基于128°YX-LiNbO_(3)压电材料的DMS滤波器设计

Design of DMS Filter Based on 128°YX-LiNbO_(3) Piezoelectric Material

设计了一种基于128°YX-LiNbO_(3)压电材料的双模耦合声表面波(DMS)滤波器。采用耦合模(COM)模型进行理论分析,得到DMS滤波器的二维器件模型,再采用COMSOL进行二维器件仿真分析,得到单级DMS滤波器。为了消除该DMS滤波器在其低端近阻带附近出现的肩峰,该文提出将DMS滤波器表面覆盖一层SiO_(2)薄膜,形成温度补偿结构,从而解决低端近阻带附近的肩峰。结果表明,设计的DMS滤波器的中心频率为891.0 MHz,最小插入损耗为-1.29 dB,1 dB带宽为34.0 MHz,相对带宽为3.8%,矩形系数为2.94,带外抑制约为-20 dB。

In this paper, a double mode surface acoustic wave(DMS) filter based on 128°YX-LiNbO_(3)piezoelectric material is designed. The two-dimensional device model of DMS filter is obtained by using the coupling of mode(COM) model to carry out the theoretical analysis, and the single-stage DMS filter is obtained by using COMSOL to carry out the simulation of the two-dimensional device. In order to eliminate the shoulder peak appearing at the low-end near stop band of the DMS filter, this paper proposes to coat a layer of SiO_(2)film on its surface to form a temperature compensation structure. The results show that the designed DMS filter has a center frequency of 891.0 MHz, minimum insertion loss of-1.29 dB, 1 dB bandwidth of 34.0 MHz, fractional bandwidth of 3.8%, rectangular coefficient of 2.94 and out-of-band rejection of about-20 dB.