S波段窄带带通体声波滤波器设计

摘要

针对无人机测控应用设计了一种S波段窄带带通体声波(BAW)滤波器,其技术指标为:中心频率2.46 GHz,带宽41 MHz,带内插损大于-3 dB,带内纹波小于1 dB,带外抑制小于-40 dB@2.385 GHz和2.506 GHz.采用Mason模型设计了BAW滤波器中各薄膜体声波谐振器(FBAR)的叠层结构;使用变迹法设计了各FBAR(电极)的形状;采用一种自行开发的自动布局方法得到紧凑的BAW滤波器布局;建立了BAW滤波器的声-电磁协同仿真模型,通过这种高保真的多物理场仿真方法对设计结果进行了性能验证.该设计流程是通用的,并且有两个特点:采用声-电磁协同仿真方法对设计阶段的BAW滤波器进行最终性能检验,可以及早发现并拒绝1D Mason模型过于乐观的设计;滤波器布局设计中采用了一种新的自动化布局方法,大大简化了在此阶段的反复尝试工作,也为声-电磁协同仿真模型输出了必需的面内结构信息.%An S band narrowband bandpass filter bulk acoustic wave(BAW) with center frequency 2.460 GHz,bandwidth 41 MHz,band insertion loss -1.154 dB,passband ripple 0.9 dB,out of band rejection about -42.5 dB@2.385 GHz and-45.5 dB@2.506 GHz was designed for potential UAV measurement and control applications.According to the design specifica-tions,each FBAR stack was designed in BAW filter by using Mason model,each FBAR's shape was designed with the method of apodizied electrode.The acoustic-electromagnetic co-simulation model was built to validate the performance of the designed BAW filter.The presented design procedure is a common one,and it has two characteristics:(1)an acoustic-electromagnetic(A&EM) co-simulation method is used for the final BAW filter performance validation in the design stage,thus ensures over-optimistic de-signs by the bare 1D Mason model are found and rejected in time;(2)An in-house developed auto-layout method is used to get compact BAW filter layout,which simplifies iterative error-and-try work here and outputs necessary in-plane geometry informa-tion to the A&EM co-simulation model.