The Design Of Bandpass Filter With The Structure Of Ladder Type For Surface Acoustic Wave Resonator

With the development of the communication technology, surface acoustic wave (SAW) devices have more and more important part in communication system. In communication system, the request of quality for system is that surface acoustic wave filter has a more superior performance. For example less insert loss and bulk, more stable pass-band and frequency characteristic. This thesis emphasize on the study about band-pass filter composed by SAW resonator (SAWR), which designed by Ladder type circuit and got a more steep transition band and stable band-pass, It is practicable by theory.First of all, the thesis introduced the basic theory of surface acoustic wave and SAW device. Three models of inter-digital transducer, the principle of SAWF and product of SAW devices, and meanwhile recommend the influence about IDT. In this thesis, the compensation of diffraction effects has been investigated in detail, and a software result of effects has been developed in this paper.Then thesis introduces two unit of SAWR and a notch filter formed by SAWR, a curve for the notch filter as well. The resulting frequency circuit of the formula by the circuit of the analysis, As last, a band-pass filter illustrated by SAWR and Ladder type circuit and the circuit of SAWF received as well. The emulation show that the frequency is successfully applied to target.