一种横向耦合改进型结构极窄带声表面波滤波器研究

该文采用波导法分析了横向耦合极窄带声表面波滤波器速度变化模式,并用多物理场COMSOL软件对横向耦合声表面波滤波器的中心耦合条结构和耦合距离的变化建模进行计算,并分析频响特性。采用石英晶体作为底衬,设计了频率为898.144 MHz,插入损耗约为6 dB的极窄带声表面波滤波器并进行验证。结果表明,中心耦合条开腔结构的声表面波滤波器的相对带宽达到7.2‰,与不开腔结构5.2‰相对带宽相比,提升了2‰。这说明横向耦合声表面波滤波器的中心耦合条结构变化,能改变极窄带声表面波滤波器的相对带宽。

Study on Ultra-Narrow Band Surface Acoustic Wave Filter with Improved Transversely Coupled Structure

In this study, the velocity change mode of a transversely coupled ultra-narrow band surface acousticwave filter is analyzed using the waveguide method.The changes in the central coupling strip structure and couplingdistance of the transversely coupled surface acoustic wave filter are modeled and calculated using the multi-physicsCOMSOL software, and the frequency response characteristics are analyzed.An ultra-narrow band SAW filter withfrequency of 898.144 MHz and insertion loss of 6 dB has been designed and verified.The results show that the fractionalbandwidth of surface acoustic wave filter using the center coupled bar with an open cavity reaches 7.2‰,which is 2‰ higher than that of the non-open cavity structure of 5.2‰.This indicates that the change of the centercoupled bar structure of a transversely coupled surface acoustic wave filter can change the fractional bandwidth of ultra-narrow band surface acoustic wave filters.