J. Phys. IV France 08 (1998) Pr9-191-Pr9-194
Super high electromechanical coupling and zero-temperature coefficient surface acoustic wave substrates in KNbO3 single crystalK. Yamanouchi, H. Odagawa, T. Kojima and T. Matsumura
Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aobaku, Sendai 980-77, Japan
This paper describes a super high electromechanical coupling SAW propagating on potassium niobate (KNbO3) substrate and its applications for low-loss, wide band and temperature stable SAW filters. KNbO3 has large piezoelectric constants. We obtained the electromechanical coupling coefficient (K2) of 0.53 for SAW in Y-cut X-propagating substrate theoretically and experimentally. It is about 10 times as large as that in LiNbO3. Moreover, we obtained a zero temperature characteristics around room temperature in rotated Y cut substrate. Experimental results of wide band SAW filters show low loss and temperature stable characteristics. The bandwidth is about 20 % and insertion losses are less than 2~6 dB.
© EDP Sciences 1998