Transmitting filter, duplexer and communication equipment comprising same

Abstract

The utility model relates to a transmission filter, a duplexer and communication equipment. The transmitting filter comprises a first end, a second end, a plurality of nodes, M series branches and N parallel branches, N is a natural number greater than or equal to 4, and M is a natural number greater than or equal to 3; a series branch is arranged between adjacent nodes, and each series branch comprises at least one series bulk acoustic wave resonator; a parallel branch is arranged between each node and the ground, and each parallel branch comprises at least one parallel acoustic resonator; parallel body acoustic resonators with the mutual cross-level larger than or equal to 2 and smaller than N-1 in parallel branches of a transmitting filter are adjacently arranged, and the distance between the parallel body acoustic resonators is set to be larger than or equal to one time of the process minimum distance and smaller than or equal to three times of the process minimum distance.

Description

Technical Field

[0001] This utility model relates to a communication device, and more specifically, to a communication device comprising a transmit filter and a duplexer. Background Technology

[0002] Portable communication devices, such as mobile phones, laptops, personal digital assistants (PDAs), GPS, and BeiDou, need to communicate through various communication networks. These portable communication devices typically include a radio frequency (RF) front-end module, in which the duplexer is a key component. With the increasing commercialization of 5G, the demand for duplexers is also growing.

[0003] A duplexer includes a transmit filter and a receive filter. When a duplexer operates, it needs to isolate the signal transmitted by the transmit filter from the signal received by the receive filter to ensure that both transmission and reception can occur simultaneously and correctly. The isolation level of a duplexer refers to the degree of signal isolation between the transmit and receive channels. Higher isolation level means better signal isolation between the transmit and receive channels.

[0004] For some duplexers, when the spacing between the transmit band of the transmit filter and the receive band of the receive filter is too small, and it is necessary to improve the isolation of the duplexer, the inductance value from the parallel branch to ground in the transmit filter is generally increased. This moves the zero point far to the right of the transmit filter's passband to near the stopband, thereby improving the duplexer's isolation. However, this setting will suppress fly-off (degradation suppression) far to the right of the filter's passband, and a large inductance is not conducive to miniaturization and achieving a high Q value. Utility Model Content

[0005] This invention addresses the aforementioned technical problems by providing a transmission filter that effectively improves near-stopband suppression on the left side of the filter through its chip layout design.

[0006] A brief overview of the present invention will be given below to provide a basic understanding of certain aspects thereof. It should be understood that this overview is not an exhaustive summary of the present invention. It is not intended to identify key or essential parts of the present invention, nor is it intended to limit the scope of the present invention. Its purpose is merely to present certain concepts in a simplified form as a prelude to the more detailed description that follows.

[0007] According to one aspect of the present invention, a transmitting filter is provided, comprising: a first end, a second end, multiple nodes, M series branches and N parallel branches, where N is a natural number greater than or equal to 4 and M is a natural number greater than or equal to 3; a series branch is provided between adjacent nodes, each series branch including at least one series acoustic resonator; a parallel branch is provided between each node and ground, each parallel branch including at least one parallel acoustic resonator; the parallel acoustic resonators in the parallel branches of the transmitting filter with a cross-stage greater than or equal to 2 and less than N-1 are arranged adjacently, and the spacing between them is set to be greater than or equal to one time the minimum process spacing and less than or equal to three times the minimum process spacing.

[0008] Furthermore, the bulk acoustic resonator in the first parallel branch closest to the first end and the bulk acoustic resonator in the Nth parallel branch closest to the second end of the transmitting filter are not arranged adjacent to each other.

[0009] Furthermore, in the parallel branch of the transmitting filter, bulk acoustic resonators with a span of 2 or more stages and less than N-1 stages are arranged adjacent to each other, and the spacing between them is set to 5-20 micrometers.

[0010] Furthermore, the thin-film bulk acoustic resonator structure includes a carrier, a cavity formed in the carrier, a lower electrode, an upper electrode, and a piezoelectric layer sandwiched between the lower electrode and the upper electrode. When viewed from above, the thin-film bulk acoustic resonator presents a polygonal structure.

[0011] Furthermore, when resonators in the parallel branches of the transmitting filter that are more than or equal to 2 stages apart and less than N-1 stages apart are arranged adjacent to each other, their adjacent sides should be arranged as parallel as possible.

[0012] Furthermore, the transmitting filter includes a T-shaped topology consisting of four series branches and four parallel branches. Each series branch includes a bulk acoustic wave resonator, and each parallel branch includes a bulk acoustic wave resonator. The bulk acoustic wave resonators in the parallel branches are grounded through an inductor or a common inductor.

[0013] Furthermore, the inductance value of the inductor or common inductor in the parallel branch is less than 0.5nH.

[0014] According to another aspect of the present invention, a duplexer is provided, comprising a receiving filter and a transmitting filter as described in any of the preceding claims.

[0015] Furthermore, the receiving filter is a B25 receiving filter, and the transmitting filter is a B25 transmitting filter.

[0016] According to another aspect of the present invention, a communication device is provided, the communication device comprising the duplexer of any of the above claims. Attached Figure Description

[0017] The specific details of this utility model are described below with reference to the accompanying drawings, which will help to more easily understand the above and other objects, features, and advantages of this utility model. The drawings are only for illustrating the principle of this utility model. The dimensions and relative positions of the units are not necessarily drawn to scale in the drawings.

[0018] Figure 1 A circuit block diagram of the duplexer provided in this disclosure is shown;

[0019] Figure 2 A schematic diagram of a specific circuit structure of the duplexer provided in this disclosure is shown;

[0020] Figure 3a This is a schematic diagram of the structure of the thin-film bulk acoustic resonator in the duplexer provided in this disclosure;

[0021] Figure 3b This is a schematic diagram of the electrode structure of the thin-film bulk acoustic resonator in the filter provided in this disclosure.

[0022] Figure 4 It shows Figure 2 A schematic diagram of the layout of the bare die for the transmission filter;

[0023] Figure 5 A schematic diagram of the layout of the first comparison example filter die is shown;

[0024] Figures 6a-6b A comparison chart showing the frequency response curves of the filter die of this embodiment and the filter chip of the first comparative example is presented. Detailed Implementation

[0025] The exemplary disclosure of this utility model will be described below with reference to the accompanying drawings. For clarity and brevity, not all features implementing this utility model are described in the specification. However, it should be understood that many utility model-specific decisions can be made in the development of any such implementation of this utility model in order to achieve the developer's specific objectives, and these decisions may vary depending on the specific implementation of this utility model.

[0026] It should also be noted that, in order to avoid obscuring the present invention with unnecessary details, only the device structure closely related to the solution according to the present invention is shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0027] It should be understood that this invention is not limited to the described embodiments by virtue of the following description with reference to the accompanying drawings. In this document, features may be substituted or borrowed between different embodiments where feasible, and one or more features may be omitted in one embodiment.

[0028] Please see Figure 1 , Figure 1 A circuit block diagram of the duplexer provided in this disclosure is shown. The duplexer includes a common port A, a transmit filter 100, and a receive filter 110.

[0029] The common port A is an external port for transmitting and receiving signals through an antenna element (not shown in the figure); the transmit filter 100 is disposed between the common port A and the first signal transmission terminal TX; the receive filter 110 is disposed between the common port A and the second signal transmission terminal RX.

[0030] A first matching unit MC1 can be further provided between the common port A and each filter. By providing the inductive first matching unit MC1, the capacitive characteristics exhibited by each filter in the duplexer are offset, so that the transmitting filter 100 and the receiving filter 110 are impedance matched to each other, thus avoiding insertion loss degradation. The first matching unit MC1 can be connected in parallel between the common port A and ground, or it can be connected in series between a filter and the common port, or the first matching unit MC1 can be a multi-port unit, with one end connected to the common port, one end grounded, and at least one end connected to the signal transmission end of a filter near the common port.

[0031] Furthermore, the transmitting filter 100 includes a first filtering network disposed between its input terminal (first terminal) and output terminal (second terminal). The receiving filter 110 includes a second filtering network disposed between its input terminal and output terminal.

[0032] The following description uses the first filter network in the transmitting filter 100 as an example. The first filter network is located between the input (first end) and output (second end) of the transmitting filter 100. The first filter network includes M series branches and N parallel branches, where M is a natural number greater than or equal to 3, and N is a natural number greater than or equal to 4. The boxes in each series and parallel branch represent resonant units. The resonant units include those composed of bulk acoustic wave resonators. Each parallel branch of the transmitting filter may also include an inductor connected to ground. Furthermore, when different resonant units have the same type of component, the component parameters can be equal or unequal. For example, when different resonant units all have inductor components, the inductor sizes can be equal or unequal. In the transmitting filter provided by this invention, the inductance value of the inductor is less than 0.5 nH.

[0033] Understandably, the second filtering network in the receiving filter 110 also includes multiple series branches and multiple parallel branches. The configuration of the series and parallel branches in the second filtering network is the same as that of the first filtering network in the transmitting filter 100, and will not be described again here.

[0034] Furthermore, such as Figure 1 As shown, at least one of the transmitting filter 100 and the receiving filter 110 in the duplexer of this invention may have its own matching unit MC2. Specifically, the matching circuit MC2 may be located at the first signal transmission terminal TX of the transmitting filter 100 and / or the second transmitting port RX of the transmitting filter 110. The matching unit MC2 is used to match the impedance of the transmitting filter 100 and / or the receiving filter 110 themselves to avoid signal reflection and signal loss. The second matching unit MC2 may be various series and parallel combinations of capacitors and / or inductors.

[0035] Please see Figure 2 , Figure 2 A schematic diagram of a specific circuit structure of the duplexer provided in this disclosure is shown. The duplexer includes a common port A, a B25 transmit filter 100, a B25 receive filter 200, a first matching unit, a matching unit for the B25 transmit filter 100 (also referred to as a second matching unit), a matching unit for the B25 receive filter 110 (also referred to as a third matching unit), a first signal transmission terminal B25TX, and a second signal transmission terminal B25RX. The passband frequency range of the B25 transmit filter 100 is 1850–1915 MHz, and the passband frequency range of the B25 receive filter 110 is 1930–2020 MHz.

[0036] The B25 transmit filter 100 is disposed between the common port A and the first signal transmission terminal B25TX; the B25 receive filter 110 is disposed between the common port A and the second signal transmission terminal B25RX. The B25 transmit filter 100 includes 4 series branches and 4 parallel branches. The B25 receive filter 110 includes 4 series branches and 5 parallel branches.

[0037] The B25 transmitting filter 100 has a first series branch including a first series acoustic resonator Se1, a second series branch including a second series acoustic resonator Se2, a third series branch including a third series acoustic resonator Se3, and a fourth series branch including a fourth series acoustic resonator Se4. The first end of the first series acoustic resonator Se2 is connected to a common port A, and the second end of the first series acoustic resonator Se2 is connected to the first end of the second series acoustic resonator Se2. The second end of the second series acoustic resonator Se2 is connected to the first end of the third series acoustic resonator Se3. The second end of the third series acoustic resonator Se3 is connected to the first end of the fourth series acoustic resonator Se4. The second end of the fourth series acoustic resonator Se4 is connected to the first signal transmission terminal B25TX.

[0038] The first parallel branch of the B25 transmitting filter 100 includes a first parallel solid acoustic resonator Sh1 and an inductor L1. The first end of the first parallel solid acoustic resonator Sh1 is connected to the second end of the first series solid acoustic resonator Se1. The second end of the first parallel solid acoustic resonator Sh1 is connected to the first end of the inductor L1, and the second end of the inductor L1 is grounded. The second parallel branch includes a second parallel solid acoustic resonator Sh2 and an inductor L2. The first end of the second parallel acoustic resonator Sh2 is connected to the second end of the second series solid acoustic resonator Se2. The second end of the second parallel acoustic resonator Sh2 is connected to the first end of the inductor L2, and the second end of the inductor L2 is grounded. The third parallel branch includes a third parallel solid acoustic resonator Sh3 and an inductor L3. The first end of the third parallel acoustic resonator Sh3 is connected to the second end of the third series solid acoustic resonator Se3. The second end of the third parallel acoustic resonator Sh3 is connected to the first end of the inductor L3, and the second end of the inductor L3 is grounded. The fourth parallel branch includes a fourth parallel acoustic resonator Sh4 and an inductor L4. The first end of the fourth parallel acoustic resonator Sh4 is connected to the second end of the fourth series acoustic resonator Se4. The second end of the fourth parallel acoustic resonator Sh4 is connected to the first end of the inductor L4, and the second end of the inductor L4 is grounded.

[0039] The second matching unit includes an inductor L5, with its first end connected to the first signal transmission terminal B25TX and its second end grounded. In the transmitting filter provided by this invention, the inductance values ​​of inductors L1-L4 are less than 0.5nH.

[0040] The first matching unit includes an inductor Lm, the first end of which is connected to a common port A, and the second end of which is connected to the first end of the first series branch of the B25 receiving filter 110.

[0041] The first series branch of the B25 receiving filter 110 includes a first series acoustic resonator S1, the second series branch includes a second series acoustic resonator S2, the third series branch includes a third series acoustic resonator S3, and the fourth series branch includes a fourth series acoustic resonator S4. The first end of the first series acoustic resonator S1 is connected to the second end of the inductor Lm; the second end of the first series acoustic resonator S1 is connected to the first end of the second series acoustic resonator S2; the second end of the second series acoustic resonator S2 is connected to the first end of the third series acoustic resonator S3; the second end of the third series acoustic resonator S3 is connected to the first end of the fourth series acoustic resonator S4; the second end of the fourth series acoustic resonator S4 is connected to the first end of the inductor L9, and the second end of the inductor L9 is connected to the second signal transmission terminal B25RX.

[0042] The first parallel branch of the B25 receiving filter 110 includes a first parallel acoustic resonator P1, the first end of which is connected to the second end of an inductor Lm; the second end of the first parallel acoustic resonator P1 is connected to the first end of a common inductor L6, and the second end of inductor L6 is grounded. The second parallel branch includes a second parallel acoustic resonator P2, the first end of which is connected to the second end of a first series acoustic resonator S1; the second end of the second parallel acoustic resonator P2 is connected to the first end of the common inductor L6. The third parallel branch includes a third parallel acoustic resonator P3 and an inductor L7, the first end of which is connected to the second end of a second series acoustic resonator S2; the second end of the third parallel acoustic resonator P3 is connected to the first end of inductor L7, and the second end of inductor L7 is grounded. The fourth parallel branch includes a fourth parallel acoustic resonator P4, whose first terminal is connected to the second terminal of the third series acoustic resonator S3; the second terminal of the fourth parallel acoustic resonator P4 is connected to the first terminal of a common inductor L8, and the second terminal of the common inductor L8 is grounded. The fifth parallel branch includes a fifth parallel acoustic resonator P5, whose first terminal is connected to the second terminal of the fourth series acoustic resonator S4; the second terminal of the fifth parallel acoustic resonator P5 is connected to the first terminal of the common inductor L8. The first terminal of inductor L10 is connected to the second terminal of inductor L9, and the second terminal of inductor L10 is grounded. Inductors L9 and L10 constitute the third matching unit of the B25 receiving filter 110.

[0043] See Figures 3a-3b , Figure 3a This is a schematic diagram of the structure of the thin-film bulk acoustic resonator in the duplexer provided in this disclosure; Figure 3b This is a schematic diagram of the electrode structure of the thin-film bulk acoustic resonator in the filter provided in this disclosure.

[0044] like Figures 3a-3b As shown, the thin-film bulk acoustic resonator structure includes a carrier 100, a cavity 101 formed in the carrier 100, a lower electrode 102, an upper electrode 104, and a piezoelectric layer 103 sandwiched between the lower electrode 102 and the upper electrode 104, wherein the lower electrode 102, the piezoelectric layer 103, and the upper electrode 104 form a "sandwich" structure. The lower electrode 102 is connected to ground via a grounding pad (not shown), and the upper electrode 104 is connected to other components via connecting lines or connecting pads (not shown). The upper electrode 104 and the lower electrode 102 can be regular or irregular polygonal shapes such as pentagons, hexagons, heptagons, or octagons; correspondingly, the upper electrode 104 and the lower electrode 102 can have five, six, seven, or eight sides. It is understood that... Figure 2The structure of the resonator is merely exemplary and should not be considered as a specific limitation on the resonator structure of this utility model. For example, a seed layer may further be present between the carrier 100 and the lower electrode 102. A mass load layer may further be present on the lower electrode 102 and / or the upper electrode 104, etc.

[0045] Figure 4 It shows Figure 2 A schematic diagram of the layout of the emitter filter die. (See attached diagram.) Figure 4 As shown, the filter die has formed with Figure 2 The resonators Se1, Se2, Se3, and Se4 in the series branch, and the resonators Sh1, Sh2, Sh3, and Sh4 in the parallel branch. The above resonators are arranged according to... Figures 3a-3b The structure and Figure 2 The topological relationships are defined and formed on the substrate of the filter die according to the layout design rules. It should be noted that in this embodiment... Figure 4 The filter layout is based on Figure 2 The circuit structure of the filter in the example is used as an example for illustrative purposes, and the layout of the resonators in the series and parallel branches of the filter is only schematically shown in the layout diagram. It should be understood by those skilled in the art that this layout design should not be regarded as a limitation on the scope of protection of this utility model.

[0046] For a transmitting filter with N parallel branches, resonators in the parallel branches of the transmitting filter that are more than or equal to 2 stages apart and less than N-1 stages apart are arranged adjacently. Specifically, "more than or equal to 2 stages apart and less than N-1 stages apart" means that the difference between the branch numbers of the i-th parallel branch and the j-th parallel branch is more than or equal to 2 and less than N-1, i.e., ji is more than or equal to 2 and less than N-1, where i is more than or equal to 1 and less than or equal to N, and j is more than or equal to 1 and less than or equal to N. The spacing between adjacent resonators is set to be more than or equal to one time the minimum allowable spacing allowed by the manufacturing process and less than or equal to three times the minimum allowable spacing allowed by the manufacturing process. Preferably, the spacing between resonators in the parallel branches of the transmitting filter that are more than or equal to 2 stages apart is set to 5-20 micrometers.

[0047] An example of a resonator in the parallel branch of a transmitting filter with a cross-stage of two or more is provided, as shown below. Figure 4 The second parallel acoustic resonator Sh2 and the fourth parallel acoustic resonator Sh4 are shown in circle A. Or as... Figure 4The diagram shows the first parallel acoustic resonator Sh1 in the first parallel branch and the third parallel acoustic resonator Sh3 in the third parallel branch. Generally, the larger the number of stages between parallel branches in a transmit filter, the better the effect on strengthening the isolation of the transmit frequency band. However, it should be noted that although the first parallel acoustic resonator Sh1 in the first parallel branch and the fourth parallel acoustic resonator Sh4 in the fourth parallel branch are also resonators with a stage difference of more than or equal to 2, it is best not to place the first parallel acoustic resonator Sh1 and the fourth parallel acoustic resonator Sh4 in the first and last parallel branches closest to the signal transmission end according to the above rule. This is because if the first parallel acoustic resonator Sh1 and the fourth parallel acoustic resonator Sh4 are placed close together according to the above rule, it may lead to the degradation of filter suppression.

[0048] Furthermore, when resonators with a span of 2 or more between each other in the parallel branches of the transmitting filter are placed adjacent to each other (excluding the resonators in the first and last parallel branches closest to the signal transmission end), their adjacent sides should be placed as parallel as possible to ensure that the cross-coupling capacitance value is maximized.

[0049] Figure 5 A schematic diagram of the layout of the first comparison example filter die is shown; Figure 5 In the layout of the intermediate filter die, the resonators in the parallel branches of the emitter filter with a span of more than or equal to 2 stages are not arranged adjacently.

[0050] To compare the frequency response characteristics and isolation performance of the filter in this embodiment with that of the first comparative example, corresponding performance tests were performed on the filter in this embodiment and the filter of the first comparative example. The following is a summary of the relevant test results. Figure 5 Please provide a detailed explanation.

[0051] Figures 6a-6b A comparison graph showing the frequency response curves of the filter die from this embodiment and the filter chip from the first comparative example is presented. The thick line represents the frequency response test results of the filter from this embodiment, and the thin line represents the frequency response test results of the filter from the first comparative example. Figure 6a As can be clearly seen at point C1, the emission filter using this embodiment shows improved suppression at a distance on the right side compared to the emission filter in the first comparative example, with no significant increase observed. And from... Figure 6b As can be seen at C2, the isolation of the transmission frequency band is improved by more than 5dB. The novel layout of the transmit filter provided by this invention not only improves the suppression of the near-stopband on the right side of the passband, but also, because a large inductor is not used in the parallel branch, facilitates miniaturization and the achievement of a high Q value, while preventing a significant increase in suppression at the far right side of the transmit filter's passband.

[0052] Furthermore, the duplexer provided by this utility model can be used in communication devices, such as mobile phones, personal digital assistants (PDAs), electronic game devices, wearable terminals, etc.

[0053] The present invention has been described above with reference to specific embodiments. However, those skilled in the art should understand that these descriptions are exemplary and not intended to limit the scope of protection of the present invention. Those skilled in the art can make various modifications and variations to the present invention based on its spirit and principles, and these modifications and variations are also within the scope of the present invention.

Claims

1. A transmitting filter, characterized in that, include: The transmitting filter includes a first terminal, a second terminal, multiple nodes, M series branches and N parallel branches, where N is a natural number greater than or equal to 4 and M is a natural number greater than or equal to 3. A series branch is provided between adjacent nodes, and each series branch includes at least one series acoustic resonator. Each node is connected to the ground via a parallel branch, and each parallel branch includes at least one parallel acoustic resonator. Parallel acoustic resonators with a span of 2 or more stages and less than N-1 stages in the parallel branches of the transmitting filter are arranged adjacently, and the spacing between them is set to be greater than or equal to one time the minimum spacing in the process and less than or equal to three times the minimum spacing in the process.

2. The transmit filter as described in claim 1, characterized in that: The parallel acoustic resonators in the first parallel branch closest to the first end and the parallel acoustic resonators in the Nth parallel branch closest to the second end of the transmitting filter are not arranged adjacent to each other.

3. The transmit filter as described in claim 1 or 2, characterized in that: In the parallel branch of the transmitting filter, bulk acoustic resonators with a span of 2 or more stages and less than N-1 stages are arranged adjacent to each other, and the spacing between them is set to 5-20 micrometers.

4. The transmit filter as described in claim 3, characterized in that: The structure of a thin-film bulk acoustic resonator includes a carrier, a cavity formed in the carrier, a lower electrode, an upper electrode, and a piezoelectric layer sandwiched between the lower electrode and the upper electrode. When viewed from above, the thin-film bulk acoustic resonator presents a polygonal structure.

5. The transmit filter as described in claim 4, characterized in that: When resonators in the parallel branches of the transmitting filter that are separated by a span of 2 or more stages but less than N-1 are placed adjacent to each other, their adjacent sides should be arranged as parallel as possible.

6. The transmit filter as described in claim 5, characterized in that: The transmitting filter comprises a T-shaped topology consisting of four series branches and four parallel branches. Each series branch includes a bulk acoustic wave resonator, and each parallel branch includes a bulk acoustic wave resonator. The bulk acoustic wave resonators in the parallel branches are grounded through an inductor or a common inductor.

7. The transmit filter as described in claim 6, characterized in that: The inductance value of the inductor or common inductor in the parallel branch is less than 0.5nH.

8. A duplexer, characterized in that, It includes a receiving filter and a transmitting filter according to any one of claims 1-7.

9. The duplexer as described in claim 8, characterized in that: The receiving filter is a B25 receiving filter, and the transmitting filter is a B25 transmitting filter.

10. A communication device, characterized in that: The communication device includes the duplexer as described in claim 8 or 9.

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