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US 6,674,345 B2Granted
Surface acoustic wave filter and communication device using the filter
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsHiroyuki Nakamura, Kazunori Nishimura, Akio Tsunekawa
Life of this patent
Estimating the term…
Abstract
A surface acoustic wave filter has a piezoelectric substrate; at least an input IDT electrod arranged on a piezoelectric substrate; and at least an output IDT electrod arranged on the piezoelectric substrate. A pitch of electrode fingers of the input IDT electrode and a pitch of electrode fingers of the output IDT electrode are different from each other.
Claims25
A surface acoustic wave filter comprising:
- a piezoelectric substrate;
- at least an input IDT electrode arranged on said piezoelectric substrate;
- and
- at least an output IDT electrode arranged on said piezoelectric substrate;
- wherein said surface acoustic wave filter is a longitudinally coupled mode surface acoustic filter and includes said input IDT electrode and said output IDT electrode disposed within a single propagation path in which a surface acoustic wave propagates,
- a pitch of electrode fingers of said input IDT electrode and a pitch of electrode fingers of said output IDT electrode are different from each other;
- one of said input IDT electrode and said output IDT electrode comprises a first IDT electrode including a pair of electrode fingers opposed to each other;
- the other of said input IDT electrode and said output IDT electrode comprises a second IDT electrode including a pair of electrode fingers opposed to each other, and a third IDT electrode including a pair of electrode fingers opposed to each other, said second IDT electrode being placed on one side of said first IDT electrode, said third IDT electrode being placed on the other side of said first IDT electrode;
- said first, second, and third IDT electrodes are arranged alone a direction in which a surface acoustic wave propagates;
- the metalization ratio of said first IDT electrode and the metalization ratio of each of said second and third IDT electrodes are substantially equal to each other;
- and
- the number of electrode fingers of said first IDT electrode is larger than the number of electrode fingers of each of said second and third IDT electrodes.
9 more elements
A surface acoustic wave filter comprising:
- a piezoelectric substrate;
- at least an input IDT electrode arranged on said piezoelectric substrate;
- and
- at least an output IDT electrode arranged on said piezoelectric substrate,
- wherein said surface acoustic wave filter is a longitudinally coupled mode surface acoustic wave filter and includes said input IDT electrode and said output IDT electrode disposed within a single propagation path in which a surface acoustic wave propagates,
- said input IDT electrode has a plurality of electrode fingers pitches,
- of the electrode fingers pitches of said input IDT electrode, an electrode fingers pitch having the most pairs of electrode fingers is defined as a main input pitch,
- said output IDT electrode has a plurality of electrode fingers pitches,
- of the electrode fingers pitches of said outout IDT electrode, an electrode fingers pitch having the most pairs of electrode fingers is defined as a main outout pitch, and
- a metalization ratio of a part corresponding to the input IDT electrode having the main input pitch and a metalization ratio of a part corresponding to the output IDT electrode having the main output pitch are different from each other.
7 more elements
A surface acoustic wave filter comprising:
- a piezoelectric substrate;
- at least an input IDT electrode arranged on said piezoelectric substrate;
- and
- at least an output IDT electrode arranged on said piezoelectric substrate,
- wherein said surface acoustic wave filter is a longitudinally coupled mode surface acoustic filter and includes said input IDT electrode and said output IDT electrode disposed within a single propagation path in which a surface acoustic wave propagates,
- said input IDT electrode has a plurality of electrode fingers pitches;
- of the electrode fingers pitches of said input IDT electrode, an electrode fingers pitch having the most pairs of electrode fingers is defined as a main input pitch,
- said output IDT electrode has a plurality of electrode fingers pitches,
- of the electrode fingers pitches of said output IDT electrode, an electrode fingers pitch having the most pairs of electrode fingers is defined as a main output pitch,
- the main input pitch of electrode fingers of said input IDT electrode and the main output pitch of electrode fingers of said output IDT electrode are different from each other, and
- the main pitch of electrode fingers of the IDT electrode larger in number of electrode fingers in said input and output IDT electrode is larger than the main pitch of electrode fingers smaller in number of electrode fingers.
8 more elements
A surface acoustic wave filter comprising:
- a piezoelectric substrate:
- at least an input IDT electrode arranged on said piezoelectric substrate;
- and
- at least an output IDT electrode arranged on said piezoelectric substrate;
- wherein said surface acoustic wave filter is a longitudinally coupled mode surface acoustic filter and includes said input IDT electrode and said output IDT electrode disposed within a single propagation path in which a surface acoustic wave propagetes,
- a pitch of electrode fingers of said input IDT electrode and a pitch of electrode fingers of said output IDT electrode are different from each other;
- and
- a film thickness of said output IDT electrode and a film thickness input IDT electrodes are different from each other.
5 more elements
A surface acoustic wave filter comprising:
- a piezoelectric substrate;
- at least an input IDT electrode arranged on said piezoelectric substrate;
- and
- at least an output IDT electrode arranged on said piezoelectric substrate;
- wherein said surface acoustic wave filter is a longitudinally coupled mode surface acoustic filter and includes said input IDT electrode and said output IDT electrode disposed within a single propagation path in which a surface acoustic wave propagates.
- a pitch of electrode fingers of said input IDT electrode and a pitch of electrode fingers of said output IDT electrode are different from each other;
- and
- a material of said output IDT electrode and a material of said input IDT electrodes are different from each other.
5 more elements
A surface acoustic wave filter comprising;
- a piezoelectric substrate;
- at least an input IDT electrode arranged on said piezoelectric substrate;
- and
- at least an output IDT electrode arranged on said piezoelectric substrate;
- wherein said surface acoustic wave filter is a longitudinally coupled mode surface acoustic filter and includes said input IDT electrode and said output IDT electrode disposed within a single propagation path in which a surface acoustic wave propagates,
- a pitch of electrode fingers of said input IDT electrode and a pitch of electrode fingers of said output IDT electrode are different from each other;
- one of said input IDT electrode and said output IDT electrode comprises a first IDT electrode including a pair of electrode fingers opposed to each other;
- the other of said input IDT electrode and said output IDT electrode comprises a second IDT electrode including a pair of electrode fingers opposed to each other, and a third IDT electrode including a pair of electrode fingers opposed to each other, said second IDT electrode being placed on one side of said first IDT electrode, said third IDT electrode being placed on the other side of said first IDT electrode;
- said first, second, and third IDT electrodes are arranged alone a direction in which a surface acoustic wave propagates;
- and
- the metalization ratio of said first IDT electrode, the metalization ratio of said second IDT electrode and the metalization ratio of said third IDT electrode are different from each other.
8 more elements
A surface acoustic wave filter comprising:
- a piezoelectric substrate;
- at least an input IDT electrode arranged on said piezoelectric substrate;
- and
- at least an output IDT electrode arranged on said piezoelectric substrate;
- wherein said surface acoustic wave filter is a longitudinally coupled mode surface acoustic filter and includes said input IDT electrode and said output IDT electrode disposed within a single propagation path in which a surface acoustic wave propagates;
- a pitch of electrode fingers of said input IDT electrode and a pitch of electrode fingers of said output IDT electrode are different from each other;
- one of said input IDT electrode and said output IDT electrode comprises a first IDT electrode including a pair of electrode fingers opposed to each other;
- the other of said input IDT electrode and said output IDT electrode comprises a second IDT electrode including a pair of electrode fingers opposed to each other, and a third IDT electrode including a pair of electrode fingers opposed to each other, said second IDT electrode being placed on one side of said first IDT electrode, said third IDT electrode being placed on the other side of said first IDT electrode;
- said first, second, and third IDT electrodes are arranged along a direction in which a surface acoustic wave propagates;
- a plurality of filter tracks each having first, second, and third IDT electrodes, and first and second reflector electrodes are formed on said piezoelectric substrate, and said plurality of filter tracks function as one filter in cooperation with each other;
- and
- each of said plurality of filter tracks is substantially identical in configuration to the others.
9 more elements
A surface acoustic wave filter comprising:
- a piezoelectric substrate;
- an input IDT electrode comprising first, fourth, and fifth IDT electrodes each including a pair of electrode fingers opposed to each other;
- an output IDT electrode comprising second and third IDT electrodes each including a pair of electrode fingers opposed to each other;
- the second IDT electrode disposed between said first and fourth IDT electrodes and the third IDT electrode disposed between said first and fifth IDT electrodes, and each of the IDT electrodes arranged on the piezoelectric substrate;
- the electrode fingers of the first IDT electrode having a first pitch;
- the electrode fingers of the second and third IDT electrodes having a second pitch;
- the electrode fingers of the fourth and fifth IDT electrodes having a third pitch;
- wherein the value of the pitches of the first, second, and third pitches have one of the following relationship:
- (a) are each different from each other;
- or
- (b) the first pitch is greater than the second pitch and the second pitch is greater than the third pitch.
8 more elements
A surface acoustic wave filter comprising:
- a piezoelectric substrate;
- a first filter track having a) at least an input IDT electrode arranged on said piezoelectric substrate, and b) at least an output IDT electrode arranged on said piezoelectric substrate,
- a second filter track having a) at least an input IDT electrode arranged on said piezoelectric substrate, and b) at least an output IDT electrode arranged on said piezoelectric substrate,
- wherein each of said first and second filter tracks are longitudinally coupled and includes input and output IDT electrodes disposed within a respective propagation path in which a surface acoustic wave propagates;
- and
- each input IDT having the majority of electrode fingers spaced to define a first main pitch,
- each output IDT having the majority of electrode fingers spaced to define a second main pitch,
- within each of said first and second filter tracks, each first main pitch is different in value from each second main pitch, and
- said first and second filter tracks are substantially identical in configuration to each other, and function as one filter in cooperation with each other.
6 more elements
A surface acoustic wave filter comprising:
- a piezoelectric substrate;
- at least an input IDT electrode arranged on said piezoelectric substrate;
- and
- at least an output IDT electrode arranged on said piezoelectric substrate,
- wherein said surface acoustic wave filter is a longitudinally coupled mode surface acoustic filter and includes said input IDT electrode and said output IDT electrode disposed within a single propagation path in which a surface acoustic wave propagates,
- said input IDT electrode has a plurality of electrode fingers pitches;
- of the electrode fingers pitches of said input IDT electrode, an electrode fingers pitch having the most pairs of electrode fingers is defined as a main input pitch,
- said output IDT electrode has a plurality of electrode fingers pitches,
- of the electrode fingers pitches of said output IDT electrode, an electrode fingers pitch having the most pairs of electrode fingers is defined as a main output pitch, and
- (a) a peak frequency of a radiation characteristic of the input IDT electrode having the main input pitch and a peak frequency of a radiation characteristic of the output IDT electrode having the main output pitch are substantially equal, or
- (b) a peak frequency of a radiation characteristic of the input IDT electrode and a peak frequency of a radiation characteristic of the output IDT electrode are substantially equal.
8 more elements
A surface acoustic wave filter comprising:
- a piezoelectric substrate;
- a first filter track having
- (a) at least an input IDT electrode arranged on said piezoelectric substrate, and
- (b) at least an output IDT electrode arranged on said piezoelectric substrate,
- a second filter track having
- (a) at least an input IDT electrode arranged on said piezoelectric substrate, and
- (b) at least an output IDT electrode arranged on said piezoelectric substrate,
- wherein each of said first and second filter tracks are longitudinally coupled and includes input and output IDT electrodes disposed within a respective propagation path in which a surface acoustic wave propagates,
- said input IDT electrode has a plurality of electrode fingers pitches;
- of the electrode fingers pitches of said input IDT electrode, an electrode fingers pitch having the most pairs of electrode fingers is defined as a main input pitch,
- said output IDT electrode has a plurality of electrode fingers pitches,
- of the electrode fingers pitches of said output IDT electrode, an electrode fingers pitch having the most pairs of electrode fingers is defined as a main output pitch, and
- in each of said first and second filter tracks, the main pitch of electrode fingers of said input IDT electrode and the main output pitch of electrode fingers of said output IDT electrode are different from each other.
10 more elements
Dependencies are inferred from the claim text.