Low loss SAW filters utilizing the natural single phase unidirectional transducer (NSPUDT)

The authors report on new parameters and a new crystal orientation for natural single-phase unidirectional transducers (NSPUDTs). The acoustic wave velocity, electromechanical coupling coefficient, static capacitance, and reflection coefficient due to both electrical and mechanical perturbations are calculated and measured for two NSPUDT orientations. As an application of the results, a filter was developed on a new NSPUDT orientation on LiTaO₃ wafers. The coupling of modes (COM) model was used as a tool in the analysis and design of the NSPUDT filter. Experimental results are given to verify the NSPUDT parameters and the COM modeling