CN112532196A - Surface acoustic wave filter, manufacturing method thereof and electronic equipment - Google Patents
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- 238000010897 surface acoustic wave method Methods 0.000 title claims abstract description 114
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 19
- 239000000758 substrate Substances 0.000 claims description 18
- 239000010453 quartz Substances 0.000 claims description 10
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 10
- 238000000034 method Methods 0.000 claims description 7
- 238000001914 filtration Methods 0.000 abstract description 25
- 239000003990 capacitor Substances 0.000 abstract description 7
- 230000000694 effects Effects 0.000 description 13
- 230000009286 beneficial effect Effects 0.000 description 7
- 238000010586 diagram Methods 0.000 description 5
- 230000006872 improvement Effects 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 238000010295 mobile communication Methods 0.000 description 4
- 230000007704 transition Effects 0.000 description 4
- 230000004075 alteration Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000013461 design 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 devices; 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 devices; 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 capacitor transducer is connected between every two adjacent structural units, and the capacitor transducer is grounded, so that the capacitor transducer plays a role of capacitance to ground, the rectangularity of the surface acoustic wave filter can be effectively improved, and the filtering performance of the surface acoustic wave filter is further improved.
Description
Technical Field
The invention relates to the technical field of surface acoustic wave filtering, in particular to a surface acoustic wave filter, a manufacturing method thereof and electronic equipment.
Background
As shown in fig. 1, the basic structure of the surface acoustic wave filter is that two acoustic 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, converts the source signal into surface acoustic wave and transmits the surface acoustic wave on the surface of a 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 utilizes the piezoelectric effect and inverse piezoelectric effect of piezoelectric materials to complete the interconversion of the electric signal and the surface acoustic wave signal and performs signal processing in the transmission process of the acoustic signal, so that the filtering function is realized, wherein the squareness is an important index for measuring the filtering performance of the surface acoustic wave filter.
Disclosure of Invention
The invention provides 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 capacitive transducer and at least two structural units; the capacitive transducer and the at least two structural units are arranged on the piezoelectric substrate;
the structure unit comprises a surface acoustic wave reflection 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 further comprises a first part of interdigital transducer fingers connected with the input signal electrode and a second part of interdigital transducer fingers connected with the output signal electrode, the first part of interdigital transducer fingers and the second part of interdigital transducer fingers are symmetrically or alternatively arranged and are all inserted in the ground electrode, and the surface acoustic wave reflection grating is connected with the ground electrode;
and 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 capacitor transducer is connected between every two adjacent structural units, and the capacitor transducer is grounded, so that the capacitor transducer plays a role of a ground capacitor, the squareness of the surface acoustic wave filter can be effectively improved, the filtering performance of the surface acoustic wave filter is further improved, and at least two structural units are connected in series for use, so that the technical effect of linearly overlapping the filtering performance can be achieved, namely the squareness 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 of radars, navigation, mobile communication and the like, and is high in applicability.
On the basis of the above scheme, the surface acoustic wave filter of the present invention can be further improved as follows.
Further, the capacitance transducer comprises a finger strip, and the extension direction of the finger strip of the capacitance transducer is vertical to that of the interdigital transducer finger strip of the first part and the second part.
The beneficial effect of adopting the further scheme is that: because the extension direction of the finger strip of the capacitance transducer is vertical to the extension direction of the finger strip of the interdigital transducer of the first part and the extension direction of the finger strip of the interdigital transducer of the second part, the capacitance transducer does not have the functions of transmitting and resonating sound waves, reduces the influence on the filtering of the surface acoustic wave, 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, and λ represents the wavelength of the surface acoustic wave to be filtered.
Furthermore, the piezoelectric substrate is made of quartz.
The beneficial effect of adopting the further scheme is that: energy of quartzIs convenient for arbitrary cutting and has high Q value characteristic (B)△Small) and high temperature stability, and is suitable for manufacturing an extremely narrow band surface acoustic wave filter.
The technical scheme of the electronic equipment comprises the following steps: a surface acoustic wave filter comprising any of the above.
The electronic equipment has the following beneficial effects:
connect one between every two adjacent constitutional units in the surface acoustic wave filter the electric capacity transducer because electric capacity transducer ground connection makes the electric capacity transducer play the effect to the earth capacitance, can effectively improve surface acoustic wave filter's rectangle degree, and then improve surface acoustic wave filter's filtering performance, moreover, through establishing ties at least two constitutional units and using, can play the linear superimposed technological effect of filtering performance promptly along with the increase of constitutional unit's quantity, can be linear improvement surface acoustic wave filter's rectangle degree, the frequency selectivity of surface acoustic wave filter has been improved promptly, and then electronic equipment's performance has been 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 reflection 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 further comprises an interdigital transducer finger of a first part connected with the input signal electrode and an interdigital transducer finger of a second part connected with the output signal electrode; the interdigital transducer fingers of the first part and the interdigital transducer fingers of the second part are symmetrically or alternatively arranged and are inserted into the ground electrode, and the surface acoustic wave reflection grating is connected with the ground electrode;
and S2, connecting one capacitive transducer between every two adjacent structural units, wherein 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 manufacturing method of the surface acoustic wave filter has the following beneficial effects:
connect one between per two adjacent constitutional units the electric capacity transducer because electric capacity transducer ground connection, make the electric capacity transducer play the effect to the earth capacitance, can effectively improve surface acoustic wave filter's rectangle degree, and then improve surface acoustic wave filter's filtering performance, and, through establishing ties the use with at least two constitutional units, can play the linear superimposed technological effect of filtering performance promptly along with the increase of constitutional unit's quantity, can be linear improvement surface acoustic wave filter's rectangle degree, surface acoustic wave filter's frequency selectivity has been improved promptly, so that but the surface acoustic wave filter wide application in radar of making, the navigation, electronic information field such as mobile communication, the suitability is strong.
On the basis of the above scheme, the manufacturing method of the surface acoustic wave filter of the present invention can be further improved as follows.
Further, the capacitance transducer comprises a finger strip, and the extension direction of the finger strip of the capacitance transducer is perpendicular to the extension direction of the interdigital transducer finger strip of the first part and the interdigital transducer finger strip of the second part.
The beneficial effect of adopting the further scheme is that: because the extension directions of the fingers of the capacitive transducer are respectively perpendicular to the extension directions of the fingers of the interdigital transducer of the first part and the fingers of the interdigital transducer of the second part, the capacitive transducer does not have the functions of transmitting and resonating sound waves, the influence on the filtering of the surface acoustic waves is reduced, and the performance of the surface acoustic wave filter is further improved.
Further, the ground electrode includes a plurality of ground electrode fingers, the interdigital transducer finger of first part and the interdigital transducer finger of second part peg graft in the ground electrode includes:
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, and λ represents the wavelength of the surface acoustic wave to be filtered.
Furthermore, the piezoelectric substrate is made of quartz.
The beneficial effect of adopting the further scheme is that: the quartz can be easily cut into any shape and has high Q value characteristic (B)△Small) and high temperature stability, and is suitable for manufacturing an extremely narrow band surface acoustic wave filter.
Drawings
Fig. 1 is a schematic structural diagram of a surface acoustic wave filter in the prior art;
FIG. 2 is a schematic diagram of the squareness of a surface acoustic wave filter;
FIG. 3 is a schematic structural diagram of a structural unit according to an embodiment of the present invention;
FIG. 4 is a second schematic structural 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 schematic flow chart illustrating 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 capacitance transducer 1 and at least two structural units are arranged on the piezoelectric substrate 3;
the structure unit comprises a surface acoustic wave reflection 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 arranged oppositely, 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 71 of the first part and the interdigital transducer finger 72 of the second part are symmetrically or alternatively arranged and are all inserted in the ground electrode 5, and the surface acoustic wave reflection 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 of each capacitive transducer 1 is connected with the ground electrode 5, wherein the input signal electrode 9 is connected with the output signal electrode 10.
The ground electrode 5 is grounded, signals are input from an input end 12 of the surface acoustic wave filter, and output from an 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 a 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 each interdigital transducer;
the squareness is an important index for measuring the filtering performance of the saw filter, and as shown in fig. 2, the calculation process of the squareness is shown based on the amplitude-frequency characteristic curve 11 of the saw filter, i.e. through B-40/B-3By performing the calculation, it can be understood that B-40/B-3The smaller the value of (A), the better the filtering performance of the surface acoustic wave filter, and the essence of "improving the squareness" in the present application is to lower, B-40/B-3The value of (d); however, for a very narrow band SAW filter, the bandwidth is very narrow, and the bandwidth of the very narrow band B-3/f00.3 to 2%, generally speaking, the narrower the bandwidth, the more difficult it is to achieve a high rectangular width because of the transition bandwidth B△＝B-40-B-3，B-3The smaller, B-40/B-3＝(B△+B-3)/B-3＝B△/B-3The larger the value of +1, i.e., the worse the rectangle width, the more narrow band surface acoustic wave filters have had in the prior art a rectangle width of 3 or more even though the highest Q value (transition band width B) was used△Minimum) quartz substrate as the piezoelectric substrate 3, B△/B-3Currently, only 2 can be achieved, and in this case, B-40/B-3＝B△/B-3The + 1-3, the rectangle degree is higher at this moment, and the filtering performance of the surface acoustic wave filter, especially the very narrow band surface acoustic wave filter, is seriously influenced;
in the actual design of surface acoustic wave, B is-3Is not changedDecrease B△Is the main technical approach for increasing the rectangularity of the surface acoustic wave. In the surface acoustic wave filter, one is connected between every two adjacent structural units capacitance transducer 1, because capacitance transducer 1 is connected with ground electrode 5 and is grounded, capacitance transducer 1 has played the effect to ground capacitance, can effectively reduce transition band width B△And then can effectively improve surface acoustic wave filter's squareness degree, and then improve surface acoustic wave filter's filtering performance, moreover, through using at least two constitutional units to establish ties, can play the linear superimposed technological effect of filtering performance promptly along with the increase of the quantity of constitutional unit, can be linear improvement surface acoustic wave filter's squareness degree, that is to say, when establishing ties a plurality of constitutional units simultaneously, can further reduce transition zone width B△Therefore, the squareness is further improved, and experiments show that the squareness can be improved to be within 2.2, namely, the frequency selectivity of the surface acoustic wave filter is improved and the stop band suppression degree is effectively increased, so that the surface acoustic wave filter can be widely applied to the field of electronic information such as radar, navigation and mobile communication, the applicability is strong, and the surface acoustic wave filter is suitable for surface acoustic waves to be filtered with the frequency within the frequency range of 10 MHz-5 GHz.
Wherein the ground electrode 5 comprises a plurality of ground electrode fingers 6, the first part of interdigital transducer fingers 71 and the second part of interdigital transducer fingers 72 are plugged with a plurality of the ground electrode fingers 6, then:
1) in a structural unit shown in fig. 3, the interdigital transducer fingers 71 of the first portion and the interdigital transducer fingers 72 of the second portion are arranged alternately;
2) in a structural unit shown in fig. 4, an interdigital transducer finger 71 of a first portion and an interdigital transducer finger 72 of a second portion are symmetrically arranged;
it can be understood that the numbers, the structures, such as the lengths and the widths, of the interdigital transducer fingers 71 of the first part and the interdigital transducer fingers 72 of the second part are the same, and the structure of the surface acoustic wave reflection grating 4 can be adjusted according to the designed interdigital transducer fingers 71 of the first part and the designed interdigital transducer fingers 72 of the second part;
wherein, every surface acoustic wave reflection bars 4 is grounded separately respectively to shield between every two adjacent structure units, specifically: and a ground electrode 5 is connected between every two adjacent structural units to shield signals between the structural units.
Preferably, in the above technical solution, the capacitive transducer 1 includes the finger 2, and the extending direction of the finger 2 of the capacitive transducer 1 is perpendicular to the extending direction of the first portion of the interdigital transducer 71 and the second portion of the interdigital transducer 72.
Because the extension direction of the finger 2 of the capacitive transducer 1 is perpendicular to the extension directions of the first part of the interdigital transducer finger 71 and the second part of the interdigital transducer finger 72, the capacitive transducer does not have the functions of transmitting and resonating sound waves, the influence on the filtering of the surface acoustic waves is reduced, and the performance of the surface acoustic wave filter is further improved.
Preferably, in the above technical solution, the material of the piezoelectric substrate 3 is quartz. The quartz can be easily cut into any shape and has high Q value characteristic (B)△Small) and high temperature stability, and is suitable for manufacturing an extremely narrow band surface acoustic wave filter. When a quartz substrate is used as the piezoelectric substrate 3, the experimental results show that: the squareness increased from 3.0 to 2.15.
Preferably, in the above technical solution, a sum of a width of a slit between any two adjacent ground electrode fingers and a width of any one ground electrode finger is λ, where λ represents a wavelength of the surface acoustic wave to be filtered.
An electronic device of an embodiment of the present invention: a surface acoustic wave filter comprising any of the above embodiments. Electronic devices such as radars, navigation devices, intelligent terminals, etc.
Connect one between every two adjacent constitutional units in the surface acoustic wave filter capacitance transducer 1 because capacitance transducer 1 ground connection, make capacitance transducer 1 play the effect of earth capacitance, can effectively improve surface acoustic wave filter's rectangle degree, and then improve surface acoustic wave filter's filtering performance, moreover, use through establishing ties at least two constitutional units, can play the linear superimposed technological effect of filtering performance promptly along with the increase of constitutional unit's quantity, can be linear improvement surface acoustic wave filter's rectangle degree, improved surface acoustic wave filter's frequency selectivity promptly, and then improved electronic equipment's performance.
As shown in fig. 6, a method for manufacturing a surface acoustic wave filter according to an embodiment of the present invention includes the following steps:
s1, arranging a capacitance transducer 1 and at least two structural units on a piezoelectric substrate 3, wherein the structural units comprise a surface acoustic wave reflection 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 fingers 71 of the first part and the interdigital transducer fingers 72 of the second part are symmetrically or alternatively arranged and are inserted into the ground electrode 5, and the surface acoustic wave reflection grating 4 is connected with the ground electrode 5;
and S2, connecting one capacitive transducer 1 between every two adjacent structural units, wherein 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.
Connect one between per two adjacent constitutional units electric capacity transducer 1 because electric capacity transducer 1 ground connection, make electric capacity transducer 1 play the effect to the earth capacitance, can effectively improve surface acoustic wave filter's rectangle degree, and then improve surface acoustic wave filter's filtering performance, and, through establishing ties at least two constitutional units and using, can play the linear superimposed technological effect of filtering performance promptly along with the increase of constitutional unit's quantity, can be linear improvement surface acoustic wave filter's rectangle degree, surface acoustic wave filter's frequency selectivity has been improved promptly, so that but the surface acoustic wave filter wide application in radar of making, the navigation, electronic information field such as mobile communication, and the suitability is strong.
Preferably, in the above technical solution, the capacitive transducer 1 includes the finger 2, and the extending direction of the finger 2 of the capacitive transducer 1 is perpendicular to the extending direction of the first portion of the interdigital transducer finger 71 and the second portion of the interdigital transducer finger 72.
Because the extension direction of the finger 2 of the capacitive transducer 1 is perpendicular to the extension directions of the first part of the interdigital transducer finger 71 and the second part of the interdigital transducer finger 72, the capacitive transducer does not have the functions of transmitting and resonating sound waves, the influence on the filtering of the surface acoustic waves is reduced, and the performance of the surface acoustic 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 plugged in the ground electrode 5, including:
the first part of interdigital transducer fingers 71 and the second part of interdigital transducer fingers 72 are plugged with a plurality of the ground electrode fingers 6.
Preferably, in the above technical solution, a sum of a width of a slit between any two adjacent ground electrode fingers and a width of any one ground electrode finger is λ, where λ represents a wavelength of the surface acoustic wave to be filtered.
Preferably, in the above technical solution, the material of the piezoelectric substrate 3 is quartz.
The quartz can be easily cut into any shape and has high Q value characteristic (B)△Small) and high temperature stability, and is suitable for manufacturing an extremely narrow band surface acoustic wave filter.
In the foregoing embodiments, although the steps are numbered as S1, S2, etc., but only the specific embodiments are given in this application, and those skilled in the art may adjust the execution order of S1, S2, etc. according to the actual situation, which is also within the protection scope of the present invention, and it is understood that some embodiments may include some or all of the above embodiments.
In the present invention, the terms "first", "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean 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 invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer 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, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (10)
1. A surface acoustic wave filter is characterized by comprising a capacitance transducer and at least two structural units; the capacitive transducer and the at least two structural units are arranged on the piezoelectric substrate;
the structure unit comprises a surface acoustic wave reflection 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 further comprises a first part of interdigital transducer fingers connected with the input signal electrode and a second part of interdigital transducer fingers connected with the output signal electrode, the first part of interdigital transducer fingers and the second part of interdigital transducer fingers are symmetrically or alternatively arranged and are all inserted in the ground electrode, and the surface acoustic wave reflection grating is connected with the ground electrode;
and 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.
2. A surface acoustic wave filter as set forth in claim 1, wherein said capacitive transducer includes fingers, and the direction of elongation of the fingers of said capacitive transducer is perpendicular to the direction of elongation of the interdigital transducer fingers of said first portion and the interdigital transducer fingers of said second portion.
3. A surface acoustic wave filter as claimed in claim 1 or 2, characterized in that the ground electrode comprises a plurality of ground electrode fingers, the first part of the interdigital transducer fingers and the second part of the interdigital transducer fingers being interleaved with the plurality of ground electrode fingers.
4. A surface acoustic wave filter as set forth in claim 3, 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.
5. A surface acoustic wave filter as set forth in claim 1, 2 or 4, characterized in that said piezoelectric substrate is made of quartz.
6. An electronic device comprising a surface acoustic wave filter according to any one of claims 1 to 5.
7. A method for 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 reflection 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 further comprises an interdigital transducer finger of a first part connected with the input signal electrode and an interdigital transducer finger of a second part connected with the output signal electrode; the interdigital transducer fingers of the first part and the interdigital transducer fingers of the second part are symmetrically or alternatively arranged and are inserted into the ground electrode, and the surface acoustic wave reflection grating is connected with the ground electrode;
and S2, connecting one capacitive transducer between every two adjacent structural units, wherein 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.
8. A method for manufacturing a surface acoustic wave filter as claimed in claim 7, wherein said capacitive transducer includes fingers, and the extension direction of the fingers of said capacitive transducer is perpendicular to the extension direction of the fingers of said first portion and the fingers of said second portion.
9. A method for manufacturing a surface acoustic wave filter as claimed in claim 7 or 8, wherein said ground electrode includes a plurality of ground electrode fingers, and said first portion of said interdigital transducer fingers and said second portion of said interdigital transducer fingers are inserted into said ground electrode, including:
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.
10. A method for manufacturing a surface acoustic wave filter as set forth in claim 9, wherein the sum of the width of the slit between any two adjacent 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.
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