Title :
Small SAW filters using optimized high-reflection-coefficient reflectors
Author :
Tanaka, N. ; Hirao, Y. ; Kobayashi, Y. ; Okano, H. ; Usuki, T. ; Shibata, K. ; Niki, K. ; Kameoka, F. ; Ikeda, M.
Author_Institution :
New Mater. Res. Center, Sanyo Electr Co. Ltd., Osaka, Japan
Abstract :
The dependence of the reflection coefficient on grating reflector parameters, such as electrode thickness, the reflector metallization ratio and Pi/Pr, was studied in detail. Pi and Pr are the electrode finger periods of interdigital transducers (IDTs) and reflectors, respectively. The maximum value of the reflection coefficient occurred at a metallization ratio of 75% and Pi/Pr of 0.990. Intermediate frequency (IF) surface acoustic wave (SAW) filters for the Advanced Mobile Phone Service (AMPS) system were made using these high-reflection-coefficient reflectors. As a result, package size was reduced from 11 mm×5 mm to 7 mm×5 mm. Their characteristics include a center frequency of 85.38 MHz, an insertion loss of 2.5 dB and a 3 dB-passband width of 54 kHz
Keywords :
interdigital transducers; mobile radio; surface acoustic wave resonator filters; 11 mm; 2.5 dB; 5 mm; 54 kHz; 7 mm; 85.38 MHz; IF filters; advanced mobile phone service system; design parameters; electrode finger periods; electrode thickness; grating reflector parameters; insertion loss; interdigital transducers; optimized high-reflection-coefficient reflectors; reduced package size; reflector metallization ratio; small SAW filters; Acoustic reflection; Acoustic transducers; Acoustic waves; Electrodes; Fingers; Frequency; Gratings; Metallization; SAW filters; Surface acoustic waves;
Conference_Titel :
Ultrasonics Symposium, 1998. Proceedings., 1998 IEEE
Conference_Location :
Sendai
Print_ISBN :
0-7803-4095-7
DOI :
10.1109/ULTSYM.1998.762105
