Harmonic GHz surface-acoustic-wave filters with unidirectional transducers

Author

Huegli, Rolf

Author_Institution

Swiss Federal Inst. of Technol., Zurich, Switzerland

Volume

40

Issue

3

fYear

1993

fDate

5/1/1993 12:00:00 AM

Firstpage

177

Lastpage

182

Abstract

The fabrication of fundamental-mode surface-acoustic-wave (SAW) filters for gigahertz frequencies requires an elaborate photolithographic process. In order to reduce process demands or to increase the possible frequency range, interdigital transducers can be designed to work on spatial harmonics. However, harmonic filters are known to be unattractive because of their high insertion loss. It is shown that harmonic gigahertz filters made with unidirectional transducers can have moderate insertion loss. Two third-harmonic filters at 1.4 GHz and 2.5 GHz, using two-phase unidirectional transducers, are described. A simple model for calculating the input impedance of harmonic surface-transverse-wave (STW) transducers is presented.<>

Keywords

acoustic microwave devices; harmonic generation; impedance matching; microwave filters; surface acoustic wave filters; ultrasonic transducers; 1.4 GHz; 11.6 dB; 2.5 GHz; 4 MHz; 7 dB; 9 MHz; gigahertz frequencies; harmonic surface transverse wave transducers; input impedance; insertion loss; model; spatial harmonics; surface-acoustic-wave filters; third-harmonic filters; two-phase unidirectional transducers; Acoustic transducers; Frequency; Gratings; Harmonic filters; Insertion loss; Optical surface waves; Power harmonic filters; Propagation losses; Surface acoustic waves; Surface waves;

fLanguage

English

Journal_Title

Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on

Publisher

ieee

ISSN

0885-3010

Type

jour

DOI

10.1109/58.216831

Filename

216831