Title :
Design of SAW expander and compressor on LiTaO/sub 3/ for a TCDMA spread spectrum system
Author :
Reindl, Leonhard ; Kalabic, F. ; Ostermayer, G. ; Pohl, A. ; Seifert, F. ; Weigel, R.
Author_Institution :
Corp. Res. & Dev., Siemens AG, Munich, Germany
Abstract :
We report on the design and performance of SAW minimum-shift-keying (MSK) tapped delay lines (TDL´s) using pseudonoise (PN) code sequences of length 128 chips. As a substrate, LiTaO/sub 3/-X112/spl deg/-rotY has been used due to the system requirements of a given CDMA/TDMA system (TCDMA). System IF frequency, bandwidth of the major lobe, and integration time were respectively 360 MHz, 63.5 MHz, and 3 /spl mu/s. We used SAW TDL´s employing non-weighted as well as cosine-apodized input transducers incorporating split-fingers. We designed both expander as well as compressor filters attaining very similar 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; surface acoustic wave filters; time division multiple access; 16 dB; 3 mus; 360 MHz; 63.5 MHz; CDMA/TDMA system; LiTaO/sub 3/; LiTaO/sub 3/ substrate; MSK tapped delay lines; PN code sequences; SAW expander/compressor; TCDMA spread spectrum system; compressor filters; cosine-apodized input transducers; expander filters; insertion loss; minimum-shift-keying; nonweighted input transducers; pseudonoise code sequences; split-fingers; Delay lines; Filters; Fingers; Multiaccess communication; Propagation losses; Radio frequency; Research and development; Spread spectrum communication; Surface acoustic waves; Transducers;
Conference_Titel :
Microwave Symposium Digest, 1997., IEEE MTT-S International
Conference_Location :
Denver, CO, USA
Print_ISBN :
0-7803-3814-6
DOI :
10.1109/MWSYM.1997.602921
