高频高阻带抑制极窄带声表面波滤波器

Extremely Narrow-Band Surface Acoustic Wave Filter with High Frequency and High Out-of-Band Rejection

该文介绍了一种双声通道纵向耦合结构的高频高阻带抑制极窄带声表面波滤波器。利用有限元仿真研究了AT石英材料上高声速的声表面横波与浅体声波的激励情况,并进行了浅体声波抑制研究。通过调节叉指换能器金属化比,大幅降低了浅体声波对滤波器阻带抑制的影响,并制作出中心频率为1220 MHz,插入损耗为5 dB、1 dB带宽700 kHz、阻带抑制50 dB的低损耗高阻带抑制极窄带声表面波滤波器。

An extremely narrow-band surface acoustic wave filter with high frequency and high out-of-band rejection using two-track longitudinal coupling structure is presented in this paper.The excitation of high velocity surface transverse wave and surface-skimming bulk waves on AT-cut quartz and the suppression of surface-skimming bulk waves are investigated by finite element methods.By adjusting the metallization ratio of the interdigital transducer,the impact of surface-skimming bulk waves on the out-of-band rejection of the filter is greatly reduced.An extremely narrow-band,low loss high out-of-stop SAW filter prototype with center frequency of 1220 MHz,insertion loss of 5 dB,the 1 dB-bandwidth of 700 kHz and the out-band rejection of 50 dB has been fabricated.