SAW reflection characteristics of Cu electrodes and their application to SAW IF devices

This paper describes the application of copper (Cu) electrodes to SAW devices employing metal grating reflectors. It is shown both theoretically and experimentally that the metal grating made of Cu electrodes on 128°YX LiNbO₃ gives much larger reflectivity than that made of Al electrodes of the same thicknesses. As one of the applications of Cu electrodes to SAW IF devices, the directivity of Cu-SPUDT is shown experimentally to be 10 dB larger than that of Al-SPUDT. It is also discussed that optimally weighted grating reflectors can be designed by employing Cu electrodes. The result concludes that Cu electrodes on 128°YX - LiNbO₃ could further enhance the performance of SAW IF devices employing metal grating reflectors.