Design and simulation of surface acoustic wave (SAW) devices on 128° YX cut Lithium Niobate

In this paper, we investigate fundamental design principles of surface acoustic wave devices based on 128° YX cut lithium niobate. Surface acoustic wave devices have many applications in gas, temperature, humidity, pressure, torque sensing and also in RF filters. 3D FEM simulations have been done in this article and effect of various parameters like pitch size and the number of electrodes pairs, amplitude and frequency of applied electrical signal and thickness of the substrate on propagating acoustic wave has been investigated. The results show the frequency of the electrical signal is inversely proportional to electrodes pitch size and displacement of atoms are proportional to signal amplitude. Also, the optimum number of pairs of electrodes for electrical signal voltage of 50 V and substrate propagation loss of 0.01 dB per wavelength is equal to 34 pairs. On the other hand, for proper propagation of Rayleigh wave, substrate thickness must not be smaller than half of the pitch size.