Title :
Design of SAW expander and compressor on LiTaO3 for a TCDMA spread spectrum system
Author :
Weigel, Robert ; Kalabic, Faris ; Ostermayer, Gerald ; Pohl, Alfred ; Seifert, Franz ; Reindl, Leonhard
Author_Institution :
Inst. for Commun. & Inf. Eng., Linz Univ., Austria
fDate :
12/1/1997 12:00:00 AM
Abstract :
We report on the design and performance of surface-acoustic wave (SAW) minimum shift keying (MSK) tapped delay lines using pseudonoise code sequences with a length of 128 chips. As a substrate, X112°rotY-LiTaO3 has been used due to the system requirements of a given CDMA/TDMA (TCDMA) radio communication system. System IF frequency, bandwidth of the major lobe, and integration time of the SAW devices were, respectively, 360 MHz, 63.5 MHz, and 3 μs. We used SAW tapped delay lines employing nonweighted as well as cosine-weighted input interdigital transducers incorporating split-fingers. We designed both expander as well as compressor filters attaining very similar experimental results. We found insertion loss values down to 16 dB and amplitude ripples of less than 2 dB. The close-in selectivity was 28 dB
Keywords :
code division multiple access; interdigital transducers; lithium compounds; minimum shift keying; pseudonoise codes; spread spectrum communication; surface acoustic wave delay lines; time division multiple access; 16 dB; 3 mus; 360 MHz; 63.5 MHz; LiTaO3; SAW compressor; SAW expander; TCDMA spread spectrum system; amplitude ripples; close-in selectivity; cosine-weighted input interdigital transducers; insertion loss values; integration time; major lobe bandwidth; minimum shift keying; pseudonoise code sequences; split-fingers; system IF frequency; tapped delay lines; Bandwidth; Delay lines; Frequency; Multiaccess communication; Radio communication; Surface acoustic wave devices; Surface acoustic waves; Surface waves; Time division multiple access; Transducers;
Journal_Title :
Microwave Theory and Techniques, IEEE Transactions on
