AlGaN/GaN HEMT器件建模技术研究

【作者】 徐鹏；

【导师】 于奇；

【作者基本信息】 电子科技大学 ， 微电子学与固体电子学（专业学位）， 2012， 硕士

【摘要】 AlGaN/GaN HEMT器件由于其高温、高频、大功率等特性方面的优势,已经在微波大功率电路方面得到了广泛应用。成功的电路设计需要准确的器件建模,小信号建模和大信号建模在微波电路设计中占有重要位置。AlGaN/GaN HEMT器件的小信号建模已经进行了广泛的研究,然而在高频部分的拟合结果并不理想。这主要是由于当器件的工作频率高于40GHz时共面波导效应的影响非常明显,所以在小信号等效电路模型中引入了栅源和栅漏共面波导电容Ccpwgs和Ccpwgs。同时引入了栅微分电阻Rfs和Rfd来表征的器件的栅极泄漏电流。在提取小信号等效电路模型参数中的寄生电容时,栅压正偏,栅微分电阻不能忽略；器件的工作频率很高,二维电子气层相当于传输线,其分布效应不能忽略。基于传统的提取算法,通过对不同栅压偏置下冷场z参数进行线性插值运算,消除了沟道分布电阻和栅微分电阻的影响,准确提取得到寄生电阻。寄生参数提取完成后,用不同偏置下的热场S参数对寄生参数部分进行去嵌得到本征Y参数,运用本征参数提取算法得到所有偏置下的本征参数值。分析表明,S参数的仿真结果与测试数据在200MHz到50GHz的频率范围内均符合很好。进而建立了AlGaN/GaN HEMT器件的大信号等效电路模型,模型包括了压控电流源以及与偏置相关的电容模型元件。运用的I-V模型能够在较大的电压范围内拟合漏电流测试结果。并提出了改进的C-V模型,运用此改进模型对器件的C-V特性进行拟合,模型拟合数据与测试数据得到了很好的符合。更多还原

【Abstract】 The AlGaN/GaN high electron mobility transistors (HEMTs) have great potential in microwave and power applications due to its high power, high frequency and high temperature characteristics. The successful system level design of microwave circuits requires accurate device modeling, so small-signal and large-signal equivalent circuit model play an important role.Small-signal modeling of AlGaN/GaN HEMTs have been studied in many literatures. However, it is still difficult to obtain precise agreement between simulation and measurement result in a wide-band frequency range (specially for higher than40GHz), because when AlGaN/GaN HEMT operates above40GHz, the coplanar waveguide (CPW) effect is obviously. In this work, CPW capacitances (CCPW) were considered in the small-signal equivalent circuit of AlGaN/GaN HEMT. Add gate differential resistance Rfs and Rfd to reflect the device gate leakage current.When extract the parasitic resistance, the gate voltage is positively biased, gate differential resistance can not be ignored. AlGaN/GaN HEMTs operating frequency is very high,2DEG channel is equivalent to a section of transmission line and the distributed effects can not be ignored. On the basis of the traditional small-signal equivalent circuit model parameter extraction algorithm, the effects of channel resistance and gate leakage current are eliminated by linear interpolation for cold Z-parameters under different gate bias. Then, de-embed the effects of parasitic, the intrinsic values can be obtained. Analysis show that, in the200MHz to40GHz frequency range, S-parameters of the simulation results and measured data are in good agreement.Thereby, a large-signal equivalent circuit model is established and applied to the device. The model includes voltage-controlled current source and bias-dependent capacitance model element. The drain current equation accurately models the Ids over a large range of biases. An improved C-V model is introduced that accurately present the C-V characteristics.更多还原