CN115664370A - Plate wave filter with multiple transmission zeros and signal processing circuit - Google Patents

Abstract

This application relates to the technical field of device preparation, and provides a plate wave filter with multiple transmission zeros and a signal processing circuit. The plate wave filter with multiple transmission zeros includes sequentially cascaded parallel resonators and series resonators, parallel resonators and There are at least two resonators in the series resonator with different in-plane transmission directions of plate wave modes, the anti-resonance point of the series resonator and the resonance point of the parallel resonator constitute multiple zero positions; the in-plane transmission direction is the fork of the resonator Refers to the normal direction of the electrode; the resonator includes an electrode assembly, a piezoelectric film, and a supporting substrate from top to bottom; there is a space between the piezoelectric film and the supporting substrate to confine the energy of the plate wave mode of the resonator to the plate The suspended structure in the wave filter, the acoustic wave modes excited by the parallel resonator and the series resonator are the same. By arranging resonators with different in-plane transmission directions, the electromechanical coupling coefficient of the resonators can be greatly adjusted, and then the plate wave filter with multiple transmission zeros can be realized more flexibly.

Description

A plate wave filter with multiple transmission zeros and signal processing circuit

technical field

The invention relates to the technical field of device preparation, in particular to a multi-transmission zero-point plate wave filter and a signal processing circuit.

Background technique

The electromechanical coupling coefficient of the existing resonator based on a single in-plane transmission direction is difficult to adjust in a large range, and it has great limitations when forming a multi-zero filter. Moreover, a filter with multiple transmission zeros is formed by cascading inductive elements and capacitive elements. The inductive elements and capacitive elements cause large device volume and serious parasitic effects, which affect the miniaturization and high performance of the device.

Contents of the invention

In order to solve the problem of low performance of existing filters, embodiments of the present application provide a plate wave filter with multiple transmission zeros and a signal processing circuit.

According to the first aspect of the present application, a plate wave filter with multiple transmission zeros is provided, including:

A parallel resonator and a series resonator, and the parallel resonator and the series resonator are cascaded in sequence;

The parallel resonator and the series resonator have at least two resonator plate wave modes with different in-plane transmission directions; the in-plane transmission direction is the normal direction of the interdigitated electrodes in the resonator;

The resonator includes an electrode assembly, a piezoelectric film, and a supporting substrate from top to bottom; there is a suspended structure between the piezoelectric film and the supporting substrate, and the suspended structure is used to confine the energy of the plate wave mode of the resonator to the plate wave resonance inside the device;

The acoustic modes excited by both the parallel resonator and the series resonator are the same.

Further, the plate wave mode includes zero-order plate wave and high-order plate wave;

Zero-order plate waves include zero-order antisymmetric Lamb waves, zero-order symmetric Lamb waves and zero-order horizontal shear waves;

Higher-order plate waves include higher-order antisymmetric Lamb waves, higher-order symmetric Lamb waves, and higher-order horizontal shear waves.

Further, when the plate wave mode of the resonator is a zero-order plate wave, the electrode assembly includes an interdigital electrode assembly and a reflective grid electrode assembly;

The metallization rate of the interdigitated electrodes in the interdigitated electrode assembly is within the interval [30%, 65%];

The ratio of the thickness of the piezoelectric film to the period of the interdigital electrode assembly is in the interval [10%, 75%].

Further, when the plate wave mode of the resonator is a high-order plate wave, the electrode assembly includes an interdigitated electrode assembly;

The metallization rate of the interdigitated electrode in the interdigitated electrode assembly is within the interval [5%, 45%];

The ratio of the thickness of the piezoelectric film to the period of the interdigital electrode assembly is in the interval [2%, 17.5%].

Further, the resonator also includes a dielectric layer disposed on the electrode assembly;

The ratio of the thickness of the dielectric layer to the period of the electrode assembly is within the interval [1%, 20%].

Further, the corresponding position of the electrode assembly on the supporting substrate coincides with the position of the suspended structure on the supporting substrate;

the suspended structure extends through the support substrate; or;

A part of the supporting substrate is etched to form a closed suspended structure with the piezoelectric film.

Further, the in-plane propagation directions of the plate wave modes of the resonators in the series resonator and the parallel resonator are different.

Further, the in-plane transmission directions of the plate wave modes in which there are at least two resonators in the series resonator and the parallel resonator are the same.

Further, the in-plane propagation direction of the plate wave mode of at least one resonator in the parallel resonator is the same as the in-plane propagation direction of the plate wave of the resonator in the series resonator.

According to the second aspect of the present application, a signal processing circuit is provided, the signal processing circuit includes the above-mentioned plate wave filter with multiple transmission zeros.

The embodiment of the present application has the following beneficial effects:

The embodiments of the present application provide a plate wave filter with multiple transmission zeros and a signal processing circuit. The plate wave filter with multiple transmission zeros includes a parallel resonator and a series resonator, and the parallel resonator and the series resonator are cascaded in sequence; There are at least two resonators in the resonator and the series resonator in which the in-plane transmission direction of the plate wave mode is different; the in-plane transmission direction is the normal direction of the interdigitated electrode in the resonator; the resonator includes the electrode assembly from top to bottom , piezoelectric film and support substrate; there is a suspended structure between the piezoelectric film and the support substrate, the suspended structure is used to confine the energy of the plate wave mode of the resonator in the plate wave filter, parallel resonators and series resonators The sound wave modes excited are all the same. Based on the embodiment of the present application, by arranging resonators with different in-plane transmission directions, the electromechanical coupling coefficient of the resonators can be greatly adjusted, thereby more flexibly realizing a plate wave filter with multiple transmission zeros. By setting the suspended structure, the energy of the plate wave mode can be better confined in the device area by taking advantage of the huge acoustic impedance mismatch with the air.

Description of drawings

In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present application or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the appended The drawings are only some embodiments of the present application, and those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is the response schematic diagram of existing traditional double-zero point filter;

Fig. 2 is a schematic diagram of the variation curve of the operating frequency and electromechanical coupling coefficient of the resonator in a plate wave filter with the wavelength of the device;

Fig. 3 is a schematic diagram of the variation curve of the operating frequency and the electromechanical coupling coefficient of the resonator in another plate wave filter with the wavelength of the device;

FIG. 4 is a schematic diagram of the topology of a plate wave filter with multiple transmission zeros provided by an embodiment of the present application;

Fig. 5 is a schematic diagram 1 of the change curve of the operating frequency and electromechanical coupling coefficient of the resonator in the plate wave filter provided by the embodiment of the present application with the in-plane transmission direction;

Fig. 6 is a second schematic diagram of the change curve of the resonator operating frequency and electromechanical coupling coefficient with the in-plane transmission direction in the plate wave filter provided by the embodiment of the present application;

FIG. 7 is a first structural schematic diagram of a resonator in a plate wave filter provided by an embodiment of the present application;

FIG. 8 is a second structural schematic diagram of a resonator in a plate wave filter provided by an embodiment of the present application;

Fig. 9 is a structural schematic diagram III of a resonator in a plate wave filter provided by an embodiment of the present application;

FIG. 10 is a schematic structural diagram of a plate wave filter provided by an embodiment of the present application;

FIG. 11 is a simulation curve diagram of a resonator and filter provided in an embodiment of the present application;

Fig. 12 is a schematic diagram of a signal processing circuit provided by an embodiment of the present application;

FIG. 13 is a schematic diagram of another signal processing circuit provided by an embodiment of the present application.

Detailed ways

In order to make the purpose, technical solution and advantages of the present application clearer, the embodiments of the present application will be further described in detail below in conjunction with the accompanying drawings. Apparently, the described embodiment is only one embodiment of the present application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of this application.

The "embodiment" referred to herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present application. In the description of the embodiments of the present application, it should be understood that the terms "first", "second", etc. are used for description purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly indicating the indicated technical features quantity. Thus, a feature defined as "first", "second", etc. may expressly or implicitly include one or more of such feature. Also, the terms "first", "second", etc. are used to distinguish similar items and not necessarily to describe a specific order or sequence. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the application described herein can be practiced in sequences other than those illustrated or described herein. Furthermore, the terms "comprising", "having" and "for", as well as any variations thereof, are intended to cover a non-exclusive inclusion.

FIG. 1 is a schematic diagram of the response of an existing traditional double-zero point filter. The existing traditional double-zero filter based on 4 series resonators and 3 parallel resonators, the resonant frequency of the series resonator is close to the anti-resonant frequency of the parallel resonator, and the zero point position of the filter directly corresponds to the series resonator The antiresonance point and the resonance point of the parallel resonator. The comprehensive electrical performance of the filter can be improved if a multi-zero design is adopted, but each resonator of the filter needs to have different resonant frequencies and electromechanical coupling coefficients.

Fig. 2 is a schematic diagram of the variation curve of the operating frequency and electromechanical coupling coefficient of a resonator in a plate wave filter with the wavelength of the device. Each resonator in the plate wave filter includes an aluminum Al electrode with a thickness of 100 nm, an X-cut lithium niobate LiNbO ₃ piezoelectric film with a total thickness of 600 nm, and a Si support substrate. The acoustic wave mode of the device is zero-order horizontal shear wave, and the in-plane transmission direction θ=25°. It can be seen from Figure 2 that the operating frequency of the device is inversely proportional to the wavelength λ, and the electromechanical coupling coefficient k _t ² changes little in the range of λ∈[1.5μm, 2.3μm]. Fig. 3 is a schematic diagram of the variation curve of the operating frequency and electromechanical coupling coefficient of the resonator in another plate wave filter with the wavelength of the device. Each resonator in the plate wave filter includes an aluminum Al electrode with a thickness of 100nm, a Y128°cut lithium niobate LiNbO ₃ piezoelectric film with a total thickness of 600nm, and a Si support substrate. The acoustic wave mode of the device is the first-order antisymmetric Lamb wave mode, and the in-plane transmission direction θ=0°. It can be seen from Figure 3 that the operating frequency of the device is inversely proportional to the wavelength λ, and the electromechanical coupling coefficient k _t ² changes little in the range of λ∈[13μm, 18μm]. It can be seen from Figure 2 and Figure 3 that no matter it is the zero-order mode or the high-order mode, the plate wave resonator based on the same in-plane transmission direction has insufficient flexibility in adjusting the electromechanical coupling coefficient. has great limitations.

Moreover, for the traditional SAW filter based on a single piezoelectric single crystal material, it is not suitable to use multiple resonators with different in-plane transmission directions, because along different in-plane transmission directions, the transmission loss of the plate wave will also appear. Large changes, that is, the Q value of the SAW resonator along the part of the in-plane transmission direction is low, which cannot meet the application requirements.

The following describes a specific embodiment of a plate wave filter with multiple transmission zeros in the present application. FIG. 4 is a schematic diagram of the topology of a plate wave filter with multiple transmission zeros provided in an embodiment of the present application. This specification provides the composition structures as shown in the embodiments or drawings, but more or less modules or components may be included based on routine or non-inventive efforts. The composition structure listed in the embodiment is only one of many composition structures, and does not represent the only composition structure. In actual implementation, it can be implemented according to the composition structure shown in the embodiment or the accompanying drawings.

As shown in FIG. 4 , in the embodiment of the present application, the plate wave filter with multiple transmission zeros may include parallel resonators and series resonators, and the parallel resonators and series resonators may be cascaded in sequence. Among them, there are at least two resonators in the parallel resonator and the series resonator with different in-plane transmission directions of the plate wave mode, which realizes a large change in the electromechanical coupling coefficient of the resonator, making it more flexible to realize the multi-zero point filter. The in-plane transmission direction may be the normal direction of the interdigitated electrodes in the resonator. The resonator can include an electrode assembly, a piezoelectric film, and a supporting substrate from top to bottom; there is a suspended structure between the piezoelectric film and the supporting substrate, and the suspended structure is used to confine the energy of the plate wave mode of the resonator in the plate wave Within the filter, the acoustic modes excited by the parallel and series resonators are the same. By arranging resonators with different in-plane transmission directions, the electromechanical coupling coefficient of the resonators can be greatly adjusted, and then the plate wave filter with multiple transmission zeros can be realized more flexibly.

In the embodiment of the present application, the plate wave mode may include zero-order plate waves and high-order plate waves. Zero-order plate waves can include zero-order antisymmetric Lamb waves, zero-order symmetric Lamb waves, and zero-order horizontal shear waves, and high-order plate waves can include high-order antisymmetric Lamb waves, high-order symmetric Lamb waves, and high-order first-order horizontal shear waves.

In some possible implementation manners, when the plate wave mode of the resonator is a zero-order plate wave, the electrode assembly may include an interdigital electrode assembly and a reflective grid electrode assembly. That is, if the excited mode is the zero-order plate wave mode, reflection gratings on the left and right sides are necessary. The metallization rate of the interdigital electrode in the interdigital electrode assembly can be within the interval [30%, 65%], and the ratio of the thickness of the piezoelectric film to the period of the interdigital electrode assembly can be within the interval [10%, 75%].

In some possible implementations, when the plate wave mode of the resonator is a high-order plate wave, the electrode assembly includes an interdigital electrode assembly. That is, if the excited mode is a high-order plate wave mode, the reflective gratings on the left and right sides can be removed. The metallization rate of the interdigital electrode in the interdigital electrode assembly can be within the interval [5%, 45%], and the ratio of the thickness of the piezoelectric film to the period of the interdigital electrode assembly can be within the interval [2%, 17.5%].

FIG. 5 is a first schematic diagram of the variation curves of the operating frequency and the electromechanical coupling coefficient of the resonator in the plate wave filter provided by the embodiment of the present application with the in-plane transmission direction. The resonator consists of an aluminum Al electrode with a thickness of 100 nm, an X-cut piezoelectric film of lithium niobate LiNbO ₃ with a total thickness of 600 nm, and a Si support substrate. The acoustic mode of the device is zero-order horizontal shear wave. It can be seen from Figure 5 that the electromechanical coupling coefficient of the resonator is as high as 36% when the in-plane transmission direction is 12°, and as low as 0 when the in-plane transmission direction is 60°, 90° and 140°, showing a large overall change. Phenomenon. Fig. 6 is a schematic diagram 2 of the variation curve of the operating frequency of the resonator and the electromechanical coupling coefficient with the in-plane transmission direction in the plate wave filter provided by the embodiment of the present application. The resonator consists of an aluminum Al electrode with a thickness of 100 nm, a Y128°-cut piezoelectric film of lithium niobate LiNbO ₃ with a total thickness of 600 nm, and a Si support substrate. The acoustic wave mode of the device is the first-order antisymmetric Lamb wave mode. It can be seen from Figure 6 that the electromechanical coupling coefficient of the resonator is as high as 65% when the in-plane transmission direction is 0°, and close to 0% when the in-plane transmission direction is 90°, with a wide range of variation. From Figures 5 and 6, it can be seen that changing the in-plane transmission direction can adjust the electromechanical coupling coefficient in a wide range, regardless of the zero-order mode or the high-order mode. Using this feature, the multi-zero plate wave filter can be realized more flexibly.

Different in-plane transmission directions can achieve the same electromechanical coupling coefficient. It can be seen from Fig. 5 that the electromechanical coupling coefficient of 29% can be achieved when the in-plane transmission direction is 27° and 175°. Therefore, the angle of device design can be flexibly selected according to layout layout and spurious mode suppression. Each resonator in the plate wave filter may have different in-plane transmission directions, or may have partly the same in-plane transmission direction, and partly different in-plane transmission directions.

In some possible implementation manners, the in-plane propagation directions of the plate wave modes of the resonators in the series resonator and the parallel resonator are different.

FIG. 7 is a first structural schematic diagram of a resonator in a plate wave filter provided by an embodiment of the present application. Wherein, the corresponding position of the electrode assembly on the supporting substrate and the position of the suspended structure on the supporting substrate may coincide, and the suspended structure may penetrate the supporting substrate. In the preparation process, the bottom of the piezoelectric film can be suspended by back etching, and the integrity of the surface piezoelectric film can be ensured. The energy of the plate wave mode can be better confined in the device by using the huge acoustic impedance mismatch with the air. area.

FIG. 8 is a second structural schematic diagram of a resonator in a plate wave filter provided by an embodiment of the present application. Wherein, a part of the supporting substrate can be etched to form a closed suspended structure with the piezoelectric film. During the preparation process, a release window can be formed on the surface of the piezoelectric film by photolithography and etching, and then the supporting substrate can be etched through the release window on the surface of the piezoelectric film, so that a part of the piezoelectric film can be released.

FIG. 9 is a third structural schematic diagram of a resonator in a plate wave filter provided in an embodiment of the present application. A dielectric layer is arranged on the electrode assembly in the resonator. The ratio of the thickness of the dielectric layer to the period of the electrode assembly can be in the interval [1%, 20%]. Wherein, the period of the electrode assembly may refer to the center-to-center distance between adjacent electrodes.

FIG. 10 is a schematic structural diagram of a plate wave filter provided by an embodiment of the present application. Dielectric layers of different thicknesses are arranged on the electrode assembly of the resonator in the filter. On the basis of setting resonators with different in-plane transmission directions, the electromechanical coupling coefficient can be further adjusted by setting dielectric layers with different thicknesses on the electrode assembly.

In some possible implementation manners, the material of the supporting substrate may be any one of silicon Si, quartz, silicon carbide SiC, sapphire, and diamond. The material of the piezoelectric film may be lithium niobate LiNbO ₃ or lithium tantalate LiTaO ₃ . The cutting type of the piezoelectric film can be X, Y, Z three tangent types, or it can be a rotating Y cutting type. Optionally, the thickness of the piezoelectric film may be within the interval [1.5 μm, 150 nm]. The material of the dielectric layer may be high resistivity materials such as silicon oxide SiO _x , silicon nitride SiN _x , aluminum oxide Al ₂ O ₃ .

This application provides an embodiment of a multi-zero band41 plate wave filter. The passband frequency band of the plate wave filter is 2496-2690 MHz, and the transmission zeros are located at 2435 MHz, 2455 MHz, 2715 MHz and 2760 MHz respectively. A plate wave filter with multiple transmission zeros can include 7 resonators. As shown in Figure 4, three resonators are connected in parallel to form a parallel resonator, and four resonators are connected in series to form a series resonator. Among the seven resonators, there are at least two resonators with different in-plane propagation directions of plate waves. For ease of understanding, the 7 resonators can be numbered 1-7 from left to right, where the series resonators are numbered 1, 3, 5, 7 from left to right, and the parallel resonators are numbered from left to right For 2, 4, 6.

In the embodiment of the present application, there may be at least two resonators in the parallel resonator with different in-plane propagation directions of the plate waves, and there may also be at least two resonators in the series resonator with different in-plane propagation directions of the plate waves.

In some possible implementations, for the seven resonators numbered above, there may be at least two resonators in the series resonators 1 , 3 , 5 , and 7 with different in-plane propagation directions of plate waves. Among the parallel resonators 2 , 4 , 6 there may be at least two resonators with different in-plane propagation directions of plate waves.

For example, the in-plane propagation directions of the plate waves of resonator 1 and resonator 3 are different, and the in-plane propagation directions of plate waves of resonator 3, resonator 5, and resonator 7 are the same. The in-plane propagation directions of the plate waves of resonator 3 and resonator 5 are different, and the in-plane propagation directions of plate waves of resonator 1, resonator 5, and resonator 7 are the same. The in-plane propagation directions of the plate waves of resonator 1, resonator 3, resonator 5 and resonator 7 are all different. The in-plane propagation directions of the plate waves of resonator 2 and resonator 4 are different, and the in-plane propagation directions of plate waves of resonator 4 and resonator 6 are the same. The in-plane propagation directions of the plate waves of resonator 4 and resonator 6 are different, and the in-plane propagation directions of plate waves of resonator 2 and resonator 4 are the same. The in-plane propagation directions of the plate waves of resonator 2, resonator 4 and resonator 6 are all different.

In the embodiment of the present application, there may be at least two resonators in the parallel resonator with different in-plane propagation directions of the plate waves, and the in-plane propagation directions of the plate waves in each resonator in the series resonators may be the same.

In some possible implementations, for the seven resonators numbered above, there may be at least two resonators in the series resonators 1 , 3 , 5 , and 7 with different in-plane propagation directions of plate waves. The in-plane propagation directions of the plate waves of each of the parallel resonators 2, 4, and 6 are the same.

For example, the in-plane propagation directions of the plate waves of resonator 1 and resonator 3 are different, and the in-plane propagation directions of plate waves of resonator 3, resonator 5, and resonator 7 are the same. The in-plane propagation directions of the plate waves of resonator 3 and resonator 5 are different, and the in-plane propagation directions of plate waves of resonator 1, resonator 5, and resonator 7 are the same. The in-plane propagation directions of the plate waves of resonator 1, resonator 3, resonator 5 and resonator 7 are all different. The in-plane propagation directions of the plate waves of resonator 2, resonator 4 and resonator 6 are all the same.

In the embodiment of the present application, the in-plane propagation directions of the plate waves of each resonator in the parallel resonators may be the same, and there may be at least two resonators in the series resonators with different in-plane propagation directions of the plate waves.

In some possible implementations, for the 7 resonators numbered above, the in-plane propagation directions of the plate waves of each resonator in the series resonators 1, 3, 5, and 7 are the same. Among the parallel resonators 2 , 4 , 6 there may be at least two resonators with different in-plane propagation directions of plate waves.

For example, the in-plane propagation directions of the plate waves of resonator 1, resonator 3, resonator 5, and resonator 7 are all the same. The in-plane propagation directions of the plate waves of resonator 2 and resonator 4 are different, and the in-plane propagation directions of plate waves of resonator 4 and resonator 6 are the same. The in-plane propagation directions of the plate waves of resonator 4 and resonator 6 are different, and the in-plane propagation directions of plate waves of resonator 2 and resonator 4 are the same. The in-plane propagation directions of the plate waves of resonator 2, resonator 4 and resonator 6 are all different.

In the embodiment of the present application, the in-plane propagation direction of the plate wave of at least one resonator in the parallel resonator is the same as the in-plane propagation direction of the plate wave of the resonator in the series resonator.

In some possible implementations, a symmetrical design can be adopted, that is, the in-plane propagation directions of the plate waves of resonator 1 and resonator 7 are the same, the in-plane propagation directions of the plate waves of resonator 2 and resonator 6 are the same, and the resonator The in-plane propagation directions of the plate waves of 3 and resonator 5 are the same.

It can be seen from the above table that the 7 resonators in the plate wave filter can have 4 different resonant frequencies and electromechanical coupling coefficients. To realize the adjustment of the electromechanical coupling coefficient in a wide range, the adjustment of the electromechanical coupling coefficient in a large range can be realized by changing the in-plane transmission direction.

Fig. 11 is a simulation graph of a resonator and a filter provided by an embodiment of the present application. The 3dB bandwidth of the filter is 2496MHz to 2690MHz, and transmission zeros are generated at 2435MHz, 2455MHz, 2715MHz, and 2760MHz respectively. The filter achieves close to 40dB out-of-band suppression while maintaining high squareness. The simulation results verify that changing the in-plane transmission direction can greatly change the electromechanical coupling coefficient of the resonator, and the resonant frequency can be changed with the change of the wavelength. , so that the design of the plate wave filter has greater flexibility.

Using the multi-transmission zero-point plate wave filter provided by the embodiment of the present application, by setting resonators with different in-plane transmission directions, the electromechanical coupling coefficient of the resonator can be greatly adjusted, and then the multi-transmission zero-point plate wave filter can be realized more flexibly device. By setting the suspended structure, the energy of the plate wave mode can be better confined in the device area by taking advantage of the huge acoustic impedance mismatch with the air.

A specific embodiment of a signal processing circuit of the present application is introduced below. FIG. 12 is a schematic diagram of a signal processing circuit provided in an embodiment of the present application, and FIG. 13 is a schematic diagram of another signal processing circuit provided in an embodiment of the present application. This specification provides the composition structures as shown in the embodiments or drawings, but more or less modules or components may be included based on routine or non-inventive efforts. The composition structure listed in the embodiment is only one of many composition structures, and does not represent the only composition structure. In actual implementation, it can be implemented according to the composition structure shown in the embodiment or the accompanying drawings.

In the embodiment of the present application, the signal processing circuit may include a plurality of plate wave filters with multiple transmission zeros, and each plate wave filter with multiple transmission zeros includes a parallel resonator and a series resonator, and the parallel resonator and the series resonator can be sequentially cascade. Wherein the parallel resonator and the series resonator have at least two resonators with different in-plane propagation directions of the plate waves. Wherein, the in-plane transmission direction may be the normal direction of the interdigitated electrodes in the resonator.

In some possible implementation manners, the plate wave filter with multiple transmission zeros can be used in radio frequency signal processing circuits such as duplexers and multiplexers.

It should be noted that: the sequence of the above-mentioned embodiments of the present application is only for description, and does not represent the advantages and disadvantages of the embodiments, and the above-mentioned specification describes specific embodiments, and other embodiments are also within the scope of the appended claims Inside. In some cases, the actions or steps recited in the claims can be performed in different order to achieve desirable results. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or connections, to achieve desirable results.

Each embodiment in this specification is described in a progressive manner, the same and similar parts of each embodiment can be referred to each other, and each embodiment focuses on the differences from other embodiments.

The above description is a preferred embodiment of the present invention, and it should be pointed out that for those skilled in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications are also considered Be the protection scope of the present invention.

Claims (10)

1. A multi-transmission-zero plate wave filter, comprising:

the resonator comprises a parallel resonator and a series resonator, wherein the parallel resonator and the series resonator are sequentially cascaded;

in-plane transmission directions in which plate wave modes of at least two of the parallel resonators and the series resonators are different; the in-plane transmission direction is the normal direction of the interdigital electrode in the resonator;

the resonator comprises an electrode assembly, a piezoelectric film and a supporting substrate from top to bottom in sequence; a suspension structure is arranged between the piezoelectric film and the supporting substrate and used for restraining the energy of the plate wave mode of the resonator in the plate wave resonator;

the acoustic wave modes excited by the parallel resonators and the series resonators are the same.

2. The filter of claim 1, wherein the plate wave modes include a zero order plate wave and a higher order plate wave;

the zero-order plate waves comprise zero-order anti-symmetric lamb waves, zero-order symmetric lamb waves and zero-order horizontal shear waves;

the high-order plate waves comprise high-order antisymmetric lamb waves, high-order symmetric lamb waves and high-order horizontal shear waves.

3. The filter of claim 2, wherein when the plate wave mode of the resonator is the zero order plate wave, the electrode assemblies comprise interdigitated electrode assemblies and reflective gate electrode assemblies;

the metallization rate of the interdigital electrodes in the interdigital electrode assembly is within an interval [30%,65% ];

the ratio of the thickness of the piezoelectric film to the period of the interdigital electrode assembly is within an interval [10%,75% ].

4. The filter of claim 2, wherein the electrode assemblies comprise interdigitated electrode assemblies when the plate wave mode of the resonator is the high order plate wave;

the metallization rate of the interdigital electrodes in the interdigital electrode assembly is within an interval [5%,45% ];

the ratio of the thickness of the piezoelectric film to the period of the interdigital electrode assembly is in an interval [2%,17.5% ].

5. The filter of claim 1, wherein the resonator further comprises a dielectric layer disposed on the electrode assembly;

the ratio of the thickness of the dielectric layer to the period of the electrode assembly is within the interval [1%,20% ].

6. The filter of claim 1, wherein the corresponding position of the electrode assembly on the support substrate coincides with the position of the suspended structure on the support substrate;

the suspended structure penetrates through the supporting substrate; or;

and partial area of the supporting substrate is etched to form a closed suspension structure together with the piezoelectric film.

7. The filter according to claim 1, wherein in-plane transmission directions of the plate wave modes of the resonators in the series resonators and the parallel resonators are different.

8. The filter according to claim 1, wherein in-plane transmission directions of the plate wave modes of at least two of the series resonators and the parallel resonators are the same.

9. The filter of claim 1, wherein the in-plane transmission direction of the plate wave mode of at least one of the resonators in the parallel resonators is the same as the in-plane transmission direction of the plate wave mode of the resonator in the series resonator.

10. A signal processing circuit comprising the multi-transmission-zero plate wave filter according to any one of claims 1 to 9.

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