A surface acoustic wave filter and a communication device

Abstract

The utility model provides a kind of acoustic surface filter and communication equipment, the acoustic surface filter includes: basic acoustic surface filter, and small resonator is arranged in the remaining space in basic acoustic surface filter layout, the remaining space in the basic acoustic surface filter layout is: in the position of basic acoustic surface filter in layout and the area outside input, output, ground electrode position of basic acoustic surface filter.The acoustic surface filter makes full use of the remaining space in basic acoustic surface filter layout, can significantly improve the rectangular degree of transition band on acoustic surface wave filter frequency response curve under the premise of not increasing equipment size, so that the frequency response of filter is more ideal.

Description

Technical Field

[0001] This utility model relates to the field of surface acoustic wave (SAW) filter design technology, specifically to a SAW filter and communication device. Background Technology

[0002] The rectangularity of a filter is an important performance indicator, especially in communication systems. Existing techniques typically improve rectangularity by adjusting the distance between series and parallel resonators using capacitive elements. The industry uses parallel capacitors to adjust the distance between the series and parallel resonators of the resonator, but this method only improves rectangularity within a limited adjustment range and has little impact on the transition band.

[0003] However, the employed capacitor adjustment method does not take into account the influence of the admittance resonance peak, resulting in insufficient adjustment effect and low sensitivity in improving rectangularity in the transition band. Traditional capacitor responses do not exhibit a significant resonance peak on the admittance curve, limiting their effectiveness in improving rectangularity. Utility Model Content

[0004] In order to overcome the defects existing in the prior art, the purpose of this utility model is to provide a sound meter filter and communication equipment.

[0005] To achieve the above-mentioned objectives of this utility model, this utility model provides a surface acoustic wave (SAW) filter, comprising: a basic SAW filter, and a small resonator disposed in the remaining space of the layout of the basic SAW filter, wherein the remaining space of the layout of the basic SAW filter is: the area outside the position of the basic SAW filter in the layout, and the positions of the input, output, and ground electrodes of the basic SAW filter.

[0006] This surface acoustic wave (SAW) filter makes full use of the remaining space in the layout of a basic SAW filter, and fabricates a small resonator without increasing the size of the device, resulting in more optimized space utilization and reduced energy consumption.

[0007] In addition, small resonators can optimize the performance of basic surface acoustic wave (SAW) filters.

[0008] Optionally, the admittance resonant peak of the miniature resonator is located at the edge of the passband on the frequency response curve of the basic surface acoustic wave (SAW) filter, which significantly improves the rectangularity of the transition band on the frequency response curve of the SAW filter, making the frequency response of the filter more ideal.

[0009] Optionally, the small resonators are connected in parallel or in series in the basic surface acoustic wave filter topology.

[0010] This alternative can further improve the rectangularity of the transition band of the SAW filter.

[0011] Optionally, when the miniature resonator is connected in parallel in the basic surface acoustic wave filter topology, one end of the miniature resonator is connected to the output side of a normal resonator, and the other end is grounded.

[0012] Optionally, when a small resonator is connected in series in a basic surface acoustic wave filter topology, the small resonator is connected to both ends of a normal resonator.

[0013] Optionally, the admittance resonant peak of the miniature resonator is located at the left or right edge of the passband of the frequency response curve of the basic surface acoustic wave filter.

[0014] This alternative approach helps to improve the rectangularity of the filter's transition band while minimizing the impact on the filter's passband response, thus ensuring the filter's filtering performance.

[0015] Optionally, the number of fingers in the miniature resonator does not exceed 100.

[0016] Optionally, the number of the small resonators is 1-3.

[0017] Optionally, the area of ​​the small resonator does not exceed 1 / 5 of the area of ​​the normal resonator connected to the small resonator in the basic surface acoustic wave filter topology, thereby achieving a small area and making full use of the remaining space in the layout.

[0018] Optionally, the aperture*number of the miniature resonator is the smallest among all resonators in the surface acoustic wave (SAW) filter. This option further ensures that the miniature resonator has minimal impact on the filter's passband response, thus guaranteeing the filter's filtering performance.

[0019] This application also proposes a communication device including the aforementioned surface acoustic wave (SAW) filter, thereby improving the filtering effect of the communication device.

[0020] The beneficial effects of this utility model are:

[0021] This invention can significantly improve the rectangularity of the transition band on the frequency response curve of the surface acoustic wave filter without increasing the size of the equipment, making the frequency response of the filter more ideal. At the same time, it can also ensure that the impact on the passband response of the filter is minimized, thus ensuring the filtering performance of the filter.

[0022] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0023] The above and / or additional aspects and advantages of this utility model will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0024] Figure 1 This is a schematic diagram of embedding a small resonator in a commonly used layout design structure;

[0025] Figure 2 This is a schematic diagram showing the relative positions of small resonators and normal resonators in the topo structure of a commonly used IEF filter; IEF6 is the added small resonator.

[0026] Figure 3 This is a schematic diagram showing the relative positional arrangement of small resonators and normal resonators in a common IEF filter topo structure; IEF6 is the added small resonator.

[0027] Figure 4 This is a schematic diagram comparing the principles of traditional methods and this utility model;

[0028] Figures 5 to 7 This is a schematic diagram comparing the rectangularity of the filter using this invention with the rectangularity of a normal filter; wherein, Figure 4 This is an overall comparison chart. Figure 5 This is a comparison chart of the transition zone. Figure 6 It is a passband comparison chart;

[0029] Figures 8 to 10 This is a schematic diagram comparing the effect of this invention on improving the rectangularity of the filter compared to the parallel capacitor method. Figure 7 This is an overall comparison chart. Figure 8 This is a comparison chart of the transition zone. Figure 9 This is a passband comparison chart. Detailed Implementation

[0030] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0031] In the description of this utility model, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "linking" should be interpreted broadly. For example, they can refer to mechanical or electrical connections, or internal connections between two components. They can be direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0032] Example 1

[0033] This invention provides a surface acoustic wave (SAW) filter, comprising a basic SAW filter and small resonators disposed within the remaining space of the basic SAW filter layout. The basic SAW filter refers to a filter whose preset electrical performance meets the device design requirements. The preset electrical performance does not include rectangularity. That is, in actual layout design, adding small resonators can further improve the rectangularity of the SAW filter, thereby achieving the overall electrical performance. In actual implementation, the preset electrical performance includes, but is not limited to, indicators such as loss and out-of-band rejection.

[0034] In terms of structure, a basic surface acoustic wave (SAW) filter refers to a SAW filter designed before the formation of a small filter on the layout. It consists of one or more resonators connected together. The specific resonator structure includes interdigital transducers fabricated on a wafer substrate, and more preferably, a temperature compensation layer and a passivation layer are fabricated on the metal finger electrodes of the interdigital transducer.

[0035] The remaining space in the layout of the basic surface acoustic wave (SAW) filter is the area outside the locations of the basic SAW filter as described in the layout, and the locations of its input, output, and ground electrodes. Preferably, the remaining space refers to the area outside the locations of the basic SAW filter, its input, output, and ground electrodes, and the locations between parallel basic SAW filters. The admittance peak of the small resonator is located at the edge of the passband on the frequency response curve of the basic SAW filter (the position of the admittance peak of the small resonator is determined by the spacing of its interdigital transducer fingers), specifically, it can be located at the left edge or the right edge of the passband, such as... Figure 1 As shown, it demonstrates how a small resonator can be fabricated and embedded into the filter topology in the remaining space on the surface acoustic wave filter layout, with the function of adjusting the steepness of the transition band region.

[0036] In this surface acoustic wave (SAW) filter, small resonators are connected in parallel or series within the basic SAW filter topology. When the small resonators are connected in parallel within the basic SAW filter topology, one end of the small resonator is connected to the output side of a normal resonator, and the other end is grounded. For example... Figure 2 As shown, one end of the miniature resonator IEF6 is connected to the output side of the normal resonator IEF4, and the other end of the miniature resonator IEF6 is grounded, acting on the right-hand transition band of the passband in the frequency response curve of the basic surface acoustic wave filter. When the miniature resonator is connected in series in the topology of the basic surface acoustic wave filter, the miniature resonator is connected to both ends of a normal resonator, such as... Figure 3 As shown, the small resonator IEF6 is connected to both ends of the normal resonator IEF4, and at this time it acts on the left transition band of the passband of the basic surface acoustic wave filter.

[0037] In this embodiment, the admittance peak of the small resonator is located at the edge of the passband on the frequency response curve of the basic surface acoustic wave (SAW) filter. The steepness of the transition band region on the frequency response curve of the basic SAW filter is adjusted, ensuring that the impact on the passband response of the basic SAW filter is minimized. For example... Figure 4 As shown, the red curve represents the admittance response of a normal resonator, and the black dashed line represents the main passband and out-of-band rejection response of a filter constructed from this type of resonator. The blue curve represents the admittance response of a small resonator, which has a lower amplitude and little impact on the passband, but significantly affects the rectangularity of the transition band. Introducing this small resonator into a conventional topo structure can significantly improve the rectangularity of the filter. When the small resonator is connected in parallel in the basic SAW filter topology, it acts on the right-hand transition band of the passband in the frequency response curve of the basic SAW filter; when the small resonator is connected in series in the basic SAW filter topology, it acts on the left-hand transition band of the passband in the frequency response curve of the basic SAW filter.

[0038] Preferably, the number of fingers in a small resonator is generally no more than 100, thereby achieving miniaturization.

[0039] In most cases, the number of miniature resonators is 1-3, preferably 1-2. The area size of the miniature resonator is significantly smaller than that of the normal resonator connected to it, preferably but not limited to not exceeding 1 / 5 of the area of ​​the normal resonator connected to the miniature resonator (e.g., the area of ​​the miniature resonator IEF6 is not more than 1 / 5 of the area of ​​the normal resonator IEF4 connected to it). In a more preferred embodiment, the aperture*number of the miniature resonator is the smallest among all resonators in the surface acoustic wave filter, thus ensuring miniaturization.

[0040] The effect of this embodiment on improving the rectangularity of the surface acoustic wave filter is as follows: Figure 5-10 As shown.

[0041] like Figure 5-7 The diagram illustrates the improvement in rectangularity achieved by this embodiment compared to a normal filter in the 800MHz band. The dashed line represents the filter response using this embodiment, while the solid line represents the response of a normal filter. It is clearly visible that this embodiment improves rectangularity by 2MHz.

[0042] like Figure 8-10 As shown, this illustrates a comparison between the traditional method of paralleling a capacitor next to a series resonator and the effect of this embodiment on improving the rectangularity of the transition band. As can be seen from the figure, using the parallel capacitor method (solid line) results in only less than 1 MHz of rectangularity improvement in the filter's transition band, approximately half that of this embodiment (dashed line). This embodiment, by adjusting the admittance response, achieves more precise control over the transition band steepness, effectively improving the rectangularity.

[0043] Example 2

[0044] This embodiment provides a communication device that includes the surface acoustic wave (SAW) filter described in Embodiment 1. This improves the filtering effect of the communication device.

[0045] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is 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.

[0046] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A surface acoustic wave (SAW) filter, characterized in that, include: A basic surface acoustic wave (SAW) filter, and a small resonator disposed in the remaining space of the basic SAW filter layout, wherein the remaining space of the basic SAW filter layout is the area outside the location of the basic SAW filter in the layout, and the locations of the input, output and ground electrodes of the basic SAW filter.

2. The surface acoustic wave (SAW) filter according to claim 1, characterized in that, The small resonators are connected in parallel or in series in the basic surface acoustic wave filter topology.

3. The surface acoustic wave filter according to claim 2, characterized in that, When a small resonator is connected in parallel in a basic surface acoustic wave filter topology, one end of the small resonator is connected to the output side of a normal resonator, and the other end is grounded.

4. The surface acoustic wave filter according to claim 2, characterized in that, When a small resonator is connected in series in a basic surface acoustic wave filter topology, the small resonator is connected to both ends of a normal resonator.

5. The surface acoustic wave (SAW) filter according to claim 1, characterized in that, The admittance peak of the small resonator is located at the edge of the passband of the frequency response curve of the basic surface acoustic wave filter, and the admittance peak of the small resonator is located at the left or right edge of the passband of the frequency response curve of the basic surface acoustic wave filter.

6. The surface acoustic wave filter according to claim 1, characterized in that, The number of fingers in the miniature resonator does not exceed 100.

7. The surface acoustic wave (SAW) filter according to claim 1, characterized in that, The number of the small resonators is 1-3.

8. The surface acoustic wave (SAW) filter according to claim 1, characterized in that, The area of ​​the small resonator does not exceed 1 / 5 of the area of ​​the normal resonator connected to the small resonator in the basic surface acoustic wave filter topology.

9. The surface acoustic wave (SAW) filter according to claim 1, characterized in that, The aperture*number of the small resonator is the smallest among all resonators in the surface acoustic wave (SAW) filter.

10. A communication device, characterized in that, Includes the surface acoustic wave filter as described in any one of claims 1 to 9.

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