Design of high selectivity low-loss ladder filters for balanced loads

Author

Orlov, V.S. ; Schwartz, A.L. ; Chvets, V.B. ; Fedorov, E.I. ; Kustova, A.O.

Author_Institution

Moscow Radiocommun. Res. Inst., Russia

Volume

3

fYear

2004

fDate

23-27 Aug. 2004

Firstpage

1905

Abstract

Ladder resonator filters (LDRF) provide the lowest insertion loss IL=0.6-1.2 dB as compared with other types of LSAW filters, such as longitudinally coupled resonator filters. A drawback of ordinary LDRF is their limited selectivity (or minimal attenuation in the stop band) about UR=40-45 dB. In addition some problems arise when matching LDRF to balanced or differential symmetric loads. The present paper describes basic symmetric Π-type and T-type sections as well as various structures of ladder filters that allow symmetric loads. An extra advantage of symmetric filters is their potentially higher selectivity thanks to low level of parasitic electromagnetic signal. The results of our study have been illustrated by a number of 600-1500 MHz filters exhibiting high selectivity UR=55-70 dB and small insertion loss IL = 1.2-4.0 dB.

Keywords

ladder filters; surface acoustic wave resonator filters; LDRF; LSAW filters; T-type sections; balanced loads; high selectivity low-loss ladder filters; ladder resonator filters; parasitic electromagnetic signal; selectivity; symmetric Π-type sections; symmetric loads; Attenuation; Ferroelectric materials; Frequency dependence; Impedance; Insertion loss; Joining processes; Matched filters; Process design; Resonator filters; Transfer functions;

fLanguage

English

Publisher

ieee

Conference_Titel

Ultrasonics Symposium, 2004 IEEE

ISSN

1051-0117

Print_ISBN

0-7803-8412-1

Type

conf

DOI

10.1109/ULTSYM.2004.1418203

Filename

1418203