CN108199697B - Surface acoustic wave filter and implementation method thereof - Google Patents
Surface acoustic wave filter and implementation method thereof Download PDFInfo
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- CN108199697B CN108199697B CN201711261735.XA CN201711261735A CN108199697B CN 108199697 B CN108199697 B CN 108199697B CN 201711261735 A CN201711261735 A CN 201711261735A CN 108199697 B CN108199697 B CN 108199697B
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- acoustic wave
- surface acoustic
- wave filter
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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
- H03H9/02551—Characteristics of substrate, e.g. cutting angles of quartz substrates
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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
- H03H9/02818—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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- Acoustics & Sound (AREA)
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Abstract
The embodiment of the invention relates to a surface acoustic wave filter and an implementation method thereof, belonging to the technical field of filters. Wherein, this sound surface filter includes: the piezoelectric transducer comprises a piezoelectric substrate and an interdigital transducer manufactured on the surface of the piezoelectric substrate, wherein the piezoelectric substrate is any one quartz piezoelectric substrate selected from quartz piezoelectric substrates of 30-35 degrees Y; the interdigital transducer is an interdigital transducer which accords with the parameter relation of metal lines. Through the technical scheme provided by the embodiment, on one hand, the technical defect of large frequency drift amount is avoided; on the other hand, the technical effect of improving the performance index of the surface acoustic wave filter is realized.
Description
Technical Field
The embodiment of the invention relates to the technical field of filters, in particular to a surface acoustic wave filter and an implementation method thereof.
Background
A Surface Acoustic Wave Filter (SAWF) is made of quartz, lithium niobate, and barium titanate crystals having a piezoelectric effect. The piezoelectric effect is a phenomenon that when a crystal is subjected to a mechanical action, an electric field proportional to a pressure is generated. When the crystal with piezoelectric effect is acted by electric signal, it will also produce elastic deformation to send out mechanical wave (sound wave), i.e. the electric signal can be converted into sound signal. Since such an acoustic wave propagates only on the crystal surface, it is called a surface acoustic wave. The performance parameters are determined by the piezoelectric substrate material, the design parameters of the interdigital transducer and the process manufacturing precision.
At present, the frequency drift amount of a filter made of a quartz piezoelectric material in the entire temperature range is 500 ppm. When the relative bandwidth of the filter reaches 1% o (1000ppm) or less, the amount of frequency drift of 500ppm has severely affected the use of the filter.
Disclosure of Invention
In order to solve the above technical problem, embodiments of the present invention provide a surface acoustic wave filter and an implementation method thereof.
According to an aspect of an embodiment of the present invention, there is provided a surface acoustic wave filter including: a piezoelectric substrate, an interdigital transducer made on the surface of the piezoelectric substrate,
the piezoelectric substrate is any one quartz piezoelectric substrate selected from quartz piezoelectric substrates of 30-35 degrees Y;
the interdigital transducer is an interdigital transducer which accords with the parameter relation of metal lines.
The embodiment provides that: the technical scheme that any one quartz piezoelectric substrate selected from the quartz piezoelectric substrates of 30-35 degrees Y is used as the piezoelectric substrate, and the interdigital transducer with the composite metal line parameter relation is used as the interdigital transducer of the surface acoustic wave filter is adopted, so that the technical defect of large frequency drift amount is avoided; on the other hand, the technical effect of improving the performance index of the surface acoustic wave filter is realized.
Further, the interdigital transducer conforming to the metal line parameter relationship is an interdigital transducer conforming to formula 1, formula 1:
4xy+y＝A
wherein x is the ratio of the width of a metal line of the interdigital transducer to the width of a gap of the metal line, y is the ratio of the thickness of the metal line to the wavelength of the surface acoustic wave filter, and the value range of A is a constant interval which enables the inflection point temperature of a temperature coefficient curve of the surface acoustic wave filter to be between 10 ℃ and 20 ℃.
The embodiment provides that: the interdigital transducer satisfying the formula 1 is an interdigital transducer conforming to the metal line relationship, so that the technical scheme that the inflection point temperature of the temperature coefficient curve of the surface acoustic wave filter is between 10 ℃ and 20 ℃ is ensured, the technical effect of reducing the frequency drift of the surface acoustic wave filter in the temperature range is realized, the technical effect of greatly improving the temperature stability of the surface acoustic wave filter is realized, and the technical effect of optimizing the performance index of the surface acoustic wave filter is realized.
Furthermore, when the variation interval of y is 2.5% -3.5%, the variation interval of x is 1.75-0.82.
The embodiment provides that: the change interval of y is 2.5% -3.5%, and the change interval of x is 1.75-0.82, so that the technical effect of reducing the insertion loss of the surface acoustic wave filter is realized.
Further, one y corresponds to one x.
Further, A takes any value between 0.15 and 0.2.
Further, the piezoelectric substrate is a 33.5 ° Y quartz piezoelectric substrate.
Further, a takes a value of 0.175.
Further, when y is 2.5%, x is 1.5;
when y is 3.5%, x is 1.0.
Furthermore, the frequency interval of the surface acoustic wave filter is 10 MHz-2 GHz.
According to another aspect of the embodiments of the present invention, an embodiment of the present invention provides a method for implementing a surface acoustic wave filter, where the method includes:
selecting any one quartz piezoelectric substrate from quartz piezoelectric substrates of 30-35 degrees Y as a piezoelectric substrate of the surface acoustic wave filter;
and manufacturing an interdigital transducer which accords with the parameter relation of the metal lines on the surface of the piezoelectric substrate.
Further, the method further comprises:
determining the interdigital transducer according to equation 1, equation 1:
4xy+y＝A
wherein x is the ratio of the width of a metal line of the interdigital transducer to the width of a gap of the metal line, y is the ratio of the thickness of the metal line to the wavelength of the surface acoustic wave filter, and the value range of A is a constant interval which enables the inflection point temperature of a temperature coefficient curve of the surface acoustic wave filter to be between 10 ℃ and 20 ℃.
Furthermore, when the variation interval of y is 2.5% -3.5%, the variation interval of x is 1.75-0.82.
Further, one y corresponds to one x.
Further, A takes any value between 0.15 and 0.2.
Further, the piezoelectric substrate is a 33.5 ° Y quartz piezoelectric substrate.
Further, a takes a value of 0.175.
Further, when y is 2.5%, x is 1.5;
when y is 3.5%, x is 1.0.
Furthermore, the frequency interval of the surface acoustic wave filter is 10 MHz-2 GHz.
Drawings
Fig. 1 is a schematic structural diagram of a surface acoustic wave filter according to an embodiment of the present invention;
FIG. 2 is a schematic diagram showing a temperature coefficient curve of a piezoelectric substrate of a surface acoustic wave filter according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a metal line parameter relationship of a surface acoustic wave filter according to an embodiment of the present invention;
fig. 4 is a schematic flowchart of a surface acoustic wave filter according to an embodiment of the present invention;
reference numerals: 1. piezoelectric substrate, 2 interdigital transducer lines, 3 interdigital transducer gaps.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth such as the particular system architecture, interfaces, techniques, etc., in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.
The embodiment of the invention provides a surface acoustic wave filter and an implementation method thereof.
According to an aspect of an embodiment of the present invention, there is provided a surface acoustic wave filter.
Referring to fig. 1, fig. 1 is a schematic structural diagram of a surface acoustic wave filter according to an embodiment of the present invention.
As shown in fig. 1, the surface acoustic wave filter includes: a piezoelectric substrate, an interdigital transducer formed on the surface of the piezoelectric substrate,
the piezoelectric substrate is any one quartz piezoelectric substrate selected from quartz piezoelectric substrates of 30-35 degrees Y;
the interdigital transducer is an interdigital transducer which accords with the parameter relation of metal lines.
In this embodiment, on the one hand, a quartz piezoelectric substrate of 30 ° Y to 35 ° Y is selected as the piezoelectric substrate. Compared with the piezoelectric substrate in the prior art, the quartz piezoelectric substrate with the temperature of 30-35 degrees Y is easier to realize high-temperature stability in the whole temperature range, and the performance index of the manufactured surface acoustic wave filter is higher.
On the other hand, by selecting the technical scheme of the interdigital transducer which accords with the parameter relation of the metal lines, the technical effect that the frequency drift amount of the surface acoustic wave filter in the whole temperature range is greatly reduced is achieved.
In one possible implementation, the interdigital transducer conforming to the metal line parameter relationship is an interdigital transducer conforming to formula 1, where formula 1:
4xy+y＝A
wherein, x is the ratio between the width of the metal lines of the interdigital transducer and the gap width of the metal lines, y is the ratio between the thickness of the metal lines and the wavelength of the surface acoustic wave filter, and the value range of A is a constant interval which can ensure that the inflection point temperature of the temperature coefficient curve of the surface acoustic wave filter is between 10 ℃ and 20 ℃.
Through the technical scheme provided by the embodiment, the frequency drift amount in the whole temperature range of the surface acoustic wave filter is reduced to below 200ppm from 500ppm in the prior art, the surface acoustic wave filter has high temperature stability, and the reliability and the accuracy of the surface acoustic wave filter are realized.
In a possible technical scheme, when the variation interval of y is 2.5% -3.5%, the variation interval of x is 1.75-0.82.
When the variation interval of y is not between 2.5% and 3.5%, the performance indexes of the acoustic surface filter, such as insertion loss, broadband and the like, are obviously deteriorated. So that the performance of the saw filter is significantly reduced.
In one possible implementation, one y corresponds to one x.
In a possible technical solution, a takes any value between 0.15 and 0.2.
In one possible implementation, the piezoelectric substrate is a 33.5 ° Y quartz piezoelectric substrate.
It will be understood that 33.5Y is a piezoelectric substrate cut by a cut line rotated 33.5 along the Y axis according to international common practice.
In one possible implementation, a is 0.175.
Please refer to fig. 2, fig. 2 is a schematic diagram of a temperature coefficient curve of a piezoelectric substrate of a saw filter according to an embodiment of the present invention.
As shown in fig. 2, when the piezoelectric substrate is a 33.5 ° Y quartz piezoelectric substrate and a is 0.175, the inflection point temperature of the temperature coefficient curve of the surface acoustic wave filter is 15 ℃. Wherein the horizontal axis represents:
temperature (unit:. degree. C.), and the ordinate represents the temperature coefficient (unit: ppm)
In one possible implementation, when y is 2.5%, x is 1.5;
when y is 3.5%, x is 1.0.
Please refer to fig. 3, fig. 3 is a schematic diagram of a metal line parameter relationship of a saw filter according to an embodiment of the present invention.
As shown in FIG. 3, x is 1.0 when y is 3.5%, and x is 1.5 when y is 2.5%.
Wherein h/λ is y, h is the thickness of the metal line, and λ is the wavelength of the surface acoustic wave filter.
d/d ═ x, d is the width of the metal lines of the interdigital transducer, and d' is the gap width of the metal lines.
In a possible technical scheme, the frequency interval of the surface acoustic wave filter is 10 MHz-2 GHz.
According to another aspect of the present invention, an embodiment of the present invention provides a method for implementing a surface acoustic wave filter.
Referring to fig. 4, fig. 4 is a schematic flow chart of a saw filter according to an embodiment of the present invention.
As shown in fig. 4, the method includes:
s100: selecting any one quartz piezoelectric substrate from quartz piezoelectric substrates of 30-35 degrees Y as a piezoelectric substrate of the surface acoustic wave filter;
s200: and manufacturing the interdigital transducer which accords with the parameter relation of the metal lines on the surface of the piezoelectric substrate.
In one possible implementation, the interdigital transducer is determined according to equation 1, where equation 1:
4xy+y＝A
wherein x is the ratio of the width of a metal line of the interdigital transducer to the width of a gap of the metal line, y is the ratio of the thickness of the metal line to the wavelength of the surface acoustic wave filter, and the value range of A is a constant interval which enables the inflection point temperature of a temperature coefficient curve of the surface acoustic wave filter to be between 10 ℃ and 20 ℃.
In a possible technical scheme, when the variation interval of y is 2.5% -3.5%, the variation interval of x is 1.75-0.82.
In one possible implementation, one y corresponds to one x.
In a possible technical solution, a takes any value between 0.15 and 0.2.
In one possible implementation, the piezoelectric substrate is a 33.5 ° Y quartz piezoelectric substrate.
In one possible implementation, a is 0.175.
In one possible implementation, when y is 2.5%, x is 1.5;
when y is 3.5%, x is 1.0.
In a possible technical scheme, the frequency interval of the surface acoustic wave filter is 10 MHz-2 GHz.
The reader should understand that in the description of this specification, reference to the description of the terms "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., means that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, 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, 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.
It should also be understood that, in the embodiments of the present invention, the sequence numbers of the above-mentioned processes do not mean the execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.
While the invention has been described with reference to specific embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (9)
1. A surface acoustic wave filter, characterized in that the surface acoustic wave filter comprises: a piezoelectric substrate, an interdigital transducer made on the surface of the piezoelectric substrate,
the piezoelectric substrate is any one quartz piezoelectric substrate selected from quartz piezoelectric substrates of 30-35 degrees Y;
the interdigital transducer is an interdigital transducer which accords with the parameter relation of metal lines;
wherein, the interdigital transducer who accords with metal lines parameter relation is the interdigital transducer who accords with formula 1, and formula 1:
4xy+y＝A
wherein x is the ratio of the width of a metal line of the interdigital transducer to the width of a gap of the metal line, y is the ratio of the thickness of the metal line to the wavelength of the surface acoustic wave filter, and the value range of A is a constant interval which enables the inflection point temperature of a temperature coefficient curve of the surface acoustic wave filter to be between 10 ℃ and 20 ℃.
2. A surface acoustic wave filter as set forth in claim 1,
when the variation interval of y is 2.5% -3.5%, the variation interval of x is 1.75-0.82.
3. A surface acoustic wave filter as set forth in claim 2,
one y for each x.
4. A surface acoustic wave filter as set forth in claim 1,
a takes any value between 0.15 and 0.2.
5. A surface acoustic wave filter according to any one of claims 1 to 4,
the piezoelectric substrate is a 33.5-degree Y quartz piezoelectric substrate.
6. A surface acoustic wave filter according to claim 5,
the value of A is 0.175.
7. A surface acoustic wave filter according to claim 5,
when y is 2.5%, x is 1.5;
when y is 3.5%, x is 1.0.
8. A surface acoustic wave filter according to any one of claims 1 to 4 and 6 to 7,
the frequency interval of the surface acoustic wave filter is 10 MHz-2 GHz.
9. A method for implementing a surface acoustic wave filter, the method comprising:
selecting any one quartz piezoelectric substrate from quartz piezoelectric substrates of 30-35 degrees Y as a piezoelectric substrate of the surface acoustic wave filter;
manufacturing an interdigital transducer which accords with the parameter relation of the metal lines on the surface of the piezoelectric substrate;
wherein the method further comprises:
determining the interdigital transducer according to equation 1, equation 1:
4xy+y＝A
wherein x is the ratio of the width of a metal line of the interdigital transducer to the width of a gap of the metal line, y is the ratio of the thickness of the metal line to the wavelength of the surface acoustic wave filter, and the value range of A is a constant interval which enables the inflection point temperature of a temperature coefficient curve of the surface acoustic wave filter to be between 10 ℃ and 20 ℃.
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