6B-2 Optimal Design of Quasi-Slanted SAW Transducer Employing Resonant SPUDT

This paper presents an innovative design technique to achieve a low-loss SAW filter by Quasi-slanted finger interdigital transducers (Q-SFITs). As subfilters, resonant single-phase unidirectional transducers (RSPUDTs) with constant group delay are used. The distances and apertures of subfilters are optimized to realize Q-SFIT filters with low loss, wide bandwidth and small group delay deviation. By this procedure, a Q-SFIT filter is designed and fabricated on a 128deg YX-LiNbO₃ substrate. The experimental results agree with the simulation, and the minimum insertion loss of 5.2 dB and small group delay deviation of 56 ns were simultaneously achieved