CN114531129A - Dual-mode acoustic coupling surface wave filter - Google Patents
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- 238000010168 coupling process Methods 0.000 title abstract description 12
- 230000008878 coupling Effects 0.000 title abstract description 11
- 238000005859 coupling reaction Methods 0.000 title abstract description 11
- 238000010897 surface acoustic wave method Methods 0.000 claims abstract description 40
- 229910003327 LiNbO3 Inorganic materials 0.000 claims abstract description 34
- 238000013461 design Methods 0.000 claims abstract description 34
- 239000000758 substrate Substances 0.000 claims abstract description 34
- 229910052681 coesite Inorganic materials 0.000 claims abstract description 11
- 229910052906 cristobalite Inorganic materials 0.000 claims abstract description 11
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 11
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 11
- 229910052682 stishovite Inorganic materials 0.000 claims abstract description 11
- 229910052905 tridymite Inorganic materials 0.000 claims abstract description 11
- 239000000463 material Substances 0.000 claims description 27
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 18
- 229910052802 copper Inorganic materials 0.000 claims description 18
- 239000010949 copper Substances 0.000 claims description 18
- 238000000034 method Methods 0.000 claims description 17
- 238000001914 filtration Methods 0.000 claims description 11
- 230000008569 process Effects 0.000 claims description 7
- 239000007772 electrode material Substances 0.000 claims description 3
- 238000003780 insertion Methods 0.000 abstract description 12
- 230000037431 insertion Effects 0.000 abstract description 12
- 239000010408 film Substances 0.000 description 10
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 5
- 229910052782 aluminium Inorganic materials 0.000 description 5
- 238000010586 diagram Methods 0.000 description 5
- 229910012463 LiTaO3 Inorganic materials 0.000 description 4
- 239000012528 membrane Substances 0.000 description 3
- 238000004088 simulation Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
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- 239000010409 thin film Substances 0.000 description 2
- 210000002659 acromion Anatomy 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
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- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 description 1
- 238000013178 mathematical model Methods 0.000 description 1
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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
- H03H9/02—Details
- H03H9/02535—Details of surface acoustic wave devices
- H03H9/02637—Details concerning reflective or coupling arrays
- H03H9/02685—Grating lines having particular arrangements
- H03H9/02724—Comb like grating lines
- H03H9/02732—Bilateral comb like grating lines
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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
- H03H9/02—Details
- H03H9/02535—Details of surface acoustic wave devices
- H03H9/02543—Characteristics of substrate, e.g. cutting angles
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02535—Details of surface acoustic wave devices
- H03H9/02818—Means for compensation or elimination of undesirable effects
- H03H9/02834—Means for compensation or elimination of undesirable effects of temperature influence
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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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- Acoustics & Sound (AREA)
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Abstract
The invention claims a dual-mode acoustic coupling surface wave filter, which is based on 128-degree YX-LiNbO3Band-pass filter of piezoelectric substrate comprising a 128 DEG YX-LiNbO3A piezoelectric substrate, three Interdigital transducers (IDTs), two reflection grids (Mirror grids), and a layer of SiO covering the Interdigital transducers and the reflection grids2And (3) a film. Compared with the traditional DMS filter, the invention introduces SiO2A film structure, which not only solves the problem of 128-degree YX-LiNbO3The piezoelectric substrate design DMS filter presents a shoulder problem and also significantly reduces insertion loss. And 128 degrees YX-LiNbO3The piezoelectric substrate is applied to a DMS filter in the design generally used as a trapezoidal surface acoustic wave filter, and the performance of the DMS filter is opposite to that of the traditional 36-degree YX-LiNbO-based filter3The DMS filter of (1) is improved.
Description
Technical Field
The invention belongs to the field of electronic element design, and particularly relates to a design of a surface acoustic wave filter.
Background
At present, Surface Acoustic Wave Filters (SAWF) are widely applied to the fields of phased array radar, satellite communication and mobile communication, and have the characteristics of small size, high stability, strong anti-interference capability, high selectivity and the like.
The surface acoustic wave filter mainly has two types, namely a Ladder surface acoustic wave filter (Ladder SAW) and a dual Mode coupling surface acoustic wave filter (Double Mode SAW, DMS), wherein the DMS structure is widely applied to the design of duplexers and filters because of its characteristics of high out-of-band rejection and small volume. Currently, the DMS filter mainly adopts LiNbO3And LiTaO3As a piezoelectric substrate material. Adopts 128-degree Y-X LiNbO3As a piezoelectric substrate material, a shoulder appears at the left end of the passband. The method adopts a copper electrode, and a layer of SiO is covered on an interdigital electrode of a filter2The design method of the membrane solves the acromion problem. Through parameter optimization, a single-stage DMS filter with the center frequency of 891MHz, the minimum insertion loss of-1.29 dB, the 1dB bandwidth of 30MHz, the out-of-band rejection of-20 dB and the relative bandwidth of 3.4% is designed.
Disclosure of Invention
The present invention is directed to solving the above problems of the prior art. A dual-mode acoustically-coupled surface wave filter is provided, comprising a piezoelectric substrate, three interdigital transducers, and two reflection gratings:
wherein structure 7 represents 128 ° YX-LiNbO3A piezoelectric substrate, structure 1 representing a first interdigital transducer, structure 2 representing a second interdigital transducer, structure 3 representing a third interdigital transducer, two structures 4 representing two reflective gratings, and structure 5 representing a layer of SiO overlying the interdigital transducers and the reflective gratings2Film, structure 6 represents the copper electrode of the interdigital transducer. Wherein the structure 2 is used as a signal input end needing filtering, and the structures 1 and 3 which are arranged at the two ends of the structure 2 in parallel are used for filtering and removing impuritiesThe two ends of the 1 and 3 of the signal output end after the wave passing are respectively provided with a short-circuit or open-circuit structure 4, the structure 4 is generally used for reflecting energy radiated to the outside to form a resonant cavity, meanwhile, the structure 1 is used as a substrate material for generating surface acoustic waves, the structure 6 is used as an interdigital electrode material, and the interdigital transducer and the reflecting grating are covered with a structure 5 for avoiding the occurrence of a shoulder peak at the left end of a pass band;
the filtering signal is input through the structure 2, at the moment, the interdigital transducer and the piezoelectric substrate act together to convert an input electric signal into a surface acoustic wave, the surface acoustic wave is transmitted to the structures 1 and 3 on two sides from the structure 2, the surface acoustic wave is transmitted to the structures 2 and 3, a passband is formed together with a wave peak transmitted and reflected by the reflection grating, the signal in the frequency range is transmitted, the signals in other frequency ranges are restrained, the interdigital electrode converts the surface acoustic wave into the electric signal at the structures 2 and 3 and transmits the electric signal outwards from an output port, and therefore a filtering process is completed.
Further, the three interdigital transducers are structures 1, 2 and 3, the three interdigital transducers are arranged in parallel, the structure 2 is arranged in the center, the structures 1 and 3 are arranged at two ends of the structure 2, and the two reflecting grids are arranged at two ends of the structures 1 and 3 in parallel to form a resonant cavity for reflecting energy radiated outwards by the interdigital transducers; all interdigital transducers and the reflection grating are etched on the surface of the structure 7, SiO2The film covers the surface of the structure 1, 2, 3, 4.
Further, the parameter design of the dual-mode surface acoustic wave filter comprises: input and Output interdigital electrode pairs Input and Output, a reflection grid pair re, a reflection grid period, an Input and Output interdigital electrode period, a distance ls between the Input and Output interdigital electrodes, a distance lg between the Output interdigital electrode and the reflection grid, a copper electrode thickness h, a reflection grid finger width, an Input and Output interdigital electrode finger width and an aperture w.
Further, the number of the structures 2 is 28.5 pairs, the number of the structures 1 and 3 is 16.5 pairs, the number of the structures 4 is 35 pairs, the period of the structure 4 is 2.15 μm, the period of the structures 1, 2 and 3 is 4.3 μm, the distance ls between the structures 1 and 2 is 0.005 λ, the distance lg between the structures 1 and 4 is 0.25 λ, the thickness h of the copper electrode 5 is 0.019 λ, the finger width of the structure 4 is 0.125 λ, the finger widths of the structures 1, 2, 3 and 4 are 0.24 λ, the aperture is 34 λ, and λ is the period of the input/output interdigital electrode.
The invention has the following advantages and beneficial effects:
the invention combines the temperature compensation technology and uses SiO2The film solves the problem that the conventional dual-mode coupling structure has a shoulder peak at the left end of a passband, and simultaneously, the 128-degree YX-LiNbO is successfully used3A DMS filter is designed as a piezoelectric substrate, the center frequency is 891MHz, the minimum insertion loss is-1.29 dB, the 1dB bandwidth is 30MHz, the out-of-band rejection can reach-20 dB, and the relative bandwidth is 3.4%.
The traditional surface acoustic wave filter is at 64 degrees YX-LiNbO3And 41 ℃ YX-LiNbO3DMS filter is designed on the surface of the piezoelectric substrate, and the temperature of the DMS filter is 128-degree YX-LiNbO3The piezoelectric substrate is generally used as a design of a ladder type surface acoustic wave filter. If the traditional design method is directly adopted, the interdigital transducer and the reflecting grating are directly prepared on the YX-LiNbO with the piezoelectric temperature of 128 degrees3The DMS filter designed on the surface always appears a shoulder peak at the left end of a pass band, the insertion loss is large and is often more than-3 dB, and the bandwidth is only dozens of megahertz. Thus, the conventional method is adopted to carry out the reaction at 128 degrees of YX-LiNbO3There are significant drawbacks to designing DMS filters.
Based on copper electrode and covered with SiO2The design model of the film dual-mode surface acoustic wave filter solves the problem that a DMS filter directly designed on the surface of a piezoelectric substrate by adopting a conventional aluminum electrode can generate a shoulder peak at the left end of a passband, and designs the DMS filter with good performance.
The invention solves the problem that the traditional method design is based on 128-degree YX-LiNbO3The problems with the DMS filter of the piezoelectric substrate and the advantages of the improved DMS filter are collectively as follows:
1.64°YX-LiNbO3is typically used to design DMS filters, and 128 ° YX-LiNbO3Are commonly used for ladder type surface acoustic wave filters. Adopts 128 degrees YX-LiNbO3DMS filters are typically designed to exhibit a shoulder at the left end of their passband, and their insertion loss is generally higher than-3 dB,and is therefore often used to design a ladder type surface acoustic wave filter. In the filter with DMS structure, a step appears at the edge of the passband due to the Bragg frequency of the piezoelectric material, and the piezoelectric material lithium niobate is greatly influenced by the temperature, and under the conventional condition, the piezoelectric material is 128-degree YX-LiNbO3Will make its own Bragg frequency lower than the frequency for which the device is designed, so if 128 ℃ YX-LiNbO is used directly3Designing a DMS filter causes a shoulder to appear at the left end of the passband because the bragg frequency of the device is lower than the device design frequency. Therefore, to improve 128 ℃ YX-LiNbO3Bragg frequency of material, positive temperature coefficient material SiO introduced in temperature compensation technology2To improve the 128-degree YX-LiNbO3And thereby designing the DMS filter. Meanwhile, in order to improve the insertion loss of the filter, a conventional aluminum electrode is changed into a copper electrode with lower conductivity.
2. The proposed copper electrode is covered with SiO2The structure of the film is successfully at 128 degrees YX-LiNbO3The DMS filter is designed on the surface of the piezoelectric material, the performance is good, the center frequency is 891MHz, the minimum insertion loss is-1.29 dB, the 1dB bandwidth is 30MHz, the out-of-band rejection can reach-20 dB, and the relative bandwidth is 3.4%.
3. The proposed copper electrode is covered with SiO2The film structure successfully solves the problems of shoulder and large insertion loss of the traditional design method.
Drawings
FIG. 1 is a schematic representation of the preferred embodiment of the present invention using 128 ° YX-LiNbO3A time DMS filter performance diagram;
FIG. 2 is a 36 degree YX-LiTaO3The performance of the time DMS filter is shown;
FIG. 3 is a two-dimensional cross-sectional view of a preferred dual-mode SAW filter according to the present invention;
FIG. 4 is a structural diagram of an interdigital electrode of a designed two-mode surface acoustic wave filter;
FIG. 5 is a schematic diagram of a filter structure using the present invention in comparison to an unmodified structure;
FIG. 6 is a schematic diagram of the performance of the proposed filter structure;
Detailed Description
The technical solutions in the embodiments of the present invention will be described in detail and clearly with reference to the accompanying drawings. The described embodiments are only some of the embodiments of the present invention.
The technical scheme for solving the technical problems is as follows:
the dual-mode coupling surface acoustic wave filter provided by the invention adopts COMSOL for simulation, and adopts COMSOL for simulation analysis to adopt an aluminum electrode at 128-degree YX-LiNbO3The performance of DMS filter prepared on the surface, DMS filter prepared by using Simply Fortran to other piezoelectric materials and DMS filter prepared by using aluminum electrode and 128-degree YX-LiNbO3And (3) carrying out simulation analysis on the DMS filter prepared from the piezoelectric material, and carrying out comprehensive comparison. As shown in FIG. 1, 128-degree YX-LiNbO is adopted3When in use, a shoulder appears at the left end of the passband, and the insertion loss is generally greater than-3 dB.
It can be seen that in FIG. 2, a conventional 36 degree YX-LiTaO is used3A shoulder appears at the right end of the passband.
In order to solve the above-mentioned problems, the DMS filter structure of this document is proposed, the principle of which is as follows.
Directly adopts 128-degree YX-LiNbO3When used as the piezoelectric substrate of the DMS filter, the piezoelectric substrate material provides a negative temperature coefficient, resulting in a shift in the Bragg frequency, since the Bragg frequency of the conventional piezoelectric material capable of exciting the leakage wave required by the DMS filter is generally higher than the designed frequency of the DMS filter, and thus, the 128 ° YX-LiNbO is directly used3The piezoelectric substrate acting as a DMS filter causes a shoulder at the left end of the passband because the bragg frequency is lower than the design frequency of the DMS filter. General SiO2Can provide positive temperature coefficient and is loaded at 128 degrees YX-LiNbO3The surface can counteract the change of Bragg frequency caused by the piezoelectric material, thereby realizing the YX-LiNbO at 128 DEG3The design of the DMS filter on top of this piezoelectric material.
At this time, as shown in fig. 3:
a design model of a dual-mode surface acoustic wave filter, comprising structural components of a dual-mode coupling filter, wherein:
comprising a dual-mode surface acoustic wave filter and a layer of SiO2The double-film surface acoustic wave filter is characterized in that a structure 2 serves as a signal input end, structures 1 and 3 which are arranged at two ends of the structure 2 in parallel serve as signal output ends, meanwhile, short-circuit or open-circuit reflecting grids are respectively arranged at two ends of the structures 1 and 3, and a structure 4 is used for reflecting energy radiated to the outside by signals to form a resonant cavity. Meanwhile, the structure 7 is used as a substrate material for generating surface acoustic waves, and the required interdigital transducer and the reflection grating both adopt the structure 6 as electrode materials. And covering a layer of SiO on the interdigital transducer and the reflecting grating2A film.
Meanwhile, the core structure of the dual-mode surface acoustic wave filter specifically comprises: structures 1, 2 and 3 as transducers, structure 4 as a reflective grating, structure 7 as a piezoelectric substrate, and structure 5 as SiO2The thin film, structure 6, acts as a copper electrode. The three interdigital transducers comprise an input structure 2 and two output structures 1 and 3, the three interdigital transducers are arranged in parallel, the structure 2 is placed in the center, and the structures 1 and 3 are placed at two ends of the structure 2. The two reflecting gratings are arranged at two ends of the two output interdigital transducers in parallel to form a resonant cavity for reflecting energy radiated outwards by the interdigital transducers. All interdigital transducers and reflective gratings are etched at 128 ° YX-LiNbO3A surface of a piezoelectric material. SiO 22The membrane covers the three interdigital transducers and the two reflective gratings.
And further comprises a design parameter part of the double-mode coupling surface acoustic wave filter.
Each design parameter includes Input and Output interdigital electrode pair number Input and Output, reflection grid pair number re, reflection grid period, Input and Output interdigital electrode period, distance ls between Input and Output interdigital electrodes, distance lg between Output interdigital electrode and reflection grid, copper electrode thickness h, reflection grid finger width, Input and Output interdigital electrode finger width and aperture w.
The specific design parameters are 28.5 pairs for structure 2, 16.5 pairs for structures 1 and 3, 35 pairs for structure 4, 2.15 μm period for structure 4, 4.3 μm period for structures 1, 2 and 3, 0.005 λ distance ls between structures 1 and 2, 0.25 λ distance lg between structures 1 and 3, 0.019 λ thickness h for structure 6, 0.125 λ finger width for structure 4, 0.24 λ finger width for structures 1, 2 and 3, and 34 λ pore size.
The overall filtering process is shown below:
the filtering signal is input through the structure 2, at the moment, the interdigital transducer and the piezoelectric substrate act together to convert an input electric signal into a surface acoustic wave, the surface acoustic wave is transmitted to the structures 1 and 3 on two sides from the structure 2, the surface acoustic wave is transmitted to the structures 2 and 3, a passband is formed together with a wave peak transmitted and reflected by the reflection grating, the signal in the frequency range is transmitted, the signals in other frequency ranges are restrained, the interdigital electrode converts the surface acoustic wave into the electric signal at the structures 2 and 3 and transmits the electric signal outwards from an output port, and therefore a filtering process is completed.
The invention provides a design model of a dual-mode surface acoustic wave filter, which uses 128-degree Y-X LiNbO by widening the selection range of DMS structure substrate materials3And designing the DMS structure surface acoustic wave filter with high frequency, broadband, low insertion loss and high out-of-band rejection.
It comprises three parts:
(1) use of the Simply Fortran design based on 36 ℃ YX-LiTaO3DMS filter made of piezoelectric material and based on 128-degree YX-LiNbO3DMS filter of piezoelectric material, (2) design of copper electrode covering SiO using COMSOL2The improved double-mode coupling surface acoustic wave filter (3) is optimized according to a COMSOL design.
And designing a dual-mode coupling surface acoustic wave filter. A mathematical model is established on Simply Fortran by adopting a COM coupling method, and the design is based on 128-degree YX-LiNbO3The DMS filter is redesigned based on 36 degrees YX-LiTaO3The DMS filter of the piezoelectric material is characterized in that the two models are designed by directly etching an aluminum electrode on the surface of a piezoelectric substrate material without adding any film. Simulating text with COMSOLThe structure proposed in (1), i.e. covering SiO with copper electrodes2The manner of the film. The design parameters are that the number of input interdigital electrodes is 28.5 pairs, the number of output interdigital electrodes is 16.5 pairs, the number of reflection grids is 35 pairs, the period of the reflection grids is 2.15 mu m, the period of the input and output interdigital electrodes is 4.3 mu m, the distance ls between the input and output interdigital electrodes is 0.005 lambda (lambda is the period of the input and output interdigital electrodes), the distance lg between the output interdigital electrodes and the reflection grids is 0.25 lambda, the thickness h of a copper electrode is 0.019 lambda, the finger width of the reflection grids is 0.125 lambda, the finger width of the input and output interdigital electrodes is 0.24 lambda, and the aperture is 34 lambda. The frequency response of various structures is shown in comparison with FIG. 5, in which FIG. 3 is a graph of the copper electrode coating SiO proposed herein2The structure is shown in a two-dimensional cross-sectional view in COMSOL, and FIG. 4 is a layout diagram of interdigital electrodes of a DMS structure.
By gradually optimizing a two-dimensional structure established in COMSOL, the main parameters such as the period of an input-output interdigital electrode, the period of a reflective gate, the number of the input-output interdigital electrodes, the thickness of a copper electrode, the distance between the input-output interdigital electrodes and the like are mainly optimized. The parameters of the two-mode coupling filter obtained after the optimization are shown in figure 6.
The invention provides a surface acoustic wave filter which is based on 128-degree YX-LiNbO3A bandpass filter of piezoelectric substrate comprising a 128 ° YX-LiNbO3A piezoelectric substrate, three Interdigital transducers (IDTs), two reflective gratings (Mirror grids), and a layer of SiO covering the Interdigital transducers and the reflective gratings2And (3) a membrane. Compared with the traditional DMS filter, the invention introduces SiO2A thin film structure, which not only solves the problem of 128-degree YX-LiNbO3The piezoelectric substrate design DMS filter presents a shoulder problem and also significantly reduces insertion loss. And 128 degrees YX-LiNbO3The piezoelectric substrate is applied to a DMS filter in the design generally used as a trapezoidal surface acoustic wave filter, and the performance of the DMS filter is opposite to that of the traditional 36-degree YX-LiNbO-based filter3The DMS filter of (1) is improved. At the same time, the method directly adopts 128-degree YX-LiNbO3As a piezoelectric substrate for DMS filters, the piezoelectric substrate material provides a negative temperature coefficient, resulting in bits at Bragg frequenciesIn drift, the Bragg frequency of the conventional piezoelectric material capable of exciting the leakage wave required by the DMS filter is generally higher than the designed frequency of the DMS filter, so that the 128-degree YX-LiNbO is directly adopted3The piezoelectric substrate acting as a DMS filter causes a shoulder at the left end of the passband because the bragg frequency is lower than the design frequency of the DMS filter. SiO in general2Can provide positive temperature coefficient and is loaded at 128 degrees YX-LiNbO3The surface can counteract the Bragg frequency return to the normal position caused by the piezoelectric material, thereby realizing the YX-LiNbO at 128 DEG3The design of the DMS filter on top of this piezoelectric material. The DMS filter design method based on the invention has good effect, the center frequency is 891MHz, the minimum insertion loss is-1.29 dB, the 1dB bandwidth is 30MHz, the out-of-band rejection of the single-stage DMS filter can reach-20 dB, and the relative bandwidth is 3.4%.
It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
The above examples are to be construed as merely illustrative and not limitative of the remainder of the disclosure. After reading the description of the invention, the skilled person can make various changes or modifications to the invention, and these equivalent changes and modifications also fall into the scope of the invention defined by the claims.
Claims (4)
1. A dual-mode acoustically-coupled surface wave filter comprising a piezoelectric substrate 7, three interdigital transducers and two reflection gratings 4:
wherein structure 7 represents 128 ° YX-LiNbO3Piezoelectric substrate, junctionConfiguration 1 represents a first interdigital transducer, configuration 2 represents a second interdigital transducer, configuration 3 represents a third interdigital transducer, two configurations 4 represent two reflective gratings, and configuration 5 represents a layer of SiO overlying the interdigital transducers and the reflective gratings2The structure 6 represents a copper electrode of the interdigital transducer, wherein the structure 2 is used as a signal input end needing filtering, the structures 1 and 3 which are arranged at the two ends of the structure 2 in parallel are used as signal output ends after noise wave filtering, meanwhile, the two ends of the structures 1 and 3 are respectively provided with a short-circuit structure or an open-circuit structure 4, the structures 4 are generally used for reflecting energy radiated to the outside to form a resonant cavity, meanwhile, the structure 1 is used as a substrate material for generating surface acoustic waves, the structure 6 is used as an interdigital electrode material, and the interdigital transducer and a reflecting grating are covered with a structure 5 for avoiding shoulder peak at the left end of a pass band;
the filtering signal is input through the structure 2, at the moment, the interdigital transducer and the piezoelectric substrate act together to convert an input electric signal into a surface acoustic wave, the surface acoustic wave is transmitted to the structures 1 and 3 on two sides from the structure 2, the surface acoustic wave is transmitted to the structures 2 and 3, a passband is formed together with a wave peak transmitted and reflected by the reflection grating, the signal in the frequency range is transmitted, the signals in other frequency ranges are restrained, the interdigital electrode converts the surface acoustic wave into the electric signal at the structures 2 and 3 and transmits the electric signal outwards from an output port, and therefore a filtering process is completed.
2. The dual-mode, acoustically-coupled surface wave filter of claim 1, wherein the three interdigital transducers are structures 1, 2, and 3, the three interdigital transducers are arranged in parallel, structure 2 is placed at the center, 1 and 3 are placed at two ends of structure 2, and two reflective gratings are placed at two ends of structures 1 and 3 in parallel to form a resonant cavity for reflecting energy radiated outward by the interdigital transducers; all interdigital transducers and the reflection grating are etched on the surface of the structure 7, SiO2The film covers the surface of the structure 1, 2, 3, 4.
3. A dual-mode, acoustically-coupled surface wave filter as claimed in claim 1, wherein the parametric design of the dual-mode, acoustically-coupled surface wave filter comprises: input and Output interdigital electrode pairs Input and Output, a reflection grid pair re, a reflection grid period, an Input and Output interdigital electrode period, a distance ls between the Input and Output interdigital electrodes, a distance lg between the Output interdigital electrode and the reflection grid, a copper electrode thickness h, a reflection grid finger width, an Input and Output interdigital electrode finger width and an aperture w.
4. A dual-mode, acoustically-coupled surface wave filter according to claim 3, in which the number of structures 2 is 28.5 pairs, the number of structures 1 and 3 is 16.5 pairs, the number of structures 4 is 35 pairs, the period of structure 4 is 2.15 μm, the period of structures 1, 2 and 3 is 4.3 μm, the distance ls between structures 1 and 2 is 0.005 λ, the distance lg between structures 1 and 4 is 0.25 λ, the thickness h of copper electrode 5 is 0.019 λ, the finger width of structure 4 is 0.125 λ, the finger widths of structures 1, 2, 3 and 4 are 0.24 λ, the aperture is 34 λ, and λ is the input and output interdigital electrode period.
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| CN116633312A (en) * | 2023-07-24 | 2023-08-22 | 常州承芯半导体有限公司 | Filter and method for forming filter |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116633312A (en) * | 2023-07-24 | 2023-08-22 | 常州承芯半导体有限公司 | Filter and method for forming filter |
| CN116633312B (en) * | 2023-07-24 | 2023-10-24 | 常州承芯半导体有限公司 | Filter and method for forming filter |
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