Research On Design Method Of SAW Delay Line Based On AlN Film

Due to the vigorous development of surface acoustic wave technology and semiconductor process technology,SAW devices are becoming more and more widely used in radar,communications,electronic confrontation and television.Meanwhile,The rapid development of wireless communication technology,especially the development of mobile communication technology,requires SAW devices with low insertion loss and higher operating frequency,SAW delay line as a signal processing device,its role is to delay the electrical signal for some time.However,the insertion loss of the surface acoustic wave delay line produced by the conventional piezoelectric material is relatively large,and it is difficult to realize high frequency.Therefore,the application of high velocity piezoelectric film material to produce low insertion loss of the surface acoustic wave delay line is an inevitable trend.Based on this background study,the surface acoustic wave delay line with high frequency and low insertion loss are realized by using high velocity piezoelectric film-AlN piezoelectric thin film,the main research contents are as follows:1.The paper introduces the basic theory,characteristics and development of SAW technology,surface acoustic wave delay lines’ types and applications,and surface acoustic wave delay lines’ development.2.The paper studies the surface acoustic wave delay lines’ working principle,the propagation characteristics of surface acoustic wave in piezoelectric film are briefly analyzed,the theoretical model of the interdigital transducer,including the δ function model,the P matrix model and the impulse response model,are described in detail.Moreover,the structural parameters of the interdigital transducer are studied and designed by these theoretical models.3.The paper introduces the electrical properties of AlN piezoelectric films,including dielectric constant,piezoelectric constant and electromechanical coupling coefficient,the theory and design method of multiple coupler based on AlN thin films are studied.Based on the IDT / AlN / Diamond structure,the number of metal strips required for the Multistrip Coupler to achieve the surface acoustic wave energy from one channel to another was design.4.The structural parameters of surface acoustic wave delay based on elliptical transducerand improved inverting transducer were design,based on IDT / Al N / Diamond structures and surface acoustic wave Multistrip Coupler,the physical model was established for elliptical IDT surface acoustic wave delay line,Similarly,Based on the IDT / AlN / Silicon structure,the physical model was established for improved inverting transducer surface acoustic wave delay line.5.Based on group delay theory,the group delay characteristic of two kinds of surface acoustic wave delay lines in the fourth point were studied by using simulation software,and the corresponding group delay simulation curve was obtained.