A surface acoustic wave resonator, a surface acoustic wave filter, and a multiplexer

Abstract

The embodiment of the present application discloses a surface acoustic wave resonator, a surface acoustic wave filter and a multiplexer. The surface acoustic wave resonator comprises a piezoelectric layer and a conductive layer. The conductive layer comprises a first conductive unit and a second conductive unit. The first conductive unit comprises an interdigital transducer electrode, a first bus bar and a second bus bar arranged at two ends of the interdigital transducer electrode. The interdigital transducer electrode comprises a plurality of first long electrode fingers and second long electrode fingers arranged alternately along a first direction and extending along a second direction. At least one pair of adjacent first long electrode fingers is short-circuited on a side away from the first bus bar along the second direction, and a second long electrode finger between the two short-circuited first long electrode fingers is arranged in a suspended manner, thereby forming a suspended finger. The second conductive unit comprises a first reflective grating and a second reflective grating. The technical scheme of the present application can shorten the distance between a resonance point and an anti-resonance point of a resonant unit. The surface acoustic wave resonator is applied to a surface acoustic wave filter, and the passband edge roll-off can be improved.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and in particular to a surface acoustic wave resonator, a surface acoustic wave filter, and a multiplexer. Background Technology

[0002] In modern mobile communication systems, filters are used to filter out signals outside the communication frequency band, playing a crucial role in improving communication quality. Surface acoustic wave (SAW) filters are characterized by good stability, small size, and high quality factor (Q), and are widely used in high-frequency filters.

[0003] From the perspective of effectively utilizing frequency resources for wireless communication, many frequency bands have been allocated for communication purposes such as portable telephones, thus narrowing the spacing between adjacent frequency bands. Given this frequency band allocation, in surface acoustic wave (SAW) filters, the rate of change of insertion loss from the passband to the attenuation band at the passband end (i.e., edge roll-off) becomes an important performance indicator.

[0004] However, in existing surface acoustic wave (SAW) resonator structures, the distance between the resonant point and the anti-resonant point of the resonant unit is relatively large, resulting in a reduction in the passband edge roll-off of the SAW filter composed of SAW resonators. Summary of the Invention

[0005] This invention provides a surface acoustic wave resonator, a surface acoustic wave filter, and a multiplexer to reduce the distance between the resonant point and the anti-resonant point of the resonant unit and improve the passband edge roll-off.

[0006] According to one aspect of the present invention, a surface acoustic wave (SAW) resonator is provided, the SAW resonator comprising:

[0007] piezoelectric layer;

[0008] A conductive layer is located on one side of the piezoelectric layer; the conductive layer includes a first conductive unit and a second conductive unit; the first conductive unit includes an interdigital transducer electrode and a first busbar and a second busbar disposed at both ends of the interdigital transducer electrode; the interdigital transducer electrode includes a plurality of first long electrode fingers and second long electrode fingers arranged alternately along a first direction and extending along a second direction; the first long electrode fingers are connected to the first busbar; the second long electrode fingers are connected to the second busbar; wherein, along the second direction, at least one pair of adjacent first long electrode fingers are short-circuited on the side away from the first busbar, and the second long electrode fingers located between the two short-circuited first long electrode fingers are suspended, forming a suspended finger; the second conductive unit includes a first reflective grid and a second reflective grid; along the first direction, the first reflective grid and the second reflective grid are respectively located on both sides of the first conductive unit; the first direction is perpendicular to the second direction.

[0009] Optionally, along the first direction, the width of the suspending finger located between the two shorted first long electrode fingers is negatively correlated with the resonant frequency of the surface acoustic wave resonator.

[0010] Optionally, along the first direction, the number of first sub-electrodes, consisting of two short-circuited first long electrode fingers and a suspended finger located between the two short-circuited first long electrode fingers, is positively correlated with the resonant frequency of the surface acoustic wave resonator.

[0011] Optionally, the interdigital transducer electrode further includes a plurality of first short electrode fingers and second short electrode fingers that are arranged alternately along a first direction and extend along a second direction; the first short electrode fingers are connected to the second busbar; the second short electrode fingers are connected to the first busbar.

[0012] Along the second direction, there is a preset gap between the corresponding first long electrode finger and the corresponding first short electrode finger; there is also a preset gap between the corresponding second long electrode finger and the corresponding second short electrode finger.

[0013] According to another aspect of the present invention, a surface acoustic wave (SAW) resonator is provided, the SAW resonator comprising:

[0014] piezoelectric layer;

[0015] A conductive layer is located on one side of the piezoelectric layer; the conductive layer includes a first conductive unit and a second conductive unit; the first conductive unit includes an interdigital transducer electrode and a first busbar and a second busbar disposed at both ends of the interdigital transducer electrode; the interdigital transducer electrode includes a plurality of first long electrode fingers and second long electrode fingers arranged alternately along a first direction and extending along a second direction; the first long electrode fingers are connected to the first busbar; the second long electrode fingers are connected to the second busbar; wherein, along the second direction, at least one pair of adjacent first long electrode fingers are short-circuited on the side away from the first busbar, and the second long electrode finger located between two short-circuited first long electrode fingers is short-circuited with the two short-circuited first long electrode fingers to form a short-circuit finger; the second conductive unit includes a first reflective grid and a second reflective grid; along the first direction, the first reflective grid and the second reflective grid are respectively located on both sides of the first conductive unit; the first direction is perpendicular to the second direction.

[0016] Optionally, along the first direction, the width of the short-circuit finger located between the two shorted first long electrode fingers is negatively correlated with the anti-resonance frequency of the surface acoustic wave resonator.

[0017] Optionally, along the first direction, the number of second sub-electrodes, consisting of two shorted first long electrode fingers and a short-circuited finger located between the two shorted first long electrode fingers, is negatively correlated with the anti-resonance frequency of the surface acoustic wave resonator.

[0018] Optionally, the interdigital transducer electrode further includes a plurality of first short electrode fingers and second short electrode fingers that are arranged alternately along a first direction and extend along a second direction; the first short electrode fingers are connected to the second busbar; the second short electrode fingers are connected to the first busbar.

[0019] Along the second direction, there is a preset gap between the corresponding first long electrode finger and the corresponding first short electrode finger; there is also a preset gap between the corresponding second long electrode finger and the corresponding second short electrode finger.

[0020] According to another aspect of the present invention, a surface acoustic wave (SAW) filter is provided, the SAW filter comprising at least one SAW resonator having a levitation finger and at least one SAW resonator having a short-circuit finger.

[0021] According to another aspect of the invention, a multiplexer is provided, which includes the surface acoustic wave filter described above.

[0022] The technical solution of this invention provides a surface acoustic wave (SAW) resonator, comprising: a piezoelectric layer; a conductive layer located on one side of the piezoelectric layer; the conductive layer including a first conductive unit and a second conductive unit; the first conductive unit including interdigital transducer electrodes and a first busbar and a second busbar disposed at both ends of the interdigital transducer electrodes; the interdigital transducer electrodes including a plurality of first long electrode fingers and second long electrode fingers arranged alternately along a first direction and extending along a second direction; the first long electrode fingers are connected to the first busbar; the second long electrode fingers are connected to the second busbar; wherein, along the second direction, at least one pair of adjacent first long electrode fingers are short-circuited on the side away from the first busbar, and the second long electrode fingers located between the two short-circuited first long electrode fingers are suspended, constituting a suspended finger. The short-circuited first long electrode fingers are equivalent to forming an equipotential surface on the side away from the first busbar, which can suppress the leakage of SAW in the second direction. The suspended finger is not connected to either the first busbar or the second busbar. The second conductive unit includes a first reflective grating and a second reflective grating. Along a first direction, the first and second reflective gratings are located on opposite sides of the first conductive unit. Surface acoustic waves propagating along the first direction are reflected by the first and second reflective gratings on both sides, and the reflected surface acoustic waves return to the interdigital transducer region. The surface acoustic wave resonator of this embodiment differs from existing structures in that, by changing the acoustic finger connection method and potential, the distance between the resonant point and the anti-resonant point of the resonant unit can be adjusted, thereby improving the passband edge roll-off.

[0023] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the structure of a surface acoustic wave resonator according to an embodiment of the present invention;

[0026] Figure 2 This is a top view schematic diagram of a surface acoustic wave resonator according to an embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of the structure of a surface acoustic wave resonator in related technologies;

[0028] Figure 4 This is a comparison diagram of the resonant frequencies of the surface acoustic wave resonator provided in the embodiments of the present invention and surface acoustic wave resonators in related technologies;

[0029] Figure 5 This is a top view schematic diagram of another surface acoustic wave resonator provided according to an embodiment of the present invention;

[0030] Figure 6 This is a top view schematic diagram of another surface acoustic wave resonator provided according to an embodiment of the present invention;

[0031] Figure 7 This is a comparison diagram of the anti-resonance frequencies of the surface acoustic wave resonator provided in the embodiments of the present invention and the surface acoustic wave resonators in related technologies;

[0032] Figure 8 This is a top view schematic diagram of another surface acoustic wave resonator provided according to an embodiment of the present invention;

[0033] Figure 9 This is a schematic diagram of the structure of a surface acoustic wave filter according to an embodiment of the present invention;

[0034] Figure 10 This is a comparison diagram of the electrical performance of the surface acoustic wave filter provided in the embodiments of the present invention and surface acoustic wave filters in related technologies;

[0035] Figure 11 This is a schematic diagram of a multiplexer according to an embodiment of the present invention. Detailed Implementation

[0036] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0037] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention 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 so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0038] Figure 1 This is a schematic diagram of the structure of a surface acoustic wave resonator according to an embodiment of the present invention; Figure 2 This is a top view schematic diagram of a surface acoustic wave resonator according to an embodiment of the present invention. Figure 1 and Figure 2 As shown, the surface acoustic wave resonator includes: a piezoelectric layer 20; a conductive layer 30 located on one side of the piezoelectric layer 20; the conductive layer 30 includes a first conductive unit 31 and a second conductive unit 32; the first conductive unit 31 includes an interdigital transducer electrode 311 and a first busbar 312 and a second busbar 313 disposed at both ends of the interdigital transducer electrode 311; the interdigital transducer electrode 311 includes a plurality of first long electrode fingers 301 and second long electrode fingers 302 arranged alternately along a first direction X and extending along a second direction Y; the first long electrode fingers 301 and the first busbar 313 are connected to the first busbar 312 and the second busbar 313. The flow bar 312 is connected; the second long electrode finger 302 is connected to the second bus bar 313; wherein, along the second direction Y, at least one pair of adjacent first long electrode fingers are short-circuited on the side away from the first bus bar 312, and the second long electrode finger located between the two short-circuited first long electrode fingers is suspended, forming a suspended finger 305; the second conductive unit 32 includes a first reflective grid 321 and a second reflective grid 322; along the first direction X, the first reflective grid 321 and the second reflective grid 322 are respectively located on both sides of the first conductive unit 31; the first direction X is perpendicular to the second direction Y.

[0039] In this embodiment of the invention, the piezoelectric layer 20 is the core functional layer for the generation and propagation of surface acoustic waves (SAWs). The material of the piezoelectric layer 20 must possess excellent piezoelectric properties. For example, the material of the piezoelectric layer 20 includes, but is not limited to, aluminum nitride, zinc oxide, or lithium tantalate. The function of the piezoelectric layer 20 is to realize the mutual conversion between electrical energy and mechanical energy. When an alternating voltage is applied to the interdigital transducer electrode 311, the piezoelectric layer 20 undergoes mechanical deformation to generate SAWs; conversely, the deformation of the piezoelectric layer 20 caused by the propagation of SAWs can also be converted into electrical signals.

[0040] The conductive layer 30, located on one side of the piezoelectric layer 20, is a structure for realizing electrical signal input / output and surface acoustic wave (SAW) modulation. The conductive layer 30 includes a first conductive unit 31 and a second conductive unit 32. The first conductive unit 31 can be an interdigital transducer, and the second conductive unit 32 can be a reflector. A first busbar 312 and a second busbar 313, disposed at both ends of the interdigital transducer electrode 311, serve as the input / output terminals for electrical signals. The second conductive unit 32 includes a first reflective grating 321 and a second reflective grating 322. Along the first direction X, the first reflective grating 321 and the second reflective grating 322 are located on both sides of the first conductive unit 31, forming a symmetrical structure of "reflective grating-interdigital transducer-reflective grating". The function of the first reflective grating 321 and the second reflective grating 322 is to reflect SAW waves, confining them within the interdigital transducer region.

[0041] like Figure 2 As shown, along the second direction Y, a pair of adjacent first long electrode fingers are short-circuited on the side away from the first busbar 312, and a second long electrode finger located between the two short-circuited first long electrode fingers is suspended, forming a suspended finger 305. The short-circuited first long electrode fingers are equivalent to forming an equipotential surface on the side away from the first busbar 312, which can suppress the leakage of surface acoustic waves in the second direction Y. The suspended finger 305 is not connected to either the first busbar 312 or the second busbar 313.

[0042] The surface acoustic wave (SAW) resonator of this invention operates based on the piezoelectric effect and the excitation, reflection, and resonance of SAW waves. The principle is as follows: When an alternating voltage of a specific frequency is applied between the first busbar 312 and the second busbar 313, an alternating electric field acts on the piezoelectric layer 20. Due to the piezoelectric effect, the lattice within the piezoelectric layer 20 undergoes periodic stretching and deformation with changes in the electric field. This deformation propagates along the surface of the piezoelectric layer 20, forming SAW waves. The propagation direction of the SAW waves is a first direction X, and its frequency is determined by the period of the interdigital transducer electrode 311 and the velocity of the SAW waves in the piezoelectric layer 20. The SAW waves propagating along the first direction X are reflected by the first reflection grating 321 and the second reflection grating 322 on both sides, and the reflected SAW waves return to the interdigital transducer region. When the frequency of the input electrical signal matches the inherent resonant frequency of the SAW waves within the "reflection grating-interdigital transducer" cavity, resonance occurs. The SAW waves in the resonant state are then converted back into an alternating electrical signal through the piezoelectric effect and output through the busbars. This exhibits obvious resonance characteristics. Surface acoustic wave (SAW) resonators can be used in filtering or frequency selection applications. Along the first direction X, when the width of the suspending finger 305 located between the two shorted first long electrode fingers decreases, the resonant frequency of the SAW resonator further increases. Furthermore, when the number of structures composed of the two shorted first long electrode fingers and the suspending finger 305 increases, the resonant frequency of the SAW resonator further increases. The SAW resonator of this embodiment can serve as a parallel resonant unit for a SAW filter, improving the left edge roll-off of the passband.

[0043] It should be noted that, along the second direction Y, multiple pairs of adjacent first long electrode fingers can be short-circuited on the side away from the first busbar 312, and the second long electrode fingers located between the two short-circuited first long electrode fingers are suspended. The specific number can be set according to actual needs, and the embodiments of the present invention do not make specific limitations here.

[0044] The technical solution of this invention provides a surface acoustic wave (SAW) resonator, comprising: a piezoelectric layer; a conductive layer located on one side of the piezoelectric layer; the conductive layer including a first conductive unit and a second conductive unit; the first conductive unit including interdigital transducer electrodes and a first busbar and a second busbar disposed at both ends of the interdigital transducer electrodes; the interdigital transducer electrodes including a plurality of first long electrode fingers and second long electrode fingers arranged alternately along a first direction and extending along a second direction; the first long electrode fingers are connected to the first busbar; the second long electrode fingers are connected to the second busbar; wherein, along the second direction, at least one pair of adjacent first long electrode fingers are short-circuited on the side away from the first busbar, and the second long electrode fingers located between the two short-circuited first long electrode fingers are suspended, constituting a suspended finger. The short-circuited first long electrode fingers are equivalent to forming an equipotential surface on the side away from the first busbar, which can suppress the leakage of SAW in the second direction. The suspended finger is not connected to either the first busbar or the second busbar. The second conductive unit includes a first reflective grating and a second reflective grating. Along a first direction, the first and second reflective gratings are located on opposite sides of the first conductive unit. Surface acoustic waves propagating along the first direction are reflected by the first and second reflective gratings on both sides, and the reflected surface acoustic waves return to the interdigital transducer region. The surface acoustic wave resonator of this embodiment differs from existing structures in that, by changing the acoustic finger connection method and potential, the distance between the resonant point and the anti-resonant point of the resonant unit can be adjusted, thereby improving the passband edge roll-off.

[0045] In an optional embodiment of the present invention, reference is made to... Figure 2 Along the first direction X, the width of the suspending finger 305 located between the two short-circuited first long electrode fingers is negatively correlated with the resonant frequency of the surface acoustic wave resonator.

[0046] Figure 3 This is a schematic diagram of the structure of a surface acoustic wave resonator in related technologies. Figure 4 This is a comparison diagram of the resonant frequencies of the surface acoustic wave resonator provided in this embodiment of the invention and surface acoustic wave resonators in related technologies. (Reference) Figures 2 to 4 In this embodiment of the invention, compared to the resonant frequency fs of a surface acoustic wave (SAW) resonator in related technologies, the resonant frequency fs1 of the SAW resonator in this embodiment further increases when the width of the suspended finger 305 located between two short-connected first long electrode fingers along the first direction X decreases. The reason is that the propagation period of the SAW is determined by the equivalent spacing between the electrodes. A decrease in the width of the suspended finger 305 compresses the effective propagation path between adjacent electrode fingers, leading to a further decrease in the equivalent period. The SAW resonant frequency is equal to the ratio of the propagation speed of the SAW within the piezoelectric layer to the equivalent period; therefore, when the equivalent period decreases, the SAW resonant frequency further increases.

[0047] Figure 5This is a top view schematic diagram of another surface acoustic wave resonator provided according to an embodiment of the present invention. In an optional embodiment of the present invention, refer to... Figures 2 to 5 Along the first direction X, the number of the first sub-electrodes 33, which consist of two short-circuited first long electrode fingers and a suspended finger 305 located between the two short-circuited first long electrode fingers, is positively correlated with the resonant frequency of the surface acoustic wave resonator.

[0048] In an embodiment of the present invention, Figure 5 The number of first sub-electrodes 33 shown is three. In other optional embodiments of the present invention, the number of first sub-electrodes 33 may also be other, depending on actual needs, and the embodiments of the present invention do not specifically limit this. Along the first direction X, when the number of first sub-electrodes 33, consisting of two short-connected first long electrode fingers and a floating finger 305 located between the two short-connected first long electrode fingers, increases, the resonant frequency of the surface acoustic wave resonator further increases.

[0049] In an optional embodiment of the present invention, reference is made to... Figure 2 and Figure 5 The interdigital transducer electrode 311 also includes a plurality of first short electrode fingers 303 and second short electrode fingers 304 that are arranged alternately along the first direction X and extend along the second direction Y; the first short electrode fingers 303 are connected to the second busbar 313; the second short electrode fingers 304 are connected to the first busbar 312; along the second direction Y, there is a preset gap between the corresponding first long electrode fingers 301 and the first short electrode fingers 303; there is a preset gap between the corresponding second long electrode fingers 302 and the second short electrode fingers 304.

[0050] In this embodiment of the invention, the preset gap is a pre-set gap between corresponding long and short electrode fingers. By setting the first short electrode finger 303 and the second short electrode finger 304, this embodiment of the invention can purify the spectrum, improve out-of-band rejection, and reduce insertion loss.

[0051] Figure 6 This is a top view schematic diagram of another surface acoustic wave resonator provided according to an embodiment of the present invention. Figure 1 and Figure 6As shown, the surface acoustic wave resonator includes: a piezoelectric layer 20; a conductive layer 30 located on one side of the piezoelectric layer 20; the conductive layer 30 includes a first conductive unit 31 and a second conductive unit 32; the first conductive unit 31 includes an interdigital transducer electrode 311 and a first busbar 312 and a second busbar 313 disposed at both ends of the interdigital transducer electrode 311; the interdigital transducer electrode 311 includes a plurality of first long electrode fingers 301 and second long electrode fingers 302 arranged alternately along a first direction X and extending along a second direction Y; the first long electrode fingers 301 are connected to the first busbar 312. The second long electrode finger 302 is connected to the second busbar 313; wherein, along the second direction Y, at least one pair of adjacent first long electrode fingers are short-circuited on the side away from the first busbar 312, and the second long electrode finger located between the two short-circuited first long electrode fingers is short-circuited with the two short-circuited first long electrode fingers to form a short-circuit finger 306; the second conductive unit 32 includes a first reflective grid 321 and a second reflective grid 322; along the first direction X, the first reflective grid 321 and the second reflective grid 322 are respectively located on both sides of the first conductive unit 31; the first direction X is perpendicular to the second direction Y.

[0052] In this embodiment of the invention, the difference from the surface acoustic wave resonator in the above embodiment is that, along the second direction Y, at least one pair of adjacent first long electrode fingers are short-circuited on the side away from the first busbar 312, and a second long electrode finger located between the two short-circuited first long electrode fingers is short-circuited with the two short-circuited first long electrode fingers, forming a short-circuit finger 306. The short-circuit finger 306 and the two short-circuited first long electrode fingers form an equipotential surface on the side away from the first busbar 312, which can suppress electric field leakage and reduce parasitic capacitance; on the other hand, it reduces the scattering of surface acoustic waves and improves the energy utilization rate of surface acoustic waves. The surface acoustic wave resonator of this embodiment can be used as a series resonant unit of a surface acoustic wave filter, which can improve the right edge roll-off of the passband.

[0053] It should be noted that, along the second direction Y, multiple pairs of adjacent first long electrode fingers can be short-circuited on the side away from the first busbar 312, and the second long electrode finger located between two short-circuited first long electrode fingers is short-circuited with the two short-circuited first long electrode fingers. The specific number can be set according to actual needs, and the embodiments of the present invention do not make specific limitations here.

[0054] The remaining technical features of the embodiments of the present invention are consistent with the description of the above embodiments, and the corresponding explanations are referred to the above embodiments. The embodiments of the present invention will not be repeated here.

[0055] The technical solution of this invention provides a surface acoustic wave (SAW) resonator, comprising: a piezoelectric layer; a conductive layer located on one side of the piezoelectric layer; the conductive layer including a first conductive unit and a second conductive unit; the first conductive unit including interdigital transducer electrodes and a first busbar and a second busbar disposed at both ends of the interdigital transducer electrodes; the interdigital transducer electrodes including a plurality of first long electrode fingers and second long electrode fingers arranged alternately along a first direction and extending along a second direction; the first long electrode fingers are connected to the first busbar; the second long electrode fingers are connected to the second busbar; wherein, along the second direction, at least one pair of adjacent first long electrode fingers are short-circuited on the side away from the first busbar, and the second long electrode finger located between two short-circuited first long electrode fingers is short-circuited with the two short-circuited first long electrode fingers, forming a short-circuit finger. The short-circuit finger and the two short-circuited first long electrode fingers form an equipotential surface on the side away from the first busbar, which on the one hand can suppress electric field leakage and reduce parasitic capacitance; on the other hand, it reduces the scattering of SAW waves and improves the energy utilization rate of SAW waves. The second conductive unit includes a first reflective grating and a second reflective grating. Along a first direction, the first and second reflective gratings are located on opposite sides of the first conductive unit. Surface acoustic waves propagating along the first direction are reflected by the first and second reflective gratings on both sides, and the reflected surface acoustic waves return to the interdigital transducer region. The surface acoustic wave resonator of this embodiment differs from existing structures in that, by changing the acoustic finger connection method and potential, the distance between the resonant point and the anti-resonant point of the resonant unit can be adjusted, thereby improving the passband edge roll-off.

[0056] In an optional embodiment of the present invention, reference is made to... Figure 6 Along the first direction X, the width of the short-circuit finger 306 located between the two shorted first long electrode fingers is negatively correlated with the anti-resonance frequency of the surface acoustic wave resonator.

[0057] Figure 7 This is a comparison diagram of the anti-resonance frequencies of the surface acoustic wave resonator provided in this embodiment of the invention and surface acoustic wave resonators in related technologies. (Reference) Figure 3 , Figure 6 and Figure 7 The anti-resonance frequency is the frequency at which the device impedance reaches its maximum value. In this embodiment of the invention, compared to the anti-resonance frequency fa of a surface acoustic wave resonator in the related art, the anti-resonance frequency fa1 of the surface acoustic wave resonator in this embodiment of the invention is further reduced when the width of the short-circuit finger 306 located between the two shorted first long electrode fingers along the first direction X increases.

[0058] Figure 8 This is a top view schematic diagram of another surface acoustic wave resonator provided according to an embodiment of the present invention. In an optional embodiment of the present invention, refer to... Figures 6 to 8Along the first direction X, the number of the second sub-electrode 34, which consists of two short-circuited first long electrode fingers and a short-circuited finger 306 located between the two short-circuited first long electrode fingers, is negatively correlated with the anti-resonance frequency of the surface acoustic wave resonator.

[0059] In an embodiment of the present invention, Figure 8 The number of second sub-electrodes 34 shown is three. In other optional embodiments of the present invention, the number of second sub-electrodes 34 may also be other, depending on actual needs, and the embodiments of the present invention do not specifically limit this. When the number of second sub-electrodes 34, which consists of two shorted first long electrode fingers and a short-circuit finger 306 located between the two shorted first long electrode fingers, increases along the first direction X, the anti-resonance frequency of the surface acoustic wave resonator further decreases.

[0060] In an optional embodiment of the present invention, reference is made to... Figure 6 and Figure 8 The interdigital transducer electrode 311 also includes a plurality of first short electrode fingers 303 and second short electrode fingers 304 that are arranged alternately along the first direction X and extend along the second direction Y; the first short electrode fingers 303 are connected to the second busbar 313; the second short electrode fingers 304 are connected to the first busbar 312; along the second direction Y, there is a preset gap between the corresponding first long electrode fingers 301 and the first short electrode fingers 303; there is a preset gap between the corresponding second long electrode fingers 302 and the second short electrode fingers 304.

[0061] In this embodiment of the invention, the preset gap is a pre-set gap between corresponding long and short electrode fingers. By setting the first short electrode finger 303 and the second short electrode finger 304, this embodiment of the invention can purify the spectrum, improve out-of-band rejection, and reduce insertion loss.

[0062] Figure 9 This is a schematic diagram of the structure of a surface acoustic wave filter according to an embodiment of the present invention. Figure 10 This is a comparison diagram of the electrical performance of the surface acoustic wave filter provided in this embodiment of the invention and surface acoustic wave filters in related technologies. For example... Figure 9 and Figure 10 As shown, the surface acoustic wave filter includes at least one surface acoustic wave resonator with a floating finger and at least one surface acoustic wave resonator with a short-circuit finger.

[0063] In embodiments of the present invention, such as Figure 9As shown, the surface acoustic wave (SAW) filter includes four SAW resonators P1, P2, P3, and P4 with floating fingers, and four SAW resonators S1, S2, S3, and S4 with short-circuit fingers. In other optional embodiments of the present invention, the number of SAW resonators with floating fingers and SAW resonators with short-circuit fingers can be set to other quantities as needed, and the embodiments of the present invention are not specifically limited here. The SAW resonators P1, P2, P3, and P4 with floating fingers can improve the left edge roll-off of the passband; the SAW resonators S1, S2, S3, and S4 with short-circuit fingers can improve the right edge roll-off of the passband.

[0064] Depend on Figure 10 Comparative analysis shows that the surface acoustic wave filter provided in this embodiment of the invention is based on existing feasible manufacturing processes and does not require the addition of circuit units. It only requires modification of the internal structure of the surface acoustic wave resonator to shorten the distance between the resonant point and the anti-resonant point. Furthermore, by adjusting the width of the short-circuit finger or the floating finger, the distance between the resonant point and the anti-resonant point can be freely adjusted, thereby improving the edge roll-off.

[0065] Figure 11 This is a schematic diagram of a multiplexer according to an embodiment of the present invention. Figure 11 As shown, the multiplexer 200 includes a surface acoustic wave filter 100 according to any embodiment of the present invention.

[0066] Specifically, the function of the multiplexer 200 is to simultaneously transmit, receive, and isolate signals across multiple frequency bands on a single RF port. Its performance directly depends on the passband selectivity and insertion loss of the integrated surface acoustic wave (SAW) filter 100. Applying the SAW filter 100 of any embodiment of the present invention to the multiplexer 200 enables independent control of each communication frequency band, reduces mutual interference between different frequency bands of the multiplexer 200, reduces the overall insertion loss of the multiplexer 200, and improves signal transmission efficiency.

[0067] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and no limitation is imposed herein.

[0068] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A surface acoustic wave resonator, characterized in that, include: piezoelectric layer; A conductive layer is located on one side of the piezoelectric layer; the conductive layer includes a first conductive unit and a second conductive unit. The first conductive unit includes an interdigital transducer electrode and a first busbar and a second busbar disposed at both ends of the interdigital transducer electrode; the interdigital transducer electrode includes a plurality of first long electrode fingers and second long electrode fingers arranged alternately along a first direction and extending along a second direction; the first long electrode fingers are connected to the first busbar; the second long electrode fingers are connected to the second busbar; wherein, along the second direction, at least one pair of adjacent first long electrode fingers are short-circuited at the end away from the first busbar, and the second long electrode fingers located between the two short-circuited first long electrode fingers are suspended, forming a suspended finger; The floating finger is not connected to either the first busbar or the second busbar; a portion of the floating finger is located within the overlapping area of ​​the first long electrode finger and the second long electrode finger; the second conductive unit includes a first reflective grid and a second reflective grid; along the first direction, the first reflective grid and the second reflective grid are respectively located on both sides of the first conductive unit; the first direction is perpendicular to the second direction.

2. The surface acoustic wave resonator according to claim 1, characterized in that, Along the first direction, the width of the suspended finger located between the two shorted first long electrode fingers is negatively correlated with the resonant frequency of the surface acoustic wave resonator.

3. The surface acoustic wave resonator according to claim 1, characterized in that, Along the first direction, the number of first sub-electrodes, consisting of two short-circuited first long electrode fingers and the suspended finger located between the two short-circuited first long electrode fingers, is positively correlated with the resonant frequency of the surface acoustic wave resonator.

4. The surface acoustic wave resonator according to any one of claims 1-3, characterized in that, The interdigital transducer electrode further includes a plurality of first short electrode fingers and second short electrode fingers arranged alternately along the first direction and extending along the second direction; the first short electrode fingers are connected to the second busbar; the second short electrode fingers are connected to the first busbar. Along the second direction, there is a preset gap between the corresponding first long electrode finger and the corresponding first short electrode finger; there is also a preset gap between the corresponding second long electrode finger and the corresponding second short electrode finger.

5. A surface acoustic wave resonator, characterized in that, include: piezoelectric layer; A conductive layer is located on one side of the piezoelectric layer; the conductive layer includes a first conductive unit and a second conductive unit. The first conductive unit includes interdigitated transducer electrodes and a first busbar and a second busbar disposed at both ends of the interdigitated transducer electrodes; the interdigitated transducer electrodes include a plurality of first long electrode fingers and second long electrode fingers arranged alternately along a first direction and extending along a second direction; the first long electrode fingers are connected to the first busbar; the second long electrode fingers are connected to the second busbar; wherein, along the second direction, at least one pair of adjacent first long electrode fingers are short-circuited at the ends away from the first busbar, and the second long electrode finger located between two short-circuited first long electrode fingers is short-circuited with the two short-circuited first long electrode fingers to form a short-circuit finger, the short-circuit finger being disconnected from the second busbar; a portion of the short-circuit finger is located in the area where the first long electrode fingers and the second long electrode fingers overlap; the short-circuit finger is connected to the first busbar; the second conductive unit includes a first reflective grid and a second reflective grid; along the first direction, the first reflective grid and the second reflective grid are respectively located on both sides of the first conductive unit; the first direction is perpendicular to the second direction.

6. The surface acoustic wave resonator according to claim 5, characterized in that, Along the first direction, the width of the short-circuited finger located between the two shorted first long electrode fingers is negatively correlated with the anti-resonance frequency of the surface acoustic wave resonator.

7. The surface acoustic wave resonator according to claim 5, characterized in that, Along the first direction, the number of second sub-electrodes, consisting of two shorted first long electrode fingers and the short-circuited finger located between the two shorted first long electrode fingers, is negatively correlated with the anti-resonance frequency of the surface acoustic wave resonator.

8. The surface acoustic wave resonator according to any one of claims 5-7, characterized in that, The interdigital transducer electrode further includes a plurality of first short electrode fingers and second short electrode fingers arranged alternately along the first direction and extending along the second direction; the first short electrode fingers are connected to the second busbar; the second short electrode fingers are connected to the first busbar. Along the second direction, there is a preset gap between the corresponding first long electrode finger and the corresponding first short electrode finger; there is also a preset gap between the corresponding second long electrode finger and the corresponding second short electrode finger.

9. A surface acoustic wave filter, characterized in that, It includes at least one surface acoustic wave resonator according to any one of claims 1-4 and at least one surface acoustic wave resonator according to any one of claims 5-8.

10. A multiplexer, characterized in that, Includes the surface acoustic wave filter as described in claim 9.

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