Exploring Transverse Mode Suppression with Tilted IDTs in TF-SAW Resonators

The TF-SAW (thin film-surface acoustic wave) resonator with POI (piezoelectric on insulator) substrate exhibits remarkable Q factor and low TCF (temperature coefficient of frequency), making it a subject of extensive research and widespread application. In TF-SAW devices, tilted IDTs (interdigitated transducers) are commonly employed to suppress the unwanted transverse modes. This study investigates the correlation between the tilted angle of IDTs and the number of electrode fingers. A general formula for determining the optimal tilted angle of IDTs at approximately 800 MHz is derived. The results indicate that the IDTs at the optimal tilted angle exhibit the highest Q factor and superior suppression capability of transverse modes.