Title :
SAW filters with combined single-mode and double-mode sections
Author :
Kiselev, S.V. ; Fedorov, E.I. ; Orlov, V.S.
Author_Institution :
Moscow Radiocommun. Res. Inst., Russia
Abstract :
In this paper, we discuss low-loss SAW filters composed as a combination of ladder or balanced bridge single-mode one-port resonator section (LDR or BBR) and double-mode longitudinally coupled resonator (LCR) section. Such combinations of single-mode and double-mode sections allows the operation of IF or RF filters with single-ended or balanced loads 50-300 Ohm and insertion loss IL=2.3-3.8 dB without additional matching circuits. Besides, the ultimate rejection increases to UR =55-70 dB in a wide frequency range. The matching of unity sections has been studied in order to decrease distortions caused by reflections. The characteristics of SAW filters with LDR-LCR-LDR; LCR-LDR-LCR; LCR-BBR-LCR; LDR-BBR structures are reported, with center frequencies 442, 484, 135, 105 and 160 MHz, respectively.
Keywords :
ladder filters; radiofrequency filters; surface acoustic wave resonator filters; 105 MHz; 135 MHz; 160 MHz; 2.3 to 3.8 dB; 442 MHz; 484 MHz; 50 to 300 ohm; 55 to 70 dB; IF filters; LCR-BBR-LCR; LCR-LDR-LCR; LDR-BBR structures; LDR-LCR-LDR; RF filters; SAW filters; balanced bridge single-mode one-port resonator section; balanced loads; distortions; double-mode longitudinally coupled resonator; double-mode section; insertion loss; ladder resonator section; low-loss SAW filters; matching; single-ended loads; single-mode; ultimate rejection; unity sections; Band pass filters; Bridge circuits; Coupling circuits; Frequency response; Impedance; Insertion loss; Matched filters; Radio frequency; Resonator filters; SAW filters;
Conference_Titel :
Ultrasonics Symposium, 2002. Proceedings. 2002 IEEE
Print_ISBN :
0-7803-7582-3
DOI :
10.1109/ULTSYM.2002.1193379
