Title :
Miniaturized IF CDMA SAW filters based on three-channel structures
Author :
Chvets, V.B. ; Orlov, V.S. ; Fedorov, E.I.
Author_Institution :
Moscow Radiocommun. Res. Inst., Russia
Abstract :
The size reduction is a permanent tendency in the development of IF SAW filters for CDMA mobile phones. The implementation of three-channel structures is known as a method, which provides reducing IF-filter size. In three-channel SAW filters, the triple transit signal serves as useful one. The direct acoustic signal is compensated due to the 120° phase shifts between the channels. However, a strong transverse acoustic coupling occurs between the adjacent channels. It results in a strong distortion of the frequency response of such filters, degradation of selectivity and increased phase ripples in the pass-band. In this paper, a modified structure of the three-channel filter, which is free of the above shortcoming, is described. The modified structure has been used in filters for CDMA system: 210.38 MHz, 220.38 MHz and 85.38 MHz in packages SMD 5.0×5.0 mm2, 5.0×7.0 mm2 and 9.0×5.0 mm2, respectively
Keywords :
code division multiple access; surface acoustic wave filters; 210.38 MHz; 220.38 MHz; 85.38 MHz; CDMA mobile phone; IF SAW filter; SMD package; frequency response; phase ripple; selectivity; three-channel structure; transverse acoustic coupling; triple transit signal; Acoustic distortion; Acoustic reflection; Acoustic transducers; Band pass filters; Frequency response; Mobile handsets; Multiaccess communication; Phase distortion; SAW filters; Surface acoustic waves;
Conference_Titel :
Ultrasonics Symposium, 2001 IEEE
Conference_Location :
Atlanta, GA
Print_ISBN :
0-7803-7177-1
DOI :
10.1109/ULTSYM.2001.991632
