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US 4,309,679 AGranted
Surface acoustic wave filter
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsNobuaki Furuya, Yoshihiro Kino, Hiroshi Miyama
Life of this patent
Estimating the term…
Abstract
In a conventional surface acoustic wave ring filter, a time-compensation element in the form of a thin strip is additionally provided for either retarding or accelerating one of the surface acoustic waves which transmit along different transmission lines, thereby the phases of two surface acoustic waves received by a single output converter included in the filter are matched with each other resulting in the improvement in the output signal characteristics.
Claims12
A surface acoustic wave filter comprising:
- (a) a substrate made of LiNbO.sub.3 ;
- (b) a first converter comprising electrodes arranged in an interdigitated grating pattern for converting an electrical signal into a pair of surface acoustic waves which propagate along the surface of said substrate;
- (c) a pair of reflecting means respectively provided in the propagation lines of said pair of surface acoustic waves;
- (c) a second converter comprising electrodes arranged in an interdigitated grating pattern for converting a pair of surface acoustic waves respectively propagated from said pair of reflecting means via first and second transmission lines, into an electrical signal;
- wherein the improvement comprises:
- means for matching the phase of said pair of reflected surface acoustic waves received by said second converter, with each other, which adjusts the time of arrival of said pair of surface acoustic waves at said second converter, said phase matching means including a thin strip made of SiO.sub.2 and, disposed on the surface of said substrate, said strip being placed in one of said first and second transmission lines, the propagation velocity of a surface acoustic wave along said strip being different from that along the surface of said substrate.
3 more elements
A surface acoustic wave filter comprising:
- (a) a substrate made of LiNbO.sub.3 ;
- (b) a first converter comprising electrodes arranged in an interdigitated grating pattern for converting an electrical signal into a pair of surface acoustic waves which propagate along the surface of said substrate;
- (c) a pair of reflecting means respectively provided in the propagation lines of said pair of surface acoustic waves;
- (d) a second converter comprising electrodes arranged in an interdigitated grating pattern for converting a pair of surface acoustic waves respectively propagated from said pair of reflecting means via first and second transmission lines, into an electrical signal;
- wherein the improvement comprises;
- means for matching the phase of said pair of reflected surface acoustic waves received by said second converter, with each other, which adjusts the time of arrival of said pair of surface acoustic waves at said second converter, said phase matching means including a thin strip made of sapphire and, disposed on the surface of said substrate, said strip being placed in one of said first and second transmission lines, the propagation velocity of a surface acoustic wave along said strip being different from that along the surface of said substrate.
3 more elements
A surface acoustic wave filter comprising:
- (a) a substrate;
- (b) a first converter comprising electrodes arranged in an interdigitated grating pattern for converting an electrical signal into a pair of surface acoustic waves which propagate along the surface of said substrate;
- (c) a pair of reflecting means respectively provided in the propagation lines of said pair of surface acoustic waves, each of said reflecting means comprising a pair of reflectors having the shape of a periodical array structure;
- (d) a second converter comprising electrodes arranged in an interdigitated grating pattern for converting a pair of surface acoustic waves respectively propagated from said pair of reflecting means via first and second transmission lines, into an electrical signal;
- wherein the improvement comprises:
- means for matching the phase of said pair of reflected surface acoustic waves received by said second converter, with each other, which adjusts the time of arrival of said pair of surface acoustic waves at said second converter, said phase matching means including a thin strip disposed on the surface of said substrate, the propagation velocity of a surface acoustic wave along said strip being different from that along the surface of said substrate, said strip being placed in one of said first and second transmission lines between said first converter and one of said reflectors.
3 more elements
A surface acoustic wave filter comprising:
- (a) a substrate;
- (b) a first converter comprising electrodes arranged in an interdigitated granting pattern for converting an electrical signal into a pair of surface acoustic waves which propagate along the surface of said substrate;
- (c) a pair of reflecting means respectively provided in the propagation lines of said pair of surface acoustic waves, each of said reflecting means comprising a pair of reflectors having the shape of a periodical array structure;
- (d) a second converter comprising electrodes arranged in an interdigitated grating pattern for converting a pair of surface acoustic waves respectively propagated from said pair of reflecting means via first and second transmission lines, into an electrical signal;
- wherein the improvement comprises:
- means for matching the phase of said pair of reflected surface acoustic waves received by said second converter, with each other, which adjusts the time of arrival of said pair of surface acoustic waves at said second converter, said phase matching means including a thin strip disposed on the surface of said substrate, the propagation velocity of a surface acoustic wave along said strip being different from that along the surface of said substrate, said strip being placed in one of said first and second transmission lines between said pair of reflectors.
3 more elements
A surface acoustic wave filter comprising:
- (a) a substrate;
- (b) a first converter comprising electrodes arranged in an interdigitated grating pattern for converting an electrical signal into a pair of surface acoustic waves which propagate along the surface of said substrate;
- (c) a pair of reflecting means respectively provided in the propagation lines of said pair of surface acoustic waves, each of said reflecting means comprising a pair of reflectors having the shape of a periodical array structure;
- (d) a second converter comprising electrodes arranged in an interdigitated grating pattern for converting a pair of surface acoustic waves respectively propagated from said pair of reflecting means via first and second transmission lines, into an electrical signal;
- wherein the improvement comprises:
- means for matching the phase of said pair of reflected surface acoustic waves received by said second converter, with each other, which adjusts the time of arrival of said pair of surface acoustic waves at said second converter, said phase matching means including a thin strip disposed on the surface of said substrate, the propagation velocity of a surface acoustic wave along said strip being different from that along the surface of said substrate, said strip being placed in one of said first and second transmission lines between one of said reflectors and said second converter.
3 more elements
Dependencies are inferred from the claim text.