薄膜体声波谐振器的研究进展

薄膜体声波滤波器作为一种发展高频滤波器的全新解决方案,比声表面波滤波器(SAWF)、陶瓷介质滤波器具有更高的Q值,低的损耗和在高频时具备更高的功率承受能力.介绍了薄膜体声波谐振器的研究历史和研究概况,薄膜体声波谐振器的原理和3种典型结构,具体阐述了薄膜体声波谐振器的关键技术及其材料体系的要求.     

2008年《声学技术》总目录

物理声学薄膜体声波谐振器的梯形射频滤波器设计汤亮郝震宏乔东海汪承灏(08.2.145)柱面型声透镜设计及验证余雅松王锦柏(08.2.150)变截面闭管中非线性驻波场的实验研究彭锋范瑜晛刘丹晓佟小朋尹铫刘克(08.2.156)亚声/声速射流式调制气流声源气动模拟研究赵云曾新吾(08.3.293)板     

薄膜体声波滤波器的材料、设计及应用

薄膜体声波谐振器及滤波器具有工作频率高、工艺简单、尺寸小、易于集成等优点,成为目前应用于高频通信前置滤波器的首选.系统介绍了用于薄膜体声波谐振器的几种主要材料(AlN、ZnO、PZT)的具体特点、制备工艺及薄膜体声波谐振器与滤波器的结构、设计及其应用.     

AlN薄膜体声波谐振器研究

采用一维Mason模型,研究了体声波谐振器的频率特性,探讨了压电薄膜AlN和上电极膜厚对谐振频率的影响,压电参数d33及压电薄膜与电极的厚度比率对机电耦合系数的影响,同时研究了谐振区域的面积和声能在衬底中的损耗对品质因数的影响.测量的体声波谐振器频率特性曲线与模拟结果吻合的较好.     

基于微机电系统的薄膜体声波谐振器技术

随着我国无线通讯的飞速发展,通讯器件的微型化、低功耗、低成本、高性能与集成化等越来越受人们关注。基于微机电系统的薄膜体声波谐振器技术是实现系统低功耗与微型化的重要技术,薄膜体声波谐振器具有体积小、频率高、换能效率高等诸多优势。为了对基于微机电系统的薄膜体声波谐振器有一个更深层次的认识,文章阐述了薄膜体声波谐振器的基本结构与工作原理,并分析了薄膜体声波谐振器及技术的应用与发展趋势。     

固贴式薄膜体声波谐振器用材料体系研究进展

固贴式薄膜体声波谐振器(SMR-FBAR)技术是近年来电子工业领域里的突破性技术,具有2GHz以上的工作频率、极高的的品质因子及良好的机械稳定性等众多的优异特性.基于其独特的优越性,固贴式薄膜体声波谐振器成为了科研工作者们关心的热点,并在第三代无线通信系统中已得到广泛应用,例如作为基本单元用来制作滤波器、双工器和振荡器等第三代无线通信系统中的频率选择器件.器件选用的材料体系是决定器件性能的关键因素.本文以器件结构为线索,综述了固贴式薄膜体声波谐振器用材料体系的研究进展,包括压电薄膜(氮化铝、氧化锌等)、高/低声阻抗材料以及电极薄膜,讨论了材料性能和器件性能的关系,并对材料体系下一步的研究方向进行了展望。     

基于Pierce振荡器架构的BAW传感器读出电路

薄膜体声波谐振器(FBAR)不仅能作为手机射频前端的滤波器,还具有充当传感器表头的潜力。为实现对体声波(BAW)传感器输出射频信号的检测,设计一种基于Pierce振荡器的BAW传感器读出电路。读出电路采用双路差分方式,将体声波谐振器构成两路振荡器,一路作为参考电路用于检测外界环境等因素的干扰,另一路作为传感电路用于检测待测物理量。两路振荡器信号通过混频滤波得到由待测物理量引起的谐振频率偏移。然后通过放大与整形将模拟信号转换为数字信号,最后送入FPGA进行频率检测。以一个2 GHz的体声波质量传感器为例,给出电路各模块的设计方法,经各模块仿真以及信号转换电路的实验验证,电路可检测的最大谐振频率偏移量为99 MHz。     

薄膜体声波滤波器AlN压电薄膜的ICP刻蚀研究北大核心CSCD

随着5G通信技术的发展,通信频段不断提高,以氮化铝(AlN)为压电薄膜材料的薄膜体声波滤波器作为目前唯一可集成的射频前段滤波器成为研究热点之一。本文开展AlN材料刻蚀工艺的实验研究,实验中采用光刻胶作为刻蚀掩膜,Cl2/BCl3作为刻蚀工艺气体,通过一系列工艺影响参数调整及相应刻蚀结果分析,获得了ICP源功率、RF偏压功率、腔体压强和BCl3气体流量对AlN材料和光刻胶掩膜刻蚀速率、刻蚀形貌的影响规律。通过综合优化工艺参数,最终得到了侧壁平坦、表面光滑的空气隙型薄膜体声波滤波器三明治结构。     

薄膜体声波滤波器AlN压电薄膜的ICP刻蚀研究

随着5G通信技术的发展,通信频段不断提高,以氮化铝(AlN)为压电薄膜材料的薄膜体声波滤波器作为目前唯一可集成的射频前段滤波器成为研究热点之一。本文开展AlN材料刻蚀工艺的实验研究,实验中采用光刻胶作为刻蚀掩膜,Cl_2/BCl_3作为刻蚀工艺气体,通过一系列工艺影响参数调整及相应刻蚀结果分析,获得了ICP源功率、RF偏压功率、腔体压强和BCl_3气体流量对AlN材料和光刻胶掩膜刻蚀速率、刻蚀形貌的影响规律。通过综合优化工艺参数,最终得到了侧壁平坦、表面光滑的空气隙型薄膜体声波滤波器三明治结构。     

2.4GHz射频薄膜体声波谐振器的研制

提出了基于ZnO压电薄膜多层结构的2.4GHz射频薄膜体声波谐振器,并进行了研究.采用修正后的Mason等效电路模型对器件的谐振特性进行了分析和模拟.给出了采用MEMS工艺制备器件的工艺流程,并利用射频网络分析仪对实验器件进行了测试.利用多点数值拟合的方法消除射频测试中引入的寄生分布参数,提取出器件的实际参数:器件的串联谐振频率fs和并联谐振频率fp分别为2.3714GHz和2.3772GHz,相应的有效机电耦合系数为0.598%;串联谐振频率处和并联谐振频率处的Q值分别为500.3和425.5,f·Q值乘积达到1.2×1012.该谐振器器件的有效直径为200μm,样品实际尺寸为1.2mm×1.2mm×0.3mm,可用来制备体积小、高性能和低相噪的射频振荡器.     

Coupled resonator filter with single-layer acoustic coupler

We discuss the operation of novel coupled-resonator filters with single-layer acoustic couplers. Our analysis employs the physical Mason model for acoustic resonators. Their simpler fabrication process is counterbalanced by the high acoustic attenuation of suitable coupler materials. At high levels of attenuation, both the phase and the acoustic impedance must be treated as complex quantities to accurately predict the filter insertion loss. We demonstrate that the typically poor near-band rejection of coupled resonator filters can be improved at the die level by connecting a small capacitance between the input and output of the filter to produce a pair of tunable transmission minima. We make use of these theoretical findings to fabricate coupled resonators filters operating at 2.45 GHz.     

均匀流直通穿孔管消声器声学特性预测的有限元法

将有限元法应用于预测有均匀流存在时直通穿孔管消声器的声学特性,推导了考虑运流效应的有限元法计算公式,并给出了声学特性的计算方法和数值实施过程。传递损失数值计算结果表明,随着气流马赫数的增加,消声器中高频的消声量有所增加。为精确预测直通穿孔管消声器的声学特性,流速对消声器内声传播的影响应加以考虑。     

Ultra-miniature coupled resonator filter with single-layer acoustic coupler

Coupled resonator filters designed using a singlelayer coupler require coupling materials with an acoustic impedance less than 5.0 MRayl. Carbon-doped oxide, with an acoustic impedance of 4.8 MRayl and an acoustic attenuation of 200 to 600 dB/cm at 1 GHz, can be used as a single-layer coupler to produce a competitive 2-stage coupled resonator filter for cellular handset applications in the gigahertz frequency range. The electrical response of our filter is superior to that of coupled resonator filters using a traditional acoustic mirror as the coupling element. We present an ultra-miniature 0.58 mm x 0.38 mm coupled resonator filter operating at a frequency of 2.15 GHz.     

一种声发射源的新型平面定位方法研究

声发射现象中产生的弹性波在传播时声压遵从指数衰减规律,文中提出一种利用声衰减特性对声发射源进行平面定位的能量定位新方法。从理论上导出了该方法的定位计算公式,并用AE21C型声发射仪在高分子合成纤维平板上以铅笔芯折断产生信号为模拟源进行了实验测量,证明这种新的源定位方法可行,并具有无须测量传声媒质的声衰减和声速等优点。     

排气消声器传递损失的实验测量与分析

介绍消声器传递损失的测量方法,包括声波分解法、两负载法、两声源法和脉冲法。在消声器声学性能试验台上采用两负载法测量无流和有流时简单膨胀腔和直通穿孔管消声器的传递损失。测量结果表明：穿孔率对穿孔管消声器低频消声性能影响较小,对中高频消声性能影响较大,增加穿孔率能够拓宽穿孔管消声器的有效消声频率范围;气流对直通穿孔管消声器的声学性能有一定影响,穿孔率越低影响越大,随着流速的增加,低频段传递损失变化不大,高频段的传递损失显著增加。     

Boundary element acoustic analysis of hybrid expansion chamber silencers with perforated facing

The substructure boundary element approach is developed to predict and analyze the acoustic attenuation characteristics of hybrid expansion chamber silencers with perforated facing. The silencers are divided into a number of acoustic domains with single medium (air or sound-absorbing material), and treating the sound-absorbing material as an equivalent fluid with complex-valued density and speed of sound (or complex-valued characteristic impedance and wavenumber), and then the boundary element method (BEM) may be applied to each domain leading to a system of equations in terms of acoustic pressure and particle velocity. Using the specific acoustic impedance of perforate, which takes into account the effect of sound-absorbing material, the relationship of acoustic pressures and particle velocities between the inlet and outlet of silencer may be obtained and then transmission loss is determined. For the straight-through perforated tube reactive and dissipative silencers, the predictions of transmission loss agree reasonably well with experimental measurements available in the literature, which demonstrated the applicability and accuracy of the present approach. The BEM is then used to investigate the effect of internal structure on the acoustic attenuation characteristics of hybrid expansion chamber silencers with perforated facing. The numerical results demonstrated that the hybrid expansion chambers may provide higher acoustic attenuation than the reactive expansion chamber in the mid to high frequency range.     

穿孔管与超材料薄膜耦合的消声结构的设计及性能研究

用于消减宽频带低频噪声的消声器的结构尺寸较大,且消声性能较差。因此,利用穿孔管的宽带消声特性和膜结构对低频噪声良好的消声性能,设计了穿孔管与超材料薄膜耦合的消声结构。分析了消声结构的消声机理,仿真分析了消声结构参数对消声性能的影响。结果表明：主管道内声波与消声结构谐振系统的耦合强度越大,薄膜的振动越剧烈,反射回上游管道的声波越强,则传入下游管道的声波越弱;消声结构传递损失峰值所对应的频率与超材料薄膜的第1阶共振频率基本一致。设计了螺旋形消声结构,对其消声性能进行仿真和实验测试,结果表明仿真结果与实验结果吻合较好。研究结果可为宽频带低频噪声的控制提供有益参考。     

On modeling biomedical ultrasound RF echoes using a power-law shot-noise model

We propose a new model for the RF ultrasound echo, namely the power-law shot-noise process. Based on this model, the in-phase and quadrature components of the echo are shown to exhibit 1/f^β -type spectral behavior, in a sense that is defined in the paper. The envelope also exhibits this type of spectral behavior, but with a different exponent. This result explains the experimental observations by other researchers of the power-law trend of the RF echo spectrum. Although the shot-noise model has been used in the past for modeling the RF echo, this is the first time that a power-law impulse response filter is used and that the resulting 1/f^β-type spectral behavior of the RF echo has been investigated. The model parameters are linked to tissue characteristics, such as scatterer density and attenuation; thus, they have the potential to be used as tissue characterization features. The validity of the proposed model is tested based on a database of 100 clinical ultrasound images of the breast     

采用IFIR技术的二级FRM滤波器的设计

为获得更好的频率瞄准式干扰效果，需设计一款过渡带尽量窄、带外衰减尽量大的带通滤波器，以避免发射干扰信号时产生的频率泄漏影响对信号的接收。由于现有硬件资源有限，且滤波器过渡带与带外衰减的设计方法无法满足高性能滤波器的设计要求，因此文章采用改进结构的二级有限脉冲响应内插-频率响应屏蔽(Interpolated FiniteImpulse Response-Frequency Response Masking,IFIR-FRM)滤波技术设计高性能带通滤波器，以满足水声对抗器材对频率瞄准技术的性能要求，同时降低了设计复杂度。仿真结果表明，该方法在降低窄带带通FRM滤波器计算复杂度方面效果明显，有效减少了乘法器的使用，降低了目标滤波器设计的阶数，达到频率瞄准式干扰工作模式的技术指标。     

A circuit model for nonlinear simulation of radio-frequency filters using bulk acoustic wave resonators

This paper describes a circuit model for the analysis of nonlinearity in the filters based on radiofrequency (RF) bulk acoustic wave (BAW) resonators. The nonlinear output is expressed by a current source connected parallel to the linear resonator. Amplitude of the nonlinear current source is programmed proportional to the product of linear currents flowing in the resonator. Thus, the nonlinear analysis is performed by the common linear analysis, even for complex device structures. The analysis is applied to a ladder-type RF BAW filter, and frequency dependence of the nonlinear output is discussed. Furthermore, this analysis is verified through comparison with experiments.