US 6,211,600 B1 · Surface acoustic wave component

Abstract

An improvement of a surface acoustic wave component is disclosed. Surface acoustic wave components of the known type are changed in such a way that the dependency of the insertion loss and/or group delay time on the frequency as asymmetric function in relation to the center frequency can be realized in a predetermined manner. Sloping passbands are particularly significant in this respect. As disclosed, in a surface acoustic wave component in which two single-phase unidirectional transducers which are composed of finger groups comprising a pair of fingers and a reflection finger are arranged on a piezoelectric substrate, wherein the two fingers of the pair of fingers have opposite polarity and are at a distance of one quarter wavelength from one another, at least one base element in at least one of the single-phase unidirectional transducers differs from the rest of the base elements with respect to its distance between the center of the reflection finger and the center of the nearest finger of its pair of fingers. The device of the invention is applicable, for example, for bandpass filters with a relative bandwidth of up to several percent and for oscillators.

Claims28

Dependent claims

A surface acoustic wave component comprising:

two single-phase unidirectional transducers which are composed of finger groups comprising a pair of fingers and a reflection finger being arranged on a piezoelectric substrate;
two fingers of the pair of fingers having opposite polarity and being at a distance of one quarter wavelength from one another;
and wherein
at least one of the finger groups in at least one of the single-phase unidirectional transducers is distinguished from the rest of the finger groups by its different distance between the center of the reflection finger and the center of a nearest finger of its pair of fingers.

1 more element

A surface acoustic wave component in which two single-phase unidirectional transducers are arranged on a piezoelectric substrate, wherein every single-phase unidirectional transducer comprises two collector bus bars from which emanate a plurality of fingers;

and wherein every three successive fingers of which two successive fingers have the same width form a finger group;
and wherein the two fingers having the same width emanate from different collector bus bars and therefore form a finger pair, wherein the distance between the centers of these two fingers is one quarter of the wavelength;
and wherein the respective third finger of the finger groups is a reflection finger;
and wherein every single-phase unidirectional transducer is composed of a plurality of finger groups, characterized in that in at least one of the single-phase unidirectional transducers, the distance between the center of the reflection finger and the center of the nearest finger of the finger pair of the respective finger group differs from the corresponding distance in the rest of the finger groups, so that in at least one of the single-phase unidirectional transducers there are at least two successive finger groups in which the distance between the center of the reflection finger and the center of the nearest finger of the respective finger pair is different.

1 more element

Dependencies are inferred from the claim text.

Surface acoustic wave component

Life of this patent

Surface acoustic wave component

Life of this patent

Abstract

Claims28