Surface acoustic wave device, equipment including the same with electric circuit connected thereto and measuring method of parameters thereof
First Claim
1. A surface acoustic wave device combined with an electric circuit connected thereto, said surface acoustic wave device comprising a surface acoustic wave substrate and at least two interdigital transducers formed on said surface acoustic wave substrate, at least one of said interdigital transducers and/or said electric circuit having an internal dissipation of input signal energy, wherein said at least one interdigital transducer includes electrode means which together with said electric circuit, connected thereto, satisfies the following equation pertaining to mechanical reflection:
- ##EQU12## where (α
) is a matrix resulting from a multiplication of a scattering matrix (S) with a complex conjugate matrix (S*) thereof when a unidirectional interdigital transducer is represented by an equivalent circuit of said at least one interdigital transducer combined with said electric circuit connected thereto, which has a first, forward acoustic terminal, a second, backward acoustic terminal and a third, electric terminal, κ
=(|S23 |2 /|S13 |2) is a directionality coefficient, θ
1 is arg(S132 S33* S11*), θ
2 is arg(α
13* S33 S13*), θ
3 is arg(α
13* S13 S11*), μ
is α
13 /|S13 | and Γ
=|S33 | is indicative of electric reflection.
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Accused Products
Abstract
A surface acoustic wave device having a novel structure capable of restricting TTE and ripple noise on a frequency characteristics and group delay time characteristics thereof is provided under a condition by which acoustic reflection is suppressed when there is internal dissipation in the device and/or a peripheral circuit thereof. When the device includes a unidirectional interdigital transducer, it is possible to restrict ripple of the frequency characteristics and the group delay time characteristics and to reduce loss without using a phase shifter. By using the surface acoustic wave device according to the present invention, a communication apparatus can be improved in performance.
14 Citations
6 Claims
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1. A surface acoustic wave device combined with an electric circuit connected thereto, said surface acoustic wave device comprising a surface acoustic wave substrate and at least two interdigital transducers formed on said surface acoustic wave substrate, at least one of said interdigital transducers and/or said electric circuit having an internal dissipation of input signal energy, wherein said at least one interdigital transducer includes electrode means which together with said electric circuit, connected thereto, satisfies the following equation pertaining to mechanical reflection:
- ##EQU12## where (α
) is a matrix resulting from a multiplication of a scattering matrix (S) with a complex conjugate matrix (S*) thereof when a unidirectional interdigital transducer is represented by an equivalent circuit of said at least one interdigital transducer combined with said electric circuit connected thereto, which has a first, forward acoustic terminal, a second, backward acoustic terminal and a third, electric terminal, κ
=(|S23 |2 /|S13 |2) is a directionality coefficient, θ
1 is arg(S132 S33* S11*), θ
2 is arg(α
13* S33 S13*), θ
3 is arg(α
13* S13 S11*), μ
is α
13 /|S13 | and Γ
=|S33 | is indicative of electric reflection. - View Dependent Claims (3)
- ##EQU12## where (α
-
2. A surface acoustic wave device combined with an electric circuit connected thereto, said surface acoustic wave device comprising a surface acoustic wave substrate and at least two interdigital transducers formed on said surface acoustic wave substrate, at least one of said interdigital transducers and/or said electric circuit having an internal dissipation of input signal energy, wherein said at least one interdigital transducer includes electrode means which together with said electric circuit, connected thereto, satisfies the following equation pertaining to acoustic reflection:
- ##EQU13## where (α
) is a matrix resulting from a multiplication of a scattering matrix (S) with a complex conjugate matrix (S*) thereof when a unidirectional interdigital transducer is represented by an equivalent circuit of said at least one interdigital transducer combined with said electric circuit, which has a first, forward acoustic terminal, a second, backward acoustic terminal and a third, electric terminal, one of said first and second terminals being selected such that elements of the scattering matrix (S) become real numbers, κ
=(|S23 |2 /|S13 |2)=(S232 /S132) is a directionality coefficient, μ
is α
13 /|S13 | and γ
=S33 is indicative of electric reflection.
- ##EQU13## where (α
-
4. A surface acoustic wave device combined with an electric circuit connected thereto, said surface acoustic wave device comprising a surface acoustic wave substrate and at least two interdigital transducers formed on said surface acoustic wave substrate, at least one of said interdigital transducers and/or said electric circuit having an internal dissipation of input signal energy, wherein said surface acoustic wave device includes electrode means such that when combined with said electric circuit satisfies the following equation pertaining to acoustic reflection:
-
space="preserve" listing-type="equation">|{ (κ
-1)/(κ
+1)!(b+g)+1}/(1+b+g)≦
1/3where (S) is a scattering matrix when a unidirectional electrode is represented by an equivalent circuit of said at least one interdigital transducer combined with said electric circuit connected thereto, which has a first, forward acoustic terminal, a second, backward acoustic terminal and a pair of third, electric terminals, (S*) is a complex conjugate matrix thereof, κ
=(|S23 |2 /|S13 |2)=(S232 /S132) is a directionality coefficient, Ga is radiation conductance of an interdigital reed electrode as viewed from the electric terminals, Gl is conductance on the side of an applied power source or load, gu is a conductance component connected as a parallel element across the electric terminals and represents the internal dissipation, g=gu/Ga and b=Gl/Ga.
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5. A surface acoustic wave device combined with an electric circuit connected thereto, said surface acoustic wave device comprising a surface acoustic wave substrate and at least two interdigital transducers formed on said surface acoustic wave substrate, at least one of said interdigital transducers and/or said electric circuit having an internal dissipation of input signal energy, wherein said surface acoustic wave device includes electrode means such that when combined with said electric circuit satisfies the following equation pertaining to acoustic reflection:
-
space="preserve" listing-type="equation">|{ (κ
-1)/(κ
+1)!+(1/b)+r}/ 1+(1/b)+r!|≦
1/3where (S) is a scattering matrix when a unidirectional electrode is represented by an equivalent circuit of said at least one interdigital transducer combined with said electric circuit connected thereto, which has a first, forward acoustic terminal, a second, backward acoustic terminal and a pair of third, electric terminals, (S*) is a complex conjugate matrix thereof, κ
=(|S23 |2)/|S13 |2)=(S232 /S132) is a directionality coefficient, Ga is radiation conductance of said interdigital transducer as viewed from the electric terminals, Gl is conductance on the side of an applied power source or load, ru is a resistive component connected as a series element between one of the electric terminals and said forward acoustic terminal and represents the internal dissipation, r=ru×
Ga, and b=Gl/Ga.
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6. A surface acoustic wave device combined with an electric circuit connected thereto, said surface acoustic wave device comprising a surface acoustic wave substrate and at least two interdigital transducers formed on said surface acoustic wave substrate and being combined with said electric circuit to form a unidirectional interdigital transducer, at least one of said interdigital transducers and/or said electric circuit having an internal dissipation of input signal energy, wherein an element α
-
33 is defined by the following equation;
##EQU14## where α
33 is an element of (α
), which is related to an electric terminal and represents a coefficient of internal dissipation, (α
) being a matrix resulting from multiplication of a scattering matrix (S) with a complex conjugate matrix (S*) thereof when the unidirectional interdigital transducer is represented by an equivalent circuit including a first, forward acoustic terminal, a second, backward acoustic terminal and a third, said electric terminal.
-
33 is defined by the following equation;
Specification