Resonator, filter and duplexer equipped with the resonator

Abstract

A resonator (20) equipped with an interdigital transducer (30) according to one embodiment of the present invention is applicable, wherein the interdigital transducer (30) comprises: a main electrode region (II) formed in a comb-tooth shape on a piezoelectric substrate (10) using a reference spacing (P0) and having a unit length along a length direction (D); and a pair of first electrode regions, including a first electrode region (III) on one side formed in a comb-tooth shape using a first increased spacing (P1) increased by a first value from the reference spacing and having the unit length, and a first reduced spacing (P1) on the piezoelectric substrate reduced by a value substantially the same as the first value from the reference spacing. ‑1 ) is formed in a comb-tooth shape and has the first electrode region (I) on the other side of the unit length. The present invention can provide a resonator (surface acoustic wave resonator) with improved performance, thereby reducing insertion loss in the characteristics of surface acoustic wave devices such as filters and duplexers equipped with the above-mentioned resonators.

Description

Technical Field

[0001] The technology disclosed in the present application relates to a surface acoustic wave (SAW) resonator, and a filter and a duplexer using the resonator. Background Art

[0002] A resonator (surface acoustic wave resonator) generally includes a series resonator arranged between signal lines and a parallel resonator arranged between a signal line and ground.

[0003] Figure 1 This is a schematic diagram comparing the characteristics of a solid part of a parallel resonator applicable to the prior art with the characteristics of a surface acoustic wave device (filter) equipped with the parallel resonator. Figure 1 , the horizontal axis represents frequency (MHz), the vertical axis (right side) represents the characteristics of the physical components of the parallel resonator, and the vertical axis (left side) represents the characteristics of the acoustic surface wave device (filter) equipped with the above-mentioned parallel resonator.

[0004] like Figure 1 As shown in FIG. 1 , in the characteristic A of the parallel resonator using the prior art, the response B generated in the frequency band (specific frequency band) above the half-resonance point is degraded. Therefore, in the surface acoustic wave device using the parallel resonator, especially in the device such as a wide-band filter and a duplexer, since the passband overlaps with the specific frequency band, there is a problem that the insertion loss C is degraded in the specific frequency band of the device as described above.

[0005] Prior art literature

[0006] Patent Literature

[0007] (Patent Document 1) Korean Patent Publication No. (10)-(20)17-0111269 ((20)17.(10).12.)

[0008] Patent content

[0009] An object of the present invention is to provide a resonator (surface acoustic wave resonator) having improved performance.

[0010] The technical problems of the present invention are not limited to the technical problems mentioned in the above content, and a person skilled in the art will be able to further clearly understand other technical problems not mentioned through the following description.

[0011] A resonator equipped with an interdigital transducer applicable to one aspect of the present invention, the interdigital transducer comprising: a main electrode region formed in a comb-teeth shape on a piezoelectric substrate using a reference spacing and having a unit length along a length direction; and a pair of first electrode regions, comprising a first electrode region on one side formed in a comb-teeth shape on the piezoelectric substrate using a first increased spacing increased by a first value from the reference spacing and having the unit length, and a first electrode region on the other side formed in a comb-teeth shape on the piezoelectric substrate using a first reduced spacing reduced by a value substantially the same as the first value from the reference spacing and having the unit length.

[0012] According to the present invention, a resonator (surface acoustic wave resonator) with improved performance can be provided, and insertion loss can be reduced in the characteristics of surface acoustic wave devices such as filters and duplexers equipped with such resonators.

[0013] The effects of the present invention are not limited to the effects described above, and a person skilled in the art will be able to further clearly understand other effects not described through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram comparing the characteristics of a solid component of a conventional parallel resonator and the characteristics of a surface acoustic wave device (filter) equipped with the parallel resonator.

[0015] Figure 2 This is a schematic diagram showing an example of the configuration of a surface acoustic wave device (filter) 1 including a resonator to which one embodiment is applied.

[0016] Figure 3 Yes Figure 2 FIG. 1 is a schematic diagram showing an example of the configuration of a parallel resonator used in the surface acoustic wave device 1 shown in FIG. 1 and comparing it with a parallel resonator using the conventional technology.

[0017] Figure 4A It is applicable Figure 3 Schematic diagram showing a comparison between the characteristics of a solid component of a parallel resonator according to an embodiment shown in FIG. 1 and the characteristics of a surface acoustic wave device (filter) equipped with the parallel resonator.

[0018] Figure 4B It is applicable Figure 3 Schematic diagram comparing the characteristics of a physical component of a parallel resonator according to an embodiment shown in FIG. 1 and the characteristics of a surface acoustic wave device (filter) equipped with the parallel resonator (after subtracting the mismatching loss).

[0019] Figure 5 It is applicable to Figure 2 Schematic diagram illustrating a specific example of a pitch in an interdigital transducer (IDT) of a parallel resonator 20 used in the surface acoustic wave device 1 illustrated in FIG.

[0020] Fig. 6A It is applicable to equipment Figure 5 Schematic diagram showing the comparison between the characteristics of the surface acoustic wave device of the parallel resonator according to the first embodiment and the characteristics of a surface acoustic wave device equipped with a conventional technique.

[0021] Figure 6B It is applicable to equipment Figure 5 Schematic diagram comparing the characteristics of the surface acoustic wave device of the parallel resonator of the first embodiment and the characteristics of a surface acoustic wave device equipped with a conventional technique (after subtracting the mismatching loss).

[0022] Fig. 7A It is applicable to equipment Figure 5 Schematic diagram showing the comparison between the characteristics of the surface acoustic wave device of the parallel resonator according to the second embodiment and the characteristics of a surface acoustic wave device equipped with a conventional technique.

[0023] Figure 7B It is applicable to equipment Figure 5 Schematic diagram showing the comparison between the characteristics of the surface acoustic wave device of the parallel resonator according to the second embodiment and the characteristics of a surface acoustic wave device equipped with a conventional technique (after subtracting the mismatch loss).

[0024] Fig. 8A It is applicable to equipment Figure 5 Schematic diagram showing the comparison between the characteristics of the surface acoustic wave device of the parallel resonator according to the third embodiment and the characteristics of a surface acoustic wave device equipped with a conventional technique.

[0025] Figure 8B It is applicable to equipment Figure 5 Schematic diagram comparing the characteristics of the surface acoustic wave device of the parallel resonator of the third embodiment shown in FIG. 1 with the characteristics of a surface acoustic wave device equipped with the conventional technology (after subtracting the mismatching loss).

[0026] Fig.9A It is applicable to equipment Figure 5 Schematic diagram showing the comparison between the characteristics of the surface acoustic wave device of the parallel resonator according to the fourth embodiment and the characteristics of a surface acoustic wave device equipped with a conventional technique.

[0027] Fig. 9B It is applicable to equipment Figure 5 Schematic diagram comparing the characteristics of the surface acoustic wave device of the parallel resonator of the fourth embodiment shown in FIG. 1 with the characteristics of a surface acoustic wave device equipped with the conventional technology (after subtracting the mismatching loss).

[0028] Fig. 10A It is applicable to equipment Figure 5 Schematic diagram showing the comparison between the characteristics of the surface acoustic wave device of the parallel resonator according to the fifth embodiment and the characteristics of a surface acoustic wave device equipped with a conventional technique.

[0029] Fig. 10B It is applicable to equipment Figure 5 Schematic diagram comparing the characteristics of the surface acoustic wave device of the parallel resonator of the fifth embodiment and the characteristics of the surface acoustic wave device equipped with the conventional technology (after subtracting the mismatching loss).

[0030] Fig.11A It is applicable to equipment Figure 5 Schematic diagram showing the comparison between the characteristics of the surface acoustic wave device of the parallel resonator according to the sixth embodiment and the characteristics of a surface acoustic wave device equipped with a conventional technique.

[0031] Fig. 11B It is applicable to equipment Figure 5 Schematic diagram comparing the characteristics of the surface acoustic wave device of the parallel resonator of the sixth embodiment shown in FIG. 1 with the characteristics of a surface acoustic wave device equipped with the conventional technology (after subtracting the mismatching loss).

[0032] Fig.12 It is applicable to Figure 2 A schematic diagram illustrating a specific example of the pitch of the parallel resonators used in the surface acoustic wave device 1 shown in FIG.

[0033] Fig.13 It is applicable to Figure 2 A schematic diagram illustrating another specific example of the pitch of the parallel resonators used in the surface acoustic wave device 1 shown in FIG.

[0034]

Explanation of symbols

[0035] 1: Surface elastic wave device

[0036] 5, 10: Piezoelectric substrate

[0037] 20: Resonator

[0038] 6.30: Interdigital transducer (IDT)

[0039] 7a, 7b, 40a, 40b: reflectors. DETAILED DESCRIPTION

[0040] Next, various embodiments of the present invention will be described with reference to the accompanying drawings. At the same time, the same reference numbers are assigned to the same components in the accompanying drawings. Moreover, it should be noted that the components shown in the accompanying drawings may be omitted in other drawings for the convenience of explanation. In addition, it should be noted that the accompanying drawings may not be illustrated according to the exact scale.

[0041] Unless otherwise clearly defined, the meaning of all terms (including technical and scientific terms) used in this specification is the same as the meaning generally understood by personnel with general knowledge of the technical field to which the present invention belongs. In addition, unless otherwise clearly defined, the commonly used terms defined in the dictionary should not be interpreted in an overly idealized or exaggerated manner. The terms used in this specification are only used to illustrate the embodiments and are not intended to limit the present invention. In this specification, unless otherwise clearly mentioned, singular statements also include plural meanings.

[0042] The terms “comprises” and / or “comprising” used in this specification do not exclude the possibility that one or more other constituent elements, steps and / or actions besides the mentioned constituent elements, steps and / or actions exist or are added.

[0043] 1. Configuration of a device equipped with a resonator applicable to an embodiment

[0044] Figure 2 This is a schematic diagram showing an example of the configuration of a surface acoustic wave device (filter) 1 including a resonator according to an embodiment of the present invention.

[0045] like Figure 2 As shown, the surface acoustic wave device 1 may include at least one resonator 20 formed on a piezoelectric substrate 10. Specifically, the surface acoustic wave device 1 may include, for example, six resonators 20A to 20F. Each resonator 20 may include a series resonator arranged between signal lines and / or a parallel resonator arranged between a signal line and ground. Figure 2 In the illustrated example, for example, the resonator 20A is a parallel resonator disposed between a signal line and a ground, and the resonator 20B is a series resonator disposed between signal lines.

[0046] In addition, Figure 2Although the surface acoustic wave device 1 is illustrated as an example in which it is a filter (bandpass filter), the surface acoustic wave device 1 may be a duplexer.

[0047] 2. Configuration of the resonator 20

[0048] Next, we will refer to Figure 3 An example of the configuration of a parallel resonator disposed between a signal line and a ground will be described.

[0049] Figure 3 Yes Figure 2 FIG. 1 is a schematic diagram showing an example of the configuration of a parallel resonator used in the surface acoustic wave device 1 shown in FIG. 1 and comparing it with a parallel resonator using the conventional technology.

[0050] exist Figure 3 On the upper left side of the figure, the upper side of the parallel resonator applicable to the prior art is illustrated, and on the lower left side, the spacing of the interdigital transducer (IDT) (hereinafter referred to as "interdigital transducer (IDT)") included in the parallel resonator is illustrated. Figure 3 On the upper right side of the figure, the upper side of a series resonator to which one embodiment of the present invention is applied is illustrated, and on the lower right side, the pitch of an interdigital transducer (IDT) included in the series resonator is illustrated.

[0051] First, the parallel resonator of the prior art is used, such as Figure 3 As shown on the upper left side of , it includes: 1 interdigital transducer (IDT) 6, which is formed on the piezoelectric substrate 5 along the length (longer) direction D; 1 reflector (Reflector) 7a, which is formed on the piezoelectric substrate 5 in a manner facing one end 6a of the interdigital transducer (IDT) 6 and separated from the above end 6a by a certain distance; and 1 reflector (Reflector) 7b, which is formed on the piezoelectric substrate 5 in a manner facing the other end 6b of the interdigital transducer (IDT) 6 and separated from the above other end 6b by a certain distance. Figure 5 As shown in the lower left side of FIG. , the pitches of the interdigital transducers (IDT) 6 along the length direction D are the same (1.385 [μm]).

[0052] In addition, a parallel resonator 20 applicable to one embodiment of the present invention may include: an interdigital transducer (IDT) 30, which is formed on the piezoelectric substrate 10 along the length direction D and constitutes a comb-shaped electrode; a reflector (Reflector) 40a, which is formed on the piezoelectric substrate 10 in a manner facing one end 30a of the interdigital transducer (IDT) 30 and separated from the above-mentioned one end 30a by a certain distance; and, a reflector (Reflector) 40b, which is formed on the piezoelectric substrate 10 in a manner facing the other end 30b of the interdigital transducer (IDT) 30 and separated from the above-mentioned other end 30b by a certain distance.

[0053] In this embodiment, the interdigital transducer (IDT) 30 is as follows: Figure 3 As shown on the upper right side of , it may include three regions, namely I, II and III, arranged along the length direction D. Regions I, II and III1 respectively constitute electrodes formed in a comb-tooth shape. Region I includes (forms) one end 30a of the interdigital transducer (IDT) 30, region III includes the other end 30b of the interdigital transducer (IDT) 30, and region II is arranged between region I and region III. Regions I, II and III may each have a unit length along the length direction D. Among them, the unit length is the length obtained by dividing the length along the length direction D from one end 30a of the interdigital transducer 30 to the other end 30b into three equal parts.

[0054] like Figure 3 As shown in the lower right side of FIG, region II is formed in a comb-tooth shape using a reference pitch (e.g., about 1.385 [μm]) and is one electrode region (main electrode region) having a unit length along the length direction D. The reference pitch of region II along the length direction D is the same (e.g., about 1.385 [μm]).

[0055] Region III is formed in a comb-tooth shape using a first increased pitch increased by a first value (e.g., about 0.013 [μm]) from the reference pitch and is one electrode region (one side first electrode region) having a unit length along the length direction D. The first increased pitch along the length direction D of region III is the same (e.g., about 1.398 [μm]).

[0056] Region I is an electrode region (first electrode region on the other side) formed in a comb-tooth shape using a first reduced pitch that is reduced from the reference pitch by a value substantially equal to the first value (e.g., approximately 0.013 [μm]) and having a unit length along the length direction D. The first reduced pitch along the length direction D of region I is uniform (e.g., approximately 1.372 [μm]).

[0057] As described above, a parallel resonator to which one embodiment of the present invention is applicable can be used to replace an interdigital transducer (IDT) having the same pitch along the length direction D from one end to the other end of the interdigital transducer (IDT) by using an interdigital transducer 30 equipped with a pair of first electrode regions including a main electrode region (region II) having a reference pitch, a first electrode region (region III) on one side having a first increased pitch increased by a first value from the reference pitch, and a first electrode region (region I) on the other side having a first reduced pitch reduced by a value substantially the same as the first value from the reference pitch.

[0058] Next, we will refer to Figure 4A as well as Figure 4B The effects that can be achieved by using the interdigital transducer (IDT) 30 configured as described above will be described. Figure 4A It is applicable Figure 3 Schematic diagram comparing the characteristics of a solid component of a parallel resonator of an embodiment illustrated in FIG. 1 with the characteristics of a surface acoustic wave device (filter) equipped with the parallel resonator. Figure 4B It is applicable Figure 3 A schematic diagram comparing the characteristics of a physical component of a parallel resonator of an embodiment illustrated in FIG. 1 with the characteristics of a surface acoustic wave device (filter) equipped with the parallel resonator (after subtracting the mismatching loss).

[0059] The losses of the SAW filter include: i) the loss due to the simple resistance of the electrodes and wiring; ii) the loss due to the leakage of the overall energy of the SAW element sealed inside the resonator; and iii) the loss due to the difference in impedance matching, etc. Here, the state in which the third loss is subtracted from the above losses (assuming that the impedance in all frequency bands is 50Ω) is defined as the mismatching loss.

[0060] exist Figure 4A as well as Figure 4B In the figure, the horizontal axis represents the frequency ([MHz]), the vertical axis (left side) represents the characteristics of the physical components of the parallel resonator 20 ([dB]), and the vertical axis (right side) represents the characteristics of the elastic surface wave device equipped with the above-mentioned parallel resonator 20 ([dB]).

[0061] like Figure 4A as well as Figure 4BAs shown, the frequency band 100A of the response in which degradation occurs in the characteristics of the entity part 20 of the parallel resonator 20 to which one embodiment is applied (indicated by a dotted line in the figure) is shifted to a higher frequency band than the frequency band 10A of the response in which degradation occurs in the characteristics of the entity part of the parallel resonator to which the prior art is applied (indicated by a solid line in the figure). Therefore, in the characteristics of the entity part of the parallel resonator 20 to which one embodiment is applied, the phenomenon of degradation (at least a part) occurring in the frequency band 10A in which degradation occurs in the characteristics of the entity part of the parallel resonator to which the prior art is applied can be suppressed.

[0062] The frequency band 100A in which the characteristics of the physical part of the parallel resonator 20 to which the embodiment is applied deteriorates is higher than the passband of the surface acoustic wave device (filter) 1 equipped with the parallel resonator 20. That is, it is the attenuation band of the surface acoustic wave device 1. Therefore, the insertion loss 100B in the characteristics (indicated by the solid line in the figure) of the surface acoustic wave device 1 equipped with the parallel resonator 20 can be suppressed compared with the insertion loss 10B in the characteristics (indicated by the dotted line in the figure) of the surface acoustic wave device equipped with the parallel resonator to which the prior art is applied.

[0063] Figure 3 The spacing used in the various areas shown in the figure is just an example. Figure 5 A specific method for selecting the pitch will be described. Figure 5 It is applicable to Figure 2 Schematic diagram illustrating a specific example of a pitch in an interdigital transducer (IDT) of a parallel resonator 20 used in the surface acoustic wave device 1 illustrated in FIG.

[0064] First, one of the three regions I to III will become the main electrode region. One of the remaining two regions will become the first electrode region on one side, and the other region will become the first electrode region on the other side. The first electrode region on one side and the first electrode region on the other side will constitute a pair of first electrode regions.

[0065] The main electrode regions have a reference pitch, the first electrode regions on one side have a first increased pitch increased by a first value from the reference pitch, and the first electrode regions on the other side have a first decreased pitch decreased by a value substantially equal to the first value from the reference pitch.

[0066] By following the rules above, you can construct Figure 5 6 embodiments are shown.

[0067] First, in embodiment 1, Figure 3As shown, region II will become the main electrode region with the reference pitch, region III will become the first electrode region on one side with the first increased pitch, and region I will become the first electrode region on the other side with the first reduced pitch.

[0068] In the second embodiment, region II becomes the main electrode region having the reference pitch, region I becomes the first electrode region on one side having the first increasing pitch, and region III becomes the first electrode region on the other side having the first decreasing pitch.

[0069] In the third embodiment, region I becomes a main electrode region having a reference pitch, region II becomes a first electrode region on one side having a first increasing pitch, and region III becomes a first electrode region on the other side having a first decreasing pitch.

[0070] In the fourth embodiment, region I becomes a main electrode region having a reference pitch, region III becomes a first electrode region on one side having a first increasing pitch, and region II becomes a first electrode region on the other side having a first decreasing pitch.

[0071] In the fifth embodiment, region III becomes the main electrode region having the reference pitch, region II becomes the first electrode region on one side having the first increasing pitch, and region I becomes the first electrode region on the other side having the first decreasing pitch.

[0072] In the sixth embodiment, region III becomes the main electrode region having the reference pitch, region I becomes the first electrode region on one side having the first increasing pitch, and region II becomes the first electrode region on the other side having the first decreasing pitch.

[0073] In the case of adopting any one of the embodiments 2 to 6, in combination with the above-mentioned embodiment 1 ( Figure 3 ), the frequency band of the response in which the degradation occurs in the characteristics of the entity components of the parallel resonator 20 will also be shifted to a higher frequency band than the frequency band of the response in which the degradation occurs in the characteristics of the entity components of the parallel resonator to which the prior art is applied. Therefore, in the characteristics of the entity components of the parallel resonator 20 to which each embodiment is applied, the phenomenon of degradation (at least a part) occurring in the frequency band 10A in which the degradation occurs in the characteristics of the entity components of the parallel resonator to which the prior art is applied can be suppressed.

[0074] As a result, the insertion loss in the surface acoustic wave characteristics of the parallel resonator 20 according to each embodiment can be suppressed (at least partially) compared to the insertion loss of the surface acoustic wave device according to the conventional parallel resonator. Figure 6A to Figure 11B The above-mentioned effects will be described.

[0075] Fig. 6A It is applicable to equipment Figure 5 Schematic diagram showing the comparison between the characteristics of the surface acoustic wave device of the parallel resonator according to the first embodiment and the characteristics of a surface acoustic wave device equipped with a conventional technique. Figure 6B It is applicable to equipment Figure 5 Schematic diagram comparing the characteristics of the surface acoustic wave device of the parallel resonator of the first embodiment and the characteristics of a surface acoustic wave device equipped with a conventional technique (after subtracting the mismatching loss).

[0076] Fig. 7A It is applicable to equipment Figure 5 Schematic diagram showing the comparison between the characteristics of the surface acoustic wave device of the parallel resonator according to the second embodiment and the characteristics of a surface acoustic wave device equipped with a conventional technique. Figure 7B It is applicable to equipment Figure 5 Schematic diagram comparing the characteristics of the surface acoustic wave device of the parallel resonator of the second embodiment shown in FIG. 1 with the characteristics of a surface acoustic wave device equipped with a conventional technique (after subtracting the mismatching loss).

[0077] Fig. 8A It is applicable to equipment Figure 5 Schematic diagram showing the comparison between the characteristics of the surface acoustic wave device of the parallel resonator according to the third embodiment and the characteristics of a surface acoustic wave device equipped with a conventional technique. Figure 8B It is applicable to equipment Figure 5 Schematic diagram comparing the characteristics of the surface acoustic wave device of the parallel resonator of the third embodiment and the characteristics of the surface acoustic wave device equipped with the conventional technology (after subtracting the mismatching loss).

[0078] Fig.9A It is applicable to equipment Figure 5 Schematic diagram showing the comparison between the characteristics of the surface acoustic wave device of the parallel resonator according to the fourth embodiment and the characteristics of a surface acoustic wave device equipped with a conventional technique. Fig. 9B It is applicable to equipment Figure 5 Schematic diagram comparing the characteristics of the surface acoustic wave device of the parallel resonator of the fourth embodiment shown in FIG. 1 with the characteristics of a surface acoustic wave device equipped with a conventional technique (after subtracting the mismatching loss).

[0079] Fig. 10A It is applicable to equipment Figure 5 Schematic diagram showing the comparison between the characteristics of the surface acoustic wave device of the parallel resonator according to the fifth embodiment and the characteristics of a surface acoustic wave device equipped with a conventional technique. Fig. 10B It is applicable to equipment Figure 5 Schematic diagram comparing the characteristics of the surface acoustic wave device of the parallel resonator of the fifth embodiment and the characteristics of the surface acoustic wave device equipped with the conventional technology (after subtracting the mismatching loss).

[0080] Fig.11A It is applicable to equipment Figure 5 Schematic diagram showing the comparison between the characteristics of the surface acoustic wave device of the parallel resonator according to the sixth embodiment and the characteristics of a surface acoustic wave device equipped with a conventional technique. Fig. 11B It is applicable to equipment Figure 5 Schematic diagram comparing the characteristics of the surface acoustic wave device of the parallel resonator of the sixth embodiment and the characteristics of a surface acoustic wave device equipped with a conventional technique (after subtracting the mismatching loss).

[0081] exist Figure 6A to Figure 11B In FIG. 1 , the solid line represents the characteristics of a surface acoustic wave device including a parallel resonator according to each embodiment, and the dotted line represents the characteristics of a surface acoustic wave device including a parallel resonator according to the conventional technology.

[0082] As shown in the figure, the insertion loss on the high-frequency side of the passband of the surface acoustic wave device equipped with the parallel resonator applicable to each embodiment is suppressed compared with the insertion loss on the high-frequency side of the passband of the surface acoustic wave device equipped with the parallel resonator applicable to the conventional technology. Although the degree of improvement of the insertion loss and the frequency band vary in different embodiments, at least a part of the insertion loss is suppressed in all embodiments.

[0083] 4. Extension Example

[0084] In the reference Figure 3In the embodiment described, the case where the interdigital transducer (IDT) 30 includes three regions (three regions having almost the same unit length) such as regions I, II, and III, obtained by dividing the length from one end 30a to the other end 30b of the interdigital transducer (IDT) 30 into three equal parts along the length direction D is described. However, the technology disclosed in the present application can also be applied to the case where the interdigital transducer (IDT) 30 including five regions (seven regions or nine regions) is obtained by dividing the length from one end 30a to the other end 30b of the interdigital transducer (IDT) 30 into five equal parts (seven equal parts or nine equal parts) along the length direction D. That is, the technology disclosed in the present application can also be applied to the case where an interdigital transducer (IDT) 30 including an odd number of regions (an odd number of regions having almost the same unit length) is obtained by dividing the length from one end 30a to the other end 30b of the interdigital transducer (IDT) 30 into equal parts by an odd number along the length direction D.

[0085] In the above case, the spacing between the regions is determined according to the following rules.

[0086] (1) One of the odd-numbered regions will become the main electrode region. Two arbitrary regions of the remaining regions will become a pair of first electrode regions. Furthermore, two arbitrary regions of the remaining regions will become a pair of second electrode regions. Furthermore, two arbitrary regions of the remaining regions will become a pair of third electrode regions. Furthermore, the remaining arbitrary regions will become the fourth electrode region. The above-mentioned process will be repeated until no remaining regions exist.

[0087] (2) The main electrode region has a reference spacing. The reference spacing d can be determined by the formula d=λ÷2. Here, λ is the wavelength of the surface elastic wave propagating in the piezoelectric substrate 10, which is determined by the material constituting the piezoelectric substrate 10 and the applied voltage V.

[0088] (3) One of the pair of first electrode regions has a first increased pitch that is increased by a first value (determined appropriately) from the reference pitch. In addition, the other of the pair of first electrode regions has a first decreased pitch that is decreased from the reference pitch by a value substantially identical to the first value. In this case, the value substantially identical to the first value is within a range of 80% to 120% of the first value, preferably within a range of 90% to 110% of the first value, and more preferably is completely identical to the first value.

[0089] (4) One side of a pair of second electrode regions has a second increased pitch that is increased by a second value (determined appropriately) from the reference pitch. In addition, the other side of the pair of second electrode regions has a second decreased pitch that is decreased from the reference pitch by a value that is substantially the same as the second value. In this case, the second value is a value different from the first value, and is a value greater than or less than the first value. In this case, the value substantially the same as the second value is within the range of 80% to 120% of the second value, preferably within the range of 90% to 110% of the second value, and more preferably is a value that is substantially the same as the second value.

[0090] (5) One side of the third electrode region in a pair of third electrode regions has a third increased pitch increased by a third value (determined appropriately) from the reference pitch. In addition, the other side of the third electrode region in the pair of third electrode regions has a third decreased pitch decreased by a value substantially the same as the third value from the reference pitch. In this case, the third value is a value different from the first value and the second value, and is a value greater than or less than the first value and the second value. In this case, the value substantially the same as the third value is within the range of 80% to 120% of the third value, preferably within the range of 90% to 110% of the third value, and more preferably is a value substantially the same as the third value.

[0091] (6) One side of a pair of fourth electrode regions has a fourth increased pitch that is increased by a fourth value (determined appropriately) from the reference pitch. In addition, the other side of a pair of fourth electrode regions has a fourth decreased pitch that is decreased from the reference pitch by a value that is substantially the same as the fourth value. In this case, the fourth value is a value different from the first to third values, and is a value greater than or less than the first to third values. In this case, the value substantially the same as the fourth value is within the range of 80% to 120% of the fourth value, preferably within the range of 90% to 110% of the fourth value, and more preferably is a value that is completely the same as the fourth value.

[0092] (7) Furthermore, when a pair of fifth electrode regions or the like exists, the pitch between the pair of fifth electrode regions may be determined in the same manner as that of the pair of second electrode regions to the pair of fourth electrode regions described above.

[0093] Next, a method of determining the pitch in the case where the interdigital transducer (IDT) 30 includes five regions such as region I to region V in the above-described extended example will be described.

[0094] Fig.12 It is applicable to Figure 2 A schematic diagram illustrating a specific example of the pitch of the parallel resonators used in the surface acoustic wave device 1 shown in FIG. Fig.13 It is applicable to Figure 2A schematic diagram illustrating another specific example of the pitch of the parallel resonators used in the surface acoustic wave device 1 shown in FIG.

[0095] exist Fig.12 as well as Fig.13 In the figure, by dividing the length from one end 30a to the other end 30b of the interdigital transducer (IDT) 30 into five equal parts along the length direction D, the interdigital transducer (IDT) 30 includes five regions, namely, regions I, II, III, IV, and V.

[0096] See also Fig.12 , region III will become the main electrode region with a reference spacing, region IV will become the 1st electrode region on one side with the 1st increased spacing, region II will become the 1st electrode region on the other side with the 1st reduced spacing, region V will become the 2nd electrode region on one side with the 2nd increased spacing, and region I will become the 2nd electrode region on the other side with the 2nd reduced spacing.

[0097] The first increase pitch P1 is a value increased by a first value from the reference pitch P0. -1 The second increase pitch P2 is a value obtained by reducing the first value from the reference pitch P0. The second decrease pitch P2 is a value obtained by increasing the second value from the reference pitch P0. -2 This is a value obtained by subtracting a second value from the reference pitch P0.

[0098] In contrast, see Fig.13 , region II will become the main electrode region with a reference spacing, region IV will become the 1st electrode region on one side with the 1st increased spacing, region V will become the 1st electrode region on the other side with the 1st reduced spacing, region I will become the 2nd electrode region on one side with the 2nd increased spacing, and region III will become the 2nd electrode region on the other side with the 2nd reduced spacing.

[0099] The spacing can be adjusted according to Fig.12 Specifically, the first increase pitch P1 is a value increased by a first value from the reference pitch P0. The first decrease pitch P -1 The second increase pitch P2 is a value obtained by reducing the first value from the reference pitch P0. The second decrease pitch P2 is a value obtained by increasing the second value from the reference pitch P0. -2 This is a value obtained by subtracting a second value from the reference pitch P0.

[0100] 5. Embodiments Related to Piezoelectric Substrate 10 and Parallel Resonator 20

[0101] In the above-mentioned embodiments, the following structures are adopted as the piezoelectric substrate 10 and the parallel resonator 20. The following structures are merely examples, and the following structures can be appropriately changed according to the required conditions.

[0102] (a) Piezoelectric substrate 10

[0103] Substrate material: LiTaO3;

[0104] Cutting angle: 42 degrees;

[0105] (2) Parallel resonator 20

[0106] Material of interdigital transducer (IDT): AlCu;

[0107] Thickness of interdigital transducer (IDT): 275 [nm];

[0108] Reference spacing: 1.385[μm].

[0109] 1st value: 0.013 [μm] (the 1st increased pitch or the 1st decreased pitch is obtained by increasing or decreasing this 1st value from the reference pitch);

[0110] Reflector spacing: 1.385 [μm];

[0111] Aperture [λ]: 17;

[0112] Number of finger pairs of each interdigital transducer (IDT): 58.5;

[0113] Duty of interdigital transducer (IDT) and reflector: 0.52;

[0114] In the above content, the embodiments of the present invention are described in conjunction with the accompanying drawings, but a person having general knowledge of the technical field to which the present invention belongs should be able to understand that the present invention can be implemented in other specific forms without changing its technical ideas or essential features. However, the embodiments described in the above content should be understood in all aspects for illustrative purposes rather than for limitation.

Claims

1. A resonator equipped with an interdigital transducer, the interdigital transducer comprising: a main electrode region formed in a comb-teeth shape on the piezoelectric substrate using a reference pitch and having a unit length along a length direction; as well as, A pair of first electrode regions, including a first electrode region on one side formed in a comb-teeth shape using a first increased spacing that increases a first value from the above-mentioned reference spacing and having the above-mentioned unit length, and a first electrode region on the other side formed in a comb-teeth shape using a first reduced spacing that decreases from the above-mentioned reference spacing to a value substantially the same as the above-mentioned first value and having the above-mentioned unit length.

2. The resonator according to claim 1, characterized in that: The main electrode region is arranged between the one-side first electrode region and the other-side first electrode region.

3. The resonator according to claim 1, characterized in that: The one-side first electrode region is arranged between the main electrode region and the other-side first electrode region.

4. The resonator according to claim 1, characterized in that: The other-side first electrode region is arranged between the main electrode region and the one-side first electrode region.

5. The resonator according to any one of claims 1 to 4, characterized in that: The unit length is a length obtained by dividing the length from one end to the other end of the interdigital transducer along the longitudinal direction into three equal parts.

6. The resonator according to claim 1, characterized in that: The above interdigital transducer further comprises: A pair of second electrode regions, including a second electrode region on one side of the piezoelectric substrate formed in a comb-teeth shape using a second increased spacing that increases the above-mentioned reference spacing by a second value different from the above-mentioned first value and having the above-mentioned unit length, and a second electrode region on the other side of the piezoelectric substrate formed in a comb-teeth shape using a second reduced spacing that decreases the above-mentioned reference spacing by a value substantially the same as the above-mentioned second value and having the above-mentioned unit length.

7. The resonator according to claim 6, characterized in that: The unit length is a length obtained by dividing the length from one end to the other end of the interdigital transducer along the longitudinal direction into five equal parts.

8. The resonator according to claim 6 or claim 7, characterized in that: The above interdigital transducer further comprises: A pair of third electrode regions, including a third electrode region on one side formed in a comb-teeth shape and having the above-mentioned unit length by using a third increased spacing that is increased from the above-mentioned reference spacing by a third value different from the above-mentioned first value and the second value, and a third electrode region on the other side formed in a comb-teeth shape and having the above-mentioned unit length by using a third reduced spacing that is reduced from the above-mentioned reference spacing by a value almost the same as the above-mentioned third value.

9. The resonator according to claim 8, characterized in that: The unit length is a length obtained by dividing the length from one end to the other end of the interdigital transducer along the longitudinal direction into seven equal parts.

10. The resonator according to claim 8 or claim 9, characterized in that: The above interdigital transducer further comprises: A pair of fourth electrode regions, including a fourth electrode region on one side formed in a comb-teeth shape and having the above-mentioned unit length by increasing a fourth increased spacing from the above-mentioned reference spacing to a fourth value different from the above-mentioned first value to the third value on the above-mentioned piezoelectric substrate, and a fourth electrode region on the other side formed in a comb-teeth shape and having the above-mentioned unit length by decreasing a fourth decreased spacing from the above-mentioned reference spacing to a value almost the same as the above-mentioned fourth value.

11. The resonator according to claim 10, characterized in that: The unit length is a length obtained by dividing the length from one end to the other end of the interdigital transducer along the longitudinal direction into 9 equal parts.

12. The resonator according to claim 10 or claim 11, characterized in that: The value which is almost the same as the first value is within the range of 80% to 120% of the first value. The value which is almost the same as the second value is within the range of 80% to 120% of the second value. The value which is almost the same as the third value is within the range of 80% to 120% of the third value. The value which is almost the same as the fourth value mentioned above is within the range of 80% to 120% of the fourth value mentioned above.

13. The resonator according to claim 12, characterized in that: The value which is almost the same as the first value is within the range of 90% to 110% of the first value. The value which is almost the same as the second value is within the range of 90% to 110% of the second value. The value which is almost the same as the third value is within the range of 90% to 110% of the third value. The value which is almost the same as the fourth value mentioned above is within the range of 90% to 120% of the fourth value mentioned above.

14. The resonator according to any one of claims 6 to 13, characterized in that: The main electrode region is arranged between the one-side first electrode region and the other-side first electrode region.

15. The resonator according to any one of claims 6 to 13, characterized in that: The main electrode region forms one end or the other end of the interdigital transducer.

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