CN216390939U

CN216390939U - XBAR filter

Info

Publication number: CN216390939U
Application number: CN202122617806.3U
Authority: CN
Inventors: 胡锦钊; 郭嘉帅
Original assignee: Shenzhen Volans Technology Co Ltd
Current assignee: Shenzhen Volans Technology Co Ltd
Priority date: 2021-10-28
Filing date: 2021-10-28
Publication date: 2022-04-26
Anticipated expiration: 2031-10-28
Also published as: WO2023071516A1

Abstract

The embodiment of the utility model discloses an XBAR filter, which comprises a piezoelectric substrate, at least two interdigital transducers and at least two insulating layers, wherein the at least two interdigital transducers and the at least two insulating layers are formed on the piezoelectric substrate; each insulating layer is arranged between the corresponding interdigital transducer and the piezoelectric substrate, or arranged on one side of the piezoelectric substrate opposite to the corresponding interdigital transducer, wherein the thicknesses of the insulating layers corresponding to at least two interdigital transducers are different, and through the mode, resonators with different resonant frequencies can be formed on the same piezoelectric substrate, so that the requirement of a ladder filter is met.

Description

XBAR filter

Technical Field

The utility model relates to the technical field of filters, in particular to an XBAR filter.

Background

The frequency band of the wireless communication technology is higher and higher from 1G to 5G, and meanwhile, the bandwidth is also larger and larger, for example, the bandwidths of N77 and N79 in the 5G frequency band reach 900MHz and 600MHz, respectively. Conventional mechanical resonator structures have been difficult to meet the associated bandwidth requirements, and XBAR filters have emerged accordingly. The XBAR Filter is one of bulk acoustic wave filters (Baw-SMR Filter) that can achieve an electromechanical coupling coefficient of 20% or more, thereby achieving a large bandwidth. The resonant frequency of the XBAR filter is generally determined by the thickness of the piezoelectric substrate, however, the piezoelectric substrate thickness of the conventional XBAR filter is single, so that when the filter having the ladder structure is required to be formed, it is difficult to realize the required filter having the ladder structure using the conventional XBAR filter because at least two different resonant frequencies are required for the filter having the ladder structure.

SUMMERY OF THE UTILITY MODEL

The embodiment of the utility model provides an XBAR filter, which can obtain at least two resonators with different resonant frequencies on the same piezoelectric substrate, thereby meeting the frequency requirement of a ladder filter, avoiding the heterogeneous integration of piezoelectric substrate materials with different thicknesses and reducing the packaging difficulty and cost.

In order to solve the above technical problem, an aspect of the present invention provides an XBAR filter, including a piezoelectric substrate, at least two interdigital transducers and at least two insulating layers formed on the piezoelectric substrate, where the insulating layers are arranged in one-to-one correspondence with the interdigital transducers, and each interdigital transducer and its corresponding insulating layer and the piezoelectric substrate are used to form a resonator;

each insulating layer sets up between corresponding interdigital transducer and piezoelectric substrate, or set up piezoelectric substrate with correspond on one side that interdigital transducer is relative, wherein at least two the thickness of the insulating layer that interdigital transducer corresponds is different.

The thickness of the piezoelectric substrate is 0.1 lambda-4 lambda, and the lambda is the wavelength of the bulk acoustic wave.

Wherein λ 2 × p, where p denotes a period of the interdigital transducer.

The duty ratio of the interdigital transducer is 0.1-0.9.

The insulating layer is a silicon dioxide insulating layer or a silicon nitride insulating layer.

The interdigital transducer is made of one or more of Al, Cu, Pt, Au and Ti.

Wherein the piezoelectric substrate is made of LiNbO3 or LiTaO 3.

Has the advantages that: the XBAR filter comprises a piezoelectric substrate, at least two interdigital transducers and at least two insulating layers, wherein the at least two interdigital transducers and the at least two insulating layers are formed on the piezoelectric substrate, the insulating layers are arranged in one-to-one correspondence with the interdigital transducers, and each interdigital transducer, the corresponding insulating layer and the piezoelectric substrate are used for forming a resonator, so that the XBAR filter comprises at least two resonators; wherein each of the insulating layers is provided between the corresponding interdigital transducer and a piezoelectric substrate, or on a side of the piezoelectric substrate opposite to the corresponding interdigital transducer, therefore, each combination of the insulating layer and the piezoelectric substrate corresponds to a whole piezoelectric base material, and the thicknesses of the insulating layers corresponding to at least two interdigital transducers are different, i.e. the thickness of at least two piezoelectric substrates, which determine the resonance frequency of the resonator, is different, so that resonators of at least two different frequencies can be obtained, therefore, by the mode, the utility model can form resonators with different frequencies on a single piezoelectric substrate, meet the requirements of the ladder filter, and each resonator adopts the same piezoelectric substrate, so that heterogeneous integration of piezoelectric substrate materials with different thicknesses can be avoided, and the packaging difficulty and cost are reduced.

Drawings

The technical solution and the advantages of the present invention will be apparent from the following detailed description of the embodiments of the present invention with reference to the accompanying drawings.

Fig. 1 is a schematic structural diagram of an XBAR filter according to an embodiment of the present invention.

Detailed Description

Referring to the drawings, wherein like reference numbers refer to like elements, the principles of the present invention are illustrated as being implemented in a suitable computing environment. The following description is based on illustrated embodiments of the utility model and should not be taken as limiting the utility model with regard to other embodiments that are not detailed herein.

Referring to fig. 1, an XBAR filter 100 according to an embodiment of the present invention includes a piezoelectric substrate 11, at least two interdigital transducers 12 formed on the piezoelectric substrate 11, and at least two insulating layers 13. The insulating layers 13 are arranged in one-to-one correspondence with the interdigital transducers 12, and each interdigital transducer 12, the corresponding insulating layer 13 thereof, and the piezoelectric substrate 11 are used for forming a resonator, so in the embodiment of the present invention, the XBAR filter 100 includes at least two resonators. As shown in fig. 1, taking two interdigital transducers 12 as an example, accordingly, the number of the insulating layers 13 is also 2, so that the resonators formed by the two interdigital transducers 12 and the corresponding insulating layers 13 and piezoelectric substrate 13 are resonator a and resonator B, respectively.

Wherein each of the insulating layers 13 is provided between the corresponding interdigital transducer 12 and the piezoelectric substrate 11, or on a side of the piezoelectric substrate 11 opposite to the corresponding interdigital transducer 12. In the embodiment shown in fig. 1, the insulating layer 13 is provided on the side of the piezoelectric substrate 11 opposite to the interdigital transducers 12, wherein the thicknesses of the insulating layers 13 corresponding to the two interdigital transducers 12 are different.

Therefore, the combination of each insulating layer 13 and the piezoelectric substrate 11 is equivalent to an integral piezoelectric base material, and the thicknesses of the insulating layers 13 corresponding to the two interdigital transducers 12 are different, that is, the thicknesses of the two piezoelectric base materials are different, and the thicknesses of the piezoelectric base materials determine the resonant frequency of the resonator, so that the resonators A and B with two different frequencies can be obtained.

Further, the thickness of the piezoelectric substrate 11 is 0.1 λ to 4 λ, where λ is a bulk acoustic wave wavelength. Where λ is 2 × p, where p denotes a period of the interdigital transducer 12, that is, p is a sum of a length of the interdigital transducer 12 and a distance between two adjacent interdigital transducers 12, the length of the interdigital transducer 12 described herein refers to a length of the interdigital transducer 12 in a horizontal direction based on the view of fig. 1.

The duty ratio of the interdigital transducer 12 is 0.1-0.9. The duty cycle of the interdigital transducer 12 is the ratio of the length of the interdigital transducer 12 to p.

Wherein the insulating layer 13 may be a silicon dioxide insulating layer or a silicon nitride insulating layer. The interdigital transducer 12 is made of one or more of Al, Cu, Pt, Au and Ti, for example, it may be made of Al alone, or a stack of Al, Cu, Pt, Au and Ti. The piezoelectric substrate 11 is made of LiNbO3 or LiTaO 3.

It is to be understood that the number of interdigital transducers 12 in the present embodiment is not limited, and may be 2, 5, or more.

In the XBAR filter 100 of the present invention, the same piezoelectric substrate 11 is used for the piezoelectric substrate of each resonator, so the thicknesses thereof are consistent, and the insulating layers 13 with different thicknesses are provided, so that the resonance frequency of the resonator can be changed to a certain extent, thereby realizing the formation of resonators with different resonance frequencies on the same piezoelectric substrate 11.

The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for those skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.

Claims

1. An XBAR filter is characterized by comprising a piezoelectric substrate, at least two interdigital transducers and at least two insulating layers, wherein the at least two interdigital transducers and the at least two insulating layers are formed on the piezoelectric substrate, the insulating layers and the interdigital transducers are arranged in a one-to-one correspondence mode, and each interdigital transducer, the corresponding insulating layer and the piezoelectric substrate are used for forming a resonator;

2. The XBAR filter of claim 1, wherein the thickness of the piezoelectric substrate is between 0.1 λ and 4 λ, where λ is the bulk acoustic wave wavelength.

3. The XBAR filter of claim 2, wherein λ -2 × p, where p represents the period of an interdigital transducer.

4. The XBAR filter of claim 1 wherein said interdigital transducer has a duty cycle of 0.1-0.9.

5. The XBAR filter of claim 1, wherein the insulating layer is a silicon dioxide insulating layer or a silicon nitride insulating layer.

6. The XBAR filter of claim 1, wherein the interdigital transducer is made of one or more of Al, Cu, Pt, Au, and Ti.

7. The XBAR filter of claim 1, wherein the piezoelectric substrate is LiNbO3 or LiTaO 3.