The Influence Of SAWF Centre Frequency With Cutting Error In Piezoelectric Substrates

Piezoelectric crystals have been broadly used in many fields of surface acoustic wave (SAW) devices, such as surface acoustic wave filter (SAWF). Different piezoelectric substrates in cutting orientation of the same crystal have different piezoelectric effect because of its anisotropy. The cutting error while using the rotated cutting in the piezoelectric crystals we think in this paper. The values of the elements of piezoelectric coefficient matrixes change with the cutting error, results in the change of SAW properties of piezoelectric substrates, especially in the centre frequency of SAWF.In the first and second chapter, we introduce the background of piezoelectric crystals and the acoustic fields and waves in solids. In the third chapter, a method of coordinate transformation for studying the variation of piezoelectric coefficients in different cutting orientation. The values of the piezoelectric coefficients matrixes elements for the cuts of the crystals of Quartz and LiNbO₃ are obtained and their curves are given. On top of that, in the last chapter, by the program of numeric solution of SAW, the velocity of SAW in cutting error piezoelectric substrates were calculated. Furthermore, the influences of SAWF center frequency are display by the curves, as a result, this cutting error have a kind of influences on centre frequency of SAWF.