摘要
摘要
AlGaN/GaN HEMT器件的工作频率比较高，功率密度比较大，而且耐高温、线性度好、易匹配、输入阻抗高，广泛应用于单片微波集成电路（MMIC）当中。而研发人员在设计微波集成电路时首先采用合适的GaN HEMT器件模型对MMIC进行仿真设计，降低了研发费用，设计成功率得到了极大的提高，同时也缩短了研发周期，因此准确的AlGaN/GaN HEMT器件模型对微波集成电路的设计来说有着重要的意义，本文以AlGaN/GaN HEMT器件为基础，围绕小信号等效电路模型和大信号等效电路模型展开研究工作，主要工作内容有以下几点： 1）依据本次研究的需要，选择合适的AlGaN/GaN HEMT器件，最终选择的器件型号是AM005WN-BI-R。为了测量该器件的S参数以方便开展后续工作，设计了测量器件S参数的测试夹具以及TRL校准件，并在矢量网络分析仪上测量了该器件在不同偏置下1-6GHz的S参数。 2）对于传统的14个元器件的小信号等效电路模型而言，其结构简单，模型参数少，提取模型参数比较方便，但是没有考虑AlGaN/GaN HEMT器件在高频下的频散效应，模型精度不够高；而22个模型参数的小信号等效电路模型考虑了器件在高频下的一些寄生效应，模型精度高，但是等效电路模型结构复杂，模型参数较多，提取模型参数比较困难；本文结合14个元器件的小信号等效电路模型和22个模型参数的
小信号等效电路模型的优缺点，折中采用了18个元器件的小信号等效电路模型，该模型在14个元器件小信号等效电路模型的基础上，考虑了电极之间的寄生电容对AlGaN/GaN HEMT器件在高频下电学特性的影响，模型精度较高，而且模型参数的提取相对比较容易。
本文基于测量得到GaN HEMT器件的S参数，分别提取了小信号模型的寄生参数，然后通过去嵌的方法提取了本征参数，最后在ADS中对模型和模型参数进行了验证。具体的做法是：利用器件偏置在截止状态下的S参数，提取了模型的寄生电容；利用器件在零偏状态下的S参数，提取了模型的寄生电阻和寄生电感；利用器件在正常工作下的S参数，通过S参数、Y参数和Z参数之间的相互转化，去嵌得到了模型的本征参数；最后在ADS中搭建小信号模型的等效电路，通过比较测量得到的S 参数和仿真得到的S参数，验证了本文采用的小信号等效电路模型和模型参数有很高的精度。
3）通过比较经典的几种大信号等效电路模型，本文采用了EEHEMT大信号等效电路模型，该模型考虑了GaN HEMT器件在大信号下的自热效应和在高频下的频散效应，模型精度较高。基于在不同偏置下测量得到的S参数和提取得到的小信号模
型参数，拟合了g m~V gs曲线和C gs~V gs曲线，并结合EEHEMT大信号模型的特点，提取了大信号模型参数；并在ADS中搭建了验证EEHEMT大信号模型及模型参数的模拟电路，通过比较测量得到的
S参数和仿真得到的S参数，验证了EEHEMT大信号模型和模型参数的精度。
关键词：AlGaN/GaN HEMT，S参数，小信号等效电路模型，大信号等效电路模型，模型参数
ABSTRACT
ABSTRACT
AlGaN/GaN HEMT device has high operating frequency, high power density, high temperature resistance, good linearity, easy matching and high input impedance, which is widely used in monolithic microwave integrated circuits (MMIC). The Research and development personnel in the design of microwave integrated circuits using suitable GaN HEMT device model for simulation and design of MMIC, which reduces the development costs, the success rate of the design has been greatly improved, but also shorten the development cycle, so accurate AlGaN/GaN HEMT model is very important for designing microwave integrated circuit. Based on the AlGaN/GaN HEMT device, this paper studies the small signal equivalent circuit model and the large signal equivalent circuit model. The main contents are as follows:
According to the needs of this study, select the appropriate AlGaN/GaN HEMT device, the final choic
e of the device type is AM005WN-BI-R. In order to measure the S-parameters of the device to facilitate the follow-up work, I designed a test fixture and a TRL calibrator，and measured the S-parameters of the device with 1-6GHz at different Bias voltage using the vector network analyzer.
For the small-signal equivalent circuit model of the traditional 14 components, the structure is simple, the model parameters are few, and get the model parameters are easy , but the model are not considered the dispersion effect at high frequency for AlGaN/GaN HEMT devices, the precision of the model is not high enough. And The model of the small signal equivalent circuit of 22 model parameters considering some parasitic effects of the device at high frequencies, and the model has high accuracy, however, the equivalent circuit model is complex and the model parameters are difficult to get. This paper uses a small signal equivalent circuit model of 18 components, which is based on the 14-component small-signal equivalent circuit model, taking into account the influence of the parasitic capacitance between the electrodes on the electrical characteristics of AlGaN/GaN HEMT devices under high frequency, the model accuracy is higher and the extraction of model parameters is relatively easy.
Based on the measured S-parameter of the GaN HEMT device, I extract the parasitic
parameters of the small signal model and then extract the intrinsic parameters by the method of de-embedding. Finally, the model and model parameters are validated in ADS. The specific approach is: Firstly, the parasitic capacitance of the model is extracted by using the S-parameter of the device in the cut-off state, and the parasitic resistance and parasitic inductance of the model are extracted by using the S-parameter of the device in the zero-bias state. Then the intrinsic parameters of the model are obtained by the mutual transformation between the S-parameter, the Y-parameter and the Z-parameter using the S-parameter of the device under normal operation. Finally, setting up the equivalent circuit of the small signal model in ADS, by comparing the S-parameters obtained by the measurement and by the simulation, it is verified that the small signal equivalent circuit model and model parameters adopted in this paper have high precision.
Based on the analysis of several classical large signal equivalent circuit models, the EEHEMT large signal equivalent circuit model is adopted in this paper, which considers the self-heating effect under the large signal and high frequency dispersion effect of the GaN HEMT devices and the model precision is high. Based on the S-parameters measured under different Bias voltage and the small-signal model parameters, I extracted the large signal model parameters by fitting the g m~V gs curve and the C gs~V gs curve and combining the characteristics of the EEHEMT large signal model. In or
der to verify the EEHEMT large signal model and model parameters,I set up the artificial circuit in ADS, and the accuracy of the EEHEMT large signal model and model parameters is verified by comparing the measured S-parameters with the simulated S-parameters.
Keywords: AlGaN/GaN HEMT, S-parameters, Small signal equivalent circuit model, Large signal equivalent circuit model, Model parameters
插图索引
插图索引
图 2.1AlGaN/GaN HEMT器件结构示意图 (12)
图 2.2二端口网络框图 (16)
图 2.3二端口网络S参数框图 (18)
视音频切换器
图 2.4器件S参数测量系统框图 (19)
图 3.1矢量网络分析仪的测量系统简化框图 (21)
图 3.2测试系统的信号流图示意图 (21)
图 3.3TRL测试架结构示意图 (27)
图 3.4AM005WN-BI-R芯片实物图 (28)
图 3.5TRL校准示意图 (28)
针式吸盘图 3.6安装了芯片的测试架实物图 (28)
图 3.7测试芯片S参数实物图 (29)
图 4.114个元器件的小信号等效电路模型 (31)
图 4.222个模型参数的小信号等效电路模型 (32)
图 4.3本文采用的18个元器件的小信号等效电路模型 (32)
图 4.4AlGaN/GaN HEMT器件小信号模型建立的总体方案 (33)
农药渗透剂图 4.5在截止情况下简化的小信号等效电路模型 (36)
试衣图 4.6在零偏情况下简化的小信号等效电路模型 (37)
图 4.7去嵌得到小信号模型本征参数的流程图 (40)
图 4.8小信号模型本征参数构成的网络示意图 (40)
图 4.9GaN HEMT器件在Vgs=-2V，Vds=28V时测量得到的S参数 (42)
电子倾斜仪
图 4.10用测量得到的S参数进行S参数仿真的电路图 (42)
图 4.11用测量的S参数仿真得到的S参数曲线 (43)
图 4.12小信号等效电路模型在ADS中的仿真验证电路图 (44)
图 4.13用小信号等效电路模型仿真得到的S参数曲线 (44)
溴化丁基橡胶
图 4.14测量的S参数曲线和用小信号模型仿真的S参数比较图 (45)
图 5.1Curtice立方模型的等效电路图 (49)
图 5.2Angelov模型的等效电路图 (51)
图 5.3CPC模型的等效电路图 (53)
图 5.4EEHEMT模型的等效电路图 (54)
图 5.5EEHEMT模型的跨导曲线示意图 (55)
图 5.6拟合得到的gm~Vgs曲线示意图 (55)
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