Title :
Harmonic GHz surface-acoustic-wave filters with unidirectional transducers
Author_Institution :
Swiss Federal Inst. of Technol., Zurich, Switzerland
fDate :
5/1/1993 12:00:00 AM
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;
Journal_Title :
Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on
