Design of nonlinear Phase Surface Acoustic Wave Filters

• Main Authors: Jian-shiun Chen, 陳建勳
• Other Authors: Shu-ming Wang
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/96804509745810549898

碩士 === 義守大學 === 電機工程學系碩士班 === 93 === Most filters used in communication systems require a flat amplitude response and linear phase response to avoid signal distortion. However, there are some applications, for example, The Intermediate filter of television, do need some prescribed degree of nonlinear phase and/or non-symmetric magnitude responses. In this thesis, a method to design a nonlinear phase surface acoustic wave (SAW) filter was discussed thoroughly. This method applies the concept of Fourier transform, and inverse Fourier transform (IFFT) in determining aperture function of a SAW interdigital transducer (IDT). The Mason’s equivalent circuits were applied to calculate the admittance parameters of interdigital transducers and then transformed to scattering parameters. By using the high frequency circuit simulator, the entire frequency response of the nonlinear phase SAW filter was obtained. Finally, as an example, a filter with two different group delays in two frequency ranges was investigated and demonstrated the validity of this method successfully. The results will also be conformed with experiment.