CN112532196B - Surface acoustic wave filter, manufacturing method thereof and electronic equipment - Google Patents
Surface acoustic wave filter, manufacturing method thereof and electronic equipment Download PDFInfo
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- CN112532196B CN112532196B CN202011353502.4A CN202011353502A CN112532196B CN 112532196 B CN112532196 B CN 112532196B CN 202011353502 A CN202011353502 A CN 202011353502A CN 112532196 B CN112532196 B CN 112532196B
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- 238000010897 surface acoustic wave method Methods 0.000 title claims abstract description 109
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 17
- 239000000758 substrate Substances 0.000 claims description 19
- 239000010453 quartz Substances 0.000 claims description 12
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 12
- 238000001914 filtration Methods 0.000 abstract description 25
- 230000000694 effects Effects 0.000 abstract description 8
- 238000010295 mobile communication Methods 0.000 abstract description 5
- 230000009286 beneficial effect Effects 0.000 description 7
- 238000010586 diagram Methods 0.000 description 5
- 238000000034 method Methods 0.000 description 5
- 230000007704 transition Effects 0.000 description 4
- 239000000463 material Substances 0.000 description 3
- 230000008569 process Effects 0.000 description 2
- 238000013459 approach Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
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- 238000002474 experimental method Methods 0.000 description 1
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- 238000012986 modification Methods 0.000 description 1
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
- H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
- H03H3/08—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of resonators or networks using surface acoustic waves
- H03H3/10—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of resonators or networks using surface acoustic waves for obtaining desired frequency or temperature coefficient
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
- H03H9/25—Constructional features of resonators using surface acoustic waves
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
- H03H9/46—Filters
- H03H9/64—Filters using surface acoustic waves
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Abstract
The invention relates to a surface acoustic wave filter, a manufacturing method thereof and electronic equipment, wherein a capacitance transducer is connected between every two adjacent structural units, and the capacitance transducer is grounded, so that the capacitance transducer plays a role of capacitance to ground, the rectangular degree of the surface acoustic wave filter can be effectively improved, the filtering performance of the surface acoustic wave filter is further improved, and the technical effect of linearly superposing the filtering performance, namely, the rectangular degree of the surface acoustic wave filter can be linearly improved along with the increase of the number of the structural units, namely, the frequency selectivity of the surface acoustic wave filter is improved, so that the surface acoustic wave filter can be widely applied to the electronic information fields such as radars, navigation, mobile communication and the like, and has strong applicability.
Description
Technical Field
The present invention relates to the field of surface acoustic wave filters, and in particular, to a surface acoustic wave filter, a method for manufacturing the same, and an electronic device.
Background
As shown in fig. 1, the basic structure of the surface acoustic wave filter is that two acoustic-electric transducers, i.e. interdigital transducers, are manufactured on a piezoelectric substrate and are respectively used as a transmitting interdigital transducer and a receiving interdigital transducer, and the filtering principle is as follows: the signal electrode of the transmitting interdigital transducer receives a source signal and converts the source signal into a surface acoustic wave and propagates on the surface of the piezoelectric substrate, and the receiving interdigital transducer receives the surface acoustic wave and converts the surface acoustic wave into an electric signal to be output, namely the surface acoustic wave filter finishes the mutual conversion of the electric signal and the surface acoustic wave signal by utilizing the piezoelectric effect and the inverse piezoelectric effect of the piezoelectric material and performs signal processing in the propagation process of the surface acoustic signal, thereby realizing the filtering function, wherein the rectangular degree is an important index for measuring the filtering performance of the surface acoustic wave filter, and at present, the rectangular degree of the surface acoustic wave filter, especially the ultra-narrow band surface acoustic wave filter, is more than 3, and seriously affecting the filtering performance of the surface acoustic wave filter, especially the ultra-narrow band surface acoustic wave filter.
Disclosure of Invention
The invention aims to solve the technical problem of providing a surface acoustic wave filter, a manufacturing method thereof and electronic equipment aiming at the defects of the prior art.
The technical scheme of the surface acoustic wave filter is as follows:
comprises a capacitance transducer and at least two structural units; the capacitive transducer and at least two structural units are arranged on the piezoelectric substrate;
The structure unit comprises a surface acoustic wave reflecting grating and an interdigital transducer, wherein the interdigital transducer comprises a ground electrode, an input signal electrode and an output signal electrode which are oppositely arranged, and also comprises interdigital transducer finger strips of a first part connected with the input signal electrode and interdigital transducer finger strips of a second part connected with the output signal electrode, the interdigital transducer finger strips of the first part and the interdigital transducer finger strips of the second part are symmetrically or alternately arranged and are respectively inserted into the ground electrode, and the surface acoustic wave reflecting grating is connected with the ground electrode;
One capacitive transducer is connected between every two adjacent structural units, one end of each capacitive transducer is connected with the input signal electrode or the output signal electrode, and the other end of each capacitive transducer is connected with the ground electrode.
The surface acoustic wave filter has the following beneficial effects:
The capacitive transducer is connected between every two adjacent structural units, and the capacitive transducer is grounded, so that the capacitive transducer plays a role of capacitance to ground, the rectangular degree of the surface acoustic wave filter can be effectively improved, the filtering performance of the surface acoustic wave filter is further improved, and the structural units are used in series, so that the technical effect of linearly superposing the filtering performance, namely the rectangular degree of the surface acoustic wave filter can be linearly improved along with the increase of the number of the structural units, namely the frequency selectivity of the surface acoustic wave filter is improved, and the surface acoustic wave filter can be widely applied to the electronic information fields such as radars, navigation and mobile communication and has strong applicability.
On the basis of the scheme, the surface acoustic wave filter can be improved as follows.
Further, the capacitive transducer includes a finger, and the direction of extension of the finger of the capacitive transducer is perpendicular to the direction of extension of the interdigital transducer finger of the first portion and the interdigital transducer finger of the second portion.
The beneficial effects of adopting the further scheme are as follows: the extending direction of the finger strip of the capacitive transducer is perpendicular to the extending direction of the finger strip of the interdigital transducer of the first part and the finger strip of the interdigital transducer of the second part, so that the capacitive transducer has no function of transmitting and resonating sound waves, reduces the influence on the filtering of the surface acoustic waves, and further improves the performance of the surface acoustic wave filter.
Further, the ground electrode comprises a plurality of ground electrode fingers, and the interdigital transducer fingers of the first part and the interdigital transducer fingers of the second part are spliced with the plurality of ground electrode fingers.
Further, the sum of the width of the slit between any two adjacent ground electrode fingers and the width of any one ground electrode finger is λ, where λ represents the wavelength of the surface acoustic wave to be filtered.
Further, the piezoelectric substrate is made of quartz.
The beneficial effects of adopting the further scheme are as follows: the quartz can be cut at will, has high Q value (B △ is small) and high temperature stability, and is suitable for manufacturing ultra-narrow band surface acoustic wave filters.
The technical scheme of the electronic equipment is as follows: a surface acoustic wave filter comprising any one of the above.
The electronic equipment has the following beneficial effects:
The capacitive transducer is connected between every two adjacent structural units in the surface acoustic wave filter, and the capacitive transducer is grounded, so that the capacitive transducer plays a role of capacitance to ground, the rectangular degree of the surface acoustic wave filter can be effectively improved, the filtering performance of the surface acoustic wave filter is further improved, and the technical effect of linearly superposing the filtering performance can be achieved by using at least two structural units in series, namely, the rectangular degree of the surface acoustic wave filter can be linearly improved along with the increase of the number of the structural units, namely, the frequency selectivity of the surface acoustic wave filter is improved, and the performance of electronic equipment is further improved.
The technical scheme of the manufacturing method of the surface acoustic wave filter is as follows:
S1, arranging a capacitance transducer and at least two structural units on a piezoelectric substrate, wherein the structural units comprise a surface acoustic wave reflecting grating and an interdigital transducer, the interdigital transducer comprises a ground electrode, an input signal electrode and an output signal electrode which are oppositely arranged, and the interdigital transducer also comprises interdigital transducer fingers of a first part connected with the input signal electrode and interdigital transducer fingers of a second part connected with the output signal electrode; the interdigital transducer finger strips of the first part and the interdigital transducer finger strips of the second part are symmetrically or alternately arranged and are inserted into the ground electrode, and the surface acoustic wave reflecting grating is connected with the ground electrode;
s2, connecting one capacitance transducer between every two adjacent structural units, wherein one end of each capacitance transducer is connected with the input signal electrode or the output signal electrode, and the other end is connected with the ground electrode.
The manufacturing method of the surface acoustic wave filter has the following beneficial effects:
The capacitive transducer is connected between every two adjacent structural units, and the capacitive transducer is grounded, so that the capacitive transducer plays a role of capacitance to ground, the rectangular degree of the surface acoustic wave filter can be effectively improved, the filtering performance of the surface acoustic wave filter is further improved, the structural units are used in series, the technical effect of linearly superposing the filtering performance can be achieved, namely, the rectangular degree of the surface acoustic wave filter can be linearly improved along with the increase of the number of the structural units, namely, the frequency selectivity of the surface acoustic wave filter is improved, and the manufactured surface acoustic wave filter can be widely applied to the electronic information fields such as radar, navigation and mobile communication and has strong applicability.
On the basis of the scheme, the manufacturing method of the surface acoustic wave filter can be improved as follows.
Further, the capacitive transducer includes a finger, and the direction of extension of the finger of the capacitive transducer is perpendicular to the direction of extension of the interdigital transducer finger of the first portion and the interdigital transducer finger of the second portion.
The beneficial effects of adopting the further scheme are as follows: the extending directions of the finger strips of the capacitive transducer are respectively perpendicular to the extending directions of the finger strips of the interdigital transducer of the first part and the finger strips of the interdigital transducer of the second part, so that the capacitive transducer has no function of transmitting and resonating sound waves, reduces the influence on the filtering of the sound surface waves, and further improves the performance of the sound surface wave filter.
Further, the ground electrode includes a plurality of ground electrode fingers, the interdigital transducer fingers of the first part and the interdigital transducer fingers of the second part are spliced on the ground electrode, and the ground electrode comprises:
The interdigital transducer finger strips of the first part and the interdigital transducer finger strips of the second part are spliced with a plurality of the ground electrode finger strips.
Further, the sum of the width of the slit between any two adjacent ground electrode fingers and the width of any one ground electrode finger is λ, where λ represents the wavelength of the surface acoustic wave to be filtered.
Further, the piezoelectric substrate is made of quartz.
The beneficial effects of adopting the further scheme are as follows: the quartz can be cut at will, has high Q value (B △ is small) and high temperature stability, and is suitable for manufacturing ultra-narrow band surface acoustic wave filters.
Drawings
Fig. 1 is a schematic diagram of a surface acoustic wave filter in the prior art;
Fig. 2 is a schematic diagram of the rectangular degree of the surface acoustic wave filter;
FIG. 3 is a schematic diagram of a structural unit according to an embodiment of the present invention;
FIG. 4 is a second schematic diagram of a structural unit according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of a surface acoustic wave filter according to an embodiment of the present invention;
Fig. 6 is a flow chart of a method for manufacturing a surface acoustic wave filter according to an embodiment of the present invention.
Detailed Description
As shown in fig. 5, a surface acoustic wave filter according to an embodiment of the present invention includes a capacitive transducer 1 and at least two structural units; the capacitive transducer 1 and at least two of the structural units are arranged on the piezoelectric substrate 3;
The structure unit comprises a surface acoustic wave reflecting grating 4 and an interdigital transducer, wherein the interdigital transducer comprises a ground electrode 5, an input signal electrode 9 and an output signal electrode 10 which are oppositely arranged, and also comprises a first part of interdigital transducer finger strips 71 connected with the input signal electrode 9 and a second part of interdigital transducer finger strips 72 connected with the output signal electrode 10, the first part of interdigital transducer finger strips 71 and the second part of interdigital transducer finger strips 72 are symmetrically or alternately arranged and are respectively inserted into the ground electrode 5, and the surface acoustic wave reflecting grating 4 is connected with the ground electrode 5;
one capacitive transducer 1 is connected between every two adjacent structural units, one end of each capacitive transducer 1 is connected with the input signal electrode 9 or the output signal electrode 10, and the other end is connected with the ground electrode 5, wherein the input signal electrode 9 is connected with the output signal electrode 10.
Wherein the ground electrode 5 is grounded, a signal is input from the input end 12 of the surface acoustic wave filter, and is output from the output end 13 of the surface acoustic wave filter to realize filtering.
As shown in fig. 1, in the prior art, the basic structure of the surface acoustic wave filter is: manufacturing interdigital transducers on a piezoelectric substrate 3, wherein gaps 8 are arranged between each interdigital transducer finger 7 of the interdigital transducers;
The rectangle degree is an important index for measuring the filtering performance of the surface acoustic wave filter, as shown in fig. 2, the calculating process of the rectangle degree is shown based on the amplitude-frequency characteristic curve 11 of the surface acoustic wave filter, namely, the calculation is carried out through B -40/B-3, it can be understood that the smaller the numerical value of B -40/B-3 is, the better the filtering performance of the surface acoustic wave filter is, the essence of the improvement of the rectangle degree is the reduction of the numerical value of B -40/B-3; however, for the ultra-narrow band saw filter, the bandwidth is extremely narrow, B -3/f0 =0.3 to 2 mill of the ultra-narrow band, in general, the narrower the bandwidth is, the more difficult the realization of high rectangle degree is, because, for the smaller the transition band width B △＝B-40-B-3,B-3 is, the larger the value of B -40/B-3＝(B△+B-3)/B-3＝B△/B-3 +1 is, i.e. the worse the rectangle degree is, in the prior art, the rectangle degree of the ultra-narrow band saw filter is all above 3, even if the quartz substrate with the highest Q value (the minimum transition band width B △) is used as the piezoelectric substrate 3, B △/B-3 can only be realized 2 at present, at this time, B -40/B-3＝B△/B-3 +1=3, at this time, the rectangle degree is higher, and the filtering performance of the saw filter, especially the ultra-narrow band saw filter, is seriously affected;
When actually designing the surface acoustic wave, since B -3 is unchanged, reducing B △ is a main technical approach to increase the rectangular degree of the surface acoustic wave. In the surface acoustic wave filter, one capacitance transducer 1 is connected between every two adjacent structural units, and the capacitance transducer 1 is connected with the ground electrode 5 to be grounded, so that the capacitance transducer 1 plays a role of capacitance to the ground, the transition band width B △ can be effectively reduced, the rectangular degree of the surface acoustic wave filter can be further effectively improved, the filtering performance of the surface acoustic wave filter is further improved, at least two structural units are used in series, the technical effect of linear superposition of filtering performance can be achieved, namely, the rectangular degree of the surface acoustic wave filter can be linearly improved along with the increase of the number of the structural units, namely, when a plurality of structural units are connected in series, the transition band width B △ can be further reduced, the rectangular degree is further improved, and experiments show that the rectangular degree can be improved to be within 2.2, namely, the frequency selectivity of the surface acoustic wave filter and the stop band suppression can be effectively improved, so that the surface acoustic wave filter can be widely applied to the electronic information fields of radars, navigation, mobile communication and the like, and the surface acoustic wave filter has strong applicability and is applicable to surface acoustic wave filter frequency ranges from 10MHz to 5 MHz.
Wherein, the ground electrode 5 includes a plurality of ground electrode fingers 6, and the interdigital transducer finger 71 of the first part and the interdigital transducer finger 72 of the second part are spliced with the plurality of ground electrode fingers 6, then:
1) As shown in fig. 3, a structural unit, a first portion of interdigital transducer fingers 71 and a second portion of interdigital transducer fingers 72 are staggered;
2) As shown in fig. 4, a structural unit, the interdigital transducer finger 71 of the first part and the interdigital transducer finger 72 of the second part are symmetrically arranged;
It can be understood that the number, the structure, such as the length and the width, of the interdigital transducer finger strips 71 of the first portion and the interdigital transducer finger strips 72 of the second portion are the same, and the structure of the surface acoustic wave reflection grating 4 can be adjusted correspondingly according to the designed interdigital transducer finger strips 71 of the first portion and the interdigital transducer finger strips 72 of the second portion according to the surface acoustic wave to be filtered;
wherein each surface acoustic wave reflecting grating 4 is respectively and independently grounded, and shielding treatment is carried out between every two adjacent structural units, specifically: a ground electrode 5 is interposed between each adjacent two of the structural units to shield signals between the structural units.
Preferably, in the above technical solution, the capacitive transducer 1 includes a finger 2, and the extension direction of the finger 2 of the capacitive transducer 1 is perpendicular to the extension direction of the interdigital transducer finger 71 of the first portion and the interdigital transducer finger 72 of the second portion.
Since the extension direction of the finger 2 of the capacitive transducer 1 is perpendicular to the extension direction of the finger 71 of the interdigital transducer of the first portion and the finger 72 of the interdigital transducer of the second portion, the function of transmitting and resonating the acoustic wave is not provided, the influence on the filtering of the acoustic surface wave is reduced, and the performance of the acoustic surface wave filter is further improved.
Preferably, in the above technical solution, the piezoelectric substrate 3 is made of quartz. The quartz can be cut at will, has high Q value (B △ is small) and high temperature stability, and is suitable for manufacturing ultra-narrow band surface acoustic wave filters. When a quartz substrate is used as the piezoelectric substrate 3, the experimental results show that: the rectangle degree is increased from 3.0 to 2.15.
Preferably, in the above technical solution, the sum of the width of the slit between any two adjacent ground electrode fingers and the width of any one ground electrode finger is λ, where λ represents the wavelength of the surface acoustic wave to be filtered.
An electronic device of an embodiment of the present invention: comprising a surface acoustic wave filter as described in any one of the embodiments above. Electronic devices such as radar, navigation devices, smart terminals, etc.
The capacitive transducer 1 is connected between every two adjacent structural units in the surface acoustic wave filter, and because the capacitive transducer 1 is grounded, the capacitive transducer 1 plays a role of capacitance to ground, the rectangular degree of the surface acoustic wave filter can be effectively improved, and the filtering performance of the surface acoustic wave filter is further improved.
As shown in fig. 6, a method for manufacturing a surface acoustic wave filter according to an embodiment of the present invention includes the steps of:
S1, arranging a capacitive transducer 1 and at least two structural units on a piezoelectric substrate 3, wherein the structural units comprise a surface acoustic wave reflecting grating 4 and an interdigital transducer, the interdigital transducer comprises a ground electrode 5, an input signal electrode 9 and an output signal electrode 10 which are oppositely arranged, and further comprises an interdigital transducer finger 71 of a first part connected with the input signal electrode 9 and an interdigital transducer finger 72 of a second part connected with the output signal electrode 10; the interdigital transducer finger strips 71 and 72 of the first part and the second part are symmetrically or alternately arranged and are inserted into the ground electrode 5, and the surface acoustic wave reflecting grating 4 is connected with the ground electrode 5;
and S2, connecting one capacitance transducer 1 between every two adjacent structural units, wherein one end of each capacitance transducer 1 is connected with the input signal electrode 9 or the output signal electrode 10, and the other end is connected with the ground electrode 5.
The capacitive transducer 1 is connected between every two adjacent structural units, and the capacitive transducer 1 is grounded, so that the capacitive transducer 1 plays a role of capacitance to ground, the rectangular degree of the surface acoustic wave filter can be effectively improved, the filtering performance of the surface acoustic wave filter is further improved, and the structural units are used in series, so that the technical effect of linearly superposing the filtering performance, namely, the rectangular degree of the surface acoustic wave filter can be linearly improved along with the increase of the number of the structural units, namely, the frequency selectivity of the surface acoustic wave filter is improved, and the manufactured surface acoustic wave filter can be widely applied to the fields of radar, navigation, mobile communication and other electronic information and has strong applicability.
Preferably, in the above technical solution, the capacitive transducer 1 includes a finger 2, and the extension direction of the finger 2 of the capacitive transducer 1 is perpendicular to the extension direction of the interdigital transducer finger 71 of the first portion and the interdigital transducer finger 72 of the second portion.
Since the extension direction of the finger 2 of the capacitive transducer 1 is perpendicular to the extension direction of the finger 71 of the interdigital transducer of the first portion and the finger 72 of the interdigital transducer of the second portion, the function of transmitting and resonating the acoustic wave is not provided, the influence on the filtering of the acoustic surface wave is reduced, and the performance of the acoustic surface wave filter is further improved.
Preferably, in the above technical solution, the ground electrode 5 includes a plurality of ground electrode fingers 6, and the first portion of interdigital transducer fingers 71 and the second portion of interdigital transducer fingers 72 are inserted into the ground electrode 5, including:
the interdigital transducer finger 71 of the first part and the interdigital transducer finger 72 of the second part are spliced with the plurality of ground electrode fingers 6.
Preferably, in the above technical solution, the sum of the width of the slit between any two adjacent ground electrode fingers and the width of any one ground electrode finger is λ, where λ represents the wavelength of the surface acoustic wave to be filtered.
Preferably, in the above technical solution, the piezoelectric substrate 3 is made of quartz.
The quartz can be cut at will, has high Q value (B △ is small) and high temperature stability, and is suitable for manufacturing ultra-narrow band surface acoustic wave filters.
In the above embodiments, although the steps S1, S2, etc. are numbered, only the specific embodiments of the present application are given, and those skilled in the art may adjust the execution sequence of the steps S1, S2, etc. according to the actual situation, which is also within the scope of the present application, and it is understood that some embodiments may include some or all of the above embodiments.
In the present disclosure, the terms "first," "second," and "second" are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implying a number of technical features being indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.
Claims (5)
1. A surface acoustic wave filter comprising a capacitive transducer and at least two structural elements; the capacitive transducer and at least two structural units are arranged on the piezoelectric substrate;
The structure unit comprises a surface acoustic wave reflecting grating and an interdigital transducer, wherein the interdigital transducer comprises a ground electrode, an input signal electrode and an output signal electrode which are oppositely arranged, and also comprises interdigital transducer finger strips of a first part connected with the input signal electrode and interdigital transducer finger strips of a second part connected with the output signal electrode, the interdigital transducer finger strips of the first part and the interdigital transducer finger strips of the second part are symmetrically or alternately arranged and are respectively inserted into the ground electrode, and the surface acoustic wave reflecting grating is connected with the ground electrode;
One capacitive transducer is connected between every two adjacent structural units, one end of each capacitive transducer is connected with the input signal electrode or the output signal electrode, and the other end of each capacitive transducer is connected with the ground electrode;
The ground electrode comprises a plurality of ground electrode finger strips, and the interdigital transducer finger strips of the first part and the interdigital transducer finger strips of the second part are spliced with the plurality of ground electrode finger strips; the interdigital transducer finger strips of the first part and the interdigital transducer finger strips of the second part are arranged in a staggered or symmetrical way;
Each surface acoustic wave reflecting grating is respectively and independently grounded, shielding treatment is carried out between every two adjacent structural units, specifically, a ground electrode is connected between every two adjacent structural units, and signals between the structural units are shielded;
the capacitive transducer comprises finger strips, and the extending direction of the finger strips of the capacitive transducer is perpendicular to the extending directions of the finger strips of the interdigital transducer of the first part and the finger strips of the interdigital transducer of the second part;
the piezoelectric substrate is made of quartz.
2. A surface acoustic wave filter according to claim 1, wherein the sum of the width of the slit between any adjacent two of the ground electrode fingers and the width of any one of the ground electrode fingers is λ, λ representing the wavelength of the surface acoustic wave to be filtered.
3. An electronic device comprising a surface acoustic wave filter according to any one of claims 1 to 2.
4. A method of manufacturing a surface acoustic wave filter, comprising:
S1, arranging a capacitance transducer and at least two structural units on a piezoelectric substrate, wherein the structural units comprise a surface acoustic wave reflecting grating and an interdigital transducer, the interdigital transducer comprises a ground electrode, an input signal electrode and an output signal electrode which are oppositely arranged, and the interdigital transducer also comprises interdigital transducer fingers of a first part connected with the input signal electrode and interdigital transducer fingers of a second part connected with the output signal electrode; the interdigital transducer finger strips of the first part and the interdigital transducer finger strips of the second part are symmetrically or alternately arranged and are inserted into the ground electrode, and the surface acoustic wave reflecting grating is connected with the ground electrode;
S2, connecting one capacitance transducer between every two adjacent structural units, wherein one end of each capacitance transducer is connected with the input signal electrode or the output signal electrode, and the other end is connected with the ground electrode;
the ground electrode comprises a plurality of ground electrode fingers, the interdigital transducer fingers of the first part and the interdigital transducer fingers of the second part are spliced in the ground electrode, and the ground electrode comprises:
The interdigital transducer finger of the first part and the interdigital transducer finger of the second part are spliced with a plurality of the ground electrode finger;
the interdigital transducer finger strips of the first part and the interdigital transducer finger strips of the second part are arranged in a staggered or symmetrical way;
Each surface acoustic wave reflecting grating is respectively and independently grounded, shielding treatment is carried out between every two adjacent structural units, specifically, a ground electrode is connected between every two adjacent structural units, signals between the structural units are shielded, the capacitive transducer comprises finger strips, the extending direction of the finger strips of the capacitive transducer is perpendicular to the extending directions of the finger strips of the interdigital transducer of the first part and the finger strips of the interdigital transducer of the second part, and the piezoelectric substrate is made of quartz.
5. The method of manufacturing a surface acoustic wave filter according to claim 4, wherein a sum of a width of a slit between any adjacent two of the ground electrode fingers and a width of any one of the ground electrode fingers is λ, and λ represents a wavelength of the surface acoustic wave to be filtered.
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| WO2019065667A1 (en) * | 2017-09-27 | 2019-04-04 | 株式会社村田製作所 | Acoustic wave filter device |
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