Dual-mode surface acoustic wave filter, receiving filter and duplexer

Abstract

A dual mode surface acoustic wave (SAW) filter includes a piezoelectric substrate, a pair of reflectors disposed on the piezoelectric substrate, and N input and output interdigital transducers (IDTs) disposed on the piezoelectric substrate and between the pair of reflectors and alternately arranged in a lateral direction. Each IDT includes a pair of comb electrodes with a plurality of electrode fingers, adjacent electrode fingers pointing in opposite directions. The total number of electrode fingers in each IDT is an odd number greater than or equal to 3. The invention also discloses a receiving filter and a duplexer.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor devices, and in particular to surface acoustic wave devices. Background Art

[0002] Generally, receive filters have strict requirements on indicators such as insertion loss and stopband suppression, and there is a continuous demand for minimizing chip size in order to reduce costs. Due to the above reasons, receive filters usually use dual-mode surface acoustic wave filters (called "dual-mode SAW (Surface Acoustic Wave) filters" or "DMS (Double-mode SAW) filters") or hybrid filters consisting of DMS filters and series / parallel single-port resonators. In this structure, the reasonable design of the parameters of the DMS component's interdigital electrodes is crucial to the overall performance of the filter, especially for insertion loss and stopband suppression.

[0003] Taking Band66 receive filter (2110 MHz to 2200 MHz) as an example, it is generally expected that the stopband suppression level of adjacent bands Band3 (1710 MHz to 1785 MHz) and Band1 (1920 MHz to 1980 MHz) should be less than -40 dB. This ensures that the terminal equipment achieves the best performance according to the working requirements. Summary of the invention

[0004] A dual-mode surface acoustic wave (SAW) filter includes a piezoelectric substrate, a pair of reflectors disposed on the piezoelectric substrate, and N input and output interdigital transducers (IDTs) disposed on the piezoelectric substrate and between the pair of reflectors and arranged alternately in the lateral direction. Each IDT includes a pair of comb-shaped electrodes with a plurality of electrode fingers, and adjacent electrode fingers point in opposite directions. The total number of electrode fingers in each IDT is an odd number greater than or equal to 3.

[0005] The dual-mode SAW filter of the present application can effectively improve out-of-band suppression and suppress interference signals of adjacent channels by configuring the parameters of the above-mentioned IDT electrodes. As a better choice, it can be used as a filter device for duplexers and communication equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The drawings of the present application illustrate the disclosed embodiments and, together with the description, are used to explain specific disclosed embodiments.

[0007] Figure 1 The diagram schematically shows a planar structure diagram of a dual-mode surface acoustic wave (DMS) filter according to an embodiment of the present disclosure.

[0008] Figure 2A parameter table of a first dual-mode SAW filter included in a first Band66 receive filter according to an embodiment of the present disclosure is summarized.

[0009] Figure 3 is a diagram of a simulated frequency response of a first Band66 receive filter including a first dual-mode SAW filter.

[0010] Figure 4 A parameter table of a second dual-mode SAW filter included in a second Band66 receive filter according to an embodiment of the present disclosure is summarized.

[0011] Figure 5 is a simulated frequency response diagram of the second Band66 filter including the second dual-mode SAW filter according to an embodiment of the present disclosure.

[0012] Figure 6 A hybrid receive filter according to one embodiment of the present disclosure is shown.

[0013] Figure 7 A duplexer according to one embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0014] The following provides a detailed description in conjunction with the specific embodiments shown in the accompanying drawings. However, these embodiments do not limit the present disclosure. The scope of protection of the present disclosure covers the changes made to the structure, method or function by ordinary technicians in this field based on these embodiments.

[0015] In order to facilitate the presentation of the drawings in this disclosure, the sizes of certain structures or parts may be enlarged relative to other structures or parts. Therefore, the drawings in this disclosure are only used to illustrate the basic structure of the subject matter of the present disclosure. Unless otherwise specified, the same numbers in different drawings represent the same or similar elements.

[0016] Additionally, terms indicating relative spatial positions in the text, such as "top," "bottom," "upper," "lower," "above," "below," etc., are used to describe the relationship between an element or feature depicted in a drawing and another element or feature therein. Terms indicating relative spatial positions may refer to positions other than those depicted in the drawings when the device is in use or operation. For example, if the device shown in the drawings is turned over, an element described as being "below" or "beneath" another element or feature would then be "above" the other element or feature. Thus, the illustrative term "below" may include both above and below positions. The device may be otherwise oriented (e.g., rotated 90 degrees or facing another orientation) and the spatially relative descriptive terms appearing in the text should be interpreted accordingly. When a component or layer is referred to as being "on" or "connected to" another member or layer, it may be directly on or directly connected to the other member or layer, or there may be intervening components or layers.

[0017] One embodiment of the present disclosure provides a dual-mode surface acoustic wave (DMS) filter. The dual-mode SAW filter includes a piezoelectric substrate, a pair of reflectors disposed on the piezoelectric substrate, and N input and output interdigital transducers (IDTs) disposed on the piezoelectric substrate and between the reflectors. The N input and output IDTs are alternately arranged in the lateral direction. Each of the N input and output IDTs includes a pair of comb electrodes with a plurality of electrode fingers, and adjacent electrode fingers point in opposite directions. N can be an odd number greater than or equal to 5.

[0018] Figure 1 FIG. 1 schematically shows a top view of a dual-mode surface acoustic wave (DMS) filter 100 according to an embodiment of the present disclosure. Figure 1 As shown, the dual-mode SAW filter 100 includes a piezoelectric substrate 10, a pair of reflectors 160 and 170 disposed on the piezoelectric substrate, and N input and output interdigital transducers (IDTs) 110, 120, 130, 140, and 150 (hereinafter referred to as "110-150") disposed on the piezoelectric substrate 10 and located between the pair of reflectors 170 and 160. N may be any odd number greater than or equal to 5. The N input and output IDTs 110-150 are arranged along the main surface of the piezoelectric substrate 10 in the lateral direction ( Figure 1 Each of the IDTs 110 to 150 includes a pair of comb electrodes having a direction perpendicular to the lateral direction ( Figure 1 The electrode fingers 101 in a pair of comb-shaped electrodes are oriented (pointed) in opposite directions.

[0019] exist Figure 1 In the embodiment shown, N is equal to 5. That is, Figure 1 The dual-mode SAW filter 100 in FIG. 1 includes five input and output IDTs, namely, IDTs 110-150. Among these IDTs 110-150, the first IDT 110, the third IDT 130, and the fifth IDT 150 work as input IDTs, while the second IDT 120 and the fourth IDT 140 work as output IDTs. Each of the IDTs 110-150 includes a pair of comb electrodes connected between an input terminal 180 or an output terminal 190 and a ground, respectively. For example, the first IDT 110 includes a comb electrode 110a connected to the input terminal 180 and a comb electrode 110b connected to the ground. The second IDT 120 includes a comb electrode 120a connected to the output terminal 190 and a comb electrode 120b connected to the ground. The third IDT 130 includes a comb electrode 130a connected to the input terminal 180 and a comb electrode 130b connected to the ground. The fourth IDT 140 includes a comb electrode 140a connected to the output terminal 190 and a comb electrode 140b connected to the ground. The fifth IDT 150 includes a comb electrode 150a connected to the input terminal 180 and a comb electrode 150b connected to the ground. The electrode fingers 101 in the comb electrode 110a point to the -Y direction, and the electrode fingers 101 in the comb electrode 110b point to the +Y direction opposite to the -Y direction; the electrode fingers 101 in the comb electrode 120a point to the +Y direction and the electrode fingers 101 in the comb electrode 120b point to the -Y direction; and the rest are analogous.

[0020] In some embodiments, within the set of N IDTs 110-150, relative to the center IDT, there is a mirror symmetry relationship between the Xth IDT and the (N+1-X)th IDT. Here, X is an integer greater than or equal to 1 and less than or equal to N, and the center IDT is the (N+1) / 2th IDT. For example, in Figure 1 In the illustrated embodiment, the first IDT 110 and the fifth IDT 150 exhibit a mirror-symmetric relationship with respect to the third IDT 130 (ie, the center IDT); and the second IDT 120 and the fourth IDT 140 exhibit a mirror-symmetric relationship with respect to the third IDT 130 .

[0021] In some embodiments, the total number of electrode fingers in each IDT is an odd number greater than or equal to 3. For example, in Figure 1In the illustrated embodiment, the first IDT 110 includes thirteen electrode fingers 101, six of which belong to the comb-shaped electrode 110a and seven of which belong to the comb-tooth electrode 110b. The second IDT 120 includes seven electrode fingers 101, three of which belong to the comb-shaped electrode 120a and four of which belong to the comb-tooth electrode 120b. The third IDT 130 includes eleven electrode fingers 101, five of which belong to the comb-shaped electrode 130a and six of which belong to the comb-tooth electrode 130b. The fourth IDT 140 includes seven electrode fingers 101, three of which belong to the comb-shaped electrode 140a and four of which belong to the comb-tooth electrode 140b. The fifth IDT 150 includes thirteen electrode fingers 101, six of which belong to the comb-shaped electrode 150a and seven of which belong to the comb-tooth electrode 150b.

[0022] In some embodiments, within an IDT region including a central IDT and an IDT located between the central IDT and the reflectors 160 and 170, there is a difference in the total number of electrode fingers in each corresponding IDT within the region. Figure 1 In the illustrated embodiment, in a specific region consisting of the first IDT 110, the second IDT 120, and the third IDT 130 (i.e., the central IDT), the total number of electrode fingers 101 on each of the IDTs 110, 120, and 130 is different. That is, the total number of electrode fingers 101 in the first IDT 110 is different from the total number of electrode fingers 101 in the second IDT 120 (i.e., 13 and 7, respectively), and the total number of finger elements 101 in the second electrode fingers 120 and the third IDT 130 (i.e., 11) are different. Similarly, in another region consisting of the third IDT 130 (i.e., the central IDT), the fourth IDT 140, and the fifth IDT 150, the total number of electrode fingers 101 on each of the IDTs 130, 140, and 150 is different.

[0023] In some embodiments, each IDT includes at least a resonant component and a modulating component. In a set of N IDTs located between a pair of reflectors 160 and 170, the first and Nth IDTs each include a resonant component adjacent to the reflector (160 or 170) and a modulating component adjacent to an adjacent IDT. In contrast, the second to (N-1)th IDTs each include two modulating components and a resonant component located between the two modulating components. For example, in Figure 1In the illustrated embodiment, the first IDT 110 includes a resonant element 111 positioned adjacent to the first reflector 160 and a modulation element 112 positioned adjacent to the second IDT 120. The second IDT 120 includes a resonant element 121 positioned between two modulation elements 122. Similarly, the third IDT 130 includes a resonant element 131 positioned between two modulation elements 132, and the fourth IDT 140 includes a resonant element 141 positioned between the two modulation elements 142. Finally, the fifth IDT 150 includes a modulation element 152 positioned adjacent to the fourth IDT 140 and a resonant element 151 positioned adjacent to the second reflector 170.

[0024] In some embodiments, within each IDT, the width of each electrode finger 101 in the resonant component measured in the lateral direction is greater than the width of each electrode finger 102 in the modulating component measured in the lateral direction. The width of each electrode finger in the resonant component is 1.05 to 1.15 times the width of each electrode finger in the modulating component. Figure 1 In the illustrated embodiment (not drawn to scale), in the first IDT 110, the width X1 of each electrode finger 101 in the resonant component 111 is greater than the width X2 of each electrode finger 101 in the modulating component 112. In addition, for example, in the third IDT 130, the width X3 of each electrode finger 101 in the resonant component 131 is greater than the width X4 of each electrode finger 101 in the modulating component 132.

[0025] In some embodiments, within each IDT, the number of electrode fingers in the resonant component is greater than the number of electrode fingers in the modulating component. Figure 1 In the illustrated embodiment, in the first IDT 110, the resonant component 111 includes a greater number of electrode fingers (i.e., 9) than the modulating component 112, which has 4 electrode fingers 101. Similarly, in the second IDT 120, the resonant component 121 includes a greater number of electrode fingers 101 (i.e., 3) than the modulating component 122, each of which has only 2 electrode fingers.

[0026] In some embodiments, in an IDT region including a central IDT and an IDT located between the central IDT and one of the reflectors, the width of each electrode finger in a resonant component of the IDT is different from the width of each electrode finger in a resonant component of another IDT in the region. Figure 1In the illustrated embodiment (not drawn to scale), in a specific region consisting of the first IDT 110, the second IDT 120, and the third IDT 130 (i.e., the central IDT), the width of each electrode finger 101 in the resonance part 111 of the first IDT 110 is different from the width of each electrode finger 101 in the resonance part 121 of the second IDT 12, which in turn is different from the width of each electrode finger 101 in the resonance part 131 of the third IDT 130. Similarly, in another region consisting of the third IDT 130 (i.e., the central IDT), the fourth IDT 140, and the fifth IDT 150, the width of each electrode finger 101 in the resonance part 131 of the third IDT 130 is different from the width of each electrode finger 101 in the resonance part 141 of the fourth IDT 140, which in turn is different from the width of each electrode finger 101 in the resonance part 151 of the fifth IDT 150.

[0027] In some embodiments, in an IDT region including a central IDT and an IDT located between the central IDT and one of the reflectors, the number of electrode fingers in a resonant component of an IDT is different from the number of electrode fingers in a resonant component of another IDT in the region. Figure 1 In the illustrated embodiment, in a specific region consisting of the first IDT 110, the second IDT 120, and the third IDT 130 (i.e., the center IDT), the number of electrode fingers 101 in the resonance part 111 of the first IDT 110 is different from the number of electrode fingers 101 in the resonance part 121 of the second IDT 120 (i.e., 9 and 3, respectively), which in turn is different from the number of finger elements 101 in the resonance part 131 of the third IDT 230 (i.e., 5). Similarly, in another region consisting of the third IDT 130 (i.e., the center IDT), the fourth IDT 140, and the fifth IDT 150, the number of electrode fingers 101 in the resonance part 131 of the third IDT 130 is different from the number of finger elements 101 in the resonance part 141 of the fourth IDT 140 (i.e., 5 and 3, respectively), which in turn is different from the number of electrode fingers 101 in the resonance part 151 of the fifth IDT 150 (i.e., 9).

[0028] In some embodiments, each of the reflectors 160 and 170 includes a plurality of reflector electrode fingers 102. The width of each reflector electrode finger 102 is greater than the width of each electrode finger in the IDT resonant component. Figure 1 In the illustrated embodiment (not to scale), the width X5 of each reflector electrode finger 102 in the first reflector 160 is greater than the width of each electrode finger 101 in the resonant elements 111 , 121 , 131 , 141 and 151 of the corresponding IDTs 110 , 120 , 130 , 140 and 150 .

[0029] The dual-mode SAW filter of the embodiment of the present application effectively enhances out-of-band suppression by configuring the parameters of the above-mentioned IDT electrode. Therefore, the dual-mode SAW filter of the embodiment of the present disclosure can be used as a superior substitute for filter devices in duplexers and communication devices.

[0030] Figure 2 2 is a table 200 summarizing the parameters of the first dual-mode SAW filter included in the first Band66 receiving filter according to an embodiment of the present disclosure. Figure 1 Similar to the dual-mode SAW filter 100 shown in FIG. 1 , the first dual-mode SAW filter summarized in Table 200 includes a first reflector, a second reflector, and first to fifth IDTs located between the first reflector and the second reflector. Table 200 lists the number of reflector electrode fingers in the first reflector and the second reflector, and the number of electrode fingers in the modulation component and the resonant component of each of the first to fifth IDTs. Table 200 also lists the total number of electrode fingers in each of the first to fifth IDTs. For example, Figure 2 As shown, in the first IDT, the resonant component includes 52 electrode fingers, the modulation component includes 6 electrode fingers, and thus the total number of electrode fingers in the first IDT is 58. Similarly, in the second IDT, the resonant component includes 20 electrode fingers, each modulation component includes 4 electrode fingers, and thus the total number of fingers in the second IDT is 28. As can be seen from Table 200, the total number of electrode fingers in each of the first to fifth IDTs is an even number.

[0031] Figure 3 Yes Figure 2 The simulated frequency response diagram of the first Band66 receive filter of the first dual-mode SAW filter. It can be seen that in Band3 (1710 MHz to 1785 MHz) of the low-frequency side stopband, the suppression level of the first Band66 receive filter is -37.8 dB. In Band1 (1920 MHz to 1980 MHz) of the low-frequency side stopband, the suppression level of the first Band66 receive filter is -40 dB.

[0032] Figure 4 4 is a parameter table 400 summarizing the second dual-mode SAW filter included in the second Band66 receiving filter according to an embodiment of the present application. Figure 1 Similar to the dual-mode SAW filter 100 shown in FIG. 1 , the second dual-mode SAW filter summarized in Table 400 includes a first reflector, a second reflector, and first to fifth IDTs located between the first reflector and the second reflector. Table 400 also lists the total number of electrode fingers in each of the first to fifth IDTs. For example, Figure 4As shown, in the first IDT of the second dual-mode SAW filter, the resonant component includes 53 electrode fingers, the modulation component includes 6 electrode fingers, and the total number of fingers in the first IDT is 59. Similarly, in the second IDT of the second dual-mode SAW filter, the resonant component includes 19 electrode fingers, each modulation component includes 4 electrode fingers, and the total number of electrode fingers in the second IDT is 27. It can be seen from Table 400 that the total number of electrode fingers in each of the first to fifth IDTs is an odd number.

[0033] Figure 5 is a simulated frequency response diagram of the second Band66 filter including the second dual-mode SAW filter of the embodiment of the present disclosure. It can be seen that in Band3 (1710 MHz to 1785 MHz) of the low-frequency side stopband, the suppression level of the second Band66 receive filter is -42 dB. In Band1 (1920 MHz to 1980 MHz) of the low-frequency side stopband, the suppression level of the second Band66 receive filter is -45 dB. Therefore, for the stopband suppression on the low-frequency side, the second Band66 receive filter including the second dual-mode SAW filter having an odd number of fingers in each IDT is superior to the first Band66 receive filter including the first dual-mode SAW filter having an even number of fingers in each IDTs.

[0034] An embodiment of the present disclosure also provides a hybrid receiving filter using the dual-mode SAW filter.

[0035] Figure 6 FIG. 6 shows a hybrid receiving filter 600 according to an embodiment of the present disclosure. Figure 6 As shown, the hybrid filter 600 includes series resonators RX_S1 and RX_S2, parallel resonators RX_P1 and RX_P2, and a dual-mode SAW filter, and the dual-mode SAW filter can be the above-mentioned dual-mode SAW filter. Resonator RX_S1, the dual-mode SAW filter and the resonator RX_S2 are connected in series between the receiving terminal RX and the antenna terminal ANT. Resonator RX_P1 is connected between the port of resonator RX_S1 and the ground. Resonator RX_P2 is connected between the port of resonator RX_S2 and the ground. In the hybrid receiving filter 600, resonators RX_S1, RX_S2, RX_P1 and RX_P2 can be formed by single-port resonators.

[0036] Figure 6 The hybrid receiving filter 600 is shown as an example, but the present disclosure is not limited thereto. Figure 6Two series resonators RX_S1 and RX_S2 and two parallel resonators RX_P1 and RX_P2 are shown, but other numbers of series resonators or parallel resonators can be used depending on the required circuit parameters. The hybrid receive filter according to the embodiment of the present disclosure may have different circuit structures or include different circuit components as long as it includes at least one of the above-mentioned dual-mode SAW filters.

[0037] An embodiment of the present disclosure also provides a duplexer using the dual-mode SAW filter.

[0038] Figure 7 FIG. 7 shows a duplexer 700 according to an embodiment of the present disclosure. Figure 7 As shown, the duplexer 700 includes a reception filter 710 connected between a reception terminal Rx and an antenna terminal ANT, and a transmission filter 720 connected between a transmission terminal Tx and an antenna terminal ANT.

[0039] The receiving filter 710 includes series resonators RX_S1 and RX_S2, parallel resonators RX_P1 and RX_P2, and a dual-mode SAW filter, which can be the above-mentioned dual-mode SAW filter. Resonator RX_S1, the dual-mode SAW filter, and resonator RX_S2 are connected in series between the receiving terminal RX and the antenna terminal ANT. Resonator RX_P1 is connected between the port of resonator RX_S1 and the ground. Resonator RX_P2 is connected between the port of resonator RX_S2 and the ground.

[0040] The transmit filter 720 includes series resonators TX_S1, TX_S2, TX_S3, TX_S4, and TX_S5, and parallel resonators TX_P1, TX_P2, TX_P3, and TX_P4. Resonators TX_S1, TX_S2, TX_S3, TX_S4, and TX_S5 are connected in series between the transmission terminal TX and the antenna terminal ANT. Resonators TX_P1 and TX_P2 are connected between the ports of resonators TX_S1 and TX_S2 and the ground respectively through inductors L1. Resonators TX_P3 and TX_P4 are connected between the ports of resonators TX_S3 and TX_S4 and the ground respectively through inductors L2. Inductors L1 and L2 are generated by bonding wires between the ground patterns of the bare die and the package or by inductors integrated in the package.

[0041] In the duplexer 700 , resonators such as RX_S1 , RX_S2 , etc. may be formed of a single-port resonator.

[0042] Figure 7 The duplexer 700 is shown as an example, but the present disclosure is not limited thereto. Figure 7A certain number of series resonators and parallel resonators are shown, but other numbers of series resonators or parallel resonators can be used depending on the required circuit parameters. The duplexer according to the embodiment of the present disclosure can have different circuit structures or include different circuit components as long as it includes at least one of the above-mentioned dual-mode SAW filters.

[0043] According to the embodiments of the present disclosure, the dual-mode SAW filter can effectively improve the stopband suppression level and suppress interference signals in adjacent frequency bands. This is achieved by reasonably configuring the parameters of the IDT interdigital electrodes. Therefore, the dual-mode SAW filter according to the embodiments of the present disclosure can be used for filters of duplexers or communication equipment. Because it can suppress interference signals and improve the overall performance of the equipment, it is the first choice for communication equipment.

[0044] It should be understood that certain features of the specification described in the context of separate embodiments for the sake of clarity may also be provided in combination in a single embodiment. Conversely, various features of the specification described in the context of a single embodiment for the sake of brevity may also be provided separately, or in any suitable sub-combination, or as appropriate in any other described embodiment of the disclosure. Unless otherwise noted, certain features described in the context of various embodiments may not be essential features of those embodiments.

[0045] It should be understood that although the terms "first" and "second" are used herein to describe various elements, these elements should not be limited by these terms, and these terms are only used to distinguish these elements. For example, without departing from the spirit and scope of the present disclosure, the first element may also be referred to as the second element, and similarly, the second element may also be referred to as the first element.

[0046] Other embodiments of the present application will be apparent to those skilled in the art by consideration of the specification and practice of the present application disclosed herein. It is intended that the specification and examples be considered exemplary only, with the true scope and spirit of the present application being indicated by the following claims.

[0047] In addition, although exemplary embodiments are described herein, those skilled in the art will appreciate the scope of any and all embodiments with equivalent elements, modifications, omissions, combinations (e.g., across aspects of the various embodiments), adaptations, and / or changes based on this disclosure. The limitations in the claims are to be interpreted broadly according to the language used in the claims and are not limited to the examples described in this specification or during the prosecution of the application. These examples should be interpreted as non-exclusive. In addition, the steps of the disclosed methods may be modified in any way, including by reordering steps and / or inserting or deleting steps. Therefore, this specification and examples are to be regarded as illustrative only, with the true scope and spirit being indicated by the following claims and their full scope of equivalents.

Claims

1. A dual-mode SAW filter, characterized in that: include: Piezoelectric substrate; a pair of reflectors disposed on the piezoelectric substrate; and N input and output IDTs, which are arranged on a piezoelectric substrate and between a pair of reflectors and are arranged alternately in the lateral direction, each IDT includes a pair of comb electrodes with multiple electrode fingers, adjacent electrode fingers point in opposite directions, and the total number of electrode fingers in each IDT is an odd number greater than or equal to 3.

2. The dual-mode SAW filter according to claim 1, wherein: N is an odd number greater than or equal to 5.

3. The dual-mode SAW filter according to claim 2, wherein: Among the N IDTs, the Xth IDT and the (N+1-X)th IDT have a mirror symmetric relationship with respect to the central IDT, where X is an integer greater than or equal to 1 and less than or equal to N, and the central IDT is the (N+1) / 2th IDT.

4. The dual-mode SAW filter according to any one of claims 1 to 3, wherein: In a region including a central IDT and an IDT disposed between the central IDT and one of the reflectors, a total number of electrode fingers in the IDT is different from a total number of electrode fingers in another IDT in the region.

5. The dual-mode SAW filter according to any one of claims 1 to 3, wherein: Each IDT includes at least a resonant component and a modulating component.

6. The dual-mode SAW filter according to claim 5, wherein: In each IDT, the width of each electrode finger in the resonant component measured in the lateral direction is greater than the width of each electrode finger in the modulation component measured in the lateral direction.

7. The dual-mode SAW filter according to claim 5, wherein: In each IDT, the width of each electrode finger in the resonance part is 1.05 to 1.15 times the width of each electrode finger in the modulation part.

8. The dual-mode SAW filter according to claim 5, wherein: In each IDT, the number of electrode fingers in the resonance component is greater than the number of electrode fingers in the modulation component.

9. The dual-mode SAW filter according to claim 5, wherein: In a region including a central IDT and an IDT between the central IDT and one of the reflectors, a width of each electrode finger in a resonance section of the IDT is different from a width of each electrode finger in a resonance section of another IDT in the region.

10. The dual-mode SAW filter according to claim 5, wherein: In a region including a central IDT and an IDT between the central IDT and one of the reflectors, the number of electrode fingers in a resonant portion of the IDT is different from the number of electrode fingers in a resonant portion of another IDT in the region.

11. The dual-mode SAW filter according to claim 5, wherein: Each of the reflectors includes a plurality of reflector electrode fingers, and a width of each of the reflector electrode fingers is greater than a width of each of the electrode fingers in a resonant component of at least one IDT disposed between the reflectors.

12. The dual-mode SAW filter according to claim 5, wherein: Each of the first IDT and the Nth IDT includes a resonant component disposed adjacent to one of the reflectors and a modulation component disposed adjacent to an adjacent IDT.

13. The dual-mode SAW filter according to claim 5, wherein: Each of the second to (N-1)th IDTs includes two modulation components and a resonance component between the two modulation components.

14. A receiving filter, characterized in that: include: A dual-mode surface acoustic wave (SAW) filter according to any one of claims 1 to 13.

15. A duplexer, characterized in that: include: Transmit filter; as well as A receiving filter, wherein the receiving filter comprises the dual-mode surface acoustic wave (SAW) filter according to any one of claims 1 to 13.

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