CN118041274A - Reflector structure for improving out-of-band selectivity of surface acoustic wave filter - Google Patents
Reflector structure for improving out-of-band selectivity of surface acoustic wave filter Download PDFInfo
- Publication number
- CN118041274A CN118041274A CN202410447339.XA CN202410447339A CN118041274A CN 118041274 A CN118041274 A CN 118041274A CN 202410447339 A CN202410447339 A CN 202410447339A CN 118041274 A CN118041274 A CN 118041274A
- Authority
- CN
- China
- Prior art keywords
- grating
- reflecting grating
- acoustic wave
- surface acoustic
- wave filter
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000010897 surface acoustic wave method Methods 0.000 title claims abstract description 29
- 230000007704 transition Effects 0.000 claims abstract description 40
- 238000000926 separation method Methods 0.000 claims 1
- 238000003780 insertion Methods 0.000 abstract description 6
- 230000037431 insertion Effects 0.000 abstract description 6
- 230000005764 inhibitory process Effects 0.000 abstract description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000013461 design Methods 0.000 description 2
- 238000002513 implantation Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000013459 approach Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000010295 mobile communication Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 230000026683 transduction Effects 0.000 description 1
- 238000010361 transduction Methods 0.000 description 1
Landscapes
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Abstract
The invention discloses a reflector structure for improving the out-of-band selectivity of a surface acoustic wave filter, which belongs to the technical field of surface acoustic wave filters and comprises two reflecting grating structures symmetrically arranged at two sides of an interdigital transducer, wherein each reflecting grating structure comprises a first reflecting grating, a second reflecting grating and at least one transition grating positioned between the first reflecting grating and the second reflecting grating. The invention can ensure that the whole surface acoustic wave filter has better passband insertion loss, out-of-band selectivity and inhibition performance through the reflector structures arranged at the two sides of the interdigital transducer, thereby realizing that the sharpness of the surface acoustic wave filter can be improved and better out-of-band selectivity is provided while the product performance is not influenced.
Description
Technical Field
The invention belongs to the technical field of surface acoustic wave filters, and particularly relates to a design of a reflector structure for improving the out-of-band selectivity of a surface acoustic wave filter.
Background
With the continuous development of communication technology, more frequency bands are needed in the market, the frequency bands are crowded, the requirements of mobile communication equipment on the out-of-band selection performance of devices are urgent, and particularly in the aspect of surface acoustic wave filters, the terminal equipment of the field Jing Duowei is used. The high-frequency filter needs to have good out-of-band selectivity on the premise of ensuring the passband performance, so that the improvement of the out-of-band selectivity of the filter and the ensuring of the passband performance are particularly important, and related products which can achieve both of the high-frequency filter and the passband performance are not available in the market at present.
Disclosure of Invention
The invention aims to provide a reflector structure for improving the out-of-band selectivity of a surface acoustic wave filter, which can improve the steepness of the surface acoustic wave filter and provide better out-of-band selectivity while not affecting the product performance.
The technical scheme of the invention is as follows: the reflector structure comprises two reflecting grating structures symmetrically arranged on two sides of an interdigital transducer, each reflecting grating structure comprises a first reflecting grating, a second reflecting grating and at least one transition grating positioned between the first reflecting grating and the second reflecting grating, the first reflecting grating is arranged at one end, close to the interdigital transducer, of the reflecting grating structure, and the second reflecting grating is arranged at one end, far away from the interdigital transducer, of the reflecting grating structure.
Further, the periods of the first reflecting grating and the second reflecting grating are 0.95-1.1 times of the periods of the interdigital transducer.
Further, the half wavelength pr1=0.95×p of the first reflective grating, where p is the half wavelength of the interdigital transducer.
Further, the half wavelength pr2=1.1×p of the second reflective grating, where p is the half wavelength of the interdigital transducer.
Further, the finger width of the transition grating is n/4 times of the period of the first reflecting grating or the second reflecting grating, wherein the value range of n is 0.1-0.8.
Further, the finger number of the transition gate is less than 6.
Further, the first reflecting grating, the transition grating and the second reflecting grating are sequentially connected.
Further, the first reflecting grating, the transition grating and the second reflecting grating are sequentially arranged in a separated mode.
The beneficial effects of the invention are as follows:
(1) The invention can ensure that the whole surface acoustic wave filter has better passband insertion loss, out-of-band selectivity and inhibition performance through the reflector structures arranged at the two sides of the interdigital transducer, thereby realizing that the sharpness of the surface acoustic wave filter can be improved and better out-of-band selectivity is provided while the product performance is not influenced.
(2) According to the invention, the periods of the first reflecting grating and the second reflecting grating are set to be 0.95-1.1 times of the periods of the interdigital transducer, so that the effect of resonant Q value distribution of the surface acoustic wave filter can be effectively improved, and the quality factor of the surface acoustic wave filter is improved.
(3) The invention sets the finger width of the transition grating as n/4 times of the period of the first reflecting grating or the second reflecting grating, and can adjust the Q value near the response frequency of the surface acoustic wave filter by modifying the value of n, thereby improving the insertion loss of the side frequency point of the passband and the steepness of the edge of the passband.
(4) The invention limits the finger number of the transition gate to less than 6, and can effectively reduce the transmission loss of the surface acoustic wave.
(5) The first reflecting grating, the transition grating and the second reflecting grating can be sequentially connected and arranged, and can also be sequentially separated, so that the structure is diversified and can be suitable for different application scenes.
Drawings
Fig. 1 is a schematic diagram of a reflector structure for improving the out-of-band selectivity of a surface acoustic wave filter according to an embodiment of the present invention.
Fig. 2 is a graph showing Q values of different transition gate finger widths according to an embodiment of the present invention.
FIG. 3 is a graph showing a comparison of performance of a gate with or without transition provided by an embodiment of the present invention.
Fig. 4 is a schematic diagram of a connection configuration of a transition gate implantation method according to an embodiment of the present invention.
Fig. 5 is a schematic diagram of a separately arranged transition gate implantation method according to an embodiment of the present invention.
Reference numerals illustrate: 1-interdigital transducer, 2-reflecting grating structure, 21-first reflecting grating, 22-second reflecting grating and 23-transition grating.
Detailed Description
Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It is to be understood that the embodiments shown and described in the drawings are merely illustrative of the principles and spirit of the invention and are not intended to limit the scope of the invention.
The embodiment of the invention provides a reflector structure for improving the out-of-band selectivity of a surface acoustic wave filter, as shown in fig. 1, the reflector structure comprises two reflecting grating structures 2 symmetrically arranged at two sides of an interdigital transducer 1, each reflecting grating structure 2 comprises a first reflecting grating 21, a second reflecting grating 22 and at least one transition grating 23 positioned between the first reflecting grating 21 and the second reflecting grating 22, the first reflecting grating 21 is arranged at one end of the reflecting grating structure 2 close to the interdigital transducer 1, and the second reflecting grating 22 is arranged at one end of the reflecting grating structure 2 far away from the interdigital transducer 1.
In the embodiment of the present invention, one transition grating 23 will be taken as an example later, and it should be noted that the number of transition gratings 23 may be plural, and when the number of transition gratings 23 is plural, any one transition grating 23 will serve as a transition structure of two adjacent transition gratings or reflection gratings.
In the embodiment of the invention, the reflector structure consisting of the two reflecting grating structures 2 and the interdigital transducer 1 form a surface acoustic wave filter. The interdigital transducer is a metal pattern shaped like a finger cross of two hands formed on the surface of a piezoelectric substrate of the surface acoustic wave filter, and has the function of realizing acoustic-electric transduction.
In the embodiment of the invention, the periods of the first reflecting grating 21 and the second reflecting grating 22 are 0.95-1.1 times of the period of the interdigital transducer 1. Wherein one period T of the interdigital transducer 1 is the distance of one wavelength.
In the embodiment of the invention, the reflective grating structure 2 is decomposed into two parts with different periods, namely a first reflective grating 21 and a second reflective grating 22, meanwhile, a transition grating 23 is added between the first reflective grating 21 and the second reflective grating 22, the finger width of the transition grating 23 is n/4 times of the period of the first reflective grating 21 or the second reflective grating 22, and the value range of n is 0.1-0.8. The number of fingers of the transition grating 23 is less than 6. Assuming that P is half wavelength of the interdigital transducer 1, the half wavelength pr1=0.95×p of the first reflective grating 21 and the half wavelength pr2=1.1×p of the second reflective grating 22.
The transition grating 23 refers to the adjustment of the width W0, which can improve the quality factor Q near the antiresonant point of the surface acoustic wave filter, and improve the passband performance and the out-of-band rejection, thereby improving the out-of-band selectivity. As shown in fig. 2, wherein the horizontal axis freq represents the frequency, Q1 is a Q-value graph without transition gate, Q2 is a Q-value graph with transition gate width w0= (pr1+pr2) 0.1/2, Q3 is a Q-value graph with transition gate width w0= (pr1+pr2) 0.5/2, and Q4 is a Q-value graph with transition gate width w0= (pr1+pr2) 0.7/2. As can be seen from fig. 2, the zero drop position can be adjusted by adjusting the period of Pr1 and Pr2, so that the width of the transition gate 23 can be adjusted to obtain a better Q value.
As shown in fig. 3, the performance comparison curve of the transition grating 23 is shown, wherein the horizontal axis freq represents the frequency, S (1, 2) represents the performance curve of the transition grating 23 not implanted in the reflective grating structure 2, S (8, 9) represents the performance curve of the transition grating 23 implanted in the reflective grating structure 2, m2 represents the insertion loss value comparison cut line of S (1, 2) and S (8, 9) at the edge frequency point 914MHz, and by comparing, it can be seen that by adjusting the finger width and the root number of the transition grating 23, the zero point on the right side approaches to the passband, and the sharpness is improved, thereby realizing better out-of-band selectivity, and meanwhile, the insertion loss of the passband on the right side of the passband is also improved by approximately 0.3dB due to the improvement of the overall Q value. Therefore, when the reflector structure provided by the embodiment of the invention is applied to the design of a filter circuit, better passband insertion loss, out-of-band selectivity and inhibition performance can be obtained.
In the embodiment of the present invention, the first reflective grating 21, the transition grating 23 and the second reflective grating 22 may be sequentially connected to each other, as shown in fig. 4, or may be sequentially separated from each other, as shown in fig. 5. Where P0 represents the half wavelength of the transition gate 23.
Those of ordinary skill in the art will recognize that the embodiments described herein are for the purpose of aiding the reader in understanding the principles of the present invention and should be understood that the scope of the invention is not limited to such specific statements and embodiments. Those of ordinary skill in the art can make various other specific modifications and combinations from the teachings of the present disclosure without departing from the spirit thereof, and such modifications and combinations remain within the scope of the present disclosure.
Claims (8)
1. The reflector structure is characterized by comprising two reflecting grating structures (2) symmetrically arranged on two sides of an interdigital transducer (1), wherein each reflecting grating structure (2) comprises a first reflecting grating (21), a second reflecting grating (22) and at least one transition grating (23) positioned between the first reflecting grating (21) and the second reflecting grating (22), the first reflecting grating (21) is arranged at one end, close to the interdigital transducer (1), of the reflecting grating structure (2), and the second reflecting grating (22) is arranged at one end, far away from the interdigital transducer (1), of the reflecting grating structure (2).
2. The reflector structure for improving the out-of-band selectivity of a surface acoustic wave filter according to claim 1, wherein the periods of the first reflecting grating (21) and the second reflecting grating (22) are each 0.95 to 1.1 times the period of the interdigital transducer (1).
3. The reflector structure for improving the out-of-band selectivity of a surface acoustic wave filter according to claim 2, characterized in that the half wavelength pr1=0.95×p of the first reflecting grating (21), p being the half wavelength of the interdigital transducer (1).
4. The reflector structure for improving the out-of-band selectivity of a surface acoustic wave filter according to claim 2, characterized in that the half wavelength pr2=1.1×p of the second reflection grating (22), p is the half wavelength of the interdigital transducer (1).
5. The reflector structure for improving the out-of-band selectivity of a surface acoustic wave filter according to claim 1, wherein the transition grating (23) has a finger width n/4 times the period of the first reflection grating (21) or the second reflection grating (22), and wherein n has a value in the range of 0.1 to 0.8.
6. The reflector structure for improving the out-of-band selectivity of a surface acoustic wave filter according to claim 1, characterized in that the number of fingers of the transition grating (23) is less than 6.
7. The reflector structure for improving the out-of-band selectivity of a surface acoustic wave filter according to claim 1, wherein the first reflecting grating (21), the transition grating (23) and the second reflecting grating (22) are sequentially connected.
8. The reflector structure for improving the out-of-band selectivity of a surface acoustic wave filter according to claim 1, wherein the first reflecting grating (21), the transition grating (23) and the second reflecting grating (22) are arranged in order with a separation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410447339.XA CN118041274A (en) | 2024-04-15 | 2024-04-15 | Reflector structure for improving out-of-band selectivity of surface acoustic wave filter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410447339.XA CN118041274A (en) | 2024-04-15 | 2024-04-15 | Reflector structure for improving out-of-band selectivity of surface acoustic wave filter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN118041274A true CN118041274A (en) | 2024-05-14 |
Family
ID=91000744
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202410447339.XA Pending CN118041274A (en) | 2024-04-15 | 2024-04-15 | Reflector structure for improving out-of-band selectivity of surface acoustic wave filter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN118041274A (en) |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001332954A (en) * | 2000-05-24 | 2001-11-30 | Matsushita Electric Ind Co Ltd | Surface acoustic wave filter |
| US20030169129A1 (en) * | 2002-01-28 | 2003-09-11 | Yuichi Takamine | Surface acoustic wave device and communication apparatus |
| US20050035831A1 (en) * | 2002-02-27 | 2005-02-17 | Osamu Kawachi | Surface acoustic wave device |
| CN106529646A (en) * | 2016-10-21 | 2017-03-22 | 天津大学 | Surface acoustic wave radio frequency identification tag with reflection gate structure |
| CN108566176A (en) * | 2018-04-12 | 2018-09-21 | 无锡市好达电子有限公司 | A kind of clutter suppression method of SAW resonator |
| CN115955210A (en) * | 2023-02-13 | 2023-04-11 | 成都频岢微电子有限公司 | Periodic gradual change surface acoustic wave filter and multiplexer |
| CN116318036A (en) * | 2023-05-15 | 2023-06-23 | 成都频岢微电子有限公司 | Surface acoustic wave resonator, surface acoustic wave filter, and duplexer |
-
2024
- 2024-04-15 CN CN202410447339.XA patent/CN118041274A/en active Pending
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001332954A (en) * | 2000-05-24 | 2001-11-30 | Matsushita Electric Ind Co Ltd | Surface acoustic wave filter |
| US20030169129A1 (en) * | 2002-01-28 | 2003-09-11 | Yuichi Takamine | Surface acoustic wave device and communication apparatus |
| US20050035831A1 (en) * | 2002-02-27 | 2005-02-17 | Osamu Kawachi | Surface acoustic wave device |
| CN106529646A (en) * | 2016-10-21 | 2017-03-22 | 天津大学 | Surface acoustic wave radio frequency identification tag with reflection gate structure |
| CN108566176A (en) * | 2018-04-12 | 2018-09-21 | 无锡市好达电子有限公司 | A kind of clutter suppression method of SAW resonator |
| CN115955210A (en) * | 2023-02-13 | 2023-04-11 | 成都频岢微电子有限公司 | Periodic gradual change surface acoustic wave filter and multiplexer |
| CN116318036A (en) * | 2023-05-15 | 2023-06-23 | 成都频岢微电子有限公司 | Surface acoustic wave resonator, surface acoustic wave filter, and duplexer |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5831493A (en) | Surface acoustic wave ladder filter utilizing a generated spurious component of the parallel arm | |
| KR100817849B1 (en) | Elastic surface wave resonator and elastic surface wave filter using the same | |
| EP0664610B1 (en) | Surface acoustic wave filter | |
| EP0795958B1 (en) | Resonator-type surface-acoustic-wave filter with improved upper stopband attenuation and reduced insertion loss | |
| WO2010058570A1 (en) | Tunable filter | |
| US7532090B2 (en) | Acoustic wave filter device and duplexer | |
| KR20050013939A (en) | Surface acoustic wave device and communication apparatus | |
| JPH07283682A (en) | Surface acoustic wave resonator filter | |
| JP3873802B2 (en) | Surface acoustic wave filter | |
| US6326864B1 (en) | Surface acoustic wave filter, duplexer and communications device with specific series resonator multiple anti-resonant point placement | |
| JP2002232264A (en) | Surface acoustic wave filter | |
| CN118041274A (en) | Reflector structure for improving out-of-band selectivity of surface acoustic wave filter | |
| KR0165849B1 (en) | Saw filter | |
| EP1076413A2 (en) | Surface acoustic wave filter, duplexer and communications apparatus | |
| EP0980138B1 (en) | Wideband surface wave filter | |
| CN115567025A (en) | Multilayer structure spurious response free SH type surface acoustic wave filter | |
| CN114785309A (en) | Resonator structure and filter with same | |
| US6437662B1 (en) | Surface acoustic wave filter, duplexer and communication apparatus with combined substrate and number of finger pairs reducing pass band ripples | |
| CN219087114U (en) | SAW filter for Band7 receiving frequency Band | |
| CN219304810U (en) | High-flatness surface acoustic wave filter circuit | |
| JP2005203996A (en) | Transversal saw filter | |
| JP3780496B2 (en) | Surface acoustic wave filter | |
| JPH10209806A (en) | Surface acoustic wave device | |
| JP3331733B2 (en) | Surface acoustic wave resonator filter | |
| JP3459494B2 (en) | Surface acoustic wave filter |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination |