Development of ladder type SAW RF filter with high shape factor

Author

Hashimoto, K. ; Ueda, M. ; Kawachi, O. ; Ohmori, H. ; Ikata, O. ; Uchishiba, H. ; Nishihara, T. ; Satoh, Y.

Author_Institution

Fujitsu Labs. Ltd., Kawasaki, Japan

Volume

1

fYear

1995

fDate

7-10 Nov 1995

Firstpage

113

Abstract

The paper presents ion implantation technology to improve the shape factor of a ladder-type SAW RF filters for mobile communication systems. The improvement of the shape factor was confirmed experimentally. However we found that the SAW phase velocity is decreased by ion implantation. To stabilize and recover the SAW phase velocity, several annealing conditions were investigated. At the annealing condition of over 450°C×1 hour, SAW phase velocity was recovered to almost the same as the initial velocity. In the past, the shape factor values of ladder-type SAW filters using a LiTaO₃ substrate have been almost 1.7. The ion implantation technology has been applied to a PDC (personal digital cellular) -1.5 GHz SAW band pass filter using a LiTaO₃ substrate. We have obtained the shape factor value of 1.4 under the following conditions; ion: double charge Ar⁺⁺, dose: 5×10¹³/cm², acceleration voltage: 180 keV

Keywords

UHF filters; annealing; band-pass filters; cellular radio; interdigital transducers; ion implantation; ladder filters; surface acoustic wave resonator filters; 1 hour; 1.5 GHz; 450 C; Ar; LiTaO₃; LiTaO₃ substrate; SAW RF filter; SAW phase velocity; annealing conditions; bandpass filter; high shape factor; ion implantation technology; ladder type; mobile communication systems; personal digital cellular communication; Annealing; Argon; Band pass filters; Ion implantation; Mobile communication; Paper technology; Radio frequency; SAW filters; Shape; Surface acoustic waves;

fLanguage

English

Publisher

ieee

Conference_Titel

Ultrasonics Symposium, 1995. Proceedings., 1995 IEEE

Conference_Location

Seattle, WA

ISSN

1051-0117

Print_ISBN

0-7803-2940-6

Type

conf

DOI

10.1109/ULTSYM.1995.495552

Filename

495552