally using two different MESFET mixers and one HEMT mixer at X band. All the tests show good agreement between measured results and the calculated results for second- and third-order IMD. The simplified model is based on modeling the derivative of the device transconductance by a sum of a Gaussian function and a linear function of the gate voltage. Drain bias dependence is ignored. The advantage of this model is that it can be used for both MESFET and HEMT mixers, and its fitting parameters can be easily determined from a nonlinear characterization of the devices at low frequencies     

GaAs MESFET微波非线性电路全频域谐波平衡分析

根据Fourier分析理论推导了全频域分析微波非线性电路的方法,此方法简单明了,适合于分析微波大信号强非线性电路.用此方法对GaAs MESFET微波非线性电路进行分析,给出了实用的分析计算结果.     

Numerical investigation of mesh size convergence rate of the finite element method in MESFET simulation

The mesh size convergence rate of the finite element method in two-dimensional GaAs MESFET simulation has been investigated numerically. The equations governing MESFET operation and the finite element formulation of these equations are summarized. The presence of corner singularities at the gate contact endpoints is noteworthy, for such singularities are known to determine the convergence rate in linear model problems. The local potential and electron concentration solutions are obtained in the neighborhood of these singularities and used to estimate a lower bound on the convergence rate for the nonlinear problem. The rate of convergence of the MESFET problem is tabulated for three mesh sequences and discussed. The common source output characteristic of a 0.25 μm gate length GaAs MESFET is calculated and compared to the characteristic of a MESFET fabricated in our laboratory. Considerable discrepancy between the two is obtained; reasons for this are hypothesized.     

基于实验与物理分析的4H-SiC射频功率MESFET大信号非线性精确电容模型

采用电荷控制理论和载流子速度饱和理论的物理分析方法,并结合Statz、Angelov等经验模型的描述方法,提出了常温下针对4H-SiC射频功率MESFET的大信号非线性电容模型.此模型在低漏源偏压区对栅源电容Cgs强非线性的描述优于Statz、Angelov等经验模型,计算量也远低于基于器件物理特性的数值模型,因而适合于大信号的电路设计与优化.     

A capacitance model for GaAs MESFETs

A capacitance model for a GaAs MESFET suitable for implementation in the circuit analysis program SPICE is presented. The model consists of nonlinear capacitances that are a function of two voltages. Such a model gives rise to ordinary nonlinear capacitances and transcapacitances. The placement of these elements in the Y matrix is shown. The empirical equations for the gate charge of a GaAs MESFET given provide an accurate SPICE model for the gate charge and capacitances of a MESFET. A comparison of measured capacitance values with the modeled values gives close enough agreement for circuit simulation purposes     

Nonlinear yield analysis and optimization of monolithic microwaveintegrated circuits

In this paper, a discussion about nonlinear yield evaluation and nonlinear yield optimization of MMIC circuits using a physics-based nonlinear lumped-element MESFET model is presented. The lumped elements of the MESFET model are directly calculated by closed expressions related to process parameters. One of the main features of the model is the easy and effective implementation in commercial CAD tools. It allows the use of nonlinear yield algorithms assuming, as statistical variables, the parameters of the technological process, such as: doping density, gate channel length, etc., maintaining at the same time, the advantages of lumped-element MESFET model, in particular fast computation and reduction of convergence problems in harmonic balance for complex circuit topologies     

微波功率GaAs MESFET本征元件与偏置关系分析

提出了一种分析和了解微波功率 Ga As MESFET非线性效应的方法。主要是采用解析优化方法 ,提取 MESFET器件在不同偏置点下的本征元件 ,并结合器件的应用类型 ,对本征元件与偏置的关系进行了系统化的分析。分析的结论有助于提高微波功率 Ga As MESFET器件设计和应用的准确性     

Analysis of microwave MESFET power amplifiers for digital wireless communications systems

The analysis of microwave MESFET power amplifiers (PAs) for digital wireless communications by using the hybrid Volterra-series method is presented in this paper. Compared with the traditional approach in the pure frequency-domain operation, the hybrid method has the advantage of fast computation for the continuous spectral signals with the same accuracy. The major modification is the equivalent baseband formulations in the time domain for the digital modulation signal, and the frequency-domain treatment with the nonlinear system via Volterra-series expansion. The MESFET two-dimensional current model is utilized and detailed current expressions are given to account for the gate-drain cross-term effects, while the nonlinear capacitors are also considered to describe the MESFET nonlinear characteristics completely. Circuit-level simulation yields the output modulation signal parameters with the measured data confirmation. System performance degradations due to nonlinear distortions of the MESFET PA are also performed for the communication link with the additive white Gaussian noise channel model. These results would be very useful in PA designs for digital wireless communications systems.     

A new analytical model for photo-dependent capacitances of GaAs MESFET’s with emphasis on the substrate related effects

A new analytical model for optical and bias dependent nonlinear capacitances of GaAs MESFET which is valid for both linear and saturation regions has been proposed in this paper. The novelty lies in modeling of internal and external photovoltaic effects that includes deep level traps in the substrate and surface recombination at metal–semiconductor interface of the gate. The effect of high field domain formation at the drain end in the saturation region has also been included to improve the accuracy of the present model. The model presents backgating effects on gate–source and gate–drain capacitances of GaAs MESFET for the first time in literature. Finally, the proposed model has been compared to the reported results to show the validity. The proposed model may be very useful for the designing of photonic MMIC’s and optical receivers using GaAs MESFET’s.