摘要
近年来,第三代半导体材料GaN以其禁带宽度大、饱和漂移速度高、临界击穿电场高和热导率高等独特的优势,成为最令人瞩目的新型半导体材料之一。各项研究表明,GaN HEMT微波内匹配大功率器件,因其具有体积小、重量轻、输出功率大、工作温度高等方面的优势,将在各类通信、雷达、导航等设备中得到了广泛的应用,特别是在航空、航天、相控阵雷达等特殊领域要求整机小型化方面,具有较大的应用前景。在以上背景下,对GaN HEMT进行了微波功率特性研究和大功率内匹配GaN HEMT器件的研制的工作。
对自主研制的2mm栅宽GaN HEMT的直流和微波功率性能进行了研究。研究结果表明,该GaN HEMT电流崩塌小于15%,饱和电流可以达到1000mA/mm,跨导为240mS/mm,截至频率ft可以达到40GHz以上。最大功率输出高于10W,功率增益高于6dB,功率附加效率高于36%。
利用Curtice立方模型,对2mm栅宽GaN HEMT进行了大信号建模。首先进行精确I-V和S参数测量,从这些数据中提取C_FET3 I-V模型、栅源电容和栅漏电容模型中的参数,以及其他寄生参数。经过验证,这种模型可以达到使用要求。在Vds=28V、Vgs=-3.6V时,模型的输入阻抗和输出阻抗分别为:(14.2-j8.3)Ω和(5.2-j4.4)Ω。
最后,基于2mm栅宽GaN HEMT阻抗和输出功率的特点,设计并制作了四管芯合成的内匹配电路,进行了封装和微波功率测试。利用wilkinson功分器设计了一分四功分器。器件栅极通过T型阻抗匹配网络连接至功分器,漏极直接连接至功分器。利用ADS软件对整个电路进行计算机仿真和优化计算,最终确定了电路中各元件参数。各电路元件制作完成后,对器件进行了封装和微波功率测试。结果表明,X波段输出功率高于30W,此时增益为6.8dB,功率附加效率为38.2%。
In recent years, the third-generation semiconductor material GaN with advantages of wide bandgap, high electron saturated velocity, high critical breakdown field and high thermal conductivity, is becoming the most attractive one of new type semiconductor materials. Various studies show that high-power internal matching GaN HEMT , because of its small size, light weight, high output power, high Operating temperature, in all types of communication, radar and navigation equipment ,have been widely applied in the aviation, aerospace, phased array radar, and will have greater prospect. Basing on above background, this paper advised to study GaN HEMT microwave power characteristics and to develop independently high-power internal matching GaN HEMT.
DC and microwave power performance of self-developed GaN HEMT of 2mm gate-width was studied. Study results showed that the GaN HEMT current collapse is less than 15 percent. Saturation currents can reach 1000 mA/mm. The transconductance of 240 mS/mm. Cut-off frequency can reach 40 GHz. The maximum output power is above 10W, power gain is higher than 6dB, and power-added efficiency is higher than 36%.
By Curtice cubic model, Large signal model has been built for self-developed GaN HEMT of 2mm gate-width. After measuring accurately I-V and S-parameter for modeling, the parasitic parameters and parameters of I-V, Cgs and Cgd model were extracted. The Certification proves that the model can be used for computer simulation. At Vds = 28V, Vgs = 3.6V, the input impedance and the output impedance are as follows: (14.2-j8.3) ? and (5.2-j4.4) ?. Basing on characteristics of output-power and impedance of self-developed GaN HEMT
of 2mm gate-width, the internal matching circuit and Splitters have been designed, and package and microwave power testing have been made. According to Wilkinson splitters, a one-to-four splitter has been designed. Through T-section impedance matching network, the gate connected whit splitter, and drain directly connected with splitter. Computer simulation and optimization has been done for the circuit by ADS, and ultimately the parameters of components in the circuit were determined. After the package device has been accomplished, microwave power testing has been made. Results show that the X-band output power is above 30W, at this time gain of 6.8dB, power-added efficiency of 38.2%.
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