A new empirical nonlinear model for HEMT and MESFET devices

A large-signal model for HEMTs and MESFETs, capable of modeling the current-voltage characteristic and its derivatives, including the characteristic transconductance peak, gate-source and gate-drain capacitances, is proposed. Model parameter extraction is straightforward and is demonstrated for different submicron gate-length HEMT devices including different δ-doped pseudomorphic HEMTs on GaAs and lattice matched to InP, and a commercially available MESFET. Measured and modeled DC and S-parameters are compared and found to coincide well     

A new empirical large-signal HEMT model

We propose an empirical large-signal model of high electron mobility transistors (HEMTs). The bias-dependent data of small-signal equivalent circuit elements are obtained from S-parameters measured at various bias settings. And C_gs, C_gd, g_m, and g_ds, are described as functions of V_gs and V_ds. We included our large-signal model in a commercially available circuit simulator as a user-defined model and designed a 30/60-GHz frequency doubler. The fabricated doubler's characteristics agreed well with the design calculations     

Analytical nonlinear HEMT model for large signal circuit simulation

A new nonlinear high electron mobility transistor (HEMT) model based on the Curtice model is described. This model introduces terms for the leakage current for subthreshold bias, drain voltage dependencies of knee voltage, drain conductance and threshold voltage, transconductance enhancement at high frequencies caused by DX centers, and the bias dependence of capacitance. Applying this model to pseudomorphic double-recessed gate HEMT's gives an average error of 2.6% for DC current and 10% for S-parameters     

A new equivalent MOSFET representation of a HEMT to analyticallymodel nonlinear charge control for simulation of HEMT devices andcircuits

It is shown that, from the point of view of the behavior of the charge and position of the Two-Dimensional Electron Gas (2-DEG) as a function of gate-source and drain-source voltages, the complex High Electron Mobility Transistor (HEMT) can be regarded as a simple Buried-Channel (BC) MOSFET. Thus, the characteristics of a HEMT, namely channel charge and capacitance/transconductance as a function of gate voltage below and above threshold are akin those of a BC MOSFET. Hence, there are discrepancies in the conventional Surface Channel MOSFET-like approach to HEMT modeling. Existing simple BC MOSFET dc and ac models can be used for on-paper analysis and computer aided simulation of HEMT devices and circuits, if the HEMT is represented by an equivalent BC MOSFET as derived in this paper. The new representation can be useful for modeling of short-channel HEMT phenomena     

一种HEMT器件可缩放的非线性紧凑模型

提供了一种应用于高电子迁移率晶体管(HEMT)的非线性紧凑模型。该模型针对传统的EE-HEMT模型理想缩放规律不准确的问题,提出采用一元函数拟合、二元曲面拟合方法,对其尺寸缩放和温度缩放规律进行修正。修正后的非线性模型可以准确地模拟HEMT器件的直流I-U、S参数和大信号特性。并将该模型应用于一款0.25 μm栅长的GaAs pHEMT工艺,对比不同尺寸的器件在高低温条件下模型仿真结果和实测结果,两者吻合良好,验证了该模型的准确性。     

Table-based nonlinear HEMT model extracted from time-domain large-signal measurements

This paper presents an empirical table-based nonlinear HEMT model fully extracted from time-domain large-signal measurements. A simple and direct extraction procedure, based on a vector nonlinear network analyzer measurement system with load-pull facilities, demonstrates by experimental results on microwave transistors how a very reduced number of measurements is enough to obtain the current and charge generators to fill a lookup model. Table-based model extraction, implementation, and validation are described in this paper.     

Triple-channel InP-based HEMT with highly nonlinear transconductance for nonlinear circuit applications

The authors report the development of a triple-channel HEMT with two undoped In/sub 0.53/Ga/sub 0.47/As layers and a spike-doped In/sub 0.52/Al/sub 0.48/As layer on InP, designed to have a strongly nonlinear transconductance. The effective electron velocity and the electron density in the InGaAs layers are higher than in the thick InAlAs layer resulting in a highly nonlinear transconductance device with the potential for improved performance in nonlinear microwave circuit applications, as compared with conventional MESFETs and HEMTs.<>     

A nonlinear integral model of electron devices for HB circuitanalysis

A technology-independent large-signal model of electron devices, the nonlinear integral model (NIM), is proposed. It is rigorously derived from the Volterra series under basic assumptions valid for most types of electron devices and is suitable for harmonic-balance circuit analysis. Unlike other Volterra-based approaches, the validity of the NIM is not limited to weakly nonlinear operation. In particular, the proposed model allows the large-signal dynamic response of an electron device to be directly computed on the basis of data obtained either by conventional measurements or by physics-based numerical simulations. In this perspective, it provides a valuable tool for linking accurate device simulations based on carrier transport physics and harmonic-balance circuit analysis algorithms. Simulations and experimental results, which confirm the validity of the NIM, are also presented     

基于非线性电阻的GaN HEMT经验基大信号模型

为了实现建立准确的氮化镓高电子迁移率晶体管（GaN high electron mobility transistor,GaN HEMT）大信号模型的目的,提出了一种基于非线性电阻的GaN HEMT经验基大信号模型. 通过对GaN HEMT在高漏极偏置和高电流密度下的电阻特性分析,将受漏源电流控制的非线性电阻模型嵌入经验基大信号模型中. 结合Matlab和ADS提取模型初值,在ADS中建立完整的大信号符号定义模型. 选择栅长为0.25 μm,栅宽分别为2×200 μm、2×250 μm、4×200 μm的GaN HEMT进行直流输出特性和大信号输出特性仿真验证,结果表明本文模型与测试数据具有较高的吻合性. 该大信号模型提高了经验基大信号模型的物理特性,具有较高的精度及良好的缩放性.     

RF properties of epitaxial lift-off HEMT devices

Epitaxial layers containing GaAs HEMT and P-HEMT structures have been lifted off the GaAs substrate and attached to other host substrates using an AlAs parting layer. The devices were on-wafer RF probed before and after the lift-off step, showing no degradation in the measured S-parameters. The maximum stable gain indicates a low frequency enhancement of the gain of 1-2 dB with some devices showing a consistent increase of F_T of 12-20% for all lifted-off HEMT structures. Comparison of the Hall measurements and small signal models show that the gain is improved and this is most probably associated with an enhanced carrier concentration     

A new empirical nonlinear model for sub-250 nm channel MOSFET

An empirical nonlinear model for sub-250 nm channel length MOSFET is presented which is useful for large signal RF circuit simulation. Our model is made of both analytical drain current and gate charge formulations. The drain current expression is continuous and infinitely derivable, and charge conservation is taken into account, as the capacitances derive from a single charge expression. The model's parameters are first extracted, prior the model's implementation into a circuit simulator. It is validated through dc, ac, and RF large signal measurements compared to the simulation.     

氮化镓HEMT器件辐射效应综述

在高频、大功率、高温、高压等领域,氮化镓高电子迁移率晶体管(HEMT)器件因其优异的耐辐射性能而被广泛地应用于卫星、太空探测、核反应堆等领域。尽管从理论和一些试验研究中可以得知,氮化镓材料具有良好的耐辐射特性,但在实际应用中,因其制作工艺及结构等因素的影响,氮化镓HEMT器件的耐辐射特性受到了很大的影响和挑战。本文介绍了氮化镓HEMT器件几种辐射效应,并对氮化镓HEMT器件辐射的研究进行了综述。     

HEMT器件质子辐射效应仿真

GaN基高电子迁移率晶体管(HEMT)器件具有抗高频、耐高温、大功率、抗辐射等特性,在核反应堆、宇宙探测等辐射环境中具有广阔的应用前景。借助SRIM软件仿真1.8 MeV质子辐射对不同AlGaN势垒层纵向尺寸下的常规耗尽型器件内部产生空位密度的影响,并观察空位密度随深度的变化规律。在最优AlGaN势垒层厚度条件下,通过仿真对比5种不同栅氧层材料的MIS-HEMT器件,发现氮化铝(AlN)栅氧层材料具有相对较好的抗辐射效果。     

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.     

Measurement of mobility in HEMT devices using high-order derivatives

In this paper, a novel approach to the measurement of mobility of GaAs HEMT devices is presented. The new approach employs high-order derivatives as a means of determining the parameters of the proposed new mobility equation. The new approach is compared to established mobility measurement methods, and shown to offer better accuracy. The results presented also consider the behavior of mobility in the linear and saturation bias regions. The mobility value extracted by this new method has permitted improvements to the MESFET/HEMT model when simulating the behavior of the device in the linear region. This is critical in many applications, such as in low current linear-mixing applications.     

氮化镓HEMT器件的新型Cold FET模型

改进等效寄生电感的提取对提高小信号等效电路模型的仿真精度具有重要意义,尤其是氮化镓器件(GaN).针对传统的等效寄生电感提取方法,本文推导了用于GaN HEMT器件的新型Cold FET模型及参数提取.通过对栅宽分别为200μm和1000μtm GaN HEMT的仿真/测试,表明:新的Cold FET模型可用于GaN HEMT器件等效寄生电感的提取.这将有助于场效应晶体管模型的研究.     

Novel structure of GaAs-based interdigital-gated HEMT plasma devices for solid-state THz wave amplifier

Theoretical analysis of potential distribution in the interdigital-gated high electron mobility transistor (HEMT) plasma wave device was carried out. The dc I–V characteristics of capacitively coupled interdigital structure showed that uniformity of electric field under the interdigital gates was improved compared to the dc-connected interdigital gate structure. Admittance measurements of capacitively coupled interdigital gate structure in the microwave region of 10–40 GHz showed the conductance modulation by drain–source voltage. These results indicate the existence of plasma wave interactions.     

AlGaN/GaN HEMT小信号模型参数提取算法

本文采用了新型的22元件AlGaN/GaN HEMT小信号等效电路模型,较传统的模型,增加了栅漏电导Ggdf和栅源电导Ggsf来表征GaN HEMT的栅极泄漏电流。同时针对新型的栅场板、源场板结构器件,提出了一种改进的寄生电容参数提取方法,使之适用于提取非对称器件的小信号模型参数。为验证此模型,获得了S参数的测试结果和模型仿真结果,此二者的吻合度较高,表明新型的22元件小信号模型精确、稳定而且物理意义明确。     

Temperature dispersion in KTP for nonlinear devices

Thermo-optic coefficients (dn/dT) determine the temperature characteristics of the nonlinear optical laser devices. These coefficients are analyzed critically by using a new model for the first time to formulate the temperature dispersion which can predict accurately the temperature bandwidths for various nonlinear interactions in a flux-grown KTP crystal. This model is based on the optical bandgaps, such as excitonic, a newly identified isentropic, and the thermal expansion coefficient