A SAW filter capable of effectively suppressing out-of-band high-frequency spur and a communication device

Abstract

The utility model provides a kind of effectively inhibiting out-of-band high-frequency spur SAW filter and communication equipment.The filter includes SAW filter chip, the bottom surface of the SAW filter chip is provided with sound-absorbing material layer, and the bottom surface of the sound-absorbing material layer is provided with plating layer.SAW filter chip includes piezoelectric material layer, and interdigital transducer arranged on the upper surface of piezoelectric material layer;The sound-absorbing material layer is arranged on the bottom surface of the piezoelectric material layer.The sound-absorbing material layer and plating layer in the SAW filter provided by the utility model can cooperatively absorb the sound wave propagating to the bottom of piezoelectric body substrate, thereby reducing the reflected sound wave, thereby achieving the purpose of inhibiting high-end out-of-band suppression spur, improving the out-of-band suppression of SAW filter.

Description

Technical Field

[0001] This utility model relates to the field of filter technology, specifically to a SAW filter and communication device that effectively suppresses out-of-band high-frequency glitches. Background Technology

[0002] With the rapid development of modern communication technology, wireless communication devices are increasingly demanding higher precision and stability in signal processing. Against this backdrop, surface acoustic wave (SAW) filters, as important passive devices, play a crucial role in radio frequency (RF) front-end signal processing due to their superior performance and reliability. SAW filters not only effectively filter out noise and interference, improving signal quality, but also enable precise frequency selection and bandwidth allocation, meeting the diverse needs of complex communication systems. In recent years, the rise of emerging fields such as 5G communication, the Internet of Things (IoT), and smart manufacturing has placed even higher demands on the performance of SAW filters. On the one hand, it is necessary to continuously improve the frequency selectivity and bandwidth control capabilities of SAW filters to adapt to the needs of high-speed data transmission and complex communication protocols; on the other hand, it is also necessary to pay attention to the miniaturization and integration trends of SAW filters to meet the space-constrained requirements of portable and wearable devices. At the same time, normal SAW filters have also encountered many challenges in their development. As the substrate thickness becomes thinner, the acoustic waves leaking from the IDT on the front of the substrate reach the back of the substrate more strongly, while the acoustic waves reflected from the back of the substrate reach the front, interfering with the main signal of the IDT. This causes the out-of-band glitches of the SAW filter to increase, which worsens the out-of-band rejection performance of the SAW filter. This is one of the challenges faced by normal SAW filters. Utility Model Content

[0003] In order to overcome the defects in the prior art, the purpose of this utility model is to provide a SAW filter and communication device that can effectively suppress out-of-band high-frequency glitches.

[0004] To achieve the above-mentioned objectives of this utility model, this utility model provides a SAW filter that effectively suppresses out-of-band high-frequency glitches, including a SAW filter chip, wherein a sound-absorbing material layer is disposed on the bottom surface of the SAW filter chip, and a coating layer is disposed on the bottom surface of the sound-absorbing material layer.

[0005] Optionally, the SAW filter chip includes a piezoelectric material layer and an interdigital transducer disposed on the upper surface of the piezoelectric material layer; the sound-absorbing material layer is disposed on the lower surface of the piezoelectric material layer.

[0006] Optionally, the sound-absorbing layer material is a polyurethane adhesive layer, or a silicone layer, or an acrylic adhesive layer, or a silicone rubber layer, or a rubber layer, or an epoxy resin adhesive layer.

[0007] Optionally, the thickness of the sound-absorbing layer material is less than 100 μm.

[0008] Optionally, the coating layer is a metal layer, a ceramic layer, or a polytetrafluoroethylene layer.

[0009] Optionally, the thickness of the coating layer is no greater than 20 μm.

[0010] Optionally, the coating layer covers the bottom and sidewalls of the sound-absorbing material layer.

[0011] Optionally, the coating layer covers the bottom and sidewalls of the sound-absorbing material layer, as well as the sidewalls of the piezoelectric material layer.

[0012] Optionally, the coating layer is encapsulated with a potting layer.

[0013] This application also provides a communication device including the aforementioned SAW filter.

[0014] The beneficial effects of this utility model are:

[0015] The sound-absorbing material layer and coating layer in the SAW filter provided by this invention can synergistically absorb sound waves propagating to the bottom of the piezoelectric substrate, thereby reducing reflected sound waves and achieving the goal of suppressing high-end out-of-band noise and improving the out-of-band rejection of the SAW filter. The thickness requirement of the sound-absorbing material layer also ensures the miniaturization and packaging requirements of the SAW filter. The coating layer's coverage of the bottom and sidewalls of the sound-absorbing material layer, as well as the sidewalls of the piezoelectric material layer, further improves the out-of-band rejection of the SAW filter.

[0016] 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

[0017] 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:

[0018] Figure 1 This is a schematic diagram of the structure of this utility model;

[0019] Figure 2 This is a comparison diagram of the overall response of the filter of this utility model and the comparative example. Detailed Implementation

[0020] 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.

[0021] 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.

[0022] Example 1

[0023] like Figure 1 As shown, this utility model provides a filter that effectively suppresses out-of-band high-frequency glitches. This filter is a normal SAW filter, comprising a SAW filter chip. The SAW filter chip includes a piezoelectric material layer and interdigital transducers disposed on the upper surface of the piezoelectric material layer. A sound-absorbing material layer is disposed on the bottom surface of the SAW filter chip, i.e., the lower surface of the piezoelectric material layer. A coating layer is disposed on the bottom surface of this sound-absorbing material layer. Preferably, the coating layer covers the bottom and sidewalls of the sound-absorbing material layer; further, it may also cover the sidewalls of the piezoelectric material layer. An encapsulating layer is applied to the outside of the coating layer.

[0024] In this embodiment, the piezoelectric material layer preferably uses, but is not limited to, lithium tantalate or lithium niobate with a Y-cut X-propagation rotation of 30° or more but less than 60°. The sound-absorbing layer material is a polyurethane adhesive layer, or a silicone layer, or an acrylic adhesive layer, or a silicone rubber layer, or a rubber layer, or an epoxy resin adhesive layer, such as one or any combination of 703 adhesive layer, 704 silicone rubber layer, Dow Corning 170 silicone rubber layer, and Shin-Etsu KE-441 silicone rubber layer, and the thickness of the sound-absorbing layer material is less than 100 μm. The coating layer is a metal layer (such as aluminum, copper, or titanium), or a ceramic layer (such as alumina or silicon nitride), or a polytetrafluoroethylene layer, and its thickness is not greater than 20 μm.

[0025] Working principle: The master mode SAW excited by the electrode propagates on the surface of the piezoelectric substrate. The leaked sound waves propagate into the piezoelectric substrate and are absorbed by the sound-absorbing material layer and coating layer at the bottom of the substrate. This reduces or even absorbs the sound waves propagating to the bottom of the piezoelectric substrate, thereby improving the out-of-band burr problem caused by sound wave reflection. This also suppresses the burrs in the high-end out-of-band suppression. Figure 2As shown, it demonstrates the overall response comparison between the embodiment of this utility model and the comparative example (without sound-absorbing layer and coating layer). It can be seen that compared with the comparative example, the filter of this utility model has a significantly better effect in suppressing high-end out-of-band noise, whether using a sound-absorbing layer alone or using both a sound-absorbing layer and a coating layer. The effect is even better when using both a sound-absorbing layer and a coating layer.

[0026] Example 2

[0027] This application also provides a communication device that includes the SAW filter described in Embodiment 1.

[0028] 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.

[0029] 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 SAW filter that effectively suppresses out-of-band high-frequency glitches, characterized in that, The device includes a SAW filter chip, wherein a sound-absorbing material layer is disposed on the bottom surface of the SAW filter chip, and a coating layer is disposed on the bottom surface of the sound-absorbing material layer.

2. The SAW filter for effectively suppressing out-of-band high-frequency glitches according to claim 1, characterized in that, The SAW filter chip includes a piezoelectric material layer and an interdigital transducer disposed on the upper surface of the piezoelectric material layer; the sound-absorbing material layer is disposed on the lower surface of the piezoelectric material layer.

3. The SAW filter for effectively suppressing out-of-band high-frequency glitches according to claim 1, characterized in that, The sound-absorbing layer material is a polyurethane adhesive layer, or a silicone layer, or an acrylic adhesive layer, or a silicone rubber layer, or a rubber layer, or an epoxy resin adhesive layer.

4. The SAW filter for effectively suppressing out-of-band high-frequency glitches according to claim 3, characterized in that, The thickness of the sound-absorbing layer material is less than 100 μm.

5. The SAW filter for effectively suppressing out-of-band high-frequency glitches according to claim 1, characterized in that, The coating layer is a metal layer, a ceramic layer, or a polytetrafluoroethylene layer.

6. The SAW filter for effectively suppressing out-of-band high-frequency glitches according to claim 1 or 5, characterized in that, The thickness of the coating layer is no greater than 20 μm.

7. The SAW filter for effectively suppressing out-of-band high-frequency glitches according to claim 1, characterized in that, The coating layer covers the bottom and sidewalls of the sound-absorbing material layer.

8. The SAW filter for effectively suppressing out-of-band high-frequency glitches according to claim 1, characterized in that, The coating layer covers the bottom and sidewalls of the sound-absorbing material layer, as well as the sidewalls of the piezoelectric material layer.

9. The SAW filter for effectively suppressing out-of-band high-frequency glitches according to claim 1, characterized in that, The coating layer is encapsulated with a potting layer.

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

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