CN203406841U - Surface Acoustic Wave Filters for Digital TV - Google Patents
Surface Acoustic Wave Filters for Digital TV Download PDFInfo
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- CN203406841U CN203406841U CN201320421215.1U CN201320421215U CN203406841U CN 203406841 U CN203406841 U CN 203406841U CN 201320421215 U CN201320421215 U CN 201320421215U CN 203406841 U CN203406841 U CN 203406841U
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- electrode
- acoustic wave
- surface acoustic
- comb handle
- wave filter
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- 238000010897 surface acoustic wave method Methods 0.000 title claims abstract description 39
- 239000000758 substrate Substances 0.000 claims abstract description 19
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 5
- 229910052751 metal Inorganic materials 0.000 claims description 5
- 239000002184 metal Substances 0.000 claims description 5
- 229910052782 aluminium Inorganic materials 0.000 claims description 4
- WSMQKESQZFQMFW-UHFFFAOYSA-N 5-methyl-pyrazole-3-carboxylic acid Chemical compound CC1=CC(C(O)=O)=NN1 WSMQKESQZFQMFW-UHFFFAOYSA-N 0.000 claims description 3
- 230000000694 effects Effects 0.000 description 11
- 230000005684 electric field Effects 0.000 description 8
- 230000005669 field effect Effects 0.000 description 4
- 238000009434 installation Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 238000004806 packaging method and process Methods 0.000 description 3
- 239000004411 aluminium Substances 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 241000216843 Ursus arctos horribilis Species 0.000 description 1
- 239000011358 absorbing material Substances 0.000 description 1
- 238000003491 array Methods 0.000 description 1
- JRPBQTZRNDNNOP-UHFFFAOYSA-N barium titanate Chemical compound [Ba+2].[Ba+2].[O-][Ti]([O-])([O-])[O-] JRPBQTZRNDNNOP-UHFFFAOYSA-N 0.000 description 1
- 229910002113 barium titanate Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000010358 mechanical oscillation Effects 0.000 description 1
- 238000001259 photo etching Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000000644 propagated effect Effects 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
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- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Abstract
The utility model relates to the technical field of surface acoustic wave filters, and relates to a surface acoustic wave filter used for a digital television. The surface acoustic wave filter comprises a piezoelectric substrate, an input interdigital transducer, and an output interdigital transducer. The output interdigital transducer comprises two comb handle electrodes disposed parallel with each other. A plurality of electrode units are disposed side by side at equal interval on each comb handle electrode between the two comb handle electrodes along a length direction of the comb handle electrode. Each electrode unit comprises two first electrode fingers and two second electrode fingers. Along the length direction of the comb handle electrode, in each electrode unit, positions of the two first electrode fingers are adjacent, two second electrode fingers are adjacent, and the first electrode fingers and the two second electrode fingers are arranged side by side at an equal interval. A top end of the first electrode finger on one of the comb handle electrode and a top end of the second electrode finger on the other comb handle electrode are arranged oppositely in a preset distance. The above surface acoustic wave filter can improve out-of-band rejection performance and satisfies application requirement.
Description
Technical field
The utility model relates to Surface Acoustic Wave Filter technical field, in particular to a kind of Surface Acoustic Wave Filter for Digital Television.
Background technology
Surface Acoustic Wave Filter is to utilize the piezoelectric effect character of the crystal such as quartz, lithium niobate, barium titanate to make.The primary structure of Surface Acoustic Wave Filter and manufacture method are: on the burnishing surface of piezoelectric substrate with piezoelectric effect, make and have certain thickness metal film, on this metal film, by photoetching technique, form two groups and be crossed as right comb handle electrode structure, wherein this two arrays of electrodes structure is called input interdigital transducer and output interdigital transducer.When input interdigital transducer loads ac voltage signal, the surface of piezoelectric substrate produces mechanical oscillation, and inspire sound wave, this sound wave is mainly propagated along the surperficial direction with interdigital electrode rise of piezoelectric substrate, therefore be called surface acoustic wave, the sound wave dividend sound-absorbing material of one of them direction absorbs, and the sound wave of other direction is sent to output interdigital transducer, is output interdigital transducer and is converted to signal of telecommunication output.Because Surface Acoustic Wave Filter has good frequency-selective filtering effect, be therefore widely used in each electronic product.
Current because analog television broadcast system and digital television broadcasting system coexist, therefore require the Surface Acoustic Wave Filter of Digital Television to there is higher Out-of-band rejection performance, but for the Out-of-band rejection poor-performing of the SAW (Surface Acoustic Wave) filter of Digital Television, cannot meet application demand in correlation technique.
Utility model content
The purpose of this utility model is to be provided for the Surface Acoustic Wave Filter of Digital Television, to solve the above problems.
A kind of Surface Acoustic Wave Filter for Digital Television is provided in embodiment of the present utility model, has comprised: piezoelectric substrate, input interdigital transducer and output interdigital transducer,
Described output interdigital transducer comprises two comb handle electrodes, and two described comb handle electrodes be arranged in parallel;
Along the length direction of described comb handle electrode and between two described comb handle electrodes, described in each on comb handle electrode all side by side spaced set have a plurality of electrode units, described in each, electrode unit includes that two the first electrodes refer to and two the second electrodes refer to, the length that described the first electrode refers to is different from the length that described the second electrode refers to;
Along the length direction of described comb handle electrode, in each electrode unit, two the first electrodes refer to that position is adjacent, and it is adjacent that two the second electrodes refer to, and two described the first electrodes refer to and two the second electrodes refer to spaced set side by side;
Being positioned at the first electrode on comb handle electrode described in one of them refers to and is positioned at the second electrode on comb handle electrode described in another and refers to that top is oppositely arranged by default spacing.
The Surface Acoustic Wave Filter for Digital Television of the utility model above-described embodiment, a plurality of electrode units on comb handle electrode, have all been arranged side by side, at each electrode unit, comprise that two the first electrodes refer to and two the second electrodes refer to, wherein be positioned at the first electrode on one of them comb handle electrode refer to another comb handle electrode on the second electrode refer to that top is oppositely arranged by default spacing, because the first electrode refers to refer to that from the second electrode length is different, therefore between two comb handle electrodes, the electrode finger that length is long is overlapping.Here interlock, have the region of sonic transmissions to be called time rail by the long electrode finger of length between two comb handle electrodes is overlapping, other region between two pectinations is called backbone.The overlap length being overlapping by controlling the electrode finger of length direction, can realize the electric field strength same phase that the top second-order effects electric field of backbone electrode finger and the inferior path sound source of time rail electrode excite contrary, the electric leakage field effect at electrode finger tip is eliminated, so can improve the Out-of-band rejection performance for the Surface Acoustic Wave Filter of Digital Television, meet application demand.
Accompanying drawing explanation
Fig. 1 shows the mounting structure schematic diagram that the utility model embodiment inputs interdigital transducer and output interdigital transducer;
Fig. 2 shows the utility model embodiment for the structural representation of the Surface Acoustic Wave Filter of Digital Television.
Accompanying drawing explanation: 1-input interdigital transducer, 2-output interdigital transducer, 3-the first electrode refers to, 4-the second electrode refers to, 5-aperture, 6-backbone, 7-rail, 11-piezoelectric substrate, the surperficial installation portion of 12-, 13-pin, 14-packaging part.
Embodiment
Below by specific embodiment, also by reference to the accompanying drawings the utility model is described in further detail.
The utility model embodiment provides a kind of Surface Acoustic Wave Filter for Digital Television, as shown in Figure 1, this Surface Acoustic Wave Filter comprises: piezoelectric substrate, input interdigital transducer 1 and output interdigital transducer 2, output interdigital transducer 2 comprises two comb handle electrodes, and two described comb handle electrodes be arranged in parallel;
Along the length direction of described comb handle electrode and between two described comb handle electrodes, described in each on comb handle electrode all side by side spaced set have a plurality of electrode units, described in each, electrode unit includes two the first electrodes and refers to that 3 and two the second electrodes refer to 4, and wherein the first electrode refers to that 3 length refers to that from the second electrode 4 length is different;
For clearly represent the structure of output interdigital transducer in Fig. 1, the shorter electrode of length is referred to refer to 3 as the first electrode, the longer electrode of length is referred to refer to 4. as the second electrode
Along the length direction of described comb handle electrode, in each electrode unit, two the first electrodes refer to that 3 and two the second electrodes refer to 4 spaced sets side by side;
Particularly, two the first electrodes refer to that 3 positions are adjacent, and two the second electrodes refer to that 4 positions are adjacent.
Further, as shown in Figure 1, be positioned at the first electrode on comb handle electrode described in one of them refer to 3 be positioned at the second electrode on comb handle electrode described in another and refer to that 4 tops are oppositely arranged by default spacing.
In conjunction with Fig. 1, the Surface Acoustic Wave Filter for Digital Television of the utility model embodiment, a plurality of electrode units on comb handle electrode, have all been arranged side by side, at each electrode unit, comprise that two the first electrodes refer to that 3 and two the second electrodes refer to 4, wherein be positioned at the first electrode on one of them comb handle electrode refer to 3 with another comb handle electrode on the second electrode refer to that 4 tops are oppositely arranged by default spacing, because the first electrode refers to that 3 refer to that from the second electrode 4 length are different, therefore between two comb handle electrodes, the electrode finger that length is long is overlapping.Here other the region long overlapping sonic transmissions region being staggered to form of electrode finger of length between two comb handle electrodes being called between time 7, two pectinations of rail is called backbone 6.The overlap length being overlapping by controlling the electrode finger of length length, can realize the electric field strength same phase that the top second-order effects electric field of backbone electrode finger and inferior rail 7 line source of time rail electrode excite contrary, the electric leakage field effect at electrode finger tip is eliminated, so can improve the Out-of-band rejection performance for the Surface Acoustic Wave Filter of Digital Television, meet application demand.
Further, in Fig. 1, the first electrode refers to that the 3 and second electrode refers to that 4 directions that are arranged side by side are called the length direction of comb handle electrode.
As Fig. 1, two comb handle electrodes are all rectangle, and the spacing sum between the width of two comb handle electrodes and two comb handle electrodes is called the aperture 5 of interdigital transducer.
In the utility model embodiment, aperture 5 length of output interdigital transducer 2 are 2185.5～2495.5 microns.
The length in the aperture 5 of input interdigital transducer 1 is 2185.5～2495.5 microns.
Preferably, input aperture 5 length of interdigital transducer 1 and the aperture 5 of output interdigital transducer 2 are equal in length.
In the utility model embodiment, by the length that is overlapping of the electrode finger that between two comb handle electrodes, length is long is rationally set, can realize the electric field strength same phase that inferior path sound source that top second-order effects electric field that in backbone 6, electrode refers to refers to electrode in time rail 7 excites contrary, the electric leakage field effect of electrode fingertip end is eliminated, in order to reach this effect, the electrode that in the utility model embodiment, length is long refers to that the length being overlapping is 7～74 microns.
In addition, in the utility model embodiment, the first electrode refers to and the second electrode refers to have identical width, is 8～12 microns.
Electrode in input interdigital transducer refers to have identical width, is 8～12 microns.
Further, the crystal with piezoelectric effect that can be used as piezoelectric substrate has multiple, preferably, in the utility model embodiment, adopt the lithium tantalate wafer of 112 degree cut types as piezoelectric substrate, the lithium tantalate wafer dielectric constant of 112 degree cut types is large, piezoelectric effect is large, and temperature stabilization performance is good, so can make the performance of the SAW (Surface Acoustic Wave) filter for Digital Television that makes more stable.
For formation input interdigital transducer 1 and output interdigital transducer 2 on piezoelectric substrate, can on piezoelectric substrate, make metal film, the metal film in the present embodiment on piezoelectric substrate is aluminium film, and the thickness of the aluminium film of wherein making is 0.7～0.9 micron.
As shown in Figure 1, in output interdigital transducer 2, first electrode laying respectively on one of them comb handle electrode is called pair of electrodes pair with second electrode relative with this first electrode being positioned on another comb handle electrode, the quantity of the electrode pair of output interdigital transducer 2 is called electrode and refers to logarithm, and in the utility model embodiment, the electrode of output interdigital transducer 2 refers to that logarithm is 25～35 pairs.
In Fig. 1, give the structural representation of input interdigital transducer 1, the electrode finger being positioned on two comb handle electrodes inputting interdigital transducer 1 is crossed as arranging, and the electrode logarithm of the electrode finger of input interdigital transducer 1 is 250～270 pairs.
On output interdigital transducer 2, the first electrode refers to that the 3 and second electrode refers to that 4 is all electrode fingers, is positioned on same comb handle electrode, and the spacing between adjacent electrode finger equates.
On input interdigital transducer 1, be positioned on same comb handle electrode, the spacing between adjacent electrode finger equates.
As shown in Figure 2, the Surface Acoustic Wave Filter of the utility model embodiment also comprises packaging part 14, is provided with surperficial installation portion 12 and pin one 3 on packaging part 14, and pin one 3 comprises input pin and output pin particularly;
Wherein, voltage substrate sticks on surperficial installation portion 12; The connection corresponding to input pin of input interdigital transducer 1, output interdigital transducer 2 connection corresponding to output pin.
Fig. 2 is the structural representation that is applied to the sound surface intermediate-frequency filter of Digital Television of the present utility model.The piezoelectric substrate 11 of this Surface Acoustic Wave Filter is X-112 ° of Y LiTaO
3substrate, input interdigital transducer 1 adopts not weighting, and output interdigital transducer 2 adopts cuts toe weighting, the wide λ of being 8 of finger that the electrode of input interdigital transducer 1 and output interdigital transducer 2 refers to.In order to obtain low insertion loss, get larger relative thickness h λ, thereby obtain larger total reflectance, the relative thickness h of the grizzly bar aluminum metal electrode λ in the present embodiment is 0.01.In order to obtain desirable filter amplitude response, the length of input interdigital transducer 1 and output interdigital transducer 2 is different, inputs interdigital transducer 1 and refer to that from the electrode of output interdigital transducer 2 logarithm is different while designing.
As shown in Figure 1, output interdigital transducer 2 adopts double track structure, backbone 6 be arranged in parallel with the inferior rail 7 of phase cancellation, the crossover length that in backbone 6, electrode refers to is controlled at λ 16～1 λ, the second-order effects electric field of backbone 6 finger tips is contrary with the electric field phase that time rail 7 line source excite, intensity is identical, and the electric leakage field effect of pectination finger tip is eliminated completely, and backbone 6 effects are compensation diffraction.
In addition, an example of the Surface Acoustic Wave Filter for Digital Television of the present embodiment, its centre frequency can be 56.125MHz, and bandwidth can be 4MHz, and Out-of-band rejection can be 50dB, meets the filtrate application demand of Digital Television.
The foregoing is only preferred embodiment of the present utility model, be not limited to the utility model, for a person skilled in the art, the utility model can have various modifications and variations.All within spirit of the present utility model and principle, any modification of doing, be equal to replacement, improvement etc., within all should being included in protection range of the present utility model.
Claims (10)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320421215.1U CN203406841U (en) | 2013-07-12 | 2013-07-12 | Surface Acoustic Wave Filters for Digital TV |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320421215.1U CN203406841U (en) | 2013-07-12 | 2013-07-12 | Surface Acoustic Wave Filters for Digital TV |
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| Publication Number | Publication Date |
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| CN203406841U true CN203406841U (en) | 2014-01-22 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201320421215.1U Expired - Fee Related CN203406841U (en) | 2013-07-12 | 2013-07-12 | Surface Acoustic Wave Filters for Digital TV |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111869104A (en) * | 2018-03-16 | 2020-10-30 | 福瑞斯恩系统 | Transducer structure for source rejection in SAW filter devices |
-
2013
- 2013-07-12 CN CN201320421215.1U patent/CN203406841U/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111869104A (en) * | 2018-03-16 | 2020-10-30 | 福瑞斯恩系统 | Transducer structure for source rejection in SAW filter devices |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20140122 Termination date: 20150712 |
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| EXPY | Termination of patent right or utility model |