Wi-Fi频段体声波滤波器的设计

Design of bulk acoustic wave filter for Wi-Fi band

为了保证移动设备在Wi-Fi频段正常工作且不受相邻频段的干扰,设计了一种用于Wi-Fi IEEE802.11b频段(2402~2482MHz)的BAW滤波器。设计基于薄膜体声波谐振器(FBAR)的一维Mason等效电路模型构成初始结构的梯形滤波器。然后,将串联FBAR的谐振区面积值以及串、并联FBAR的谐振区面积的比值设置为优化参数,以所需的滤波器的带内插损和带外抑制为优化目标,使用ADS软件基于遗传和梯度的优化算法对滤波器进行优化。在滤波器的设计过程中,为了使仿真结果更加精确,采用声电磁协同仿真方法对滤波器进行仿真,并与Mason等效电路模型仿真结果对比,结果表明,滤波器性能有所下降,带内插损增大1.6dB,带内纹波增大1.1dB,带外抑制基本一致。所设计的Wi-Fi频段的BAW滤波器具有低插入损耗(小于3dB)、高带外抑制(大于40dB)性能。

In order to ensure the normal operation of mobile devices in the Wi-Fi band without interference from adjacent frequency bands, a bulk acoustic wave （BAW） filter for the Wi-Fi 802.11b band （2401-2482 MHz） is designed. An initial structure ladder filter based on a one-dimensional Mason equivalent circuit model using thin-film bulk acoustic resonators （FBARs） is designed. The resonance area value of series FBARs and the ratio of resonance area value of parallel FBARs to series FBARs were made into two types of optimization parameters reasonably. Using the required insertion loss and out of band rejection of filter as the optimization objectives, the optimized values were obtained by the algorithm based on gradient and genetics in ADS software. In order to make the simulation results more accurate, the combined acoustic-electromagnetic method is used to simulate and compare with the simulation results of the Mason equivalent circuit model in the filter design process. The results show that the performance of the filter is decreased, with 1.6 dB insertion loss increase and 1.1 dB ripple increase, while out of band rejection is basically the same. The designed Wi-Fi band BAW filter has low insertion loss （less than 3 dB） and high out of band rejection （more than 40 dB） performance.