WO2020114413A1

WO2020114413A1 - Piezoelectric acoustic wave filter and duplexer

Info

Publication number: WO2020114413A1
Application number: PCT/CN2019/122863
Authority: WO
Inventors: 庞慰; 柴竹青; 郑云卓
Original assignee: 天津大学; 诺思(天津)微系统有限责任公司
Priority date: 2018-12-05
Filing date: 2019-12-04
Publication date: 2020-06-11
Also published as: CN109831176B; CN109831176A

Abstract

Provided in the present invention are a piezoelectric acoustic wave filter and a duplexer. The piezoelectric acoustic wave filter comprises serial-connected resonators on multiple serial-connected branches, parallel-connected resonators connected in parallel on interconnecting nodes of the serial-connected resonators, an inductor connected at one end to the parallel-connected resonators and connected at the other end to a ground node, and a T-shaped structure consisting of multiple hybrid-connected resonators. The present invention adds multiple zero transmission points by connecting in parallel and introducing a T-shaped network structure to the topology of the piezoelectric acoustic wave filter, thus achieving the goal of increasing simultaneously the out-of-band suppression performance and harmonic suppression performance of the filter; moreover, remaining zero transmission points generated by the piezoelectric acoustic wave filter also significantly increase the suppression performance for out-of-band GPS frequency bands.

Description

Piezoelectric acoustic wave filter and duplexer

Technical field

The invention relates to the technical field of piezoelectric acoustic wave filters, in particular to a piezoelectric acoustic wave filter and a duplexer capable of improving the out-of-band suppression and harmonic suppression of the duplexer transmission channel.

Background technique

With the rapid development of wireless communication systems, a large number of modules with different functions are designed and installed in handheld mobile devices with strictly limited volume. At the same time, the increasingly crowded frequency resources make the guard interval between different communication bands narrower and narrower. Under this development trend, in order to ensure that each module in the system can work normally and do not affect each other, it will put forward higher requirements for various components of the communication equipment. For example, the RF front-end must be toward miniaturization and integration Development, high performance, low power consumption and low cost.

At present, piezoelectric acoustic wave filters have gradually become the mainstream components in the field of RF filters due to their high quality factor, good temperature characteristics, small insertion loss, and rapid roll-off. Piezoelectric acoustic wave filters usually include a plurality of piezoelectric acoustic wave resonators and inductors. In order to make the piezoelectric acoustic wave filter have a strong suppression effect on the input signal in specific frequency bands such as the ISM frequency band and the GSM frequency band, the piezoelectric acoustic wave filter usually has a transmission zero point in these frequency bands.

In order to adjust the transmission zero point and move the zero point to reach the target frequency, the traditional technical solution is to adjust the frequency point corresponding to these transmission zero points by selecting the inductance value of the inductor in the piezoelectric acoustic wave filter. This action can also be called adjusting the voltage The electroacoustic wave filter transmits the zero point. Specifically, there are two technical methods for adjusting the inductance value. One method is to increase or decrease the inductance of the inductor connected in series with the parallel resonator, so that the transmission zero of the filter moves to the high-frequency or low-frequency direction, thereby improving the out-of-band suppression; another solution is to The grounding end of the multi-channel inductor is grounded, and the inductor after grounding is equivalent to introducing mutual inductance coupling, thereby equivalently changing the inductance value of the inductor.

However, due to the constraints of the filter architecture, moving the transmission zero outside the passband frequency to the vicinity of the passband passband, although it can improve the performance of the passband, the suppression of the far-end high frequency will be deteriorated, especially for the filter Harmonic frequencies that are more concerned, such as the second harmonic frequency, instead bring a reduction in the degree of suppression.

In summary, how to improve the suppression of high-frequency harmonics without reducing the suppression of the out-of-band harmonics is still an urgent issue in the design of RF chips.

Summary of the invention

In view of this, the present invention provides a piezoelectric acoustic wave filter and a duplexer that can improve the out-of-band suppression and harmonic suppression of the duplexer transmission channel, while ensuring that the suppression of high-frequency harmonic frequency does not decrease To improve the out-of-band suppression.

The first object of the present invention is to provide a piezoelectric acoustic wave filter including a plurality of series resonators on a series branch, a parallel resonator connected in parallel on the interconnection node of the series resonator, one end connected to the parallel resonator, and the other end connected to the ground Inductors connected to nodes, and T-shaped structures composed of multiple hybrid resonators.

Further, the T-shaped structure is composed of three hybrid resonators, and the first port of the first hybrid resonator is connected to the interconnection node between the first port and the second port of two adjacent series resonators. The second port of the first hybrid resonator is divided into two channels, one of which is connected to the non-ground terminal of the second hybrid resonator, and the ground terminal of the second hybrid resonator is grounded; The second port of a hybrid resonator is connected to the first port of the third hybrid resonator, and the second port of the third hybrid resonator is connected to the ground of the parallel resonator near one end of the series branch.

Alternatively, the T-shaped structure is composed of three hybrid resonators, and the first port of the first hybrid resonator is connected to the interconnection node between the first port and the second port of the two adjacent series resonators. The second port of a hybrid resonator is divided into two channels, one branch is connected to the non-ground terminal of the second hybrid resonator, the ground terminal of the second hybrid resonator is grounded; in the other branch, the first The second port of the hybrid resonator is connected to the first port of the third hybrid resonator, and the second port of the third hybrid resonator is connected to the non-grounded end of the parallel resonator near one end of the series branch.

Alternatively, the T-shaped structure is composed of three hybrid resonators, and the first port of the first hybrid resonator is connected to the interconnection node between the first port and the second port of the two adjacent series resonators. The second port of a hybrid resonator is divided into two channels, one branch is connected to the non-ground terminal of the second hybrid resonator, the ground terminal of the second hybrid resonator is grounded; in the other branch, the first The second port of the hybrid resonator is connected to the first port of the third hybrid resonator, and the second port of the third hybrid resonator is connected to the ground of the parallel resonator near the other end of the series branch.

A second object of the present invention is to provide a duplexer including the piezoelectric acoustic wave filter as described above.

The invention introduces a plurality of transmission zeros by introducing a T-shaped network structure in parallel with the topological structure of the piezoelectric acoustic wave filter, thereby achieving the purpose of simultaneously improving the out-of-band suppression performance and harmonic suppression performance of the filter, and the piezoelectric acoustic wave filtering The remaining transmission zeros generated by the transmitter also greatly improve the suppression performance of the out-of-band GPS frequency band.

BRIEF DESCRIPTION

The drawings are used for a better understanding of the present invention and do not constitute an improper limitation of the present invention. among them:

Figure 1 is a schematic diagram of the structure of the existing piezoelectric acoustic wave filter;

2A and 2B are the effect diagram of the existing piezoelectric acoustic wave filter;

FIG. 3 is a schematic structural diagram of a piezoelectric acoustic wave filter of this embodiment;

4 is a schematic diagram of the structure of the two piezoelectric acoustic wave filter of this embodiment;

5 is a schematic diagram of the structure of the three piezoelectric acoustic wave filter of this embodiment;

6 is a schematic diagram of the structure of a four piezoelectric acoustic wave filter of this embodiment;

7 is a schematic structural view of a five-piezoacoustic wave filter of this embodiment;

8 is a schematic diagram of the structure of the six piezoelectric acoustic wave filter of this embodiment;

9 is a schematic diagram of the structure of the seven piezoelectric acoustic wave filter of this embodiment;

10 is a schematic structural view of an eight piezoelectric acoustic wave filter of this embodiment;

FIG. 11 is an effect diagram of the out-of-band suppression degree of the electroacoustic wave filter of this embodiment;

12 is a second harmonic suppression effect diagram of the electroacoustic wave filter of this embodiment;

13 is an architecture diagram of the existing duplexer;

FIG. 14 is an architecture diagram of the duplexer proposed in this embodiment.

detailed description

The present invention will be further described below with reference to the drawings and embodiments.

FIG. 1 shows a schematic structural diagram of a conventional piezoelectric acoustic wave filter. As shown in FIG. 1, the structure of the existing piezoelectric acoustic wave filter is a ladder filter, which includes a plurality of series resonators (101, 102, 103, 104) connected in series on parallel connection nodes of the series resonator The parallel resonators (111, 112, 113, 114), and the inductor (123, 124, 125, 126) connected to the parallel resonator at one end and the ground plane at the other end, the electrical response is shown in Figure 2A and 2B. When the inductance value of the inductor (124) is increased, the transmission zero of the filter moves down, improving the suppression of the adjacent band (1.93 GHz to 1.99 GHz), but at the second harmonic of the filter (3.7 GHz To 3.83GHz), the performance deteriorates, but instead brings a reduction in the degree of suppression.

In order to improve the out-of-band suppression while ensuring that the suppression of high-frequency harmonic frequencies does not decrease, the present invention provides a piezoelectric acoustic wave filter for a duplexer transmission channel, a duplexer transmission channel, and improved duplex The method of the transmitter's transmission channel performance is to increase multiple transmission zero points by introducing a T-shaped network structure in parallel, so as to achieve the purpose of simultaneously improving the filter out-of-band suppression performance and harmonic suppression performance, to overcome the above disadvantages, and also greatly improve the band Suppression performance of external GPS frequency bands.

Example one

This embodiment provides a piezoelectric acoustic wave filter for the transmission channel of a duplexer. As shown in FIG. 3, the piezoelectric acoustic wave filter includes a plurality of series resonators (101, 102, 103, 104) connected in series on a branch, and parallel resonators (111, 113, 114) connected in parallel on the interconnection node of the series resonator ), an inductor (123, 124, 125, 126) connected to the parallel resonator at one end and a ground node at the other end, and a T-shaped structure 151.

In this embodiment, the T-shaped structure 151 is composed of three resonators added with a mass loading layer, and the interconnection node between the first port of the first resonator and the first port and the second port of the adjacent two series resonators a is connected, the second port of the first resonator is divided into two paths, one branch is connected to the non-ground terminal of the second parallel resonator, the ground terminal of the second resonator is connected to the ground node through the inductor 124; the other In the branch, the second port of the first resonator is connected to the first port of the third resonator, and the second port of the third resonator is connected to the ground b of the parallel resonator 111 close to the port 131.

An inductor 121 is connected between the input end 131 of the piezoelectric acoustic wave filter and one end of the series resonator 101 near the input end of the piezoelectric acoustic wave filter; the output end 132 of the piezoelectric acoustic wave filter is close to the piezoelectric An inductor 122 is connected between one end of the series resonator 104 at the output end of the acoustic wave filter.

The piezoelectric acoustic wave filter proposed in this embodiment increases multiple transmission zero points by introducing a T-shaped network structure in parallel, thereby achieving the purpose of simultaneously improving the filter out-of-band suppression performance and harmonic suppression performance, and the piezoelectric acoustic wave filter The remaining transmission zeros also greatly improve the suppression performance of the out-of-band GPS frequency band.

Example 2

This embodiment provides a piezoelectric acoustic wave filter for the transmission channel of a duplexer. As shown in FIG. 4, the piezoelectric acoustic wave filter includes a plurality of series resonators (101, 102, 103, 104) connected in series on a branch, and parallel resonators (111, 113, 114) connected in parallel on the interconnection node of the series resonator ), an inductor (123, 124, 125, 126) connected to the parallel resonator at one end and a ground node at the other end, and a T-shaped structure 151.

In this embodiment, the T-shaped structure 151 is composed of three resonators added with a mass loading layer, and the interconnection node between the first port of the first resonator and the first port and the second port of the adjacent two series resonators a is connected, the second port of the first resonator is divided into two channels, one branch is connected to one port of the second resonator, and the other port of the second resonator is connected to the ground node through the inductor 124; In the branch, the second port of the first resonator is connected to the first port of the third resonator, and the second port of the third resonator is connected to the non-ground terminal c of the parallel resonator 111 close to the port 131.

Example Three

This embodiment provides a piezoelectric acoustic wave filter for the transmission channel of a duplexer. As shown in FIG. 5, the piezoelectric acoustic wave filter includes a plurality of series resonators (101, 102, 103, 104) on a series branch, and parallel resonators (111, 113, 114) connected in parallel on the interconnection node of the series resonator ), an inductor (123, 124, 125, 126) connected to the parallel resonator at one end and a ground node at the other end, and a T-shaped structure 151.

In this embodiment, the T-shaped structure 151 is composed of three resonators added with a mass loading layer, and the interconnection node between the first port of the first resonator and the first port and the second port of the adjacent two series resonators a is connected, the second port of the first resonator is divided into two paths, one branch is connected to the non-ground terminal of the second parallel resonator, the ground terminal of the second resonator is connected to the ground node through the inductor 124; the other In the branch, the second port of the first resonator is connected to the first port of the third resonator, and the second port of the third resonator is connected to the ground terminal d of the parallel resonator 114 close to the port 132.

Example 4

This embodiment provides a piezoelectric acoustic wave filter of a transmission channel of a duplexer. As shown in FIG. 6, the piezoelectric acoustic wave filter includes a plurality of series resonators (101, 102, 103, 104) connected in series on a branch, and parallel resonators (111, 113, 114) connected in parallel on the interconnection node of the series resonator ), an inductor (123, 124, 125, 126) connected to the parallel resonator at one end and a ground node at the other end, and a T-shaped structure 151.

In this embodiment, the T-shaped structure 151 is composed of three resonators connected in series. The first port of the first resonator is connected to the interconnecting node a of the first port and the second port of the two adjacent series resonators. The second port of the resonator is divided into two channels, one of which is connected to the non-ground terminal of the second parallel resonator, and the ground terminal of the second resonator is connected to the ground node through the inductor 124; The second port of a resonator is connected to the first port of the third resonator, and the second port of the third resonator is connected to the ground b of the parallel resonator 111 close to the port 131.

In this embodiment, the first resonator and the second resonator are respectively resonators added with a mass load layer, and the third resonator is a resonator not added with a mass load layer.

Example 5

This embodiment provides a piezoelectric acoustic wave filter of a transmission channel of a duplexer. As shown in FIG. 7, the piezoelectric acoustic wave filter includes a plurality of series resonators (101, 102, 103, 104) connected in series on a branch, and parallel resonators (111, 113, 114) connected in parallel on the interconnection node of the series resonator ), an inductor (123, 124, 125, 126) connected to the parallel resonator at one end and a ground node at the other end, and a T-shaped structure 151.

In this embodiment, the second resonator and the third resonator are respectively resonators added with a mass load layer, and the first resonators are resonators not added with a mass load layer.

Example Six

This embodiment provides a piezoelectric acoustic wave filter for the transmission channel of a duplexer. As shown in FIG. 8, the piezoelectric acoustic wave filter includes a plurality of series resonators (101, 102, 103, 104) connected in series on a branch, and parallel resonators (111, 113, 114) connected in parallel on the interconnection node of the series resonator ), an inductor (123, 124, 125, 126) connected to the parallel resonator at one end and a ground node at the other end, and a T-shaped structure 151.

In this embodiment, the first resonator and the third resonator are respectively resonators added with a mass load layer, and the second resonators are resonators without added mass load layer.

Example 7

This embodiment provides a piezoelectric acoustic wave filter for the transmission channel of a duplexer. As shown in FIG. 9, the piezoelectric acoustic wave filter includes a plurality of series resonators (101, 102, 103, 104) connected in series on a branch, and parallel resonators (111, 113, 114) connected in parallel on the interconnection node of the series resonator ), an inductor (123, 124, 125, 126) connected to the parallel resonator at one end and a ground node at the other end, and a T-shaped structure 151.

In this embodiment, the T-shaped structure 151 is composed of two resonators and a capacitor connected in series. The first port of the first resonator is connected to the interconnection node a of the first and second ports of the adjacent two series resonators , The second port of the first resonator is divided into two paths, one branch is connected to the non-ground terminal of the second parallel resonator, and the ground terminal of the second resonator is connected to the ground node through the inductor 124; the other branch In, the second port of the first resonator is connected to the first port of the capacitor, and the second port of the capacitor is connected to the ground b of the parallel resonator 111 close to the port 131.

In this embodiment, the first resonator and the second resonator are respectively resonators added with a mass load layer.

Example 8

This embodiment provides a piezoelectric acoustic wave filter for the transmission channel of a duplexer. As shown in FIG. 10, the piezoelectric acoustic wave filter includes a plurality of series resonators (101, 102, 103, 104) connected in series on a branch, and parallel resonators (111, 113, 114) connected in parallel on the interconnection node of the series resonator ), an inductor (123, 124, 125, 126) connected to the parallel resonator at one end and a ground node at the other end, and a T-shaped structure 151.

In this embodiment, the T-shaped structure 151 is composed of two resonators and an inductor connected in series. The first port of the first resonator is connected to the interconnection node a of the first and second ports of the two adjacent series resonators , The second port of the first resonator is divided into two paths, one branch is connected to the non-ground terminal of the second parallel resonator, and the ground terminal of the second resonator is connected to the ground node through the inductor 124; the other branch In, the second port of the first resonator is connected to the first port of the inductor, and the second port of the inductor is connected to the ground terminal b of the parallel resonator 111 close to the port 131.

In the above embodiments, the series resonator is a resonator without a mass load layer, and the parallel resonator is a resonator with a mass load layer. The present invention also provides a duplexer including the piezoelectric acoustic wave filter described in any of the above embodiments. As shown in FIG. 14, the duplexer can be used in the topology of the transmission channel filter The T-shaped structure is added to achieve the purpose of simultaneously improving the out-of-band suppression and harmonic suppression of the duplexer transmission channel.

The architecture diagram of the existing duplexer is shown in FIG. 13, a transmission channel is between

port

131 and 132, a reception channel is between

port

133 and 134, and port 161 is an antenna. The transmission channel of the existing duplexer is filtered The device does not join the T-shaped structure.

As shown in FIG. 11, in the degree of out-of-band suppression, the curve (thick line) produced by the duplexer structure of the present disclosure is superior to the curve (thin line) produced by the duplexer structure of the prior art; As shown in FIG. 12, in the degree of second harmonic suppression, the curve (thick line) produced by the duplexer structure of the present disclosure is superior to the curve (thin line) produced by the duplexer of the prior art.

Although the specific embodiments of the present invention have been described above with reference to the accompanying drawings, it does not limit the protection scope of the present invention. Those skilled in the art should understand that based on the technical solutions of the present invention, those skilled in the art do not need to pay creative work The various modifications or deformations that can be made are still within the protection scope of the present invention.

Claims

A piezoelectric acoustic wave filter is characterized in that it includes a plurality of series resonators on a series branch, a parallel resonator connected in parallel on the interconnection node of the series resonator, one end is connected to the parallel resonator, and the other end is connected to the ground node Inductor, and T-type structure composed of multiple hybrid resonators.
The piezoelectric acoustic wave filter according to claim 1, wherein the T-shaped structure is composed of three hybrid resonators, and the first port of the first hybrid resonator resonates with two adjacent series The first port of the resonator is connected to the interconnection node of the second port. The second port of the first hybrid resonator is divided into two paths, one of which is connected to the non-grounded end of the second hybrid resonator, the second hybrid The ground terminal of the resonator is grounded; in another branch, the second port of the first hybrid resonator is connected to the first port of the third hybrid resonator, and the second port of the third hybrid resonator is close to the series branch The ground of the parallel resonator at one end of the circuit is connected.
The piezoelectric acoustic wave filter according to claim 1, wherein the T-shaped structure is composed of three hybrid resonators, and the first port of the first hybrid resonator resonates with two adjacent series The first port of the resonator is connected to the interconnection node of the second port. The second port of the first hybrid resonator is divided into two paths, one of which is connected to the non-grounded end of the second hybrid resonator, the second hybrid The ground terminal of the resonator is grounded; in another branch, the second port of the first hybrid resonator is connected to the first port of the third hybrid resonator, and the second port of the third hybrid resonator is close to the series branch The non-ground terminal of the parallel resonator at one end of the circuit is connected.
The piezoelectric acoustic wave filter according to claim 1, wherein the T-shaped structure is composed of three hybrid resonators, and the first port of the first hybrid resonator resonates with two adjacent series The first port of the resonator is connected to the interconnection node of the second port. The second port of the first hybrid resonator is divided into two paths, one of which is connected to the non-grounded end of the second hybrid resonator, the second hybrid The ground terminal of the resonator is grounded; in another branch, the second port of the first hybrid resonator is connected to the first port of the third hybrid resonator, and the second port of the third hybrid resonator is close to the series branch The ground of the parallel resonator at the other end of the road is connected.
The piezoelectric acoustic wave filter according to claim 2, 3, or 4, wherein the first hybrid resonator and the second hybrid resonator are respectively resonators added with a mass load layer or without mass loads Layer resonator.
The piezoelectric acoustic wave filter according to claim 2, 3 or 4, wherein the third hybrid resonator is a resonator added with a mass load layer, a resonator without added mass load layer, a capacitor or an inductor One of them.
The piezoelectric acoustic wave filter according to claim 1, wherein the series resonator is a resonator without a mass load layer added, and the parallel resonator is a resonator with a mass load layer added.
The piezoelectric acoustic wave filter according to claim 1, wherein in the series branch, the first port of the series resonator is connected to the second port of the adjacent series resonator to form a series branch; The first port of a series resonator is connected to the input of the filter, and the second port of the last series resonator is connected to the output of the filter.
A duplexer characterized by comprising the piezoelectric acoustic wave filter according to any one of claims 1 to 8.