Duplexer and communication device

Abstract

The invention relates to the technical field of filters, and discloses a duplexer and a communication device.The duplexer comprises a sending filter and a receiving filter, and at least one of the sending filter and the receiving filter comprises a coupling resonant filter, at least one first impedance element filter and a functional unit, the coupling resonant filter comprises a plurality of first resonators arranged along a first direction; the at least one first impedance element filter is arranged on at least one side of the coupled resonant filter in the second direction, and a blank area exists on at least one side of the coupled resonant filter in the first direction; the functional unit is located in the blank area, and the functional unit is electrically connected with at least one of the coupling resonance filter and the first impedance element filter. According to the invention, by arranging the function unit, the available area on the layout can be fully utilized, the influence caused by mutual coupling of sound wave energy between the coupling resonant filter and the function unit which are arranged side by side can be avoided, and the out-of-band rejection and the isolation degree can be improved.

Description

Technical Field

[0001] This invention relates to the field of filter technology, and more specifically to a duplexer and communication device. Background Technology

[0002] As mobile communication technology evolves from 4G to 5G and even higher levels in the future, the number of frequency bands that smart terminals need to support has increased dramatically. Surface Acoustic Wave (SAW) filters, as core frequency selection devices in radio frequency front-end modules, play a role in efficiently filtering out interference and retaining useful signals in complex electromagnetic environments. Their performance directly determines the sensitivity, anti-interference capability, and overall efficiency of the communication system.

[0003] To maintain high filter performance while achieving miniaturization, the filter structure in a duplexer typically places an impedance element filter (IEF) alongside the coupled resonator filter (CRF), meaning the CRF and IEF structures are arranged side-by-side. However, this side-by-side arrangement causes the bulk acoustic energy of the CRF and IEF structures to interfere with each other. Undesirable spurious modes and higher-order modes may appear in the near-band out-of-band of the filter, deteriorating out-of-band rejection. In the duplexer's filter structure, this not only worsens near-band out-of-band rejection but also degrades isolation. Summary of the Invention

[0004] This invention provides a duplexer and communication device to solve the problems of near-end out-of-band suppression degradation and isolation degradation caused by the side-by-side arrangement of CRF and IEF structures.

[0005] In a first aspect, the present invention provides a duplexer, which includes a transmitting filter and a receiving filter. At least one of the transmitting filter and the receiving filter includes: a coupled resonant filter, at least one first impedance element filter, and a functional unit. The coupled resonant filter includes a plurality of first resonators arranged along a first direction. The at least one first impedance element filter is disposed on at least one side of the coupled resonant filter in a second direction, and a blank area exists on at least one side of the coupled resonant filter in the first direction. The functional unit is located in the blank area, and the functional unit is electrically connected to at least one of the coupled resonant filter and the first impedance element filter.

[0006] The duplexer provided by this invention, by setting functional units in blank areas, can make full use of the available area on the layout while avoiding the influence of the mutual coupling of acoustic energy between the CRF structure and functional units when the CRF structure and functional units are set side by side. This improves the near-end out-of-band suppression effect and isolation, and maintains the working performance of the duplexer.

[0007] In one optional implementation, the functional unit includes an interdigitated capacitor structure, which includes two busbars and a plurality of electrode fingers arranged alternately between the two busbars; wherein the arrangement direction of the electrode fingers of the interdigitated capacitor structure intersects with the arrangement direction of the electrode fingers of the first resonator, and the difference between the effective capacitance value of the interdigitated capacitor structure and the effective capacitance value of the target resonator is less than or equal to a preset difference.

[0008] In this embodiment, since the aperture direction of the interdigitated capacitor structure placed side by side intersects (e.g., perpendicular) with the aperture direction of the coupled resonant filter, and the propagation direction of the acoustic wave energy excited on the piezoelectric material by the electrical signal on the electrode fingers also intersects (e.g., mutually orthogonal), the interference effect between the acoustic waves in the two intersecting directions is weakened relative to the parallel direction (the superposition effect is weakened). Therefore, the influence of the mutual coupling of acoustic wave energy between the coupled resonant filter and the functional unit can be reduced.

[0009] In one alternative implementation, the preset difference is less than or equal to 30% of the effective capacitance value of the target resonator.

[0010] In one alternative implementation, the effective capacitance value of the interdigitated capacitor structure is determined by the following formula:

[0011] In the formula, This indicates the effective capacitance value of the interdigital capacitor structure. The number of electrodes in an interdigital capacitor structure. This indicates the aperture size of the interdigital capacitor structure. , This indicates the duty cycle of the metal.

[0012] In one optional embodiment, the interdigitated capacitor structure further includes multiple dummy fingers, with the multiple dummy fingers connected to the same busbar alternating with multiple electrode fingers; and / or, at least one electrode finger includes multiple sub-electrode fingers arranged in parallel; and / or, the interdigitated capacitor structure includes two interdigitated units, and the two interdigitated units are symmetrically distributed about the central axis of the interdigitated capacitor structure in a second direction; and / or, in the interdigitated capacitor structure, an electrode finger connected to one busbar forms a gap with another busbar, and the gap is arranged in a preset manner.

[0013] In one optional implementation, the functional unit includes a second impedance element filter with the same electrode finger arrangement direction as the coupled resonant filter. The second impedance element filter includes a second resonator and a third resonator that share a common busbar. The electrode fingers of the second resonator and the third resonator are distributed in a preset manner to reduce the coupling effect between the sound waves excited in the functional unit and the sound waves in the coupled resonant filter.

[0014] In one optional implementation, the second resonator and the third resonator have the same preset structural parameters, and the sound wave excited by the second resonator and the sound wave excited by the third resonator have a 180° phase difference.

[0015] In one alternative implementation, the electrode fingers in the second and third resonators are staggered by an odd multiple of the finger spacing.

[0016] In this embodiment, the two resonators are staggered by an odd multiple of the half-cycle wavelength (Pt) along the current entry direction, resulting in a 180° phase difference between the surface acoustic waves excited by the resonators and the acoustic energy transmission direction perpendicular to the electrode fingers. That is, the surface acoustic waves of the two resonators are equal in amplitude and out of phase. The peaks and troughs of the two surface acoustic waves meet at different times. According to the interference principle (the principle of vector superposition), the two acoustic wave energies cancel each other out in the aperture propagation direction, thereby reducing the influence of surface acoustic wave coupling between the CRF structure and functional units.

[0017] In one alternative implementation, in the first direction: the electrodes of the second resonator and the third resonator with the same electrical polarity are aligned; or, the electrodes of the second resonator and the third resonator with different electrical polarities are aligned.

[0018] In a second aspect, the present invention provides a communication device including a duplexer of the first aspect or any corresponding embodiment thereof. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of a B28 duplexer according to an embodiment of the present invention; Figure 2 This is a schematic diagram of another B28 duplexer according to an embodiment of the present invention; Figure 3 yes Figure 1 A schematic diagram of the isolation curve corresponding to the structure shown; Figure 4 yes Figure 2 A schematic diagram of the isolation curve corresponding to the structure shown; Figure 5 This is a schematic diagram of a duplexer according to an embodiment of the present invention; Figure 6This is a schematic diagram of the structure of another B28 duplexer according to an embodiment of the present invention; Figure 7 This is a schematic diagram of a duplexer structure in which an interdigitated capacitor structure is placed in the blank area according to an embodiment of the present invention. Figure 8 yes Figure 6 The structure shown and Figure 7 A comparative diagram of the isolation curves corresponding to the structures shown; Figure 9 This is a schematic diagram of the first type of interdigitated capacitor structure according to an embodiment of the present invention; Figure 10 This is a schematic diagram of the second type of interdigitated capacitor structure according to an embodiment of the present invention; Figure 11 This is a schematic diagram of the third type of interdigitated capacitor structure according to an embodiment of the present invention; Figure 12 This is a schematic diagram of the fourth type of interdigitated capacitor structure according to an embodiment of the present invention; Figure 13 This is a schematic diagram of the fifth type of interdigitated capacitor structure according to an embodiment of the present invention; Figure 14 This is a schematic diagram of the structure of a second impedance element filter according to an embodiment of the present invention; Figure 15 This is a schematic diagram of the structure of a target resonator according to an embodiment of the present invention; Figure 16 This is a schematic diagram of the structure of another second impedance element filter according to an embodiment of the present invention.

[0021] Figure label: 01. CRF structure; 02. Impedance element filter; 03. IEF structure; 101. Blank area; 110. Transmitting filter; 120. Receiving filter; 121. Coupled resonant filter; 1211. First resonator; 122. First impedance element filter; 123. Functional unit; 123a. Interdigitated capacitor structure; 123b. Second impedance element filter; 1231. Second resonator; 1232. Third resonator; 21. First busbar; 22. Second busbar; 23. Electrode finger; 231. Sub-electrode finger; 24. Pseudo-finger; 25. First interdigitated unit; 26. Second interdigitated unit; 27. Center busbar. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0023] In the following description, descriptions of well-known structures and techniques are omitted to avoid unnecessarily obscuring the concepts of the present invention. Various structural schematic diagrams according to embodiments of the present invention are shown in the accompanying drawings. These drawings are not to scale, and some details are enlarged for clarity, and some details may be omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed. In the context of the present invention, when a layer / element is referred to as being "on" another layer / element, the layer / element may be directly on the other layer / element, or there may be an intermediate layer / element between them. Additionally, if a layer / element is "on" another layer / element in one orientation, then when the orientation is reversed, the layer / element may be "below" the other layer / element.

[0024] A duplexer is used to enable bidirectional communication on the same frequency, allowing the transmitting (TX) and receiving (RX) devices in a communication system to share the same frequency at the same time without interfering with each other.

[0025] To adapt to the development of communication systems, the design goals of SAW filters in devices such as duplexers are becoming increasingly stringent, mainly evolving in three directions: high power, small size, and high rectangularity. High power is to meet the requirements of transmit links with larger bandwidth and higher output power; small size is to cope with the extremely limited layout space inside mobile communication terminals and the challenge of the exponential increase in the number of filters brought about by multiple frequency bands; high rectangularity pursues a frequency response that is closer to an ideal rectangle, thereby ensuring a wide passband while obtaining a steep roll-off adjacent to the passband and extremely high out-of-band rejection to cope with increasingly dense frequency band distribution.

[0026] Among methods for miniaturizing filters, the coupled resonant filter (CRF) structure exhibits significant advantages. By combining different resonant modes, the CRF structure can achieve a wide operating bandwidth, low insertion loss, and good out-of-band rejection, while maintaining a small overall filter size. The core of the CRF structure is the interconnection of multiple resonators through a coupling structure, thereby achieving frequency selection and filtering functions within a specific frequency band.

[0027] Compared to traditional trapezoidal structures based on multiple independent resonators connected by circuitry, CRF structures achieve filtering characteristics through acoustic coupling between resonators. This coupling mechanism allows CRF structures to naturally generate transmission zeros on both sides of the passband without the need for additional resonators. This characteristic brings two major benefits: first, CRF structures can achieve extremely high out-of-band rejection with fewer structural units, effectively suppressing interference from adjacent channels; second, while achieving equal or even better filtering performance, CRF structures occupy a significantly smaller chip area compared to traditional trapezoidal or lattice-type filter structures.

[0028] Therefore, the CRF structure has become a key technology for achieving high performance and miniaturization in the design of current SAW filters, especially in the design of receiver filters with stringent requirements for size and out-of-band suppression.

[0029] Figure 1 A schematic diagram of a B28 duplexer in related technology is provided. The B28 duplexer includes a receive (RX) filter and a transmit (TX) filter. The receive (RX) filter adopts a hybrid structure of a coupled resonant filter (CRF) structure 01 and an impedance element filter (IEF) structure 02. The TX filter can adopt a pure IEF structure (not shown in the figure). The B28 duplexer is an RF duplexer adapted to the B28 frequency band (700MHz band).

[0030] like Figure 1 As shown, the introduction of the CRF structure in the B28 duplexer brings excellent out-of-band performance, but it also limits the flexibility in the selection of layout and topology, resulting in wasted area on both sides of the CRF structure 01 perpendicular to the resonator aperture direction (i.e., the first direction X).

[0031] When it is necessary to further reduce the area of ​​the filter structure to lower costs, in order to maintain the high performance of the filter, it is necessary to make full use of the available space (blank areas) in the layout design. Therefore, such as Figure 2 As shown, IEF structure 03 is also placed on one side of CRF structure 01 along the first direction X.

[0032] However, in practice, it was found that the above arrangement caused the bulk acoustic wave energy between the CRF structure 01 and the IEF structure 03 arranged along the first direction X to affect each other. Some unwanted spurious modes and higher-order modes appeared in the near-end out-of-band of the filter, causing deterioration of out-of-band suppression. In the duplexer, it not only caused deterioration of near-end out-of-band suppression, but also deterioration of isolation. Moreover, this effect could not be weakened by adding a blocking structure (e.g., a metal block) between the side-by-side IEF structure 03 and CRF structure 01 to block the propagation of surface acoustic waves.

[0033] Specifically, when there are no other resonators or filters placed side-by-side in CRF structure 01, the isolation (ISO) curve from the duplexer TX module to the RX module is as follows: Figure 3 As shown; when there are IEF structures 03 placed side by side in CRF structure 01, the isolation (ISO) curve from the duplexer TX module to the RX module is as follows. Figure 4 As shown, comparison Figure 3 and Figure 4 It can be seen that after the presence of the IEF structure 03 placed side by side in the CRF structure 01, the number of out-of-band suppression anomaly peaks increases, and the amplitude also increases, indicating a deterioration in near-band out-of-band suppression and isolation. Figure 3 and Figure 4 The horizontal axis represents frequency (freq), in MHz, and the vertical axis (dB) (S(2,3)) represents the transmission coefficient (characterizing isolation) from the TX port to the RX port of the duplexer, in decibels (dB). Figure 3 and Figure 4 The horizontal line on the left corresponds to the transmission frequency band (703MHz-748MHz), and the horizontal line on the right corresponds to the reception frequency band (758MHz-803MHz).

[0034] In view of this, the present invention provides a duplexer and a communication device. In the blank area of ​​the CRF structure along the first direction X, the original IEF structure is replaced by a functional unit. This can make full use of the available area on the layout, and at the same time avoid the effects caused by the mutual coupling of acoustic wave energy between the CRF structure and the functional unit when the CRF structure and the functional unit are arranged side by side, such as out-of-band suppression and deterioration of duplexer isolation performance caused by coupling, thus maintaining the working performance of the duplexer.

[0035] The duplexer provided by the present invention will now be described in detail with reference to the accompanying drawings.

[0036] like Figure 5 As shown, the duplexer includes a transmitting filter 110 and a receiving filter 120. At least one of the transmitting filter 110 and the receiving filter 120 includes a coupled resonant filter 121, at least one first impedance element filter 122, and a functional unit 123.

[0037] It should be noted that, Figure 5 Taking the receiving filter 120, which includes a coupled resonant filter 121, two first impedance element filters 122, and a functional unit 123, as an example, the specific structure of the transmitting filter 110 is not illustrated. It can adopt a structural layout similar to or different from that of the receiving filter 120. For example, the transmitting filter 110 can include a coupled resonant filter, at least one first impedance element filter, and a functional unit, or it can adopt a pure IEF structure. When the transmitting filter 110 includes a functional unit, the receiving filter can also be composed of a pure IEF structure.

[0038] The coupled resonant filter 121 includes a plurality of first resonators 1211 disposed along a first direction X. The first direction X is perpendicular to the extension direction of the electrode fingers of the first resonators 1211. The extension direction of the electrode fingers of the first resonators 1211 is also the aperture direction of the first resonators 1211, and the aperture direction is parallel to the direction of the first resonator 1211. Figure 5 The second direction Y. At least one first impedance element filter 122 is disposed on at least one side of the coupled resonant filter 121 in the second direction Y. The coupled resonant filter 121 has a blank area 101 on at least one side in the first direction X. The blank area may be formed by the coupled resonant filter 121 and the first impedance element filter 122 on at least one side and / or a metal connection structure for electrical connection between different filters (or a connection port for connection between the duplexer and external circuits or signals).

[0039] Functional unit 123 is located in blank region 101. Functional unit 123 is electrically connected to at least one of coupled resonant filter 121 and first impedance element filter 122. Functional unit 123 is used to replace, for example, Figure 6 The IEF structure 03 shown is located in the blank area, and the electrode extension direction is the same as the electrode extension direction of the coupled resonant filter. The functional unit 123 can suppress (reduce) the coupling effect between the surface acoustic wave (hereinafter referred to as acoustic wave) excited by itself and the acoustic wave excited by the coupled resonant filter 121.

[0040] The coupling effect between surface acoustic waves (SAWs) is a phenomenon in which energy is transferred and interacts between multiple SAWs. Simply put, the coupling effect is a new energy distribution formed by the superposition and interference of the energies of multiple SAWs. Specifically, in this embodiment, functional unit 123 can reduce the coupling effect by changing the direction of SAW energy transmission and reducing the vector superposition of sound wave energy.

[0041] The present invention does not specifically limit the structure of the functional unit 123, as long as it can be placed in the blank area 101 and can suppress the influence of the coupling effect between sound waves. For example, Figure 7 As shown, functional unit 123 may include interdigitated capacitor structure 123a; for example, such as Figure 14 As shown, the functional unit 123 can be a second impedance element filter 123b that includes two resonators with a common busbar, and the arrangement direction of the electrode fingers in its resonators (first direction X) is the same as the arrangement direction of the electrode fingers in the coupled resonant filter.

[0042] In some embodiments, such as Figure 7As shown, functional unit 123 includes an interdigitated capacitor structure 123a. The interdigitated capacitor structure 123a includes two busbars (a first busbar and a second busbar) and multiple electrode fingers alternately arranged between the two busbars. The arrangement direction of the electrode fingers of the interdigitated capacitor structure 123a intersects (e.g., perpendicularly intersects) the arrangement direction of the electrode fingers of the first resonator 1211 (the second direction Y), that is, the extension direction of the electrode fingers of the interdigitated capacitor structure 123a is parallel to the first direction X. The difference between the effective capacitance value of the interdigitated capacitor structure 123a and the effective capacitance value of the target resonator is less than or equal to a preset difference. The target resonator is as follows: Figure 6 In the relevant scheme shown, the IEF structure 03, which is in the blank area, has the same area occupied by the target resonator as the interdigital capacitor structure 123a. The occupied area refers to the area of ​​the blank area it occupies.

[0043] Furthermore, the angle formed between the arrangement direction of the electrode fingers of the interdigital capacitor structure 123a and the arrangement direction of the electrode fingers of the first resonator 1211 is in the range of 30° to 90°, for example, it can be 30°, 45°, 60° or 90°. When this angle meets the above range, the interference effect of the acoustic waves in the interdigital capacitor structure 123a on the coupled resonant filter 121 can be reduced. However, when the angle is too small, for example, less than 30°, the reduction effect of the interference effect is limited, and it may still affect the performance of the duplexer.

[0044] When determining the effective capacitance value of the interdigital capacitor structure 123a, the effective capacitance value of the target resonator is first determined as the initial capacitance value of the interdigital capacitor structure 123a. Then, the initial capacitance value is adjusted to optimize the small-signal electrical performance (such as insertion loss) of the filter to a certain extent, so that the electrical performance of the duplexer replaced with the interdigital capacitor structure 123a is consistent with the electrical performance of the duplexer before replacement.

[0045] The effective capacitance value of the target resonator is preset to be less than or equal to 30%, that is, the effective capacitance value of the interdigitated capacitor structure 123a is obtained by adjusting the effective capacitance value of the target resonator within ±30%, so as to ensure that the interdigitated capacitor structure 123a will not affect the electrical performance of the duplexer after replacing the IEF structure 03 located in the blank area.

[0046] It should be understood that there may be an error between the calculated effective capacitance value of the target resonator and the actual capacitance value. Therefore, the initial capacitance value of the interdigital capacitor structure 123a is determined based on the effective capacitance value of the target resonator and the error amount. The initial capacitance value of the interdigital capacitor structure 123a is the calculated effective capacitance value of the target resonator ± the error amount (e.g., 0.2pF).

[0047] For example, when the arrangement direction of the electrode fingers of the interdigital capacitor structure 123a is perpendicular to the arrangement direction of the electrode fingers of the coupled resonant filter 121, the effective capacitance value of the interdigital capacitor structure 123a can be calculated by the following formula (1):

[0048] In the formula, This indicates the effective capacitance value of the interdigital capacitor structure 123a. This indicates the electrode index quantity of the interdigital capacitor structure 123a. This indicates the aperture of the interdigital capacitor structure 123a. , Indicates the duty cycle of the metal. , Indicates the width of the electrode fingers. This represents the half-cycle wavelength of the interdigital capacitor structure 123a (please refer to [reference needed]). Figure 9 ).

[0049] In this embodiment, since the aperture direction of the interdigital capacitor structure 123a placed side by side intersects (e.g., perpendicularly intersects) the aperture direction of the coupled resonant filter 121, and the propagation direction of the acoustic wave energy excited on the piezoelectric material by the electrical signal on the electrode fingers of the interdigital capacitor structure 123a also intersects (e.g., mutually orthogonal), the interference effect between the acoustic waves in the two intersecting directions is weakened (the superposition effect is weakened), thus reducing the influence of the mutual coupling of acoustic wave energy between the coupled resonant filter 121 and the interdigital capacitor structure 123a.

[0050] Specifically, Figure 8 The middle dashed line indicates Figure 6 The near-end suppression S-parameters of the structure shown are tested in the receiving band. Figure 8 The solid line represents the out-of-band rejection S-parameter after replacing the IEF structure 03 in the blank area with an interdigitated capacitor structure. Figure 8 It is quite obvious from the text that... Figure 7 The interdigitated capacitor structure 123a shown exhibits fewer out-of-band suppression spikes and smaller amplitudes. The influence of acoustic energy coupling between the coupled resonant filter 121 and the functional unit 123 (i.e., the interdigitated capacitor structure 123a) is almost negligible, demonstrating the effectiveness of the functional unit 123. Figure 8 S(4,5) in the figure represents Figure 7 The S-parameters (isolation) corresponding to the structure shown are as follows. Figure 8 S(1,2) in the figure represents Figure 6 The S-parameters corresponding to the structure shown.

[0051] The present invention does not specifically limit the interdigital capacitor structure 123a. Based on the inclusion of two busbars (a first busbar and a second busbar) and multiple electrode fingers alternately arranged between the two busbars, the interdigital capacitor structure 123a may further include: multiple pseudo-fingers, with the multiple pseudo-fingers connected to the same busbar alternating with the multiple electrode fingers connected to that busbar; and / or, at least one electrode finger may further include multiple sub-electrode fingers arranged in parallel (i.e., a multi-finger structure or a withdrawable finger structure); and / or, the interdigital capacitor structure 123a includes two interdigital units, and the two interdigital units are symmetrically distributed about the central axis of the interdigital capacitor structure in the second direction Y; and / or, in the interdigital capacitor structure 123a, an electrode finger connected to one busbar forms a gap with another busbar, the gap being arranged in a preset manner, the preset manner including being parallel to the extension direction of the busbar (i.e., without aberration design), or not parallel to the extension direction of the busbar, for example, exhibiting a wavy or other shaped aberration. In the case of the interdigital capacitor structure 123a without dummy fingers, the gap is the distance between the tip of the electrode finger connected to one busbar and another busbar. Please refer to the relevant documentation. Figure 9 The gap d shown; when the interdigital capacitor structure 123a includes dummy fingers, the gap is the distance between the tip of an electrode finger connected to one busbar and the tip of a corresponding dummy finger connected to another busbar. Please refer to [reference needed]. Figure 10 The gap d shown.

[0052] The following five examples illustrate the structure of the interdigital capacitor structure 123a.

[0053] In the first example, such as Figure 9 As shown, the interdigitated capacitor structure 123a includes multiple electrode fingers 23 and a first bus bar 21 and a second bus bar 22 arranged opposite to each other along the first direction X. A portion of the electrode fingers 23 are spaced apart along the second direction Y on the side of the first bus bar 21 near the second bus bar 22, and another portion of the electrode fingers 23 are spaced apart along the second direction Y on the side of the second bus bar 22 near the first bus bar 21. The portion of electrode fingers 23 and the other portion of electrode fingers 23 are arranged in a cross pattern in the second direction Y.

[0054] in, Figure 9 In This indicates the width of electrode 23. This represents the half-cycle wavelength of the interdigital capacitor structure 123a, i.e., the wavelength. , Also known as interdigital spacing, W d represents the aperture of the interdigital capacitor structure 123a, and d represents the gap formed between the electrode finger connected to one busbar and another busbar.

[0055] In the second example, compared to Figure 9 , Figure 10 The illustrated interdigitated capacitor structure also includes multiple dummy fingers 24. A portion of the dummy fingers 24 are spaced apart on the side of the first busbar 21 near the second busbar 22, while another portion of the dummy fingers 24 are spaced apart on the side of the second busbar 22 near the first busbar 21. A portion of the electrode fingers 23 and the other portion of the dummy fingers 24 are arranged opposite each other along the first direction X, and correspond one-to-one. Furthermore, the electrode fingers 23 and their corresponding dummy fingers 24 have a gap (d) in the first direction X.

[0056] In this embodiment, by setting a pseudo-finger, the transverse mode can be reflected through the abrupt change in sound speed boundary of the pseudo-finger region, thus avoiding the formation of resonance conditions and achieving better resonator performance.

[0057] In the third example, such as Figure 11 As shown, electrode finger 23 includes a plurality of sub-electrode fingers 231 arranged in parallel in the second direction Y. Figure 11 Taking each electrode finger 23 as an example, which includes two sub-electrode fingers 231 arranged side by side, but not limited to this. For example, some electrode fingers may contain sub-electrode fingers, while other electrode fingers may not contain sub-electrode fingers. The number of sub-electrode fingers contained in an electrode finger may be 3, 4, or 6, etc.

[0058] In this embodiment, multiple sub-electrode fingers are arranged in parallel and then alternately, which can broaden the filtering bandwidth, enhance out-of-band suppression capability, and adapt to wideband scenarios.

[0059] In the fourth example, such as Figure 12 As shown, the interdigital capacitor structure 123a includes two interdigital units (first interdigital unit 25 and second interdigital unit 26), and the two interdigital units are symmetrically distributed about the central axis of the interdigital capacitor structure 123a in the second direction Y. That is, the interdigital capacitor structure 123a is divided into two interdigital units in the second direction Y, and the electrode fingers in the first interdigital unit 25 and the electrode fingers in the second interdigital unit 26 are symmetrically arranged along the central axis O.

[0060] In this embodiment, the two interdigital units are arranged symmetrically along the center. The harmonic / lateral mode signal excited by the first interdigital unit 25 on the left is out of phase with the signal of the same frequency excited by the second interdigital unit 26 on the right. This can cancel out the interference of odd and even harmonics and lateral mode, greatly reduce out-of-band spurious signals, and also improve the isolation.

[0061] In the fifth example, such as Figure 13 As shown, in the interdigital capacitor structure 123a, the gap d formed between the electrode finger connected by one busbar and another busbar varies along the second direction Y (such as being wavy), that is, the lengths of multiple electrode fingers gradually change and / or the lengths of multiple pseudo-fingers gradually change.

[0062] In this embodiment, by apodizing the electrode fingers and / or dummy fingers (gradual length variation), the acoustic energy intensity excited by the finger strips is inconsistent, which can suppress sidelobes and diffraction clutter and improve the out-of-band suppression ratio. Different lengths of finger strips correspond to different equivalent resonant frequencies, and multiple resonant frequencies are superimposed to form a broadband response. At the same time, the gradual length of the finger strips makes the acoustic energy coupling of different frequencies more continuous and reduces the insertion loss fluctuation in the passband.

[0063] In other embodiments, such as Figure 14 As shown, the functional unit 123 includes a second impedance element filter 123b with the same electrode finger arrangement direction as the coupled resonant filter 121. The second impedance element filter 123b includes a second resonator 1231 and a third resonator 1232 that share a busbar. The electrode fingers of the second resonator 1231 and the third resonator 1232 are distributed in a preset manner to reduce the coupling effect between the sound waves excited in the functional unit and the sound waves in the coupled resonant filter.

[0064] The preset method is not specifically limited, as long as it reduces the coupling between the sound waves excited in the functional unit and the sound waves in the coupled resonant filter. For example, by creating a 180° phase difference between the sound waves excited by the second resonator 1231 and the sound waves excited by the third resonator 1232, the coupling effect can be suppressed. The preset structural parameters of the second resonator 1231 and the third resonator 1232 are the same, such as the same electrode index, finger spacing Pt, and aperture. The finger spacing Pt can also be called the half-cycle wavelength, and it can be the distance between two adjacent electrode fingers on the same side in the electrode finger arrangement direction (first direction X).

[0065] For example, by offsetting the electrode finger distributions in the second resonator 1231 and the third resonator 1232 by an odd multiple of the finger spacing, the sound waves excited by the second resonator 1231 and the sound waves excited by the third resonator 1232 have a phase difference of 180°.

[0066] The structure of the target resonator (e.g., the aforementioned IEF structure 03) originally located in the blank area can be as follows: Figure 15 As shown, the busbar on the left is the input terminal (in), and the busbar on the right is the output terminal (out). In this embodiment, the target resonator, which was originally located in the blank area, is split into two resonators (the second resonator and the third resonator) with the same electrode exponent, half-cycle wavelength, and aperture. Figure 14 As shown, the busbar for the second resonator as the input terminal and the busbar for the third resonator as the input terminal are the same (denoted as center busbar 27). The output terminal of the second resonator is out1, and the output terminal of the third resonator is out2.

[0067] Furthermore, the two resonators are offset by an odd multiple of the finger spacing along the current-entry direction (i.e., the first direction X). This finger spacing refers to the finger spacing of the second resonator and also the finger spacing of the third resonator.

[0068] In this embodiment, the two resonators are offset by an odd multiple of Pt along the current entry direction, so that the surface acoustic waves excited by the resonators and perpendicular to the direction of acoustic energy transmission of the electrodes have a phase difference of 180°. That is, the surface acoustic waves of the two resonators are equal in amplitude and out of phase. The peaks and troughs of the two surface acoustic waves meet at different times. According to the principle of interference (the principle of vector superposition), the two acoustic wave energies cancel each other out in the aperture propagation direction, thereby reducing the influence of the mutual coupling of surface acoustic waves between the CRF structure and the IEF structure.

[0069] For example, for design flexibility, the area of ​​the second resonator is half the area of ​​the target resonator. The area of ​​the resonator can be characterized by the product of the aperture and the number of electrode fingers. To make the areas of the second and third resonators half that of the target resonator, one feasible approach is to have the electrode indices of both the second and third resonators be the same as those of the target resonator, and the aperture be half the aperture of the target resonator.

[0070] In some embodiments, such as Figure 14 As shown, in the first direction, the electrode fingers with the same electrical properties in the second and third resonators are aligned. That is, the third and fourth electrode fingers are mirror-symmetrically distributed along the central axis of the common bus bar (i.e., the central bus bar 27). The third electrode finger is the electrode finger of the second resonator located on the common bus bar, and the fourth electrode finger is the electrode finger of the third resonator located on the common bus bar.

[0071] In other embodiments, such as Figure 16 As shown, in the first direction, the electrode fingers with different electrical polarities in the second and third resonators are aligned. That is, the electrode fingers on the busbar at the output terminal of the second resonator are aligned with the electrode fingers on the central busbar of the third resonator, and vice versa. Figure 16 As shown, the surface acoustic wave generated by the second resonator and the surface acoustic wave generated by the third resonator have a phase difference of 180 deg.

[0072] For example, a coupled resonant filter can be a double-mode surface acoustic wave (SAW) filter. The DMS structure is a longitudinally coupled filter based on surface acoustic wave (SAW) technology. Through a special interdigital transducer structure, two SAW vibration modes are excited within a single filter unit, thereby achieving efficient frequency selection and interference suppression.

[0073] Specifically, the duplexer also includes a piezoelectric material layer and a substrate. The piezoelectric material layer covers the upper surface of the substrate, and the coupled resonant filter, at least one first impedance element filter, and functional unit are located on the upper surface of the piezoelectric material layer. The piezoelectric material layer can be a single-crystal piezoelectric layer. Under the excitation of an electric field, the piezoelectric layer excites surface acoustic waves through the inverse piezoelectric effect. The materials of the piezoelectric material layer include, but are not limited to, lithium tantalate (LiTaO3) and lithium niobate (LiNbO3).

[0074] For example, the substrate may include a first substrate layer and a second substrate layer. The material of the first substrate layer may be a low-velocity material such as silicon dioxide (SiO2), and the material of the second substrate layer may be a high-velocity material such as high-resistivity silicon, silicon carbide, sapphire, quartz, or magnesium aluminum spinel.

[0075] The present invention also provides a communication device, which includes the duplexer provided in any of the above embodiments.

[0076] For example, the duplexer can be a B28 duplexer.

[0077] In the description of this specification, the references to terms such as "this embodiment," "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples, without contradiction.

[0078] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0079] The above description does not provide detailed explanations of the technical aspects of each layer's patterning and etching. However, those skilled in the art should understand that various technical means can be used to form layers and regions of the desired shape. Furthermore, to form the same structure, those skilled in the art can design methods that are not entirely identical to those described above. Additionally, although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be effectively combined.

[0080] The above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described above, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention.

[0081] Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention.

Claims

1. A diplexer, characterized by The duplexer includes a transmitting filter and a receiving filter, at least one of the transmitting filter and the receiving filter comprising: a coupled resonant filter, at least one first impedance element filter, and a functional unit, wherein... The coupled resonant filter includes a plurality of first resonators arranged along a first direction; The at least one first impedance element filter is disposed on at least one side of the coupled resonant filter in the second direction, and the coupled resonant filter has a blank area on at least one side in the first direction; The functional unit is located in the blank area, and the functional unit is electrically connected to at least one of the coupled resonant filter and the first impedance element filter.

2. The duplexer according to claim 1, wherein The functional unit includes an interdigitated capacitor structure, which comprises two busbars and multiple electrode fingers arranged alternately between the two busbars; wherein, The electrode arrangement direction of the interdigitated capacitor structure intersects with the electrode arrangement direction of the first resonator, and the difference between the effective capacitance value of the interdigitated capacitor structure and the effective capacitance value of the target resonator is less than or equal to a preset difference.

3. The duplexer according to claim 2, wherein The preset difference is less than or equal to 30% of the effective capacitance value of the target resonator.

4. The duplexer of claim 2, wherein The effective capacitance value of the interdigital capacitor structure is determined by the following formula: wherein represents an effective capacitance value of the interdigital capacitance structure, represents the number of electrode fingers of the interdigital capacitance structure, represents an aperture of the interdigital capacitance structure, , represents a metal duty cycle.

5. The duplexer according to claim 2, characterized in that, The interdigitated capacitor structure further includes multiple dummy fingers, with the multiple dummy fingers connected to the same busbar alternately arranged with the multiple electrode fingers; and / or At least one of the electrode fingers includes a plurality of sub-electrode fingers arranged in parallel; and / or, The interdigitated capacitor structure includes two interdigitated units, and the two interdigitated units are symmetrically distributed about the central axis of the interdigitated capacitor structure in the second direction; and / or, In the interdigitated capacitor structure, a gap is formed between the electrode fingers connected to one of the busbars and the other busbar, and the gaps are arranged in a preset manner.

6. The duplexer of claim 1, wherein The functional unit includes a second impedance element filter with the same electrode finger arrangement direction as the coupled resonant filter. The second impedance element filter includes a second resonator and a third resonator that share a common bus bar. The electrode fingers of the second resonator and the third resonator are distributed in a preset manner to reduce the coupling effect between the sound waves excited in the functional unit and the sound waves in the coupled resonant filter.

7. The duplexer of claim 6, wherein The second resonator has the same preset structural parameters as the third resonator, and the sound wave excited by the second resonator has a 180° phase difference with the sound wave excited by the third resonator.

8. The duplexer of claim 6, wherein The electrode finger distributions in the second resonator and the third resonator are staggered by an odd multiple of the finger spacing.

9. The duplexer according to claim 6, characterized in that, In the first direction: The electrodes of the second resonator and the third resonator with the same electrical polarity are aligned; or, The electrodes with different electrical properties in the second resonator and the third resonator are aligned and distributed.

10. A communication device, characterized in that, The duplexer includes any one of claims 1 to 9.

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