Title :
Wideband low loss double mode SAW filters
Author :
Morita, Takahito ; Watanabe, Yoshitaka ; Tanaka, Masaki ; Nakazawa, Yuzo
Author_Institution :
Toyo Commun. Equipment Co. Ltd., Kanagawa, Japan
Abstract :
A method is discussed for achieving a wideband low-loss longitudinally coupled double mode surface acoustic wave (SAW) (DMS) filter using a leaky SAW on a 36° Y-X LiTaO3 and 64° Y-X LiNbO3 substrate with a high electromechanical coupling factor. Its characteristics are analyzed by computer simulation. With the use of the first-mode and third-mode resonance on a 64° Y-X LiNbO3 substrate and the selection of the optimum values for the distance between input and output interdigital transducers (IDTs), the electrode film thickness and the input/output IDT pair number, it is possible to achieve favorable characteristics with a 1-dB bandwidth of 33 MHz, and insertion loss of 2.1 dB, and an attenuation in the rejection band of 28 ~ 38 dB
Keywords :
acoustic impedance; frequency response; losses; radiofrequency filters; surface acoustic wave filters; 1-dB bandwidth; 2.1 dB; 33 MHz; 836.5 MHz; 930.5 MHz; I/O IDT distance; LiNbO3 substrate; LiTaO3 substrate; Y-X substrate; computer simulation; electrode film thickness; first mode resonance; frequency response; high electromechanical coupling factor; impedance; input/output IDT pair number; insertion loss; leaky SAW; longitudinal coupling; output interdigital transducers; rejection band attenuation; third-mode resonance; wideband low loss double mode SAW filter; Acoustic waves; Bandwidth; Computer simulation; Electrodes; Resonance; SAW filters; Substrates; Surface acoustic waves; Transducers; Wideband;
Conference_Titel :
Ultrasonics Symposium, 1992. Proceedings., IEEE 1992
Conference_Location :
Tucson, AZ
Print_ISBN :
0-7803-0562-0
DOI :
10.1109/ULTSYM.1992.276057
