Tc-saw resonator and filter
By setting protrusions and depressions on the temperature compensation layer of the TC-SAW resonator, the surface acoustic wave velocity is adjusted, the problem of suppressing spurious modes is solved, clearer signal output and energy limitation are achieved, and the performance of the resonator is improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 深圳新声半导体有限公司
- Filing Date
- 2026-04-15
- Publication Date
- 2026-07-24
AI Technical Summary
Existing TC-SAW resonators are not effective at suppressing spurious modes and require additional metal strips.
By setting protruding and recessed structures on the upper surface of the temperature compensation layer of the TC-SAW resonator, the velocity difference of the surface acoustic wave is modulated to suppress the excitation and propagation of stray modes without changing the original structure of the interdigital transducer.
It effectively suppresses spurious modes, improves the clarity of signal response, reduces energy leakage, and enhances the quality factor (Q) of the resonator.
Smart Images
Figure CN122457016A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of surface acoustic wave technology, for example to a TC-SAW resonator and filter. Background Technology
[0002] Surface acoustic waves (SAWs) are elastic waves that propagate along the surface of a solid, with their energy concentrated primarily near the surface. SAW resonators are an important structure and device for the widespread application of SAW technology, characterized by high Q-values, miniaturization, and low power consumption. Traditional SAW resonators consist of piezoelectric materials, interdigital transducers (IDTs), and reflective gratings. To mitigate the impact of temperature variations on resonator performance, a temperature-compensated surface acoustic wave (TC-SAW) resonator was designed, using lithium niobate as the substrate, silicon dioxide as the temperature compensation layer, and an interdigital transducer embedded beneath it. However, TC-SAW resonators frequently encounter various spurious modes. The presence of these spurious modes generates passband ripples and limits out-of-band rejection, thus impairing the performance of acoustic wave filters.
[0003] In related technologies, a metal strip is added above the silicon dioxide at the electrode end of the surface acoustic wave resonator to create a sound velocity difference through the mass loading effect, thereby suppressing transverse mode strays.
[0004] In the process of implementing the embodiments of this disclosure, at least the following problems were found in the related art: The related technology requires the addition of an extra metal strip and does not completely suppress stray particles.
[0005] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention
[0006] To provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not intended as a general commentary, nor is it intended to identify key / important components or describe the scope of protection of these embodiments, but rather as a prelude to the detailed description that follows.
[0007] This disclosure provides a TC-SAW resonator and filter to improve the spurious suppression capability of the TC-SAW resonator without adding additional metal strips.
[0008] In some embodiments, the TC-SAW resonator includes a piezoelectric substrate, an electrode layer, and a temperature compensation layer stacked sequentially. The electrode layer includes an interdigital transducer, which includes two opposing busbars connected to each other. The busbars are connected to finger strips that extend toward the opposite busbars but have gaps with them. This results in the electrode layer including an active region formed by alternating finger strips and gap regions formed at both ends of the active region. The upper surface of the temperature compensation layer has two pairs of protruding and recessed structures. In the orthographic projection onto the electrode layer, both pairs of protruding and recessed structures are disposed between the two busbars and parallel to the extension direction of the busbars. The recessed structures at least cover a portion of the gap regions, and the protruding structures at least cover a portion of the active regions. One side edge of each recessed structure corresponds to one side edge of a busbar, and the other side edge of each recessed structure is connected to one side edge of a protruding structure.
[0009] Optionally, the electrode layer further includes reflectors arranged opposite each other on both sides of the interdigital transducer in an extension direction parallel to the busbar.
[0010] Optionally, in the extension direction parallel to the busbar, the two ends of the protruding structure and the recessed structure do not extend beyond the interdigital transducer; or, in the extension direction parallel to the busbar, the two ends of the protruding structure and the recessed structure extend beyond the interdigital transducer and cover the reflector.
[0011] Optionally, in the extension direction parallel to the generatrix, the two ends of the protruding structure are flush with the two ends of the recessed structure.
[0012] Optionally, the recessed structure covers part of the gap area, and the raised structure covers the remaining gap area and part of the active area; or, the recessed structure covers the entire gap area, and the raised structure covers part of the active area; or, the recessed structure covers the entire gap area and part of the active area, and the raised structure covers part of the active area.
[0013] Optionally, the protrusion height of the protrusion structure ranges from [0.1λ, 2λ]; and / or the recess depth of the recess structure ranges from [0.1λ, 2λ]; where λ is the wavelength of the surface acoustic wave.
[0014] Optionally, the width of the protruding structure is in the range of [0.1λ, 2λ]; and / or the width of the recessed structure is in the range of [0.1λ, 2λ]; where λ is the wavelength of the surface acoustic wave.
[0015] Optionally, the shape of the protruding structure includes at least one of a rectangular, triangular, or semi-circular structure; and / or, the shape of the recessed structure includes at least one of a rectangular, triangular, or semi-circular structure.
[0016] Optionally, the temperature compensation layer further includes a central protruding structure and / or a central recessed structure disposed between the two pairs of protruding and recessed structures.
[0017] Optionally, the height of the central protrusion structure ranges from [0.1λ, 2λ]; and / or the depth of the central depression structure ranges from [0.1λ, 2λ]; where λ is the wavelength of the surface acoustic wave.
[0018] Optionally, the temperature compensation layer has the opposite temperature elastic coefficient to that of the piezoelectric substrate.
[0019] In some embodiments, the filter includes a TC-SAW resonator as described above.
[0020] The TC-SAW resonator and filter provided in this disclosure can achieve the following technical effects: In this embodiment, without altering the original structure of the interdigital transducer, protruding and recessed structures are formed on the upper surface of the temperature compensation layer of the TC-SAW resonator. The projections of these structures onto the electrode layer fall within the gap and active regions, respectively, thus achieving a modulation effect. The protruding structure covering the active region reduces the surface acoustic wave velocity (SAW) in that region, while the recessed structure covering the gap region increases it. This creates a larger sound velocity difference to suppress the excitation and propagation of stray modes without significantly affecting the main resonance. Therefore, without adding additional materials, simply altering the temperature compensation layer structure through protruding and recessed structures effectively adjusts the sound wave velocity and dispersion characteristics, improving the stray suppression capability of the TC-SAW resonator and achieving a stray-free signal response and clearer signal output. Furthermore, the structure of this embodiment helps confine energy within the resonator, reducing lateral energy leakage and improving the resonator's quality factor.
[0021] The above general description and the description below are exemplary and illustrative only and are not intended to limit this application. Attached Figure Description
[0022] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations and drawings do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are shown as similar elements. The drawings are not to be scaled. And wherein: Figure 1 This is a three-dimensional structural schematic diagram of a TC-SAW resonator provided in an embodiment of this disclosure; Figure 2 This is a side view of a TC-SAW resonator provided in an embodiment of this disclosure; Figure 3 This is a top view of another TC-SAW resonator provided in this embodiment; Figure 4 This is a top view of another TC-SAW resonator provided in this embodiment; Figure 5 (a) is a side view of a TC-SAW resonator provided in an embodiment of this disclosure. Figure 5 (b) is a top view of a TC-SAW resonator provided in an embodiment of this disclosure. Figure 5 (c) is a surface acoustic wave velocity diagram of a TC-SAW resonator provided in an embodiment of this disclosure; Figure 6 (a) is a side view of another TC-SAW resonator provided in an embodiment of this disclosure. Figure 6 (b) is a top view of another TC-SAW resonator provided in an embodiment of this disclosure. Figure 6 (c) is a surface acoustic wave velocity diagram of another TC-SAW resonator provided in an embodiment of this disclosure; Figure 7 (a) is a side view of another TC-SAW resonator provided in an embodiment of this disclosure. Figure 7 (b) is a top view of another TC-SAW resonator provided in an embodiment of this disclosure. Figure 7 (c) is a surface acoustic wave velocity diagram of another TC-SAW resonator provided in an embodiment of this disclosure; Figure 8 (a) is a side view of another TC-SAW resonator provided in an embodiment of this disclosure. Figure 8 (b) is a top view of another TC-SAW resonator provided in an embodiment of this disclosure. Figure 8 (c) is a surface acoustic wave velocity diagram of another TC-SAW resonator provided in an embodiment of this disclosure; Figure 9 (a) is a side view of another TC-SAW resonator provided in an embodiment of this disclosure. Figure 9 (b) is a top view of another TC-SAW resonator provided in an embodiment of this disclosure. Figure 9 (c) is a surface acoustic wave velocity diagram of another TC-SAW resonator provided in an embodiment of this disclosure; Figure 10 (a) is a side view of another TC-SAW resonator provided in an embodiment of this disclosure. Figure 10 (b) is a top view of another TC-SAW resonator provided in an embodiment of this disclosure. Figure 10 (c) is a surface acoustic wave velocity diagram of another TC-SAW resonator provided in an embodiment of this disclosure; Figure 11 This is a side view of another TC-SAW resonator provided in an embodiment of this disclosure; Figure 12 This is a side view of another TC-SAW resonator provided in an embodiment of this disclosure; Figure 13 This is the admittance diagram of a traditional TC-SAW resonator; Figure 14 This is a comparative admittance diagram of a TC-SAW resonator provided in an embodiment of this disclosure; Figure 15 This is a comparative admittance diagram of another TC-SAW resonator provided in an embodiment of this disclosure.
[0023] Reference numerals: 10, piezoelectric substrate; 20, electrode layer; 21, interdigital transducer; 22, busbar; 23, finger strip; 24, active region; 25, gap region; 26, reflector; 30, temperature compensation layer; 31, raised structure; 32, recessed structure; 33, central raised structure; 34, central recessed structure. Detailed Implementation
[0024] To provide a more detailed understanding of the features and technical content of the embodiments of this disclosure, the implementation of the embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. The accompanying drawings are for illustrative purposes only and are not intended to limit the embodiments of this disclosure. In the following technical description, for ease of explanation, several details are used to provide a full understanding of the disclosed embodiments. However, one or more embodiments may still be implemented without these details. In other cases, well-known structures and devices may be simplified in their depiction to simplify the drawings.
[0025] The terms "first," "second," etc., used in the technical solutions described in this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this disclosure described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.
[0026] Unless otherwise stated, the term "multiple" means two or more.
[0027] In this embodiment of the disclosure, the character " / " indicates that the objects before and after it are in an "or" relationship. For example, A / B means: A or B.
[0028] The term "and / or" describes an association between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or A and B.
[0029] The term "correspondence" can refer to an association or binding relationship. The correspondence between A and B means that there is an association or binding relationship between A and B.
[0030] Combination Figure 1 and Figure 2As shown, this embodiment of the present disclosure provides a TC-SAW resonator, including a piezoelectric substrate 10, an electrode layer 20, and a temperature compensation layer 30 stacked sequentially. The electrode layer 20 includes interdigital transducers 21, each including two opposing busbars 22. Each busbar 22 is connected to a finger strip 23, which extends toward the opposite busbar 22 but has a gap with it. This results in the electrode layer 20 including an active region 24 formed by alternating arrangement of the finger strips 23, and gap regions 25 formed at both ends of the active region 24. The upper surface of the temperature compensation layer 30 is provided with two pairs of protruding structures 31 and recessed structures 32. In the orthographic projection onto the electrode layer 20, the two pairs of protruding structures 31 and recessed structures 32 are both disposed between two busbars 22 and are disposed parallel to the extension direction of the busbars 22. The recessed structure 32 covers at least part of the gap region 25, and the protruding structure 31 covers at least part of the active region 24. One side edge of each recessed structure 32 corresponds to one side edge of a busbar 22, and the other side edge of each recessed structure 32 is connected to one side edge of a protruding structure 31.
[0031] In this embodiment, without altering the original structure of the interdigital transducer 21, a protruding structure 31 and a recessed structure 32 are provided on the upper surface of the temperature compensation layer 30 of the TC-SAW resonator. The projections of the protruding structure 31 and the recessed structure 32 onto the electrode layer 20 are located in the gap region 25 and the active region 24, respectively, thus achieving a modulation effect. The protruding structure 31 covering the active region 24 reduces the surface acoustic wave velocity in that region, while the recessed structure 32 covering the gap region 25 increases the surface acoustic wave velocity in that region. This creates a larger sound velocity difference to suppress the excitation and propagation of stray modes without significantly affecting the main resonance. Therefore, without adding additional materials, by simply changing the structure of the temperature compensation layer 30 through the protruding structure 31 and the recessed structure 32, the sound wave velocity and dispersion characteristics can be effectively adjusted, improving the stray suppression capability of the TC-SAW resonator, achieving a stray-free signal response and clearer signal output. Furthermore, the structure of the embodiments disclosed herein also helps to confine energy within the resonator, thereby reducing lateral energy leakage and improving the quality factor of the resonator.
[0032] Optionally, the interdigital transducer 21 has 10 to 1000 IDT cycles.
[0033] Optionally, combined Figure 3 As shown, the electrode layer 20 also includes reflectors 26 arranged opposite each other on both sides of the interdigital transducer 21 in an extension direction parallel to the busbar 22.
[0034] In this embodiment, when the surface acoustic wave is excited from the interdigital transducer 21 and propagates along the substrate surface, it will be reflected back when it encounters the array of reflectors 26 on both sides. The reflectors 26 arranged opposite to each other on both sides together with the interdigital transducer 21 form a resonant cavity, which can effectively localize and confine the acoustic wave energy within the spatial region defined by the two reflectors 26, preventing the energy from being dissipated indefinitely to both ends of the device.
[0035] Alternatively, reflector 26 has 10 to 30 pairs of reflective gratings.
[0036] Optionally, combined Figure 3 As shown, in the extension direction parallel to the busbar 22, the two ends of the protruding structure 31 and the recessed structure 32 do not extend beyond the interdigital transducer 21.
[0037] In this embodiment, the acoustic modulation range of the protruding structure 31 and the recessed structure 32 can be strictly limited to the active region 24 and the gap region 25 of the interdigital transducer 21. Since the modulation structure does not exceed the IDT range, its disturbance to the propagation path of the resonant master mode is limited to the necessary minimum area. This effectively limits lateral energy leakage and minimizes excessive interference with the propagation characteristics of the master resonant mode itself, thus helping to maintain the stability of the master resonant frequency and the Q value.
[0038] Optionally, combined Figure 4 As shown, in the extension direction parallel to the busbar 22, the two ends of the protruding structure 31 and the recessed structure 32 extend beyond the interdigital transducer 21 and cover the reflector 26.
[0039] In this embodiment, extending the protruding structure 31 and the recessed structure 32 to the reflector 26 region further extends the sound velocity modulation and acoustic waveguide effect from the IDT range to the entire resonant cavity, thereby establishing a more complete and uniform acoustic waveguide structure along the entire length of the resonant cavity. This confines energy not only in the active region 24 but also along the propagation path to and inside the reflector 26, and further suppresses the leakage and loss of acoustic energy at both ends of the resonant cavity.
[0040] Optionally, in the extension direction parallel to the generatrix 22, the two ends of the protruding structure 31 are flush with the two ends of the recessed structure 32.
[0041] In this embodiment, the protruding structure 31 and the recessed structure 32 are completely aligned in the longitudinal length parallel to the generatrix 22, creating a structurally regular and symmetrical modulation unit. This simplifies the device layout design and subsequent micro / nano fabrication processes such as photolithography and etching, improving process repeatability and yield. Furthermore, it ensures that the boundary of the sound velocity modulation region is clear and continuous in the longitudinal direction, contributing to the formation of a more defined and efficient acoustic waveguide structure. It also avoids parasitic modes or inhomogeneities introduced by structural misalignment and ensures the integrity and consistency of the modulation effect in the longitudinal direction of the resonant cavity.
[0042] Optionally, combined Figure 5 As shown, the recessed structure 32 covers a portion of the gap region 25, and the protruding structure 31 covers the remaining portion of the gap region 25 and a portion of the active region 24. Among these, Figure 5 (a) is a side view of the TC-SAW resonator. Figure 5 (b) is a top view of the TC-SAW resonator. Figure 5 (c) shows the surface acoustic wave velocity diagram of the TC-SAW resonator. Figure 5 In (a), L 1a The width of the recessed structure is greater than 0 and less than the IDT gap; L 1b L is the width of the protruding structure, which is greater than 0. 1c The length of the gap area covered by the raised structure is greater than 0; L 1d The length of the active region covered by the protruding structure is greater than 0; H 1a The depth of the recessed structure is greater than 0 and less than the thickness of the temperature compensation layer; H 1b The height of the raised structure is greater than 0.
[0043] In this embodiment, part of the gap region 25 is covered by the recessed structure 32 and part of the gap region 25 is covered by the protruding structure 31, which realizes the differentiation of sound velocity in the gap region 25. This enables more precise control of the sound wave in the transition region when entering or leaving the active region 24, which helps to optimize the mode matching of the main resonant mode at the boundary between the gap region 25 and the active region 24.
[0044] Optionally, combined Figure 6 As shown, the recessed structure 32 covers the entire gap region 25, and the raised structure 31 covers part of the active region 24. Among them, Figure 6 (a) is a side view of the TC-SAW resonator. Figure 6 (b) is a top view of the TC-SAW resonator. Figure 6 (c) shows the surface acoustic wave velocity diagram of the TC-SAW resonator. Figure 6 In (a), L 2a L is the width of the recessed structure, which is equal to the IDT gap; 2bH is the width of the protruding structure, which is greater than 0. 1a The depth of the recessed structure is greater than 0 and less than the thickness of the temperature compensation layer; H 1b The height of the raised structure is greater than 0.
[0045] In this embodiment, the gap region 25 is completely covered by the recessed structure 32, and the recessed structure 32 does not cover the active region 24. This can consistently and maximize the surface acoustic wave velocity of the gap region 25 across the entire width of the gap region 25, thereby forming two complete and continuous high-speed acoustic barriers on both sides of the active region 24. This can most effectively confine the acoustic wave energy within the central active region 24, thereby significantly suppressing transverse energy leakage and stray modes based on transverse resonance.
[0046] Optionally, combined Figure 7 As shown, the recessed structure 32 covers the entire gap region 25 and part of the active region 24, while the protruding structure 31 covers part of the active region 24. Among these, Figure 7 (a) is a side view of the TC-SAW resonator. Figure 7 (b) is a top view of the TC-SAW resonator. Figure 7 (c) shows the surface acoustic wave velocity diagram of the TC-SAW resonator. Figure 7 In (a), L 3a L represents the width of the recessed structure, which is greater than 0 and greater than the IDT gap; 3b L is the width of the protruding structure, which is greater than 0. 3c L is the length of the gap area covered by the recessed structure, which is greater than 0. 3d The length of the active region covered by the concave structure is greater than 0; H 3a The depth of the recessed structure is greater than 0 and less than the thickness of the temperature compensation layer; H 3b The height of the raised structure is greater than 0.
[0047] In this embodiment, the recessed structure 32 not only covers the entire gap region 25, but also extends into the active region 24, which can expand the high-speed region and compress the width of the low-speed waveguide region, forming an acoustic waveguide with stronger confinement capability, thereby highly localizing the energy at the center of the resonator and further reducing any form of energy diffusion.
[0048] Optionally, the protrusion height of the protrusion structure 31 is in the range of [0.1λ, 2λ]; and / or the recess depth of the recess structure 32 is in the range of [0.1λ, 2λ]; where λ is the wavelength of the surface acoustic wave.
[0049] Optionally, the width of the protruding structure 31 is in the range of [0.1λ, 2λ]; and / or the width of the recessed structure 32 is in the range of [0.1λ, 2λ]; where λ is the wavelength of the surface acoustic wave.
[0050] In this embodiment, the protrusion height of the protrusion structure 31, the recess depth of the recessed structure 32, and the width range of the protrusion structure 31 and the recessed structure 32 are set to be proportional to the wavelength of the surface acoustic wave. This ensures that the dimensions of the protrusion structure 31 and the recessed structure 32 are on the same physical order of magnitude as the processed acoustic wave, thereby ensuring that the protrusion structure 31 and the recessed structure 32 can generate a sufficiently strong and controllable modulation effect on the surface acoustic wave in the target frequency band, effectively suppressing spurious modes and improving the Q value, while ensuring that the structure is feasible and reliable in manufacturing. It should be understood that the protrusion height of the protrusion structure 31 and the recess depth of the recessed structure 32 do not need to be equal, nor do the widths of the protrusion structure 31 and the recessed structure 32 need to be equal.
[0051] Optionally, the shape of the protruding structure 31 includes at least one of a rectangular, triangular, or semi-circular structure; and / or, the shape of the recessed structure 32 includes at least one of a rectangular, triangular, or semi-circular structure.
[0052] In this embodiment, different geometries allow the protruding structure 31 and the recessed structure 32 to have different boundary profiles and slopes with the surrounding medium. Based on requirements such as target frequency, suppression of specific stray modes, or optimization of process conditions, the most suitable boundary profile can be selected, increasing the flexibility of acoustic design and the compatibility of process implementation. Combined with Figure 5 , Figure 6 , Figure 7 As shown, both the protruding and recessed structures are rectangular in shape. The rectangular structure has vertical boundaries, which generate the steepest abrupt change in acoustic impedance, resulting in a strong contrast in sound velocity and a well-defined waveguide mode. Combined with... Figure 8 As shown, both the protruding and recessed structures are triangular in shape. Among them, Figure 8 (a) is a side view of the TC-SAW resonator. Figure 8 (b) is a top view of the TC-SAW resonator. Figure 8 (c) shows the surface acoustic wave velocity diagram of the TC-SAW resonator. Figure 8 In (a), L 5a The width of the recessed structure is greater than 0 and less than the IDT gap; L 5b L is the width of the protruding structure, which is greater than 0. 5c The length of the gap area covered by the raised structure is greater than 0; L 5d The length of the active region covered by the protruding structure is greater than 0; H 5a The depth of the recessed structure is greater than 0 and less than the thickness of the temperature compensation layer; H 5bThe height of the protrusion in the convex structure is greater than 0. The triangular structure has sloping boundaries, providing a gradual transition in acoustic impedance, which helps reduce sound wave scattering and reflection losses at the boundaries, resulting in a smoother sound field distribution and lower insertion loss. Combined with... Figure 9 As shown, both the raised and recessed structures are semi-circular in shape. Among them, Figure 9 (a) is a side view of the TC-SAW resonator. Figure 9 (b) is a top view of the TC-SAW resonator. Figure 9 (c) shows the surface acoustic wave velocity diagram of the TC-SAW resonator. Figure 9 In (a), L 6a The width of the recessed structure is greater than 0 and less than the IDT gap; L 6b L is the width of the protruding structure, which is greater than 0. 6c The length of the gap area covered by the raised structure is greater than 0; L 6d The length of the active region covered by the protruding structure is greater than 0; H 6a The depth of the recessed structure is greater than 0 and less than the thickness of the temperature compensation layer; H 6b The height of the raised structure is greater than 0.
[0053] The semi-circular structure has a continuously varying curvature boundary, providing another form of smooth transition. It can also produce unique sound field focusing or diffraction effects at specific frequencies, thereby modulating specific stray modes or optimizing frequency response.
[0054] Optionally, combined Figure 10 , Figure 11 , Figure 12 As shown, the temperature compensation layer 30 further includes: a central protruding structure 33 and / or a central recessed structure 34 disposed between the two pairs of protruding structures 31 and recessed structures 32. Wherein, Figure 10 The temperature compensation layer 30 also includes a central recessed structure 34. Figure 10 (a) is a side view of the TC-SAW resonator. Figure 10 (b) is a top view of the TC-SAW resonator. Figure 10 (c) shows the surface acoustic wave velocity diagram of the TC-SAW resonator. Figure 10 In (a), L 4a The width of the recessed structure is greater than 0 and less than the IDT gap; L 4b L is the width of the protruding structure, which is greater than 0. 4c The length of the gap area covered by the raised structure is greater than 0; L 4d H is the length of the active region covered by the protruding structure, which is greater than 0; 4a The depth of the recessed structure is greater than 0 and less than the thickness of the temperature compensation layer; H4b The height of the protrusion in the protruding structure is greater than 0; L A H is the width of the central concave structure, which is greater than 0; A The depth of the central recessed structure is greater than 0 and less than the thickness of the temperature compensation layer. Figure 11 The temperature compensation layer 30 also includes a central protrusion structure 33. Figure 12 The temperature compensation layer 30 also includes a central protrusion structure 33 and a central recessed structure 34.
[0055] In this embodiment, a central protruding structure 33 and / or a central recessed structure 34 are added between the original pair of protruding structures 31 and recessed structures 32. This allows for the introduction of an additional acoustic modulation layer in the central region of the resonator, enabling more precise and multi-dimensional shaping and control of the internal sound field of the resonator. By adding a structure in the central region, the acoustic characteristics of that region can be specifically altered, thereby disrupting the resonance conditions of higher-order or specific stray modes, optimizing waveguide capabilities, and suppressing various stray modes. The introduction of the central structure can also actively shape the amplitude and phase distribution of surface acoustic waves within the resonant cavity, guiding sound wave energy to be more concentrated in the intended waveguide region, or counteracting certain unfavorable wavefronts that cause energy leakage. This helps to more tightly confine sound wave energy within the effective region of the resonator, further reducing energy leakage in any direction.
[0056] Optionally, the height of the central protrusion structure 33 is in the range of [0.1λ, 2λ]; and / or the depth of the central depression structure 34 is in the range of [0.1λ, 2λ]; where λ is the wavelength of the surface acoustic wave.
[0057] It should be understood that the height of the central protrusion structure 33 and the depth of the central depression structure 34 need not be equal, the height of the central protrusion structure 33 and the height of the protrusion structure 31 need not be equal, and the depth of the central depression structure 34 and the depth of the depression structure 32 need not be equal.
[0058] Optionally, the temperature compensation layer 30 has the opposite temperature elastic coefficient to the piezoelectric substrate 10.
[0059] In this embodiment, the elastic constants of the temperature compensation layer 30 and the piezoelectric substrate 10 change in opposite directions with temperature. When the temperature changes, the frequency change caused by the temperature compensation layer 30 can be offset or significantly weakened by the change caused by the piezoelectric substrate 10, thereby achieving passive compensation for the frequency temperature drift of the resonator, significantly reducing the frequency temperature coefficient of the entire resonator and improving the working stability of the resonator in variable temperature environments.
[0060] Optionally, the material of the busbar 22 and the finger bar 23 of the electrode layer 20 includes at least one of aluminum, copper, gold, tungsten, molybdenum or silver.
[0061] Optionally, the temperature compensation layer 30, the recessed structure 32, and the raised structure 31 may be made of silicon dioxide.
[0062] Optionally, the piezoelectric substrate 10 may be made of at least one of lithium niobate, lithium tantalate, or quartz.
[0063] In this embodiment, the materials of the busbars 22 and fingers 23 of the electrode layer 20 enable efficient electroacoustic conversion and provide the required electrical, mechanical, and process performance. The materials of the temperature compensation layer 30, the recessed structure 32, and the raised structure 31 provide temperature compensation and serve as structured functional layers. The material of the piezoelectric substrate 10 enables efficient excitation and propagation of surface acoustic waves and provides the required piezoelectric coupling and performance foundation. Furthermore, the selection of these three types of materials collectively constitutes the material basis for the TC-SAW resonator to achieve core performance characteristics such as high Q value, high temperature stability, and high frequency selectivity, realizing synergistic optimization of function, performance, and process.
[0064] It should be understood that the present disclosure does not impose specific limitations on the materials of the piezoelectric substrate 10, the electrode layer 20, and the temperature compensation layer 30.
[0065] In traditional TC-SAW resonators, no protrusion or recess structure is incorporated; its admittance diagram is as follows: Figure 13 As shown, without any structure to suppress spurious modes, various transverse spurious modes will appear. However, the TC-SAW resonator provided in this embodiment can significantly suppress transverse modes by setting the protruding structure 31 and the recessed structure 32.
[0066] In one specific embodiment, with Figure 5 Taking the structure shown as an example, at the protrusion height H of the protrusion structure 31 1b The depth H of the recessed structure 32 1a The value is 0.18λ, and the length L of the protrusion structure 31 covering the gap region 25 is... 1c The length L of the active region 24 covered by the protruding structure 31 1d The value varies within the range of 0.7λ to 0.75λ, and the width L of the concave structure 32 is... 1a When varying within the range of 0.4λ to 0.5λ, its admittance plot is as follows: Figure 14 As shown, the lateral pattern is suppressed. In another specific embodiment, the length L of the gap region 25 covered by the protruding structure 31 is... 1c The length L of the active region 24 covered by the protruding structure 31 1d The value is 0.75λ, and the width L of the recessed structure 32 is... 1a The value is 0.5λ, and the protrusion height H of the protrusion structure 31 is... 1b The depth H of the recessed structure 321a When varying within the range of 0.1λ to 0.225λ, its admittance plot is as follows: Figure 15 As shown, lateral modes are suppressed. Therefore, the TC-SAW resonator provided in this embodiment can significantly suppress spurious modes and improve resonator performance. By providing a protruding structure 31 and a recessed structure 32 on the upper surface of the temperature compensation layer 30 of the TC-SAW resonator, the acoustic velocity or dispersion characteristics in the gap region 25 are changed. This not only suppresses spurious modes but also helps to confine energy within the resonator, reducing lateral energy leakage, achieving a spurious-free signal response and clearer signal output, and effectively improving the quality factor Q.
[0067] This disclosure also provides a filter, including the TC-SAW resonator as described above. Therefore, the filter possesses all the technical advantages of the TC-SAW resonator, which will not be elaborated further here.
[0068] The foregoing description and accompanying drawings fully illustrate embodiments of this disclosure to enable those skilled in the art to practice them. Other embodiments may include structural, logical, electrical, procedural, and other changes. The embodiments represent only possible variations. Individual components and functions are optional unless explicitly required, and the order of operation may vary. Parts and features of some embodiments may be included in or replace parts and features of other embodiments. Moreover, the terminology used in this application is for describing embodiments only and is not intended to limit the technical solutions described herein. As used in the technical solutions described herein, the singular forms “a,” “an,” and “the” are intended to equally include the plural forms unless the context clearly indicates otherwise. Similarly, the term “and / or” as used herein refers to any and all possible combinations of one or more of the associated listed elements. Additionally, when used in this application, the term "comprise" and its variations "comprises" and / or "comprising" refer to the presence of stated features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof. Without further limitations, an element defined by the phrase "comprises a..." does not exclude the presence of other identical elements in the process, method, or apparatus that includes said element. In this document, each embodiment may focus on the differences from other embodiments, and similar or identical parts between embodiments can be referred to mutually. For methods, products, etc., disclosed in the embodiments, if they correspond to the method section disclosed in the embodiments, the relevant parts can be referred to the description of the method section.
Claims
1. A TC-SAW resonator, characterized in that, It includes a piezoelectric substrate, an electrode layer, and a temperature compensation layer stacked sequentially. The electrode layer includes an interdigital transducer, which includes two oppositely arranged busbars. Each busbar is connected to a finger strip, which extends toward the opposite busbar but has a gap with the opposite busbar. This results in the electrode layer including an active region formed by alternating finger strips and gap regions formed at both ends of the active region. The upper surface of the temperature compensation layer is provided with two pairs of protruding structures and recessed structures. In the orthographic projection onto the electrode layer, both pairs of protruding structures and recessed structures are located between two busbars and are arranged parallel to the extension direction of the busbars. The recessed structures cover at least part of the gap area, and the protruding structures cover at least part of the active area. One side edge of each recessed structure corresponds to one side edge of a busbar, and the other side edge of each recessed structure is connected to one side edge of a protruding structure.
2. The TC-SAW resonator according to claim 1, characterized in that, The electrode layer also includes reflectors arranged opposite each other on both sides of the interdigital transducer in an extension direction parallel to the generatrix.
3. The TC-SAW resonator according to claim 2, characterized in that, In the extension direction parallel to the generatrix, the ends of the protruding and recessed structures do not extend beyond the interdigital transducer; or, In the direction of extension parallel to the generatrix, the two ends of the protruding and recessed structures extend beyond the interdigital transducers and cover the reflector.
4. The TC-SAW resonator according to claim 1, characterized in that, In the extension direction parallel to the generatrix, the two ends of the protruding structure are flush with the two ends of the concave structure.
5. The TC-SAW resonator according to claim 1, characterized in that, The recessed structure covers part of the gap region, and the raised structure covers the remaining gap region and part of the active region; or, The recessed structure covers the entire gap region, while the raised structure covers part of the active region; or, The concave structure covers the entire gap region and part of the active region, while the convex structure covers part of the active region.
6. The TC-SAW resonator according to claim 1, characterized in that, The protrusion height of the protrusion structure ranges from [0.1λ, 2λ]; and / or, The depth range of the concave structure is [0.1λ, 2λ]; Where λ is the wavelength of the surface acoustic wave.
7. The TC-SAW resonator according to claim 1, characterized in that, The width of the protrusion is in the range of [0.1λ, 2λ]; and / or, The width of the concave structure ranges from [0.1λ, 2λ]; Where λ is the wavelength of the surface acoustic wave.
8. The TC-SAW resonator according to claim 1, characterized in that, The shape of the protruding structure includes at least one of the following: rectangular, triangular, and semi-circular; and / or, The shape of the recessed structure includes at least one of the following: rectangular, triangular, and semi-circular.
9. The TC-SAW resonator according to claim 1, characterized in that, The temperature compensation layer also includes a central protruding structure and / or a central recessed structure disposed between the two pairs of protruding and recessed structures.
10. The TC-SAW resonator according to claim 9, characterized in that, The height range of the central protrusion structure is [0.1λ, 2λ]; and / or, The depth range of the central concave structure is [0.1λ, 2λ]; Where λ is the wavelength of the surface acoustic wave.
11. The TC-SAW resonator according to any one of claims 1 to 10, characterized in that, The temperature compensation layer has the opposite temperature elastic coefficient to the piezoelectric substrate.
12. A filter, characterized in that, Includes the TC-SAW resonator as described in any one of claims 1 to 11.