MMIC用多层磁膜电感研究

采用磁控溅射生长磁膜工艺,结合BCB(苯并环丁烯)平坦化技术,首次制作了"金属线圈/磁膜/金属线圈(M/F/M)"和"磁膜/金属线圈/磁膜/金属线圈(F/M/F/M)"两种结构的多层磁膜电感,整个工艺与标准MMIC工艺兼容.在2 GHz处,"金属线圈/磁膜/金属线圈"结构电感的电感量为7.5 nH,品质因数为7.17,...     

微波FET有源电感的分析

提出用FET实现四种高性能的微波有源电感基本电路结构，通过分析各个电路的特性表明，这四个有源电感均是低损耗或无损耗的。另外还选择了其中的一种电路结构，详细分析了FET参数变化对有源电感用抗的影响。     

GaAs MMIC在移动通信中的应用

便携式无线通信系统是ＧａＡｓＭＭＩＣ潜在的民用大户。在简要陈述该新兴市场现状及前景的基础上，着重讨论ＧａＡｓＭＭＩＣ占据该市场并成为其核心技术的策略。     

GaAs MMIC抗静电能力研究

用人体静电放电模拟器对以ＧａＡｓ ＭＥＳＦＥＴ为主要有源器件的ＭＭＩＣ的静电敏感度进行研究,叙述了在ＭＭＩＣ设计、工艺制作等环节防静电和提高ＭＭＩＣ抗静电能力的措施,采用这些措施后,低噪声ＭＭＩＣ静电损伤阈值达到５００～８００ Ｖ。     

提高砷化镓功率MMIC中电容成品率的研究

金属－绝缘体－金属（ＭＩＭ）电容量影响ＧａＡｓ微波单元集成电路（ＭＭＩＣ）成品率的主要原因之一，ＰＥＣＶＤ氮化硅膜又是影响ＭＩＭ电容质量和成品率的主要因素。本文通过实验和分析，提出了提高氮化硅膜质量和减少薄膜针孔的方法，结果大大提高了ＭＩＭ电容ＧａＡｓＭＭＩＣ的成品率，降低了ＧａＡｓ ＭＭＩＣ的成本。     

蓬勃发展的GaAs MMIC──1994 IEEE GaAs IC讨论会侧记

本文简要介绍了１９９４年ＧａＡｓＩＣ讨论会概况以及所展示的ＧａＡｓＭＭＩＣ的进展，并侧重于其应用领域的介绍。     

GaAs MMIC可靠性研究与进展

介绍了GaAs器件及MMIC的可靠性研究现状 ,给出了GaAs器件的几种失效模式和失效机理     

高效率GaN MMIC优化技术的研究

使用国产SiC衬底的GaN HEMT外延材料实现了大功率、高效率的GaN HEMT器件,建立了大信号模型,利用ADS软件建立了GaN MMIC的拓扑,仿真了驱动比对电路性能的影响.仿真结果表明,驱动比由2(电路1)增加到3(电路2),效率提高10%.工艺上分别实现了两种电路,测试表明,效率由25%(电路1)提高到30%(电路2),验证了仿真结果.电路2在测试频率为8-10 GHz时,脉冲输出功率大于21 W,增益大于15 dB,效率大于35%;频率为8 GHz时,输出功率最大值为25 W,效率最大值为45%,具有较好的性能.     

MMIC在片测试探头的研究与设计

微波单片集成电路（MMIC）在片测试技术是应用于MMIC和高速集成电路研究、生产的新型测试技术。MMIC在片测试探头是MMIC在片测试系统的关键部件。本文研究并设计了介质基片共面波导（CPW）探头,测试并分析了探头性能。该探头在2－18GHz范围内插入损耗小于1．5dB,回波损耗大于16dB。     

MMIC毫米波倍频器的研究

在介绍倍频器工作原理、各种实现方法及其优缺点的基础上,阐明了采用MMIC(单片微波集成电路)工艺实现高性能、高可靠性、小型化毫米波倍频器芯片的技术特点及应用需求,比较了单管和平衡两种不同结构MMIC毫米波倍频器的优点与不足,全面综述了国内外对MMIC毫米波倍频器的研究情况,介绍了MMIC毫米波倍频器的最新研究进展,展望了MMIC毫米波倍频器的发展趋势,提出了一些建议。     

射频集成电感器的快速傅立叶变换模拟及制备

应用磁像法和快速傅立叶变换（FFT）法对单片微波集成电路（MMIC）的薄膜平面射频集成电感器进行了电磁学模拟，并把模拟结果和有限元法（FEM）模拟的结果进行了比较。根据模拟结果，对薄膜平面射频集成电感器结构参数和加工参数进行了优化，改进了薄膜平面频集成电感器的工艺方案。最后结合薄膜平面射频集成电感器薄膜的高频损耗分析，讨论了平面薄膜集成电感器薄膜微细加工技术。     

Study of the Thin Film Pulse Transformer

A great interest has been attracted in planar magnetic devices to miniature various electronic equipment including pulse transformers and inductors, especially for the IT electronics applications and ISND modem systems, such as switching converters and inverters in portable equipments[1~3]. In Internet system,the thin film pulse transformer, with the sandwich structure of core/coil/core and coil/core/coil, in general,will be fabricated directly on ceramics substrate by lithography and ion et…     

Enhanced Nucleation of Vortices in Soft Magnetic Materials Prepared by Silica Nanosphere Lithography

Magnetic vortices show promise as data storage structures, however the vortex formation process imposes a lower limit on the element’s size. In this article a technique is presented, which application increases the probability of nucleating of magnetic vortices in sub‐micrometer sized soft magnetic thin film elements. By tailoring the edge geometry of the elements, the symmetry of their magnetic configuration is broken in a manner which favors vortex nucleation. Micromagnetic simulations are presented, which demonstrate this effect in soft‐magnetic disks with beveled edges. The favored edge geometry is realized by applying nanosphere lithography directly on top of a ferromagnetic thin film material. In this process, the film is masked with a self assembled monolayer of SiO₂‐nanospheres and subsequently ion‐etched. The resulting magnetic reversal loops show that in both magnetically isolated as well as in closely packed arrays of beveled disks, vortex formation takes place. The technique presented facilitates the vortex formation even in closely packed and small elements. The lowering of the minimum critical diameter for vortex formation enables a significant increase of data storage density in devices based on magnetic vortices.     

纳米Fe-In2O3颗粒膜的低温磁效应

采用射频溅射法制备了纳米Fe—In2O3颗粒膜，研究了颗粒膜在低温下的两种特殊磁效应——巨磁电阻效应和磁性弛豫效应。磁电阻测量结果表明，当Fe体积分数为35％时，颗粒膜样品的室温磁电阻变化率(△ρ/ρ0)为4．5％，而在温度T=2K时，∑ρ／ρ0达85％。根据颗粒膜低场磁化率-温度(x-T)关系证实，在一定温度下，颗粒膜中纳米Fe颗粒表现出磁性弛豫效应，当截止温度TB=50K时，颗粒膜的磁特性由超顺磁性转变为铁磁性；在截止温度以上，其饱和磁化强度与温度关系符合Bloch的T^3/2定律。     

激光微细熔覆快速原型制造厚膜电感元件

采用激光微细熔覆快速制造技术直接将电感元件集成在电路板上,使之由插装或表面贴装元件直接转化成平面膜式电感,大大减少了焊点,缩短互连,减少了占用面积,从而提高了可靠性和电性能。另外,不需要掩模的制作和高温烧结,简化了工艺,降低了成本,提高了效率。     

Circular Nanomagnets: Enhanced Nucleation of Vortices in Soft Magnetic Materials Prepared by Silica Nanosphere Lithography (Adv. Funct. Mater. 5/2011)

Magnetic vortices show promise as data storage structures, however the vortex formation process imposes a lower limit on the element’s size. In this article a technique is presented, which application increases the probability of nucleating of magnetic vortices in sub‐micrometer sized soft magnetic thin film elements. By tailoring the edge geometry of the elements, the symmetry of their magnetic configuration is broken in a manner which favors vortex nucleation. Micromagnetic simulations are presented, which demonstrate this effect in soft‐magnetic disks with beveled edges. The favored edge geometry is realized by applying nanosphere lithography directly on top of a ferromagnetic thin film material. In this process, the film is masked with a self assembled monolayer of SiO₂‐nanospheres and subsequently ion‐etched. The resulting magnetic reversal loops show that in both magnetically isolated as well as in closely packed arrays of beveled disks, vortex formation takes place. The technique presented facilitates the vortex formation even in closely packed and small elements. The lowering of the minimum critical diameter for vortex formation enables a significant increase of data storage density in devices based on magnetic vortices.     

Fe-In2O3纳米复合颗粒膜的制备和磁特性研究

采用射频溅射法制备了“纳米铁磁金属颗粒．半导体基体”Fe-In2O3复合颗粒膜，研究了颗粒膜磁特性随晶格结构的变化规律。实验结果表明，通过真空退火处理可改变Fe-In2O3复合颗粒膜中纳米Fe颗粒的尺寸大小；颗粒膜的比饱和磁化强度σs随Fe颗粒尺寸的减小而降低，矫顽力日e随Fe颗粒尺寸的变化出现峰值，表现出磁性单畴颗粒的临界特性。     

精确高效的渐变结构片上螺旋电感的电感值分析技术

与传统的金属线宽和间距固定不变的无源片上螺旋电感相比,线宽和间距由外圈到内圈渐变的新型结构电感能有效提高电感品质因子.这种新结构电感的出现使得Jenei等人提出的闭合电感公式已不再适用于其电感值的计算,而改进的wheeler公式计算误差又较大.针对这种情况,文中提出了一种以圈为单位分圈迭代求自感,用整体平均法计算互感的平面螺旋电感的电感值计算方法.该算法分析值与HFSS仿真值相比,误差小于3%,与样品测量值相比,误差小于4%.因此该算法具有计算速度快、精度高的特点,能用于渐变结构片上螺旋电感的高效设计,并可缩短设计周期.     

Dynamic Interface Formation in Magnetic Thin Film Heterostructures

Magnetic thin film heterostructures have been widely studied for fundamental interests in the emergence of novel phenomena associated with the heterointerface formation as well as their promising practical potential. Combining X‐ray magnetic circular dichroism with scanning tunneling microscopy, it is shown for fcc Fe thin films grown on Cu(001) with Mn overlayers (Mn/Fe thin film heterostructures) that the interfacial factors dominating the electronic and magnetic properties of the entire system dynamically change with the amount of the Mn overlayer. Element specific magnetization curves of the Fe layer exhibit a two‐step spin reorientation transition from out‐of‐plane to in‐plane direction by increasing the Mn coverage. The atomic‐scale characterizations of structural and electronic properties in combination with the first‐principles calculations successfully unravel the roles of the entangled interfacial factors and clarify the driving forces of the transition. The first step of the transition at a low Mn coverage is dominantly induced by the formation of FeMn disordered alloy at the heterointerface, and the electronic hybridization with the interfacial FeMn ordered alloy is dominant as the origin of the second step of the transition at a high Mn coverage.