CN214205476U

CN214205476U - Surface acoustic wave filter

Info

Publication number: CN214205476U
Application number: CN202120357534.5U
Authority: CN
Inventors: 刘长顺; 张伟; 董谦; 张修华; 姜琳; 马子轩
Original assignee: Shenzhen Zhongxun Sound Meter Research Center Co ltd
Current assignee: Huayuan Microelectronics Technology Shenzhen Co ltd
Priority date: 2021-02-08
Filing date: 2021-02-08
Publication date: 2021-09-14
Anticipated expiration: 2031-02-08

Abstract

The utility model provides a surface acoustic wave filter, including interdigital transducer and substrate, interdigital transducer is used for converting the signal of telecommunication into the surface acoustic wave, interdigital transducer sets up in the first surface of substrate, the substrate includes first terminal surface and second terminal surface, the slope contained angle has between first terminal surface and the surface acoustic wave propagation direction, the slope contained angle has between second terminal surface and the surface acoustic wave propagation direction. By adopting the chip end face oblique smearing technology, the first end face and the second end face of the substrate are processed into planes with oblique included angles, namely, the propagation direction of the surface acoustic wave has a certain included angle, so that the surface acoustic wave propagated to the first end face and the second end face of the substrate is reflected to the outside of the boundaries of the first end face and the second end face of the substrate and does not return to the transducer, the parasitic clutter interference caused by reflected waves is greatly weakened, and the parasitic clutter is not generated.

Description

Surface acoustic wave filter

Technical Field

The utility model belongs to the technical field of the surface acoustic wave chip technique and specifically relates to indicate a surface acoustic wave filter.

Background

In the prior art, the chip end face of the surface acoustic wave filter is vertical and perpendicular to the propagation direction of the surface acoustic wave. The surface acoustic wave propagates on the chip surface and is reflected by the chip end face when propagating to the chip end face. According to the wave reflection principle, the surface acoustic wave is reflected to an interdigital strip area of an interdigital transducer (IDT) along the normal direction, the IDT is excited to generate parasitic response, parasitic clutter is formed, adverse effects are generated on performance indexes such as pass band fluctuation, out-of-band rejection and the like of an acoustic surface filter, and the end face of a chip is required to be processed for reducing the influence of the parasitic clutter on the performance of the device.

SUMMERY OF THE UTILITY MODEL

The embodiment of the utility model provides a technical problem who solves is: the surface acoustic wave can generate parasitic clutter, which affects the performance of the device.

In order to solve the technical problem, the embodiment of the utility model provides an adopt technical scheme is:

the embodiment of the utility model provides a surface acoustic wave filter, including interdigital transducer group and substrate, interdigital transducer group is used for becoming the surface acoustic wave with electric signal conversion, interdigital transducer group sets up in the first surface of substrate, the substrate includes first terminal surface and second terminal surface, first slope contained angle has between first terminal surface and the surface acoustic wave direction of propagation, second slope contained angle has between second terminal surface and the surface acoustic wave direction of propagation.

Further, the first inclined included angle and the second inclined included angle are 60-80 degrees.

Furthermore, the first end face and the second end face are provided with metal blocks, and the surfaces of the metal blocks are arranged in parallel with the first end face and the second end face.

Further, the cross-sectional shape of the metal block is prismatic.

Further, the number of the interdigital transducer groups is two.

Furthermore, the substrate is made of quartz, lithium tantalate or lithium niobate.

The beneficial effects of the utility model reside in that: the embodiment of the utility model provides a surface acoustic wave filter, including interdigital transducer group and substrate, interdigital transducer group is used for becoming the surface acoustic wave with electric signal conversion, interdigital transducer group sets up in the first surface of substrate, the substrate includes first terminal surface and second terminal surface, the slope contained angle has between first terminal surface and the surface acoustic wave direction of propagation, has the slope contained angle between second terminal surface and the surface acoustic wave direction of propagation. The embodiment adopts the chip end face oblique smearing technology, and the first end face and the second end face of the substrate are processed into planes with oblique included angles, namely, the propagation direction of the surface acoustic wave has a certain included angle, so that the surface acoustic wave propagated to the first end face and the second end face of the substrate is reflected to the outside of the boundaries of the first end face and the second end face of the substrate and does not return to the interdigital transducer group, the parasitic clutter interference caused by reflected waves is greatly weakened, and the parasitic clutter is not generated.

Drawings

The following detailed description of the embodiments of the present invention with reference to the drawings

Fig. 1 is a schematic view of a first structure of an embodiment of the present invention;

fig. 2 is a second schematic structural diagram of the embodiment of the present invention.

Detailed Description

In order to explain technical contents, structural features, and objects and effects of the present invention in detail, the following description is given in conjunction with the embodiments and the accompanying drawings.

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are exemplary and intended to be used for explaining the present invention, and should not be construed as limiting the present invention.

Referring to fig. 1 and fig. 2, an embodiment of the present invention provides a surface acoustic wave filter, including an interdigital transducer group 1 and a substrate 2, where the interdigital transducer group 1 is configured to convert an electrical signal into a surface acoustic wave 3, the interdigital transducer group 1 is disposed on a first surface 21 of the substrate, the substrate 2 includes a first end surface 22 and a second end surface, a first inclined included angle 23 is formed between the first end surface 22 and a propagation direction of the surface acoustic wave 3, and a second inclined included angle is formed between the second end surface and a propagation direction of the surface acoustic wave 3.

When an electrical signal is connected to the interdigital transducer group 1, the first surface 21 of the substrate 2 will generate a surface acoustic wave 3 (mechanical vibration wave) having the same frequency as the input electrical signal, the surface acoustic wave 3 propagates along the first surface 21 of the substrate 2 and is transmitted to the interdigital transducer group 1 after a certain delay time, and the interdigital transducer group 1 converts the surface acoustic wave 3 into an electrical signal again for output. In the transformation process, useful components in the signal are selected, and useless interference signals are attenuated and filtered.

The surface acoustic wave 3 forms reflections at the first end surface 22 and the second end surface of the substrate 2 during propagation, and the reflection of the wave follows the principle that the angle between the reflection line and the normal (i.e., the reflection angle) is equal to the angle between the incident line and the normal (i.e., the incident angle). According to the principle, a chip end face oblique smearing technology is adopted, the first end face 22 and the second end face of the substrate 2 are processed into planes with oblique included angles, namely, the propagation direction of the surface acoustic wave 3 has a certain included angle, so that the surface acoustic wave 3 propagated to the first end face 22 and the second end face of the substrate 2 is reflected to the outside of the boundaries of the first end face 22 and the second end face of the substrate 2 and does not return to the interdigital transducer group 1, parasitic clutter interference caused by reflected waves is greatly weakened, and parasitic clutter is not generated any more.

Further, the first inclined included angle 23 and the second inclined included angle are 60-80 degrees.

In the embodiment, factors such as the size of the shell and the size of the chip are comprehensively considered, and after repeated tests, when the first inclined included angle 23 and the second inclined included angle are about 68 degrees, the electrical performance index requirements of the product can be well met.

Further, the first end face 22 and the second end face are provided with a metal block 24, and the surface of the metal block 24 is parallel to the first end face 22 and the second end face.

In this embodiment, the surface acoustic wave 3 propagates to the first end face 22 and the second end face of the substrate 2 to form reflections, and the reflected waves return to the interdigital transducer group 1 to generate parasitic clutter, which adversely affects electrical performance indexes such as passband ripple and out-of-band rejection of the device. In order to suppress the parasitic clutter and block or interfere the propagation of the parasitic clutter, in the embodiment, the metal blocks 24 are arranged at the first end face 22 and the second end face, when the parasitic clutter passes through the metal blocks 24, most of the parasitic clutter will be reflected to the outside of the interdigital transducer group 1 and will not be received by the interdigital transducer group 1, only a small part of the parasitic clutter may enter the interdigital transducer group 1, and because the wave front of the parasitic clutter is not parallel to the finger strips of the interdigital transducer group 1, the phase changes accordingly, the influence on the main signal is not generated, and further, the influence on the electric performance indexes such as the passband ripple and the out-of-band suppression of the device is effectively reduced.

Further, the metal block 24 has a prismatic cross-sectional shape, which can better match the first inclined angle 23 and the second inclined angle.

Further, the interdigital transducer group 1 is two. The interdigital transducer group 1 comprises an input interdigital transducer and an output interdigital transducer, and is very suitable for a plurality of wavelengths to pass through based on the low-speed characteristic of the interdigital transducer.

Further, the substrate 2 is made of quartz, lithium tantalate (LiTaO3), or lithium niobate.

The quartz in this embodiment has piezoelectricity; the lithium tantalate has the advantages of good mechanical and physical properties, low cost and the like; lithium niobate is a good piezoelectric transduction material, ferroelectric material and electro-optic material.

To sum up, the utility model provides a surface acoustic wave filter smears oblique technique, chip end face metal block surface acoustic wave reflection technology through adopting the chip end face, has reduced parasitic clutter effectively to the influence of device electrical property index, has guaranteed the flatness of passband waveform, has improved the outband and has restrained, has satisfied the index requirement of the high rectangle surface acoustic wave filter of intermediate frequency narrowband.

The above only is the embodiment of the present invention, not limiting the patent scope of the present invention, all the equivalent structures or equivalent processes that are used in the specification and the attached drawings or directly or indirectly applied to other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A surface acoustic wave filter includes an interdigital transducer group and a substrate, and is characterized in that: the interdigital transducer group is used for converting an electric signal into a surface acoustic wave, the interdigital transducer group is arranged on a first surface of the substrate, the substrate comprises a first end face and a second end face, a first inclined included angle is formed between the first end face and the surface acoustic wave propagation direction, and a second inclined included angle is formed between the second end face and the surface acoustic wave propagation direction.

2. A surface acoustic wave filter as set forth in claim 1, wherein: the first inclined included angle and the second inclined included angle are 60-80 degrees.

3. A surface acoustic wave filter as set forth in claim 2, wherein: the first end face and the second end face are provided with metal blocks, and the surfaces of the metal blocks are arranged in parallel with the first end face and the second end face.

4. A surface acoustic wave filter as set forth in claim 3, wherein: the cross section of the metal block is prismatic.

5. A surface acoustic wave filter as set forth in claim 4, wherein: the number of the interdigital transducer groups is two.

6. A surface acoustic wave filter as set forth in claim 5, wherein: the substrate is made of quartz, lithium tantalate or lithium niobate.