Optimimal Design Of Saw Filter With Multilayer Films

SAW technology is the combination of acoustic and electrical edge of a discipline. Because of its unique nature, it is easy to simulate the various features of e-learning, and to achieve multifunction and miniaturization. SAW filter is a combination of the various advantages in the wireless data transmission, telecommunications and other areas of access to a wide range of applications.In recent years, with the third generation of the rapid development of mobile communication systems, and SAW duplexer filters on the market to a huge demand on behalf of high-frequency, low loss surface acoustic wave devices become a major object of study. However, the traditional SAW material, because of its sound velocity is low, usually less than 4000 m/s, so for high-frequency surface acoustic wave interdigital for the manufacture of lithographic process put forward higher requirements.In order to obtain high-frequency surface acoustic wave devices, we can change the width of the fork under the premise that can improve the speed of sound substrate material. GHz band high-frequency surface acoustic wave (SAW) devices, SAW wavelength is very short (severalμm), substrate surface roughness, defects and grain boundaries are likely to cause scattered to produce energy loss. So, for the manufacture of high-frequency multilayer diamond SAW devices, the concern is flatness, roughness, defect density, sound transmission loss of CVD diamond film, and impurity control is a secondary requirement for diamond-like carbon (DLC) films and diamond films with similar hardness, abrasion resistance, high resistance, chemical resistance and smooth surface, few defects, low temperature deposition, large area, low cost, easy and IC-compatible, so the diamond (DLC) films has become hot spots of materials science research in the last 20 years. DLC film is a series of amorphous carbon with sp3 bond, and the proportion which the sp3/sp2 can be adjusted according to different applications. The results show that, sp2 bond decides the electrical and optical properties, and sp3 bonds determine the mechanical properties of DLC films. Therefore, the ratio of sp2 and sp3 bond directly affects the final properties of DLC films , these features make it a versatile new material.In this experiment, diamond-like films were prepared by plasma enhanced chemical vapor deposition (PECVD). The surface morphology and microstructure of the films were measured using atomic force microscope (AFM), Fourier transform infrared spectroscopy (FTIR), Raman Spectroscopy, and UV spectrophotometer.The paper also focuses on the interdigital SAW filter and the basic characteristics of the transducer, and introduces the surface acoustic wave, interdigital transducer, and the basic principle of SAW filters. On this basis, the design method of SAW filters was discussed.The topics are designed to select the staggered cross finger interdigital filter and image-impedance connection horizontal structure, so that the design of SAW filters have high resistance with inhibition and low insertion loss.