基于硅表面加工工艺的射频体声波滤波器研究

计算并讨论了由电极－压电薄膜－电极的三明治结构组成的体声波谐振器在有衬底情况下的阻抗，特别说明了厚的支撑膜对滤波器性能的严重影响。同时比较了在制作体声波滤波器时硅的体加工工艺和表面加工工艺的优劣，给出了利用硅的表面加工工艺制作的射频体声波滤波器的设计。     

Balanced RF Duplexer with Low Interference Using Hybrid BAW Resonators for LTE Application

A balanced RF duplexer with low interference in an extremely narrow bandgap is proposed. The Long‐Term Evolution band‐7 duplexer should be designed to prevent the co‐existence problem with the WiFi band, whose fractional bandgap corresponds to only 0.7%. By implementing a hybrid bulk acoustic wave (BAW) structure, the temperature coefficient of frequency (TCF) value of the duplexer is successfully reduced and the suppressed interference for the narrow bandgap is performed. To achieve an RF duplexer with balanced Rx output topology, we also propose a novel balanced BAW Rx topology and RF circuit block. The novel balanced Rx filter is designed with both lattice‐ and ladder‐type configurations to ensure excellent attenuation. The RF circuit block, which is located between the antenna and the Rx filter, is developed to simultaneously function as a balance‐to‐unbalance transformer and a phase shift network. The size of the fabricated duplexer is as small as 2.0 mm × 1.6 mm. The maximum insertion loss of the duplexer is as low as 2.4 dB in the Tx band, and the minimum attenuation in the WiFi band is as high as 36.8 dB. The TCF value is considerably lowered to ?16.9 ppm/°C.     

Method for improving ladder bulk acoustic wave filters rejection

This paper address design guidelines for improving the rejection of ladder bulk acoustic wave filters. An overview of the bulk acoustic wave filters technology enables to outcome the principal features of ladder filters. The lack of out-of-band rejection is currently an important weakness of this topology. The design technique presented enables to improve bulk acoustic wave ladder filters rejection by using their input/output bonding wires. Finally, the technique is used for design and fabrication of a bulk acoustic wave ladder filter for application in W-CDMA reception (2.11–2.17 GHz) front-ends. The filter measurement results show a significant improvement on the filter rejection at the transmission band (from ?19 to 34 dB) and on the return loss (from ?10 to ?16 dB) without considerable modification of filter insertion loss and selectivity.     

一种射频体声波滤波器的版图设计与仿真

射频体声波滤波器品质因子高,尺寸小,其性能已超过声表面波滤波器,将其替代传统的射频滤波器极具性能和价格优势。本文建立了适用于体声波滤波器性能分析的巴特沃斯—范戴克（MBVD）模型,采用梯形级联方式设计了一种射频体声波滤波器的版图。在此基础上以中心频率为1.99GHz,带宽56MHz的体声波滤波器为例,对不同连接级数梯形滤波器的插入损耗、阻带抑制进行了仿真与分析讨论,在4阶滤波器中其带外衰减达到了-29.708dB。采用微机电机械系统工艺制备的2阶和3阶滤波器传输特性的测试曲线与仿真结果基本吻合,表明射频体声波滤波器具有广泛的应用前景。该模拟结果可作为射频体声波滤波器设计的一个重要参考。     

体声波双工器的优化设计方法

体声波(BAW)双工器中Rx滤波器对Tx滤波器的负载效应,会使Tx滤波器的插入损耗性能退化而带外抑制性能过剩,进而使得BAW双工器性能不佳。为了解决这一问题,提出了一种BAW双工器的优化设计方法。设置BAW双工器中Tx滤波器的串联薄膜体声波谐振器(FBAR)单元谐振区面积,及并联FBAR单元与串联FBAR单元谐振区面积比值为两组优化变量,通过牺牲Tx滤波器过剩带外抑制性能的方式,采用基于梯度的优化算法计算得到了两组优化变量的最终取值。以一个工作在FDD-LTE band 7的BAW双工器优化设计案例展示了该方法的应用流程。优化设计结果的仿真验证表明,Tx滤波器的插入损耗性能从2dB提升至1.1dB,带内波动性能从1dB提升至0.3dB。由此验证了该方法的可行性。     

单晶LN BAW谐振器有限元仿真研究

利用离子注入剥离法(CIS)制备的铌酸锂(LN)压电薄膜可用于制备体声波(BAW)器件,近年来备受关注。滤波器的指标与谐振器的性能密切相关,但基于LN单晶薄膜的BAW谐振器,对其结构的仿真优化还未有较深入的报道。该文以LN单晶薄膜为核心压电层材料,构建了固态反射型(SMR)单晶薄膜谐振器有限元仿真模型,对其压电层厚度和布喇格反射层厚度进行了设计,并重点针对谐振器上电极的台阶结构进行了二维模型仿真,为高频LN BAW滤波器的制备提供了理论依据。     

体声波滤波器自动布局工具的设计开发

为了实现体声波（BAW）滤波器版图的自动排布和构建滤波器的三维模型,开发了一款体声波滤波器自动布局工具。根据文献提出的BAW梯形滤波器布局设计流程,基于.NET平台,使用C#语言,创建生成滤波器版图的功能界面。根据输入的薄膜体声波谐振器(FBAR)个数和面积大小生成对应的多边形外接圆,通过FBARs的串并联连接情况,生成放置外接圆的位置,并生成多边形。生成多边形后,用户只需对其进行微调(拖动、旋转等),即可在保证滤波器性能的情况下,得到面积尽可能小的版图。在所完成的滤波器版图基础上,根据滤波器的结构参数和建模方式, 在AutoCAD中导入写好的动态链接库,创建生成滤波器三维模型的功能界面。输入FBAR膜层厚度等参数后,软件自动生成滤波器的三维模型。并自动保存为可导入电磁仿真软件的dwg文件或sat文件,方便滤波器的电磁仿真。设计开发过程中所用滤波器的结构参数等即为该文验证所设计软件的案例。证明了所开发软件的可行性。即软件在保证滤波器性能的情况下,最大限度地缩小版图面积,提高滤波器在晶圆上的面积利用率,且节省了滤波器设计人员的时间和精力。     

微波体声波延迟线的电磁屏蔽

本文分析了微波体声波延迟线多层介质的电磁屏蔽效应，结果表明，全屏蔽方式可以有效地解决微波延迟线研制中的直通抑制问题。实验结果证实了理论分析。     

C波段宽带薄膜体声波滤波器设计及验证

介绍了一种适用于三维堆叠的凸点式晶圆级封装的小型化C波段宽带薄膜体声波滤波器的设计方法,并进行了工艺验证。通过对压电层薄膜进行钪掺杂、材料参数提取、结构模型优化实现了相对带宽大于5%的薄膜体声波滤波器设计。通过表面硅基微机电系统(MEMS)工艺制备与凸点式晶圆级封装实现滤波器制备。研制出标称频率5 800 MHz、插入损耗小于2.8 dB、阻带抑制大于40 dBc、体积仅1.0 mm×1.0 mm×0.35 mm的C波段宽带薄膜体声波滤波器。     

一种用于图书档案库的小波加权式声表面波温度传感器的关键问题研究

本文提出把声表面波温度传感器用于图书档案库的温度控制系统中.当图书档案库中温度变化时,该温度传感器的输出频率与温度成线性关系,从而达到测量温度的目的.同时还提出将输入换能器变迹加权函数、换能器的指条数对声表面波功率的影响作为两个关键问题进行了研究,并且解决了这两个关键问题.在声表面波温度传感器的研究中,用小波函数对输入换能器进行变迹加权,导致于抑制了该温度传感器频率特性曲线的旁瓣.换能器的指条数越多,产生的体声波越弱(即换能器的指条数越多,产生的声表面波越强).只要换能器的指条数大于40条时,产生的体声波可以忽略,而产生的声表面波是很强的.并且对该温度传感器的设计、制作及实验进行了详细研究.     

Advances in Microwave Acoustic Frequency Sources

This paper reviews the principal advances with microwave frequency sources that use mechanical vibrations and waves in their frequency-controlling elements. Specifically, the review discusses the direction microwave acoustic technology has taken in the utilization of bulk acoustic-wave (BAW), surface acoustic-wave (SAW), shallow bulk acoustic wave (SBAW), thin-film membrane, and composite structures to generate stable microwave frequency sources in the range from 100 MHz to 1 GHz and above.     

体声波介导磁电天线的研究进展与技术框架

为突破传统"电源型"天线尺寸微缩难、阻抗匹配难、辐射效率低等原理性桎梏,基于器件物理本质首次准确定义了体声波(bulk acoustic wave,BAW)介导的磁电(magnetoelectric,ME)耦合天线,即BAW ME天线.这是一种新型"磁源型"天线或机械天线,其工作机理迥异于"电源型"天线,有望通过原理颠...     

Microwave acoustic materials, devices, and applications

This paper surveys applications of acoustic waves in microwave devices. After a general and historical introduction to bulk acoustic waves (BAWs), surface acoustic waves (SAWs), practical wave types, and acoustoelectric transducers, a review is given of technologically important materials for microwave acoustic applications. Following this, we discuss BAW and SAW microwave devices and their technologies. Specifically reviewed are thin-film resonators and filters, transversal filters, and filters for correlative analog signal processing. Finally, an overview of the most important microwave applications is given, along with manufacturing and packaging issues     

高频高阻带抑制极窄带声表面波滤波器

该文介绍了一种双声通道纵向耦合结构的高频高阻带抑制极窄带声表面波滤波器。利用有限元仿真研究了AT石英材料上高声速的声表面横波与浅体声波的激励情况,并进行了浅体声波抑制研究。通过调节叉指换能器金属化比,大幅降低了浅体声波对滤波器阻带抑制的影响,并制作出中心频率为1 220 MHz,插入损耗为5 dB、1 dB带宽700 kHz、阻带抑制50 dB的低损耗高阻带抑制极窄带声表面波滤波器。     

Flexible Engineering Tool for Radiofrequency Parameter Identification of RF‐MEMS BAW Filters

In this paper, we present a new specific and customized interface tool with parameter identification of Modified Butterworth‐Van Dyke models for ladder bulk acoustic wave filters. The aforementioned tool is easy to use and flexible because it allows simulations and reengineering to be conducted in an application. A modular design approach is applied to simplify the extension of the proposed tool for different topologies. The proposed tool was validated using measurements from an aluminum‐nitride based ladder BAW filter dedicated to the frequency ranges of the Universal Mobile Telecommunications Service and standards and Wideband Code Division Multiple Access.     

The fabrication of thin-film bulk acoustic wave resonatorsemploying a ZnO/Si composite diaphragm structure using porous siliconlayer etching

Thin-film bulk acoustic wave resonators (FBARs) are used in monolithic microwave integrated circuits (MMICs) for semiconductor devices. FBARs are more attractive than surface acoustic wave resonators since they have the advantages of small size, low cost, and mass-production ability. In this letter, an FBAR with an air gap is fabricated by a surface micromachining technique which utilizes porous silicon layer (PSL) etching. This FBAR has a forward reflection coefficient of -18.912 dB when the thickness of the ZnO thin film measures 1 μm. The FBAR is composed of a piezoelectric zinc oxide (ZnO) thin film and top and bottom electrode thin films of Au(1000 Å)/Ni-Cr(50 Å). The ZnO thin film is deposited by RF magnetron sputtering. This fabrication process is compatible with conventional IC processes, thereby enabling the development of monolithic-integrated FBAR's on Si or GaAs substrates     

Polarization-independent integrated optical, acoustically tunabledouble-stage wavelength filter in LiNbO3

We report a polarization-independent integrated acousto-optical double-stage wavelength filter in X-cut, Y-propagating LiNbO₃. The device consists of a combination of four acousto-optical mode converters, a TE- and a TM-pass polarizer, and two polarization splitters; their specific design and properties are discussed. The filter has a bandwidth of 1.4 nm and a tuning range of 76 nm around λ1.55 μm. Maximum filter transmission is achieved with a RF drive power of only 80 mW; it excites via a single unidirectional transducer a guided surface acoustic wave driving the four polarization converters of both stages. Fiber-to-fiber insertion loss is 4.6 dB for TM- and 4.8 dB for TE-polarized waves. Multiwavelength filtering has been demonstrated     

确定BAW梯形滤波器阶数的方法

为确定体声波(BAW)梯形滤波器的阶数,使用仿真法研究了滤波器的带外抑制与并、串联薄膜体声波谐振器(FBAR)的电容比Cps和滤波器阶数N的关系。基于FBAR的Mason 解析电路模型构建了1~6阶BAW梯形滤波器,Cps取值为1~6,对1~6阶BAW梯形滤波器进行仿真,取滤波器的左带外抑制进行统计并绘制曲线图。此外,BAW梯形滤波器的阶数可包括半阶数,用同样仿真法改变阶数(N=1.5,…,5.5)对滤波器进行仿真。仿真结果表明,当Cps一定时,带外抑制基本随滤波器的阶数等量增加。当滤波器的阶数一定时,带外抑制随Cps的增加而增加。在优化设计时,并、串联FBAR谐振器区面积比(即Cps)一般设置为1~4,在此范围内滤波器阶数每增加一阶,带外抑制平均增加约10 dB;滤波器的阶数增加半阶时,带外抑制约增加整阶数的一半,即5 dB,而此时通带内的插损基本保持不变。故设计滤波器时,根据设计指标中的带外抑制可初步确定滤波器的阶数。     

压电和铁电薄膜及其应用的发展趋势

本文讨论了压电和铁电薄膜材料及其在固体器件中应用的发展趋势。薄膜生长技术的进展,为压电和铁电薄膜集成固体器件在各个领域的应用开辟了广阔的前景。ZnO和AIN薄膜将广泛地用于SAW和BAW器件。特别是成功地制作了薄膜体声波谐振器和高次谐波体波谐振器。以PbTiO_3为基的PZT和PLZT固溶体外延薄膜将应用于热电探测器和SAW器件。在实现了对多层薄膜的界面结构及其特性的成功控制之后,铁电薄膜将在铁电存储和集成光学领域发挥重要作用。     

IDT在YZ—LiNbO3基片上的体声波激励研究

具有广泛应用前景的声板波液体密度传感器采用了叉指换能器（ＩＤＴ）在基片上的体声波（ＢＡＷ）激励效应．文章针对常见的ＹＺ－ＬｉＮｂＯ３基片，研究ＩＤＴ激励ＢＡＷ的响应与激励频率之间的关系。压电基片表面的ＩＤＴ激励的ＢＡＷ在基片内来回反射，选择恰当的ＩＤＴ激励频率，可得到极大的ＢＡＷ响应。实验结果和理论分析表明，ＢＡＷ的极大响应与发射接收ＩＤＴ的间距、基片厚度和激励频率有确定关系。