体声波滤波器的设计与微加工方法

发布时间：2018-04-07 16:34

本文选题：微机电系统(MEMS)　切入点：滤波器　出处：《压电与声光》2017年02期

【摘要】：提出了一种易于使用的薄膜体声波(FBAR)滤波器的4步设计方法,以一种FDD-LTE Band7的Rx滤波器为例展示了该方法的应用流程。第一步,根据FBAR滤波器的中心频率和带宽指标,确定FBAR薄膜叠层中各层薄膜的厚度。第二步,得到滤波器的电路结构。第三步,得到每个FBAR单元的谐振区面积;为此,将串联FBAR单元的谐振区面积、并联FBAR单元与串联FBAR单元的谐振区面积比值作为两组优化参数;将给定滤波器的插入损耗和带外抑制指标作为优化目标,利用ADS软件中的梯度优化算法,得到其优化值。第四步,旨在使滤波器的带内纹波最小化。设计中采用一种新的FBAR电极厚度调整方法,故意使串联FBAR的串联谐振频率与并联FBAR的并联谐振频率频率值不等,但相差很小,实现了该目标。由于案例设计结果中,SiO2支撑层的厚度仅300nm,需要在背面通孔刻蚀的微加工工艺中工序保留良好,因此,提出了一种基于绝缘衬底上的Si(SOI)圆片中埋氧层(BOX)缓冲的两步通孔刻蚀工艺方案,该方法利用了BOX的刻蚀自停止特性。研究结果表明,Rx滤波器插入损耗为0.6dB,在Tx频段的带外抑制为40.4dB,带内纹波为0.4dB。由此验证了该设计方法的可行性。
[Abstract]:A four-step design method of thin film bulk acoustic wave filter is presented. The application flow of this method is illustrated by an example of a FDD-LTE Band7 RX filter.In the first step, according to the central frequency and bandwidth of the FBAR filter, the thickness of each layer in the FBAR thin film stack is determined.In the second step, the circuit structure of the filter is obtained.In the third step, the resonant area of each FBAR cell is obtained. For this reason, the resonant area of the series FBAR unit and the ratio of the resonant area area of the parallel FBAR unit to the series FBAR unit are taken as two optimized parameters.Taking the insertion loss and out-of-band suppression index of the given filter as the optimization objective, the optimization value is obtained by using the gradient optimization algorithm in ADS software.The fourth step is to minimize the band ripple of the filter.A new method of adjusting the thickness of FBAR electrode is used in the design. The series resonant frequency of series FBAR is not equal to the frequency of parallel resonant frequency of parallel FBAR, but the difference is very small.Because the thickness of the support layer of SiO2 is only 300 nm in the case design, it is necessary to keep the working procedure well in the process of etching through hole on the back side, so the thickness of the support layer is only 300 nm.A two-step through hole etching process based on the buried oxygen layer (box) buffer in a Si Si SOI wafer on an insulating substrate is presented. The method utilizes the etching self-stopping characteristic of BOX.The results show that the insertion loss of the Rx filter is 0.6 dB, the out-of-band suppression is 40.4 dB and the in-band ripple is 0.4 dB in the Tx band.The feasibility of the design method is verified.
【作者单位】：中国工程物理研究院电子工程研究所;核探测与核电子学国家重点实验室(中国科学院高能物理研究所);西南科技大学信息工程学院;重庆大学新型微纳器件与系统技术国防重点学科实验室;
【基金】：国家自然科学基金资助项目(61574131) 中国工程物理研究院超精密加工技术重点实验室基金资助项目(2014ZA001) 核探测与核电子学国家重点实验室开放课题基金资助项目(2016KF-02) 特殊环境机器人技术四川省重点实验室(西南科技大学)开放基金资助项目(14ZXTK01)
【分类号】：TN713;TN65

【相似文献】