横向耦合谐振滤波器寄生模式抑制的研究

Investigation of Spuressing Spurious Response of Transversal Coupling Resonator Filter

该文应用耦合模理论,重点研究了几个关键因素对横向耦合谐振滤波器高次模式对应旁瓣相对于主通带相对衰减量的影响。这几个关键因素包括相对膜厚、反射栅与换能器周期比、换能器间汇流条宽度等。研究表明,该文在设计频率为159.2 MHz的横向耦合谐振滤波器时,对高次模式引起的旁瓣作了抑制处理,该文给出了此滤波器的计算模拟结果和实验测试数据。实验器件匹配后具有高阻带抑制(通带外抑制达50 dB)、低插损(2.9 dB)和平坦的通带(通带波纹小于0.3 dB),1 dB带宽为130 kHz。

By using coupling of modes theory,the effects of some key factors including the relative film thickness,the ratio of the grating to the IDT period and the common grounded bus bar width between two resonators on the relative attenuation of the corresponding sidelobe of the high-order mode of the transversal coupling resonator filter with respect to the main pass band.The sidelobe caused by the high-order mode has been suppressed in designing the the transversal coupling resonator filter operating at 159.2 MHz frequency.The simulation results and the measured data ot the filter have been given.The fabricated device has been characterized by the high stop band rejection（50 dB of out-of-band rejection）,low insertion loss（2.9 dB） and flat pass band（the ripple less than 0.3 dB） as well as bandwidth of 130 kHz at 1 dB.It showed that the theorical and experimental results agreed well.