GaAs MESFET开关的设计和建模

简要分析了MESFET开关的等效电路模型和MESFET开关器件的设计考虑，以及材料参数和器件结构对开关性能的影响，并设计制作了6组不同栅宽的MESFET开关．应用Modeling建模软件，分别对6组不同栅宽的MESFET开关进行建模，提取出开关的等效电路模型参数；从参数分析中找到了其随栅宽的线性变化规律，根据此变化规律，可以实现对任意栅宽MESFET开关的定标。     

X波段GaAs单片五位数字移相器

设计并制作了X波段五位GaAs MMIC(微波单片集成电路)数字移相器,采用MESFET作为开关元件,五个移相位线性级联布置。在9～10GHz的频率范围内,用HP-8510网络分析仪测试得到的微波性能表明:移相器的插入损耗为(7.2±1)dB,RMS(均方根)相位误差小于5°,回波损耗优于-13dB。     

InGaP/GaAs HBT单管6GHz 大功率低噪声压控振荡器

A 6 GHz voltage controlled oscillator （VCO） optimized for power and noise performance was designed and characterized. This VCO was designed with the negative-resistance （Neg-R） method, utilizing an InGaP/GaAs hetero-junction bipolar transistor in the negative-resistance block. A proper output matching network and a high Q stripe line resonator were used to enhance output power and depress phase noise. Measured central frequency of the VCO was 6.008 GHz. The tuning range was more than 200 MHz. At the central frequency, an output power of 9.8 dBm and phase noise of-122.33 dBc/Hz at 1 MHz offset were achieved, the calculated RF to DC efficiency was about 14%, and the figure of merit was -179.2 dBc/Hz.     

采用Ni/Ti/Ni多层金属在N型4H-SiC衬底改善粘附性和界面的欧姆接触

The Ni/Ti/Ni multilayer ohmic contact properties on a 4H-SiC substrate and improved adhesion with the Ti/Au overlayer have been investigated. The best specific contact resistivity of 3.16 × 10^-5 Ω.cm^2 was obtained at 1050 ℃. Compared with Ni/SiC ohmic contact, the adhesion between Ni/Ti/Ni/SiC and the Ti/Au overlayer was greatly improved and the physical mechanism under this behavior was analyzed by using Raman spectroscopy and X-ray energy dispersive spectroscopy （EDS） measurement. It is shown that a Ti-carbide and Ni-silicide compound exist at the surface and there is no graphitic carbon at the surface of the Ni/Ti/Ni structure by Raman spectroscopy, while a large amount of graphitic carbon appears at the surface of the Ni/SiC structure, which results in its bad adhesion. Moreover, the interface of the Ni/Ti/Ni/SiC is improved compared to the interface of Ni/SiC.     

基于InGaP/GaAs HBT的X波段MMIC功率放大器研制

研制了X波段的InGaP/GaAs HBT单级MMIC功率放大器,该电路采用自行开发的GaAs HBT自对准工艺技术制作.电路偏置于AB类,小信号S参数测试在8～8.5GHz范围内,线性增益为8～9dB,输入驻波比小于2,输出驻波比小于3,优化集电极偏置后,线性增益为9～10dB.在8.5GHz进行连续波功率测试,在优化的负载阻抗条件下,P1dB输出功率为29.4dBm,相应增益7.2dB,相应PAE〉40%,电路的饱和输出功率Psat为30dBm.     

基于InGaP/GaAs HBT的X波段MMIC功率放大器研制

研制了X波段的InGaP/GaAs HBT 单级MMIC功率放大器,该电路采用自行开发的GaAs HBT自对准工艺技术制作.电路偏置于AB类,小信号S参数测试在8～8.5GHz范围内,线性增益为8～9dB,输入驻波比小于2,输出驻波比小于3,优化集电极偏置后,线性增益为9～10dB.在8.5GHz进行连续波功率测试,在优化的负载阻抗条件下,P1dB输出功率为29.4dBm,相应增益7.2dB,相应PAE＞40%,电路的饱和输出功率Psat为30dBm.     

C波段3.5W/mm,PAE＞40%的InGaP/GaAs HBT功率管

通过优化InGaP/GaAs异质结双极晶体管(HBT)的材料结构和器件结构,采用BE金属自对准、发射极镇流和电镀空气桥等工艺技术,研制了C波段InGaP/GaAs HBT功率管.其击穿电压BVCBO大于31V,BVCEO大于21V;在5.4GHz时连续波(CW)饱和输出功率达到1.4W,功率密度达到3.5W/mm,功率附加效率(PAE)大于40%.     

C波段3.5W/mm,PAE＞40%的InGaP/GaAs HBT功率管

通过优化InGaP/GaAs异质结双极晶体管(HBT)的材料结构和器件结构,采用BE金属自对准、发射极镇流和电镀空气桥等工艺技术,研制了C波段InGaP/GaAs HBT功率管.其击穿电压BVCBO大于31V,BVCEO大于21V;在5.4GHz时连续波(CW)饱和输出功率达到1.4W,功率密度达到3.5W/mm,功率附加效率(PAE)大于40%.     

GaAs MMIC用无源元件的模型

制作了不同结构参数的GaAs MMIC无源元件,包括矩形螺旋电感、MIM电容和薄膜电阻,建立了无源元件的等效电路模型库,采用多项式公式表征无源元件的模型参数和性能参数,便于电路设计的应用.并提取得到MIM电容的单位面积电容值,约为195pF/mm2,NiCr薄膜电阻的方块电阻约为16.1Ω/□.分析结构参数对螺旋电感性能的影响可知,减小线圈面积相关的寄生损耗有助于获得高品质的电感.     

具有在片稳定网络的GaAs HBT微波功率管

采用GaAs标准MMIC工艺制作了具有片上RC并联稳定网络的InGaP/GaAs HBT微波功率管单胞.依据K稳定因子,RC网络使功率管在较宽的频带内具有绝对稳定特性.Load-pull测试表明RC网络没有严重影响功率管的大信号特性,在5.4GHz饱和输出功率为30dBm,在11GHz 1dB压缩点输出功率大于21.6dBm.功率合成电路验证了该功率管具有高稳定性,非常适合制作微波大功率HBT放大器.