A filter, multiplexer, and electronic device

Abstract

This invention relates to the field of filter technology, and discloses a filter, multiplexer, and electronic device. The filter includes: at least one series resonator, connected in series on a filter path formed by two input / output multiplexing ports, the series resonator including a first interdigital transducer and a first reflective grating, the first reflective grating being disposed along at least one side of a first direction of the first interdigital transducer; at least one parallel resonator, connected in parallel between the filter path and a ground terminal, the parallel resonator including a second interdigital transducer and a second reflective grating, the second reflective grating being disposed along at least one side of the first direction of the second interdigital transducer; the wavelength of at least one first reflective grating in the at least one series resonator is different from the wavelength of the corresponding first interdigital transducer, and / or, the wavelength of at least one second reflective grating in the at least one parallel resonator is different from the wavelength of the corresponding second interdigital transducer. This invention can reduce in-band insertion loss and in-band flatness of the filter.

Description

Technical Field

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

[0002] Surface acoustic wave (SAW) filters are devices that utilize the piezoelectric effect and the physical characteristics of surface acoustic wave propagation to achieve acoustic filtering, frequency control, and other functions. Due to their advantages such as low insertion loss, low cost, and miniaturization, they are widely used in mobile communication devices.

[0003] To improve data transmission speed in mobile communication devices, multi-band systems are used. Since multiple frequency bands are involved in transmission and reception, multiple filters are configured in the front-end circuit of the mobile communication device to allow high-frequency signals from different bands to pass through. In this case, due to space constraints in the front-end circuit, the filters are close together. The filters need to be miniaturized while further reducing insertion loss and in-band flatness to ensure communication quality; traditional resonators are insufficient to meet these requirements. Summary of the Invention

[0004] This invention provides a filter, multiplexer, and electronic device to address the problem of difficulty in further reducing insertion loss and in-band flatness.

[0005] In a first aspect, the present invention provides a filter comprising: at least one series resonator connected in series on a filter path formed by two input-output multiplexed ports, the series resonator comprising a first interdigital transducer and a first reflective grating, the first reflective grating being disposed along at least one side of a first direction of the first interdigital transducer; at least one parallel resonator connected in parallel between the filter path and a ground terminal, the parallel resonator comprising a second interdigital transducer and a second reflective grating, the second reflective grating being disposed along at least one side of the first direction of the second interdigital transducer; the wavelength of at least one first reflective grating in the at least one series resonator being different from the wavelength of the corresponding first interdigital transducer, and / or the wavelength of at least one second reflective grating in the at least one parallel resonator being different from the wavelength of the corresponding second interdigital transducer.

[0006] The filter provided by this invention optimizes insertion loss and in-band flatness by setting the wavelength of the reflective grating in at least one resonator to be different from the wavelength of the corresponding resonator, thereby changing the position of the resonant frequency and anti-resonant frequency, and achieving the purpose of reducing the in-band insertion loss and in-band flatness of the filter.

[0007] In one alternative implementation, the wavelength of at least one first reflective grating is greater than the wavelength of the corresponding first interdigital transducer, and / or the wavelength of at least one second reflective grating is less than the wavelength of the corresponding second interdigital transducer.

[0008] In this embodiment, the wavelength of at least one first reflective grating is greater than the wavelength of the corresponding first interdigital transducer, which can make the resonant frequency fall at the high end of the passband (close to the maximum value of the passband), thereby improving out-of-band suppression and isolation; the wavelength of at least one second reflective grating is less than the wavelength of the corresponding second interdigital transducer, which can make the anti-resonant frequency fall at the low end of the passband (close to the minimum value of the passband), thereby reducing insertion loss and improving in-band flatness.

[0009] In one alternative implementation, the first difference between the wavelength of the first reflective grating and the wavelength of the corresponding first interdigital transducer is 0.5% to 6%, and / or the second difference between the wavelength of the second reflective grating and the wavelength of the corresponding second interdigital transducer is 0.5% to 6%.

[0010] In this embodiment, the first difference and / or the second difference are controlled within a certain range. Within this range, in-band insertion loss and in-band flatness can be optimized better without affecting communication quality.

[0011] In one alternative implementation, if the filter is a trapezoidal filter, the first difference and / or the second difference is 1% to 3%; if the filter is a filter in a duplexer, the first difference and / or the second difference is 2% to 5%; if the filter is a broadband filter with a relative bandwidth greater than a first threshold, the first difference and / or the second difference is 3% to 6%; if the filter is a narrowband filter with a relative bandwidth less than a second threshold, the first difference and / or the second difference is 0.5% to 2%, and the first threshold is greater than the second threshold.

[0012] In this implementation, setting the first and / or second difference in a trapezoidal filter to 1%~3% can improve out-of-band suppression while ensuring low loss; in a duplexer, setting the first and / or second difference to 2%~5% can better adjust the transmission zero position, thereby improving transmit-receive isolation; in a broadband filter, setting the first and / or second difference to 3%~6% can broaden the bandwidth and improve flatness; in a narrowband filter, setting the first and / or second difference to 0.5%~2% can maintain a high Q value and achieve precise filtering.

[0013] In one optional embodiment, the first interdigital transducer includes a first central region and two first edge regions, the two first edge regions being located on both sides of the first central region along a first direction; the second interdigital transducer includes a second central region and two second edge regions, the two second edge regions being located on both sides of the second central region along the first direction; the wavelength of the first interdigital transducer in the first central region is greater than the wavelength of the first interdigital transducer in the first edge regions, and / or, the wavelength of the second interdigital transducer in the second central region is greater than the wavelength of the second interdigital transducer in the second edge regions.

[0014] In this embodiment, the wavelength of the edge region of the interdigital transducer is smaller than that of the center region, which can compensate for the phase delay caused by acoustic wave diffraction, reduce edge energy loss, and improve the Q value. The improvement of the Q value can make the filter have lower insertion loss.

[0015] In one alternative implementation, the wavelength of the first interdigital transducer in the first edge region varies periodically or gradually along the first direction; and / or, the wavelength of the second interdigital transducer in the second edge region varies periodically or gradually along the first direction.

[0016] In this embodiment, the interdigital transducer has a wavelength in the edge region that is shorter than that in the center region, and the wavelength in the edge region changes periodically or gradually, which is equivalent to introducing frequency chirp. This not only reduces edge reflection, improves Q value, and reduces insertion loss, but also suppresses lateral spurious modes and improves out-of-band suppression.

[0017] In one optional embodiment, both the first interdigital transducer and the second interdigital transducer include a plurality of electrode fingers spaced apart; the first interdigital transducer has fewer than or equal to 20 electrode fingers in the first edge region; and / or, the second interdigital transducer has fewer than or equal to 20 electrode fingers in the second edge region.

[0018] This embodiment limits the number of electrode fingers in the edge region to less than 20, resulting in a smaller phase accumulation error. This allows the advantages of wavelength gradient to be fully utilized, while preventing the deterioration of communication performance due to phase mismatch.

[0019] In one alternative embodiment, the ends of the plurality of electrode fingers of the first interdigital transducer are provided with metal blocks; and / or, the ends of the plurality of electrode fingers of the second interdigital transducer are provided with metal blocks.

[0020] This embodiment, by setting a metal block, can effectively suppress transverse modes using a piston mode, thereby improving out-of-band suppression and reducing insertion loss.

[0021] Secondly, the present invention provides a multiplexer including the filter of the first aspect above or any corresponding embodiment thereof.

[0022] Thirdly, the present invention provides an electronic device including a multiplexer comprising the second aspect described above or any corresponding embodiment thereof. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the topology of a filter according to the present invention; Figure 2 This is a schematic diagram of the structure of a resonator included in a filter according to the present invention; Figure 3 This is a schematic diagram of the regional distribution of the interdigital transducer in this invention; Figure 4 This is a schematic diagram of the structure of a resonator included in another filter of the present invention; Figure 5 This is a schematic diagram of the simulation comparison results of in-band loss according to the present invention; Figure 6 This is a schematic diagram of the simulation comparison results of out-of-band suppression according to the present invention.

[0025] Reference numerals: 10, interdigitated transducer; 101, electrode bar; 102, first busbar; 103, second busbar; 104, central region; 105, first peripheral region; 106, second peripheral region; 107, metal block; 20, reflective grating; 201, reflective electrode. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the invention, not the entire structure.

[0027] In the following description, descriptions of well-known structures and techniques are omitted to avoid unnecessarily obscuring the concepts of the invention. Various structural schematic diagrams according to embodiments of the invention are shown in the accompanying drawings. These drawings are not to scale, and some details are enlarged for clarity, and some details may be omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0028] This invention provides a filter, multiplexer, and electronic device. By setting the wavelength of the reflective grating in at least one resonator on the series arm and / or at least one resonator on the parallel arm, the positions of the resonant frequency and anti-resonant frequency in the passband are adjusted to reduce the in-band insertion loss and reduce the in-band flatness of the filter.

[0029] The structure of the filter provided by the present invention will be described below with reference to the accompanying drawings.

[0030] like Figure 1 As shown, the filter provided by the present invention includes at least one series resonator and at least one parallel resonator. Figure 1 Taking a filter comprising five series resonators (first series resonator S1, second series resonator S2, third series resonator S3, fourth series resonator S4 and fifth series resonator S5) and four parallel resonators (first parallel resonator P1, second parallel resonator P2, third parallel resonator P3 and fourth parallel resonator P4) as an example, but not limited to this.

[0031] At least one series resonator is connected in series on the filter path formed by two input-output multiplexed ports (first input-output multiplexed port 1 and second input-output multiplexed port 2) to achieve the desired effect. Figure 1 For example, the first series resonator S1, the second series resonator S2, the third series resonator S3, the fourth series resonator S4, and the fifth series resonator S5 are connected in sequence. The first series resonator S1, which is at the beginning, is connected to the first input-output multiplexing port 1, and the fifth series resonator S5, which is at the end, is connected to the second input-output multiplexing port 2.

[0032] Specifically, when the first input / output multiplexing port 1 is used as an input (in), the second input / output multiplexing port 2 is used as an output (out); when the first input / output multiplexing port 1 is used as an output (out), the second input / output multiplexing port 2 is used as an input (in).

[0033] At least one parallel resonator is connected in parallel between the filter path and the ground terminal, so as to Figure 1 For example, one end of the first parallel resonator P1, the second parallel resonator P2, the third parallel resonator P3, and the fourth parallel resonator P4 are connected to the connection node between the five series resonators, and the other end is grounded.

[0034] like Figure 2 As shown, the resonator includes an interdigital transducer 10 and a reflective grating 20 disposed on at least one side along a first direction X of the interdigital transducer 10. Figure 2 Taking the example of providing reflective gratings 20 on both sides of the interdigital transducer 10 along the first direction X, but not limited to this. For example, reflective gratings 20 can be provided only on the left side of the interdigital transducer 10, or only on the right side of the interdigital transducer 10.

[0035] For ease of distinction, a resonator connected in series in the filter path is called a series resonator. The interdigital transducer in the series resonator is denoted as the first interdigital transducer, and the reflective grating in the series resonator is denoted as the first reflective grating. The first reflective grating is arranged along at least one side of the first direction of the first interdigital transducer. A resonator connected in parallel in the filter path is called a parallel resonator. The interdigital transducer in the parallel resonator is denoted as the second interdigital transducer, and the reflective grating in the parallel resonator is denoted as the second reflective grating. The second reflective grating is arranged along at least one side of the first direction of the second interdigital transducer.

[0036] Specifically, the interdigital transducer 10 includes multiple electrode fingers 101, a first busbar 102, and a second busbar 103. The multiple electrode fingers 101 are arranged alternately in a first direction X, and the extension direction of the electrode fingers 101 is a second direction Y. The first busbar 102 and the second busbar 103 are arranged opposite each other along the second direction Y. A portion of the electrode fingers 101 are spaced apart on the side of the first busbar 102 near the second busbar 103, and another portion of the electrode fingers 101 are spaced apart on the side of the second busbar 103 near the first busbar 102. The portion of electrode fingers 101 and the other portion of the electrode fingers 101 are arranged alternately along the first direction X.

[0037] Wherein, the first direction X and the second direction Y intersect. This invention takes the first direction X and the second direction Y as being perpendicular to each other as an example, but is not limited thereto.

[0038] The reflective grating 20 includes a plurality of reflective electrodes 201 arranged at intervals along the first direction X, which are used to reflect surface acoustic waves, so that the surface acoustic waves oscillate back and forth between the interdigital transducer and the reflective grating to form standing waves, thereby enhancing the resonance effect.

[0039] In this invention, the wavelength of at least one first reflective grating in at least one series resonator is different from the wavelength of the corresponding first interdigital transducer, and / or the wavelength of at least one second reflective grating in at least one parallel resonator is different from the wavelength of the corresponding second interdigital transducer.

[0040] In other words, if a resonator whose wavelength of at least one reflective grating is different from the wavelength of the interdigital transducer in the same resonator is denoted as a target resonator, then the present invention may contain one or more target resonators in at least one series resonator and at least one parallel resonator, or one or more target resonators in at least one series resonator, or one or more target resonators in at least one parallel resonator.

[0041] Wherein, the wavelength of the first reflective grating , The spacing between the fingers of the reflective electrodes in the first reflective grating represents the distance between the reflective electrodes. Figure 2 When the reflective grating 20 is the first reflective grating, the spacing between two adjacent reflective electrodes 201 on the same side along the first direction is... That is ; Wavelength of the first interdigital transducer , This indicates the finger spacing of the electrode fingers in the first interdigital transducer. Figure 2 When the interdigital transducer 10 is the first interdigital transducer, the spacing between two adjacent electrode fingers 101 on the same side along the first direction is... That is .

[0042] Wavelength of the second reflective grating , The spacing between the fingers of the reflective electrodes in the second reflective grating indicates the distance between them. Figure 2 When the reflective grating 20 is the second reflective grating, That is ; Wavelength of the second interdigital transducer , This indicates the finger spacing of the electrode fingers in the second interdigital transducer. Figure 2 When the interdigital transducer 10 is the second interdigital transducer That is .

[0043] The filter provided by this invention optimizes insertion loss and in-band flatness by setting the wavelength of the reflective grating in at least one resonator to be different from the wavelength of the corresponding resonator, thereby changing the position of the resonant frequency and anti-resonant frequency, and achieving the purpose of reducing the in-band insertion loss and in-band flatness of the filter.

[0044] Optionally, the wavelength of at least one first reflective grating is greater than the wavelength of the corresponding first interdigital transducer, and / or, the wavelength of at least one second reflective grating is less than the wavelength of the corresponding second interdigital transducer. In other words, at least one , and / or, at least one .

[0045] It should be understood that the wavelength of the first reflective grating in other series resonators can be the same as the wavelength of the corresponding first interdigital transducer; the wavelength of the second reflective grating in other parallel resonators can be the same as the wavelength of the corresponding second interdigital transducer.

[0046] For example, if the wavelength of the first reflective grating in the first series resonator S1 is greater than the wavelength of the first interdigital transducer in the first series resonator, and the wavelength of the first reflective grating in the third series resonator S3 is greater than the wavelength of the first interdigital transducer in the third series resonator S3, then the wavelength of the first reflective grating and the wavelength of the corresponding first interdigital transducer in the other series resonators (second series resonator S2, fourth series resonator S4 and fifth series resonator S5) can be the same.

[0047] Specifically, the higher the impedance of the passband resonator, the more severe the signal attenuation and the greater the in-band insertion loss; conversely, the lower the impedance, the lower the in-band insertion loss. Increasing the wavelength of the first reflective grating, which originally had the same wavelength as the first interdigital transducer, increases the resonant frequency. By precisely aligning the passband center of the filter, the series arm formed by the series resonator remains in the low impedance range throughout the entire operating frequency band, thereby reducing in-band insertion loss. The wavelength of the second reflective grating, originally the same as the second interdigital transducer, is reduced to achieve the anti-resonance frequency. Within the passband range, the parallel arms formed by the parallel resonators exhibit high impedance, significantly reducing signal shunting to ground and further reducing passband loss.

[0048] In-band flatness characterizes the loss difference at different frequency points within the passband; the smaller the difference, the better the flatness. Increasing the wavelength of the first reflective grating, which originally had the same wavelength as the first interdigital transducer, and / or decreasing the wavelength of the second reflective grating, which originally had the same wavelength as the second interdigital transducer, is equivalent to changing the impedance curve of the resonator. The multiple impedance curves corresponding to at least one series resonator and at least one parallel resonator are superimposed and complementary, which can cancel out passband loss fluctuations and reduce in-band flatness.

[0049] The wavelength of at least one first reflective grating is greater than the wavelength of the corresponding first interdigital transducer, which can make the resonant frequency fall at the high end of the passband (close to the maximum value of the passband), thereby improving out-of-band suppression and isolation; the wavelength of at least one second reflective grating is less than the wavelength of the corresponding second interdigital transducer, which can make the anti-resonant frequency fall at the low end of the passband (close to the minimum value of the passband), thereby reducing insertion loss and improving in-band flatness.

[0050] Furthermore, the first difference between the wavelength of the first reflective grating and the wavelength of the corresponding first interdigital transducer is 0.5% to 6%, i.e., the first difference. And / or, the second difference between the wavelength of the second reflective grating and the wavelength of the corresponding second interdigital transducer is 0.5% to 6%, i.e., the second difference For example, the first difference and the second difference can be 0.5%, 2%, 3%, or 6%, etc. The first difference and the second difference can be the same or different.

[0051] Specifically, if the first difference and / or second difference If the value is too small, the resonant and anti-resonant frequencies will have almost no shift, making it difficult to achieve impedance complementarity, and the improvement in flatness and loss will be minimal; if the first difference is... and / or second difference If the value is too large, the resonant and anti-resonant frequencies will deviate excessively, potentially causing new impedance spikes and spurious peaks within the passband, thus affecting communication quality. This invention addresses this by using the first difference... and / or second difference Controlled Within this range, in-band insertion loss and in-band flatness can be optimized better without affecting communication quality.

[0052] For example, if the filter is a trapezoidal filter, the first difference and / or the second difference is 1% to 3%, for example, the first difference and the second difference can be 1%, 1.5%, or 3%, etc.; if the filter is a filter in a duplexer, the first difference and / or the second difference is 2% to 5%, for example, the first difference and the second difference can be 2%, 4%, or 5%, etc.; if the filter is a broadband filter with a relative bandwidth greater than the first threshold, the first difference and / or the second difference is 3% to 6%, for example, the first difference and the second difference can be 3%, 4%, or 6%, etc.; if the filter is a narrowband filter with a relative bandwidth less than the second threshold, the first difference and / or the second difference is 0.5% to 2%, for example, the first difference and the second difference can be 0.5%, 1%, or 2%, etc. Wherein, the first threshold is greater than the second threshold; for example, the first threshold can be 20%, and the second threshold can be 5%.

[0053] A trapezoidal filter is a filter whose circuit topology is trapezoidal; a duplexer is a three-port radio frequency device that includes two filters with different center frequencies, which transmit and receive simultaneously through the same antenna; a narrowband filter has a high Q value, such as a Q value greater than 20.

[0054] When the filter is a trapezoidal filter, limiting the first difference and / or the second difference to within 1% to 3% results in a smaller shift in the resonant frequency and anti-resonant frequency. This can create additional suppression points near the passband edge, thereby improving out-of-band rejection. At the same time, the smaller shift does not cause distortion, thus improving out-of-band rejection without increasing loss.

[0055] When the filter is a filter in a duplexer, limiting the first difference and / or the second difference to within 2% to 5% results in a larger offset between the resonant frequency and the anti-resonant frequency. This allows the transmission zero point (impedance change point) to fall precisely in the frequency band that needs to be suppressed (such as the receiving frequency band), thereby improving the transmit-receive isolation.

[0056] When the filter is a broadband filter, limiting the first difference and / or the second difference to within 3% to 6% results in a larger offset between the resonant frequency and the anti-resonant frequency, which can extend the operating frequency band of the resonator. After multiple resonators are superimposed, the bandwidth of the filter is increased. At the same time, the series resonators and parallel resonators are offset in different directions, and their low-impedance / high-impedance ranges are staggered and superimposed, which can eliminate loss fluctuations in the passband and improve flatness.

[0057] When the filter is a narrowband filter, the first difference and / or the second difference are limited to within 0.5% to 2%. The wavelengths of the reflector grating and the interdigital transducer are almost the same. The sound wave has high reflection efficiency in the reflector grating, low energy loss, can maintain a high Q value, has strong frequency selectivity, and can achieve precise filtering.

[0058] In other words, in trapezoidal filters, setting the first and / or second difference to 1%~3% can improve out-of-band rejection while ensuring low loss; in duplexers, setting the first and / or second difference to 2%~5% can better adjust the transmission zero position, thereby improving transmit-receive isolation; in broadband filters, setting the first and / or second difference to 3%~6% can broaden the bandwidth and improve flatness; in narrowband filters, setting the first and / or second difference to 0.5%~2% can maintain a high Q value and achieve precise filtering.

[0059] In some alternative implementations, such as Figure 3As shown, the interdigital transducer 10 includes a central region 104 and two edge regions (a first peripheral region 105 and a second peripheral region 106), with the two edge regions located on either side of the central region 104 along a first direction X. When the interdigital transducer 10 is a first interdigital transducer, the central region 104 is the first central region, and the two first edge regions are the first peripheral region 105 and the second peripheral region 106; when the interdigital transducer 10 is a second interdigital transducer, the central region 104 is the second central region, and the two second edge regions are the first peripheral region 105 and the second peripheral region 106.

[0060] The first interdigital transducer includes a first central region and two first edge regions, and the second interdigital transducer includes a second central region and two second edge regions; the wavelength of the first interdigital transducer in the first central region... Greater than the wavelength of the first interdigital transducer in the first edge region And / or, the wavelength of the second interdigital transducer in the second central region The wavelength greater than that of the second interdigital transducer in the second edge region .Right now , .For example, ,like It can be , or wait; ,like It can be , or wait.

[0061] in, , , , , This indicates the spacing between the fingers of the interdigital transducer in the central region. This indicates the spacing between the fingers of the interdigital transducer in the edge region.

[0062] In this embodiment, the wavelength of the edge region of the interdigital transducer is smaller than that of the center region, which can compensate for the phase delay caused by acoustic wave diffraction, reduce edge energy loss, and improve the Q value. The improvement of the Q value can make the filter have lower insertion loss.

[0063] Furthermore, the wavelength of the first interdigital transducer in the first edge region varies periodically or gradually along the first direction X; and / or, the wavelength of the second interdigital transducer in the second edge region varies periodically or gradually along the first direction X.

[0064] For example, the wavelength of the first interdigital transducer decreases periodically or gradually in the first edge region, and the wavelength of the second interdigital transducer decreases periodically or gradually in the second edge region. Periodicity means that the wavelength changes in the multiple sub-regions divided by the edge region are the same, and the wavelength of the interdigital transducer in the sub-region also decreases gradually. This invention does not limit the method of gradual change; for example, the wavelength can change linearly, according to a trigonometric function, or according to a quadratic function, etc.

[0065] In this embodiment, the interdigital transducer has a wavelength in the edge region that is shorter than that in the center region, and the wavelength in the edge region changes periodically or gradually, which is equivalent to introducing frequency chirp. This not only reduces edge reflection, improves Q value, and reduces insertion loss, but also suppresses lateral spurious modes and improves out-of-band suppression.

[0066] Furthermore, the first interdigital transducer has fewer than or equal to 20 electrode fingers in the first edge region; and / or, the second interdigital transducer has fewer than or equal to 20 electrode fingers in the second edge region. For example, the number of electrode fingers in the first or second edge region can be 5, 10, or 20, etc. The number of electrode fingers in the first and second edge regions can be the same or different.

[0067] The edge region where the wavelength changes continuously is sensitive to the number of electrode fingers. The more electrode fingers there are, the greater the cumulative phase deviation between different wavelength bands. Limiting the number of electrode fingers in the edge region to less than 20 results in a smaller cumulative phase error, which can fully utilize the advantages of the gradual wavelength change, while preventing the deterioration of communication performance due to phase mismatch.

[0068] This invention does not limit the specific structure of the resonator; in some optional embodiments, such as... Figure 4 As shown, the ends of the multiple electrode fingers of the first interdigital transducer are provided with metal blocks 107; and / or, the ends of the multiple electrode fingers of the second interdigital transducer are provided with metal blocks 107. The ends of the electrode fingers refer to the free ends of the electrode fingers that are not connected to the busbars (first busbar or second busbar).

[0069] In surface acoustic wave (SAW) and other elastic wave devices, transverse stray modes not only degrade the in-band ripple and out-of-band suppression characteristics of the filter, leading to increased insertion loss, but also significantly reduce the Q value of the resonator. This invention, by incorporating a metal block 107, can effectively suppress transverse modes using a piston mode, thereby improving out-of-band suppression and reducing insertion loss.

[0070] The performance of the filter provided by this invention will be described below with specific examples.

[0071] Comparative Example 1 In this embodiment, the filter is a conventional filter. , The wavelength of the interdigital transducer is a fixed value.

[0072] Example 1 In the series resonator, the wavelength of the first reflecting grating is 1.03 times the wavelength of the first interdigital transducer, that is... , In the parallel resonator, the wavelength of the second reflective grating is 0.98 times the wavelength of the second interdigital transducer, that is... , The other parameters of the filter in this embodiment are the same as those of a conventional filter.

[0073] Example 2 Compared with Example 1, this embodiment is different. , The wavelength of the first interdigital transducer gradually decreases in the first edge region, the wavelength of the second interdigital transducer gradually decreases in the second edge region, the number of electrode fingers in the first edge region is 20, and the number of electrode fingers in the second edge region is 20.

[0074] The simulation comparison graphs of in-band loss for Comparative Example 1, Example 1, and Example 2 can be seen as follows: Figure 5 As shown, the simulation comparison of out-of-band suppression between Comparative Example 1 and Example 1 can be seen as follows: Figure 6 As shown. Figure 5 and Figure 6 The horizontal axis represents frequency (freq), with the unit being GHz. The vertical axis represents the transmission coefficient from the input-output multiplexed port of the filter as the input to the input-output multiplexed port as the output. The transmission coefficient can be used to characterize the amount of loss or attenuation of the signal during transmission from the input to the output, i.e., the S-parameter, with the unit being decibels (dB).

[0075] from Figure 5 It can be seen that the in-band loss of conventional filters fluctuates significantly between 1.71 GHz and 1.76 GHz, while the in-band loss of the filters provided in Embodiments 1 and 2 fluctuates less (smaller loss deviation) between 1.71 GHz and 1.76 GHz, and is closer to 0 dB. The closer the value is to 0 dB, the lower the loss. The design of this invention reduces the in-band insertion loss and in-band flatness of the filter, thus improving its in-band performance. In addition, by reducing the wavelength in the edge region, the in-band insertion loss of the filter can be further reduced.

[0076] Moreover, from Figure 6 It can be seen that the out-of-band suppression effect of the filter provided in Example 1 is basically the same as that of the conventional filter. The present invention can reduce the in-band insertion loss and in-band flatness of the filter without affecting the out-of-band suppression effect, thereby improving the in-band performance of the filter.

[0077] The present invention also provides a multiplexer, which includes the filter provided in any of the above embodiments. The multiplexer includes multiple filters of different frequency bands, and at least one of the multiple filters of different frequency bands can be the filter provided by the present invention. For example, the multiplexer can be a duplexer or a quadplexer, etc.

[0078] The present invention also provides an electronic device, which includes the multiplexer provided in any of the above embodiments.

[0079] In the description of this specification, the references to terms such as "this embodiment," "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples, without contradiction.

[0080] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0081] The above description does not provide detailed explanations of the technical aspects of each layer's patterning and etching. However, those skilled in the art should understand that various technical means can be used to form layers and regions of the desired shape. Furthermore, to form the same structure, those skilled in the art can design methods that are not entirely identical to those described above. Additionally, although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be effectively combined.

[0082] The above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described above, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention.

[0083] Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention.

Claims

1. A filter, characterized in that, The filter includes: At least one series resonator is connected in series on a filter path formed by two input-output multiplexed ports. The series resonator includes a first interdigital transducer and a first reflective grating. The first reflective grating is disposed along at least one side of the first interdigital transducer in a first direction. At least one parallel resonator is arranged in parallel between the filter path and the ground terminal. The parallel resonator includes a second interdigital transducer and a second reflective grating. The second reflective grating is arranged along at least one side of a first direction of the second interdigital transducer. In at least one of the series resonators, the wavelength of at least one first reflective grating is different from the wavelength of the corresponding first interdigital transducer, and / or, in at least one of the parallel resonators, the wavelength of at least one second reflective grating is different from the wavelength of the corresponding second interdigital transducer.

2. The filter according to claim 1, characterized in that, At least one of the first reflective gratings has a wavelength greater than the wavelength of the corresponding first interdigital transducer, and / or at least one of the second reflective gratings has a wavelength less than the wavelength of the corresponding second interdigital transducer.

3. The filter according to claim 1, characterized in that, The first difference between the wavelength of the first reflective grating and the wavelength of the corresponding first interdigital transducer is 0.5% to 6%, and / or the second difference between the wavelength of the second reflective grating and the wavelength of the corresponding second interdigital transducer is 0.5% to 6%.

4. The filter according to claim 3, characterized in that, If the filter is a trapezoidal filter, then the first difference and / or the second difference is 1% to 3%; If the filter is a filter in a duplexer, then the first difference and / or the second difference is 2% to 5%; If the filter is a broadband filter with a relative bandwidth greater than the first threshold, then the first difference and / or the second difference is 3% to 6%; If the filter is a narrowband filter with a relative bandwidth less than the second threshold, then the first difference and / or the second difference is 0.5% to 2%, and the first threshold is greater than the second threshold.

5. The filter according to any one of claims 1 to 4, characterized in that, The first interdigital transducer includes a first central region and two first edge regions, the two first edge regions being located on both sides of the first central region along a first direction; the second interdigital transducer includes a second central region and two second edge regions, the two second edge regions being located on both sides of the second central region along a first direction. The wavelength of the first interdigital transducer in the first central region is greater than the wavelength of the first interdigital transducer in the first edge region, and / or the wavelength of the second interdigital transducer in the second central region is greater than the wavelength of the second interdigital transducer in the second edge region.

6. The filter according to claim 5, characterized in that, The wavelength of the first interdigital transducer in the first edge region varies periodically or gradually along the first direction; and / or, the wavelength of the second interdigital transducer in the second edge region varies periodically or gradually along the first direction.

7. The filter according to claim 5, characterized in that, Both the first interdigital transducer and the second interdigital transducer include a plurality of electrode fingers arranged at intervals; The number of electrode fingers of the first interdigital transducer in the first edge region is less than or equal to 20; And / or, the number of electrode fingers of the second interdigital transducer in the second edge region is less than or equal to 20.

8. The filter according to claim 7, characterized in that, The ends of the plurality of electrode fingers of the first interdigital transducer are provided with metal blocks; and / or, the ends of the plurality of electrode fingers of the second interdigital transducer are provided with metal blocks.

9. A multiplexer, characterized in that, The filter includes any one of claims 1 to 8.

10. An electronic device, characterized in that, Includes the multiplexer as described in claim 9.

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