DC and transmission line models for a high electron mobilitytransistor

Two improved DC models are developed to describe the output I -V (current-voltage) characteristics and small-signal parameters of a GaAs high-electron-mobility transistor (HEMT). A simple analytical, nonlinear, charge-control model for a two-dimensional electron gas is introduced and included in one of the DC models. The HEMT is modeled as a transmission line for the microwave-frequency AC analysis, and its microwave performance is predicted by the parameters obtained from fitting DC characteristics. Both DC and AC model predictions show a good agreement with experimental results for a 0.3-μm GaAs HEMT     

基于GaAs STATZ模型的RF MOSFET DC建模技术

STATZ模型是表征GaAsMESFET特性的常用模型,具有表达式简洁、参数少的优点。通过尝试将STATZ模型用于表征射频MOSFET的直流特性,提取并在ADS软件中优化了STATZ直流模型的参数。为了提高仿真精度,模型必须考虑晶体管漏极与源极的寄生电阻,根据MOSFET处于强反型区且漏-源电压为零时的等效电路模型提取了晶体管的漏极和源极的寄生电阻。在ADS软件中利用STATZ模型对MOSFET的直流特性进行了仿真,测量的MOSFET直流曲线与仿真曲线一致性很好,验证了模型的良好的精确度,证明了GaAs STATZ模型可以用于表征射频MOSFET的直流特性。晶体管采用中芯国际的0.13μm RF CMOS工艺制作。     

Compact DC model of GaAs FETs for large-signal computer calculation

A modified, simple and fairly accurate explicit expression of DC current-voltage characteristics of GaAs FETs is presented. A departure from the square-law behavior in saturation of the short channel transistor is included by introducing drain-source voltage bias dependent pinch-off potential. The model proposed here needs four parameters extracted by the global curve-fitting technique of a measured family of drain current-voltage characteristics. A comparison with other DC compact models of MESFETs valid over the entire range of drain-source voltages shows good compromise between simplicity and accuracy of the model proposed. The model can be easily implemented in programs of computer-aided analysis and design of circuits with GaAs FETs.     

有机薄膜晶体管直流电流-电压模型的研究

通过对有机薄膜晶体管(OTFT)电流-电压特性的研究,建立了一种用于电路模拟的仿真程序(SPICE)的OTFT直流电流-电压模型,所用的参数都可从实验特性曲线中提取。对一种基于并五苯(Pentacene)的底栅顶接触(TC)结构的OTFT的实验曲线进行参数提取,并利用所得的参数与建立的模型进行仿真,得到的输出特性和转移特性曲线与实验结果无论在线性区还是在饱和区都具有较强的一致性,验证了本文所建模型及参数的准确性。建立的模型能够准确描述OTFT的直流特性,可用于有机电路的SPICE仿真。     

基于直流伺服系统的模糊自适应控制应用

在建立无刷直流电机的数学模型的基础上,针对直流电机伺服系统中存在的非线性、强耦合及结构参数变化范围大的特点进行模糊推理,实现对控制参数（Kp,Ki,Kd）的在线整定,以达到优化控制。通过MATLAB/Simulink仿真得到了与理论分析一致的实验结果,同时对模糊自适应PID控制在无刷直流电动机系统中的应用进行了仿真研究,仿真结果验证了传统的PID控制方式很难达到理想的效果,参数自整定模糊PID控制优于传统PID控制,前者具有响应速度更快、超调更小、稳定性和跟踪性能更好的特点并且模糊自适应PID控制策略能加快无刷直流电动机系统的响应速度,使整个系统具有较强的鲁棒性。     

A short-channel DC SPICE model for polysilicon thin-filmtransistors including temperature effects

A semi-empirical analytical model for the DC characteristics of both n- and p-channel polysilicon thin-film transistors is described. The model is suitable for implementation in a SPICE circuit simulator. Our semi-empirical approach results in a physically based model with a minimum of parameters, which are readily related to the device structure and fabrication process. The intrinsic DC model describes all four regimes of operation: leakage, subthreshold, above threshold, and kink. The effects of temperature and channel length are also included in the short-channel model     

直流电机PID控制系统仿真研究

直流电机是将直流电能转换成机械能或将机械能转换成直流电能的旋转电机。PID（比例-积分-微分）控制器,由比例单元P、积分单元I和微分单元D组成,通过Kp,Ki和Kd 3个参数的设定,主要适用于基本线性和动态特性不随时间变化的系统。PID控制器作为最早实用化的控制器已有70多年的历史,产品已在工程实际中得到了广泛的应用。PID控制器由于简单易懂,在使用中不需精确的系统模型等先决条件,因而成为应用最为广泛的控制器。文章针对常规直流电动机PID控制系统的参数整定存在一定复杂性的问题,分析了PID控制系统的结构和原理,根据参数的选择,建立了数学模型。对直流电动机模型进行仿真分析,并对PID控制的仿真结果进行对比分析,通过仿真结果发现PID控制系统具有良好的静、动态性能和鲁棒性。     

Extended behavioural modelling of FET and lattice-mismatched HEMT devices

This study presents an improved large signal model that can be used for high electron mobility transistors (HEMTs) and field effect transistors using measurement-based behavioural modelling techniques. The steps for accurate large and small signal modelling for transistor are also discussed. The proposed DC model is based on the Fager model since it compensates between the number of model’s parameters and accuracy. The objective is to increase the accuracy of the drain-source current model with respect to any change in gate or drain voltages. Also, the objective is to extend the improved DC model to account for soft breakdown and kink effect found in some variants of HEMT devices. A hybrid Newton’s–Genetic algorithm is used in order to determine the unknown parameters in the developed model. In addition to accurate modelling of a transistor’s DC characteristics, the complete large signal model is modelled using multi-bias s-parameter measurements. The way that the complete model is performed is by using a hybrid multi-objective optimisation technique (Non-dominated Sorting Genetic Algorithm II) and local minimum search (multivariable Newton’s method) for parasitic elements extraction. Finally, the results of DC modelling and multi-bias s-parameters modelling are presented, and three-device modelling recommendations are discussed.     

DC machine models for SPICE2 simulation

A four-level computer model is proposed for DC machine simulation using SPICE2 to meet different simulation requirements. The most complex model takes account of magnetic saturation, armature reaction, current dependence of winding circuit parameters, and eddy current effects. The models have been developed to enable designers to simulate the static and dynamic characteristics of a complete converter drive system including the DC machine more simply, practically, and reliably in one simulation run. Some simulations have been investigated to demonstrate the benefits of the SPICE2 machine models     

Modeling and characterization of an 80 V silicon LDMOSFET foremerging RFIC applications

This paper describes the design and optimization of an 80 V silicon RF LDMOSFET used in a power amplifier for base station applications. The transistor was prototyped using the doping profiles extracted from an experimental device and extensive two-dimensional (2-D) simulations were performed to characterize the DC and RF performance of the device. A good match between the measured and simulated data is reported. A simple circuit model was developed which accurately predicts the DC and RF characteristics in circuit simulators. It is shown through 2-D simulations that the LDD region in the LDMOSFET can be modeled as a JFET. A methodology for the accurate extraction of model parameters for the circuit model is discussed. It is shown that the DC and RF performances of the circuit model closely match the measured data. Advanced mixed device and circuit simulations were used to obtain S-parameters of the device which provide new insights into device physics and also the basis for statistical process control studies     

DC, small-signal, and noise modeling for two-dimensional electrongas field-effect transistors based on accurate charge-controlcharacteristics

A practical model for DC, small-signal, and noise characteristics in two-dimensional electron gas field-effect transistors is discussed. The model includes accurate charge-control characteristics based on analytical functions relating carrier concentration to Fermi level. This model allows the influence of drain current, frequency, and device parameters on the noise figure (NF) to be studied. The theory explains the experimentally observed trend in NF behaviors     

DBRTD直流特性的水动力学模拟

利用ISE软件的水动力学模型对不同材料结构的AlAs／GaAs／inGaAs双势垒共振隧穿二极管（DBRTD）直流特性进行了模拟。当势垒厚度、势垒高度、子阱厚度、间隔层厚度、掺杂浓度改变时。可以观察到DBRTD直流特性也随之改变。采用薄的子阱厚度、高的掺杂浓度以及恰当的间隔层厚度、势垒厚度和高度,可以提高RTD器件的峰谷电流比（PVCR）和峰电流密度,从而满足实际应用的需要。     

The low frequency noise in HFETs estimates the effect of electrical stress

The effect of electrical stress on the low frequency noise in heterostructure field effect transistors is investigated in detail and is compared to the DC characteristics. Additionally, a model has been developed to describe the increase of the low frequency noise, depending on the change of other transistor parameters during the stress. Finally, a discussion about the model ability to be used for other devices is given.     

精密数字多用表的开发应用

为正确利用精密数字多用表具有的噪声抑制能力强、稳定性高、线性度好、分辨力高以及采样速率快等优点,对其进行进一步开发,利用比较、直接测量和间接测量等方法,可使其替代检测器、比较仪,在直流电压、电阻、电流等参数的校准/检定和测试工作中发挥更大作用。     

Si肖特基二极管直流及高频建模

采用分段提参的方法,针对SMIC 130nm CMOS工艺下CoSi2-Si肖特基二极管的直流及高频特性建立统一模型。直流时除了热发射效应,也考虑了势垒不均匀效应、大注入效应及隧穿效应的影响。高频时,在直流特性基础上特别考虑了衬底以及金属寄生效应的影响。该模型直流拟合误差为1.26%,高频时在整个测试频段（1GHz~67GHz）内电阻、电容拟合误差分别为3.16%和2.25%。据我们所知,这是首次针对CoSi2-Si肖特基二极管建立完整模型,考虑直流及高频特性并给出了相应的提参步骤。     

Improved temperature model of AlGaN/GaN HEMT and device characteristics at variant temperature

In this paper, an improved temperature model for AlGaN/GaN high electron mobility transistor (HEMT) is presented. Research is being conducted for a high-performance building block for high frequency applications that combine lower costs with improved performance and manufacturability. The effects of channel conductance in the saturation region and the parasitic resistance due to the undoped GaN buffer layer have been included. The effect of both spontaneous and piezoelectric polarization induced charges at the AlGaN/GaN heterointerface has been incorporated. The proposed model is used to determine the transfer characteristics, output current-voltage characteristics and small-signal microwave parameters of HEMTs. The investigated temperature range is from 100–600 K. The small signal microwave parameters have been evaluated to determine the unity current gain cut-off frequency (f _T ). High f _T (10–70 GHz) values and high current levels (～550 mA/mm) are achieved for a 1 μm AlGaN/GaN HEMTs. A custom DC measurement system is used to facilitate the DC characterization of the unpackaged GaN HEMT test device. The calculated critical parameters and the simulation results suggest that the performance of the proposed device degrades at elevated temperatures.     

Optimization of pseudomorphic HEMT's supported by numericalsimulations

Measurements and simulations of three different pseudomorphic high electron mobility transistors (PHEMT's) are presented. The PHEMT's possess the same epitaxial structure but different geometrical properties. For the simulations, the generic device simulator MINIMOS-NT is employed. This simulator is not restricted to planar device surfaces but is able to model complex surface topologies including the effect of passivating dielectric layers. Mixed hydrodynamic and drift-diffusion simulations are demonstrated. They include the DC characteristics as well as the bias-dependent gate capacitances. Thus, bias-dependent current-gain cutoff frequencies f_T can be calculated. The results compare very well with the values obtained by small-signal parameter extractions from S-parameter measurements. Although a single consistent set of parameters is used for the simulations of all three devices, their characteristics are reproduced with an accuracy to our knowledge not reported before. Therefore, the DC and RF properties of PHEMT's with geometries significantly different from the measured devices can be reliably predicted     

DC parameter extraction of equivalent circuit model in InGaAsSb heterojunction bipolar transistors including non-ideal effects in the base region

This paper presents the DC parameter extraction of the equivalent circuit model in an InP-InGaAsSb double heterojunction bipolar transistor (HBT). The non-ideal collector current is modeled by a non-ideal doping distribution in the base region. Then several consequent non-ideal effects, which have always been neglected in typical HBTs, are studied using Medici device simulator. Moreover, the associated DC parameters of VBIC model are extracted accordingly. The equivalent circuit model is in good agreement with the measured data in I_C-V_CE characteristics.     

The DC characteristics of GaAs/AlGaAs heterojunction bipolartransistors with application to device modeling

A complete DC model for the heterojunction bipolar transistor (HBT) is presented. The DC characteristics of the HBT are compared with the Ebers-Moll (EM) model used by conventional bipolar junction transistors (BJTs) and implemented in simulation and modeling programs. It is shown that although the details of HBT operation can differ markedly from those of a BJT, a model and a parameter extraction technique can be developed which have physical meaning and are exactly compatible with the EM models widely used for BJTs. Device I- V measurements at 77 and 300 K are used to analyze the HBT physical device performance in the context of an EM model. A technique is developed to extract the device base, emitter, and collector series resistances directly from the measured I-V data without requiring an ideal exp(qV_be/kT) base current as reference. Accuracies of the extracted series resistances are assessed. AC parameters of HBT are calculated numerically from the physical device structure. For modeling purposes, these parameters are shown to be comparable with those of conventional BJTs