Filter circuit and radio frequency front-end module

Abstract

The utility model relates to the technical field of integrated circuits, in particular to a filter circuit and a radio frequency front-end module, the filter circuit comprises a series resonance unit connected in series between a first terminal and a second terminal, and the series resonance unit comprises a series resonance arm and a plurality of nodes which are connected in series; the parallel resonance unit is connected between the node and the grounding end and comprises a first parallel resonance arm, a second parallel resonance arm, a third parallel resonance arm and a fourth parallel resonance arm; the first inductor is connected between the second end of the first parallel resonance arm and the grounding end; and the second inductor is connected between the common node and the grounding end. According to the embodiment of the invention, the first end of the second parallel resonance arm is connected with the first end of the first parallel resonance arm, and the second end of the second parallel resonance arm, the second end of the third parallel resonance arm and the second end of the fourth parallel resonance arm are connected to form a common node and then are grounded through the second inductor, so that the performance of the filter circuit can be improved; the suppression effect and the isolation degree of the filter circuit are improved.

Description

Technical Field

[0001] The present application relates to the field of integrated circuit technology, and in particular to a filter circuit and a radio frequency front-end module. Background Art

[0002] At present, the RF front-end module usually has two groups of filter circuits with different frequencies, namely the transmitting filter circuit and the receiving filter circuit. The transmitting filter circuit usually includes a series arm and a plurality of parallel arms arranged between the series arm and the ground terminal. The suppression level of the transmitting filter circuit and the isolation of the receiving passband have a certain influence on the signal quality. In the prior art, the connection method of the series arm and the parallel arm in the transmitting filter circuit has a poor suppression level and low isolation. In order to improve the suppression level and isolation, it is often necessary to introduce additional devices, which is not conducive to reducing the area of ​​the transmitting filter circuit. How to improve the connection method of the series arm and the parallel arm in the transmitting filter circuit and improve the performance of the filter circuit without increasing the circuit area has become a technical problem that needs to be solved in this field. Utility Model Content

[0003] In view of the above problems, the embodiments of the present application provide a filter circuit and a radio frequency front-end module to solve the above technical problem of improving the performance of the filter circuit without increasing the circuit area.

[0004] In a first aspect, an embodiment of the present application provides a filter circuit, comprising:

[0005] A series resonance unit connected in series between the first terminal and the second terminal, the series resonance unit comprising a plurality of series resonance arms connected in series and a plurality of nodes, the plurality of nodes being respectively arranged on a connection path between each two adjacent series resonance arms;

[0006] a parallel resonance unit connected between the node and the ground terminal, the parallel resonance unit comprising a first parallel resonance arm, a second parallel resonance arm, a third parallel resonance arm and a fourth parallel resonance arm, the first end of the first parallel resonance arm and the first end of the second parallel resonance arm are respectively connected to the first node, the first end of the third parallel resonance arm is connected to the second node, and the first end of the fourth parallel resonance arm is connected to the third node, wherein the first node, the second node and the third node are respectively one of the plurality of nodes, and the first node, the second node and the third node are sequentially arranged on a connection path from the first terminal to the second terminal;

[0007] a first inductor connected between the second end of the first parallel resonant arm and the ground end;

[0008] A second inductor is connected between a common node and the ground terminal, wherein a second end of the second parallel resonant arm, a second end of the third parallel resonant arm and a second end of the fourth parallel resonant arm are respectively connected to the common node.

[0009] Optionally, an inductance value of the second inductor is smaller than an inductance value of the first inductor.

[0010] Optionally, a difference between an inductance value of the first inductor and an inductance value of the second inductor is a first difference, and the first difference is 0.1 nh to 0.3 nh.

[0011] Optionally, the first inductor and the first parallel resonant arm form a first adjustment unit, the second inductor, the second parallel resonant arm, the third parallel resonant arm and the fourth parallel resonant arm form a second adjustment unit, and the resonant frequency of the first adjustment unit is greater than the resonant frequency of the second adjustment unit.

[0012] Optionally, the second inductor is wound on a circuit substrate; the series resonance unit and the parallel resonance unit are respectively integrated into a chip, and the second parallel resonance arm, the third parallel resonance arm and the fourth parallel resonance arm are connected to the second inductor through bonding wires or metal bumps;

[0013] And / or, the first inductor is wound on a circuit substrate; the first parallel resonant arm is connected to the first inductor via a bonding wire or a metal bump.

[0014] Optionally, the series resonance unit includes a first series resonance arm, a second series resonance arm, a third series resonance arm and a fourth series resonance arm connected in series in sequence, the first series resonance arm is connected to the first terminal, the fourth series resonance arm is connected to the second terminal, the first node is formed between the first series resonance arm and the second series resonance arm, the second node is formed between the second series resonance arm and the third series resonance arm, and the third node is formed between the third series resonance arm and the fourth series resonance arm;

[0015] The number of resonators included in the second series resonant arm is the same as the number of resonators included in the third series resonant arm, the number of resonators included in the first series resonant arm is the same as the number of resonators included in the fourth series resonant arm, and the number of resonators included in the second series resonant arm is greater than the number of resonators included in the first series resonant arm.

[0016] Optionally, the first terminal is used to connect to an antenna, and the second terminal is used to connect to a power amplifier.

[0017] In a second aspect, an embodiment of the present application provides a radio frequency front-end module, comprising the above-mentioned filtering circuit.

[0018] Optionally, a chip is further included, wherein the first terminal and the second terminal in the filter circuit are respectively integrated into the chip, and in the setting area of ​​the filter circuit of the chip, the first terminal and the second terminal are set away from each other; the series resonance unit and the parallel resonance unit in the filter circuit are respectively integrated in the setting area of ​​the chip. Optionally, the setting area includes a first direction parallel to the propagation direction of the surface acoustic wave and a second direction perpendicular to the first direction, and the multiple nodes in the series resonance unit are respectively multiple series bus bars arranged in sequence along the second direction, and the two adjacent series resonance arms in the series resonance unit are respectively connected to the two sides of the corresponding series bus bar, and the two adjacent series resonance arms are set diagonally relative to the corresponding series bus bar.

[0019] Optionally, the series resonance unit includes a first series resonance arm, a second series resonance arm, a third series resonance arm and a fourth series resonance arm connected in series in sequence, the first node is a first series bus bar arranged between the first series resonance arm and the second series resonance arm, the second node is a second series bus bar arranged between the second series resonance arm and the third series resonance arm, and the third node is a third series bus bar arranged between the third series resonance arm and the fourth series resonance arm;

[0020] The first terminal is connected to the first series resonant arm through the fourth series bus bar, and the first terminal is arranged on a side away from the first series bus bar, and the second terminal is connected to the fourth series resonant arm through the fifth series bus bar, and the second terminal is arranged on a side away from the third series bus bar.

[0021] Optionally, the first parallel resonant arm and the first series resonant arm are respectively connected to two sides of the first series-connected bus bar and are arranged side by side in the second direction;

[0022] The second parallel resonant arm and the second series resonant arm are respectively connected to two sides of the first series-connected bus bar and are arranged side by side in the second direction;

[0023] The first series resonant arm and the second parallel resonant arm are arranged in sequence along a first direction, and the first parallel resonant arm and the second series resonant arm are arranged in sequence along the first direction.

[0024] Optionally, the third parallel resonant arm and the fourth parallel resonant arm are arranged side by side between the second series bus bar and the third series bus bar in the second direction, and the third parallel resonant arm and the fourth parallel resonant arm are connected through a first parallel bus bar, and the first parallel bus bar is arranged between the third parallel resonant arm and the fourth parallel resonant arm.

[0025] Optionally, the RF front-end module further includes a substrate, and the first inductor and the second inductor in the filter circuit are respectively wound on the substrate;

[0026] The filter circuit also includes a third terminal for connecting the first inductor and a fourth terminal for connecting the second inductor, the third terminal and the fourth terminal are far away from each other in the setting area, the third terminal is set in the area between the first parallel resonant arm and the third series resonant arm, the fourth terminal and the third parallel resonant arm are set side by side in the first direction, and the fourth terminal is located on a side of the third parallel resonant arm away from the third terminal.

[0027] Optionally, the fourth terminal is the common node, the fourth terminal is respectively connected to the third parallel resonant arm and the fourth parallel resonant arm through the first parallel bus bar, the fourth terminal is connected to the second parallel resonant arm through the second parallel bus bar, and the fourth terminal is connected to the side of the second parallel resonant arm away from the first series bus bar.

[0028] Optionally, the setting area is rectangular, and the first terminal and the second terminal are respectively arranged at two ends of a diagonal line of the rectangle.

[0029] The filter circuit and the RF front-end module provided by the embodiment of the present application include a series resonance unit connected in series between a first terminal and a second terminal, the series resonance unit includes a plurality of series resonance arms connected in series and a plurality of nodes, the plurality of nodes are respectively arranged on the connection path of each two adjacent series resonance arms; a parallel resonance unit connected between the node and the ground end, the parallel resonance unit includes a first parallel resonance arm, a second parallel resonance arm, a third parallel resonance arm and a fourth parallel resonance arm; a first inductor, the first inductor is connected between the second end of the first parallel resonance arm and the ground end; a second inductor, the second inductor is connected between a common node and the ground end, wherein the second end of the second parallel resonance arm, the second end of the third parallel resonance arm and the second end of the fourth parallel resonance arm are respectively connected to the common node; in the above manner, the first end of the second parallel resonance arm is connected to the first end of the first parallel resonance arm, the second end of the second parallel resonance arm, the second end of the third parallel resonance arm and the second end of the fourth parallel resonance arm are connected to form a common node and then grounded through the second inductor, which can improve the performance of the filter circuit, so as to improve the suppression effect and isolation of the filter circuit.

[0030] These and other aspects of the present application will become more clearly understood in the description of the following embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The circuit structure diagram of the filter circuit provided in the embodiment of the present application is shown.

[0032] Figure 2 The circuit structure diagram of the filter circuit provided in the embodiment of the present application is shown.

[0033] Figure 3 The circuit structure diagram of the filter circuit provided in the embodiment of the present application is shown.

[0034] Figure 4 The figure shows an application scenario of the filter circuit provided in the embodiment of the present application.

[0035] Figure 5 An application scenario diagram of the filter circuit provided in Comparative Example 1 of the present application is shown.

[0036] Figure 6 An application scenario diagram of the filter circuit provided in Comparative Example 2 of the present application is shown.

[0037] Figure 7a A comparison diagram of frequency characteristic curves of the filter circuits of the embodiment and comparative example 1 is shown.

[0038] Figure 7b Shows Figure 7a Magnified view of the middle Z section.

[0039] Figure 7c A comparison diagram of isolation curves of the filter circuits of the embodiment and comparative example 1 is shown.

[0040] Figure 8a A comparison diagram of the frequency characteristic curves of the filter circuits of the embodiment and comparative example 2 is shown.

[0041] Figure 8b A comparison diagram of isolation curves of the filter circuits of the embodiment and comparative example 2 is shown.

[0042] Fig. 9 A structural block diagram of a radio frequency front-end module provided in an embodiment of the present application is shown.

[0043] Fig.10a A top view of the electrode structure of the first series resonant arm and the first parallel resonant arm in the RF front-end module provided in an embodiment of the present application is shown.

[0044] Fig.10b A top view of an IDT electrode of a surface acoustic wave resonator in a radio frequency front-end module provided in an embodiment of the present application is shown.

[0045] Fig.11 A schematic diagram of the chip setting area in the RF front-end module provided in an embodiment of the present application is shown.

[0046] Fig.12A schematic diagram of the chip setting area in the RF front-end module provided in an embodiment of the present application is shown.

[0047] Fig.13 A schematic diagram of the chip setting area in the RF front-end module provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0048] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0049] In order to enable those skilled in the art to better understand the solutions of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application.

[0050] In the embodiments of the present application, it should be noted that, in this article, relational terms such as first and second, etc. are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0051] Moreover, the terms "comprises," "comprising," or any other variation thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0052] In the description of the embodiments of the present application, words such as "example" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "example" or "for example" in the embodiments of the present application is not to be interpreted as being more preferred or having more advantages than another embodiment or design. The use of words such as "example" or "for example" is intended to present relative concepts in a clear manner.

[0053] In addition, the "plurality" in the embodiments of the present application refers to two or more than two. In view of this, in the embodiments of the present application, "plurality" can also be understood as "at least two". "At least one" can be understood as one or more, for example, one, two or more. For example, including at least one means including one, two or more, and there is no limit on which ones are included. For example, including at least one of A, B and C, then A, B, C, A and B, A and C, B and C, or A, B and C can be included.

[0054] It should be noted that, in the embodiments of the present application, "and / or" describes the association relationship of the associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / ", unless otherwise specified, generally indicates that the associated objects before and after are in an "or" relationship.

[0055] It should be noted that in the embodiments of the present application, "connection" can be understood as electrical connection, and the connection between two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be either a direct connection between A and B or an indirect connection between A and B through one or more other electrical components.

[0056] An embodiment of the present application provides a filter circuit 100, see Figure 1 As shown, the filter circuit 100 of this embodiment includes: a series resonance unit 110, a parallel resonance unit 120, a first inductor L1 and a second inductor L2.

[0057] The series resonant unit 110 is connected in series between the first terminal 11 and the second terminal 12. The series resonant unit 120 includes a plurality of series resonant arms SR connected in series and a plurality of nodes n. The plurality of nodes n are respectively arranged on the connection path of each two adjacent series resonant arms SR. A node n is arranged between two adjacent series resonant arms SR.

[0058] Among them, the parallel resonance unit 120 is connected between the node n and the ground terminal GND, and the parallel resonance unit 120 includes a first parallel resonance arm PR1, a second parallel resonance arm PR2, a third parallel resonance arm PR3 and a fourth parallel resonance arm PR4 which are connected in parallel with each other, the first end of the first parallel resonance arm PR1 and the first end of the second parallel resonance arm PR2 are respectively connected to the first node n1, the first end of the third parallel resonance arm PR3 is connected to the second node n2, and the first end of the fourth parallel resonance arm PR4 is connected to the third node n3, wherein the first node n1, the second node n2 and the third node n3 are respectively one of the multiple nodes n, and the first node n1, the second node n2 and the third node n3 are arranged in sequence on the connection path from the first terminal 11 to the second terminal 12.

[0059] Exemplarily, the first node n1 and the second node n2 may be two adjacent nodes n, i.e., there is no other node n between the first node n1 and the second node n2; or, the first node n1 and the second node n2 may be two non-adjacent nodes n, i.e., there is at least one other node n between the first node n1 and the second node n2.

[0060] Exemplarily, the second node n2 and the third node n3 may be two adjacent nodes n, i.e., there is no other node n between the second node n2 and the third node n3; or, the second node n2 and the third node n3 may be two non-adjacent nodes n, i.e., there is at least one other node n between the second node n2 and the third node n3.

[0061] The first inductor L1 is connected between the second end of the first parallel resonant arm PR1 and the ground end GND.

[0062] The second end of the second parallel resonant arm PR2, the second end of the third parallel resonant arm PR3 and the second end of the fourth parallel resonant arm PR4 are respectively connected to the common node n0. The second inductor L2 is connected between the common node n0 and the ground terminal GND.

[0063] In this example, see Figure 2 As shown, the first parallel resonant arm PR1 and the first inductor L1 form a first adjustment unit 121, and the second parallel resonant arm PR2, the third parallel resonant arm PR3, the fourth parallel resonant arm PR4 and the second inductor L2 form a second adjustment unit 122. The equivalent capacitances of the second parallel resonant arm PR2, the third parallel resonant arm PR3 and the fourth parallel resonant arm PR4 are C2, C2 and C4 respectively, and the resonant frequency of the second adjustment unit Among them, the equivalent capacitance C of the second regulating unit 122 T is the parallel capacitance of the second parallel resonant arm PR2, the third parallel resonant arm PR3 and the fourth parallel resonant arm PR4, that is, C T =C2+C3+C4, under the premise of generating the same resonant frequency f2, the equivalent capacitance C of the second adjustment unit 122 is increased. T , which is beneficial to reduce the inductance value L.

[0064] The following is an example of the second inductor L2 being wound around a circuit substrate. Under the same installation area, the inductance value of the second inductor L2 is reduced, and the line width of the second inductor L2 can be increased and / or the number of windings of the second inductor L2 can be reduced, thereby improving the quality factor of the second inductor L2.

[0065] In the filter circuit of this embodiment, the first end of the second parallel resonant arm PR2 is connected to the first end of the first parallel resonant arm PR1, and the second end of the second parallel resonant arm PR2, the second end of the third parallel resonant arm PR3 and the second end of the fourth parallel resonant arm PR4 are connected to form a common node n0 and then grounded through the second inductor L2, which can improve the performance of the filter circuit and improve the suppression effect and isolation of the filter circuit.

[0066] As an implementation mode, the inductance value of the second inductor L2 is less than the inductance value of the first inductor L1. In this implementation mode, on the one hand, reducing the inductance value of the second inductor L2 further improves the quality factor of the second inductor L2, which is beneficial to improving the overall performance of the filter circuit; on the other hand, reducing the inductance value of the second inductor L2 is beneficial to improving the resonant frequency f2 of the second adjustment unit 122, which is beneficial to increasing the near-end out-of-band suppression level of the filter circuit; increasing the inductance value of the first inductor L1 is beneficial to reducing the resonant frequency f1 of the first adjustment unit 121, which is beneficial to increasing the far-end out-of-band suppression level of the filter circuit.

[0067] In some implementations, the difference between the inductance of the first inductor L1 and the inductance of the second inductor L2 is a first difference, and the first difference is 0.1nh to 0.3nh. In this implementation, by controlling the first difference within a certain range, the performance of the filter circuit is further improved.

[0068] In some embodiments, the resonant frequency f1 of the first adjustment unit 121 is greater than the resonant frequency f2 of the second adjustment unit 122. In this embodiment, the first adjustment unit 121 suppresses the far-end frequency band signal of the filter passband, and the second adjustment unit 122 suppresses the near-end frequency signal of the filter passband.

[0069] As an implementation mode, the second inductor L2 is wound on the circuit substrate; the series resonance unit 110 and the parallel resonance unit 120 are respectively integrated into the chip, and the second parallel resonance arm PR2, the third parallel resonance arm PR3 and the fourth parallel resonance arm PR4 are connected to the second inductor L2 through bonding wires or metal bumps. In this implementation mode, by setting it in a winding manner, the quality factor of the second inductor can be further improved, and the overall performance of the filter circuit can be improved. Exemplarily, the metal bump can be a copper column, a solder ball or other conductive connection structure.

[0070] As an implementation mode, the first inductor L1 is wound on the circuit substrate; the first parallel resonant arm PR1 is connected to the first inductor L1 through a bonding wire or a metal bump. In this implementation mode, the quality factor of the first inductor can be further improved by winding, and the overall performance of the filter circuit can be improved. Exemplarily, the metal bump can be a copper column, a solder ball or other conductive connection structure.

[0071] As an implementation manner, each series resonant arm SR may include one resonator or multiple series resonators, and the first parallel resonant arm PR1, the second parallel resonant arm PR2, the third parallel resonant arm PR3 and the fourth parallel resonant arm PR4 may include one resonator or multiple series resonators.

[0072] As an implementation, see Figure 3 As shown, the series resonant unit 120 includes a first series resonant arm SR1, a second series resonant arm SR2, a third series resonant arm SR3 and a fourth series resonant arm SR4 which are connected in series in sequence, the first series resonant arm SR1 is connected to the first terminal 11, the fourth series resonant arm SR4 is connected to the second terminal 12, a first node n1 is formed between the first series resonant arm SR1 and the second series resonant arm SR2, a second node n2 is formed between the second series resonant arm SR2 and the third series resonant arm SR3, and a third node n3 is formed between the third series resonant arm SR3 and the fourth series resonant arm SR4.

[0073] In some embodiments, the number of resonators included in the second series resonant arm SR2 is the same as the number of resonators included in the third series resonant arm SR3, the number of resonators included in the first series resonant arm SR1 is the same as the number of resonators included in the fourth series resonant arm SR4, and the number of resonators included in the second series resonant arm SR2 is greater than the number of resonators included in the first series resonant arm SR1. For example, please continue to refer to Figure 3 As shown, the first series resonant arm SR1 includes a series resonator S1, the second series resonant arm SR2 includes a series resonator S21 and a series resonator S22 connected in series with each other, the third series resonant arm SR3 includes a series resonator S31 and a series resonator S32 connected in series with each other, and the fourth series resonant arm SR1 includes a series resonator S4. The first parallel resonant arm PR1 includes a parallel resonator P1, the second parallel resonant arm PR2 includes a parallel resonator P2, the third parallel resonant arm PR3 includes a parallel resonator P3, and the fourth parallel resonant arm PR4 includes a parallel resonator P4.

[0074] In some embodiments, the first terminal 11 is used to connect to an antenna, and the second terminal 12 is used to connect to a power amplifier. In this embodiment, the filter circuit 100 is used to filter the RF transmission signal, and the RF transmission signal output after power amplification by the power amplifier is input from the second terminal 12. After the RF transmission signal is filtered by the filter circuit 100, the filtered RF transmission signal is output from the first terminal 11.

[0075] In some embodiments, see Figure 3As shown, the filter circuit 100 further includes a third inductor L3 and a fourth inductor L4. The third inductor L3 is connected between the first terminal 11 and the ground terminal, and the fourth inductor L4 is connected between the second terminal 12 and the second end of the fourth series resonant arm SR4.

[0076] See also Figure 4 As shown, Figure 3 The filter circuit 100 shown is applied to a filter device 201, and the filter device 201 includes a first terminal 11, a second terminal 12, a receiving terminal 13, a filter circuit 100, and a filter circuit 130. The first terminal 11 is connected to the antenna, and the second terminal 12 is connected to the power amplifier. The filter circuit 100 is arranged between the first terminal 11 and the second terminal 12. The filter circuit 100 is used to filter the radio frequency transmission signal (the radio frequency signal transmitted on the transmission path), and the filter circuit 130 is used to filter the radio frequency reception signal (the radio frequency signal transmitted on the reception path). The radio frequency transmission signal (the radio frequency signal transmitted on the transmission path) and the radio frequency reception signal (the radio frequency signal transmitted on the reception path) have different signal frequency ranges, respectively. The filter circuit 100 of this embodiment needs to ensure that the receiving end has a good suppression level and isolation, so as to avoid the radio frequency signal strength transmitted on the reception path from affecting the quality of the radio frequency transmission signal transmitted on the transmission path when the radio frequency signal strength is large.

[0077] In some implementations, the filter device 201 further includes a fifth inductor L5 , which is connected between the filter circuit 130 and the receiving terminal 13 .

[0078] In related art, see Figure 5 As shown, Figure 4 A variation of the filter device 201 shown, Figure 5 The difference between the filter circuit 101 for filtering the RF transmission signal (the RF signal transmitted on the transmission path) in the filter device 202 shown is that the first end of the second parallel resonant arm PR2 (parallel resonator P2) is connected to the first end of the third parallel resonant arm PR3 (parallel resonator P3).

[0079] In some embodiments, Figure 5 The filter circuit 101 shown in FIG. 1 is adjusted so that the first end of the second parallel resonant arm PR2 (parallel resonator P2) is not connected to the first end of the third parallel resonant arm PR3 (parallel resonator P3), but the first end of the second parallel resonant arm PR2 (parallel resonator P2) is connected to the first end of the fourth parallel resonant arm PR4 (parallel resonator P4). The structures and connection methods of the other parts are the same as those of FIG. Figure 5 The filter circuits 101 shown are identical.

[0080] In related art, see Figure 6As shown, Figure 4 A variation of the filter device 201 shown, Figure 5 The difference between the filter circuit 102 for filtering the RF transmission signal (transmitting end) in the filter device 203 shown is that the first end of the second parallel resonant arm PR2 (parallel resonator P2) is connected to the first end of the first parallel resonant arm PR1 (parallel resonator P1), the second end of the second parallel resonant arm PR2 (parallel resonator P2) is connected to the second end of the first parallel resonant arm PR1 (parallel resonator P1) and then grounded through the first inductor L1, and the second end of the third parallel resonant arm PR3 (parallel resonator P3) is connected to the second end of the fourth parallel resonant arm PR4 (parallel resonator P4) and then grounded through the second inductor L2.

[0081] It should be noted that Figure 4 The filter circuit 100 in the filter device 201 is hereinafter referred to as an embodiment, the filter circuit 101 is referred to as a comparative example 1, and the filter circuit 102 is referred to as a comparative example 2.

[0082] See also Figure 7a , which is a comparison diagram of the frequency characteristic curves of the filter circuits of the embodiment and comparative example 1, the solid line is the frequency characteristic of the filter circuit 100 of the embodiment, and the dotted line is the frequency characteristic of the filter circuit 101 of comparative example 1. Figure 7a It can be seen that in the far-end out-of-band frequency band of A1 Hz to A2 Hz, compared with the attenuation of comparative example 1, the attenuation of the embodiment is improved by more than 10 dB, thereby improving the far-end out-of-band suppression level.

[0083] Figure 7b for Figure 7a The enlarged diagram of the middle passband Z, the solid line is the frequency characteristic of the filter circuit 100 of the embodiment, and the dotted line is the frequency characteristic of the filter circuit 101 of the comparative example 1. Figure 7b It can be seen that for the near-end frequency band B1 Hz to B2 Hz of the receiving end, the attenuation of the embodiment is improved by more than 7 dB compared with the attenuation of comparative example 1, and the steepness of the passband edge in the curve of the embodiment is increased.

[0084] Figure 7c : is a comparison diagram of the isolation curves of the filter circuits of the embodiment and comparative example 1, the solid line is the isolation curve of the filter circuit 100 of the embodiment, and the dotted line is the isolation curve of the filter circuit 101 of comparative example 1. Figure 7c It can be seen that, for the near-end frequency band C1 Hz to B2 Hz at the receiving end, compared with the attenuation of comparative example 1, the attenuation of the embodiment is improved by more than 7 dB.

[0085] according to Figures 7a to 7cAccording to the passband diagram results, compared with comparative example 1, the far-end out-of-band suppression level, the near-end suppression level at the receiving end, and the near-end isolation of the filter circuit in the embodiment of the present application are respectively improved, and the overall performance is better.

[0086] See also Figure 8a As shown, it is a comparison diagram of the frequency characteristic curves of the filter circuits of the embodiment of the present application and the comparative example 2, the solid line is the frequency characteristic of the filter circuit 100 of the embodiment, and the dotted line is the frequency characteristic of the filter circuit 102 of the comparative example 2. Figure 8a It can be seen that for the near-end frequency band B1 Hz to B2 Hz of the receiving end, the attenuation of the embodiment of the present application is improved by more than 5 dB compared with the attenuation of comparative example 2, and the rectangularity of the right side of the passband in the curve of the embodiment of the present application is better.

[0087] Figure 8b : is a comparison diagram of the isolation curves of the filter circuits of the embodiment of the present application and comparative example 2, the solid line is the isolation curve of the filter circuit 100 of the embodiment of the present application, and the dotted line is the isolation curve of the filter circuit 102 of comparative example 2. Figure 8b It can be seen that, for the near-end frequency band C1 Hz to B2 Hz of the receiving end, compared with the attenuation of comparative example 2, the attenuation of the embodiment of the present application is improved by more than 5 dB.

[0088] according to Figure 8a to Figure 8b According to the passband diagram results, compared with comparative example 2, the near-end suppression level and near-end isolation of the receiving end of the filter circuit in the embodiment of the present application are respectively improved, and the overall performance is better.

[0089] An embodiment of the present application provides a radio frequency front-end module, see Fig. 9 As shown, the RF front-end module 300 includes the above-mentioned filter circuit 100.

[0090] As an implementation method, the RF front-end module 300 further includes a chip, see Fig.11 As shown, the first terminal 11 and the second terminal 12 in the filter circuit 100 are respectively integrated in the chip, and in the filter circuit setting area 100a of the chip, the first terminal 11 and the second terminal 12 are set away from each other, which is beneficial to reduce signal interference. The chip can be a piezoelectric wafer.

[0091] For example, the series resonator and the parallel resonator in the embodiment of the present application can respectively adopt surface acoustic wave (SAW, surface acoustic wave) resonator, see Fig.10a As shown, the series resonator S1 and the parallel resonator P1 include an IDT (Inter Digital Transducer) electrode 1101 and a pair of reflectors 1102, respectively. Fig.10bAs shown, the IDT electrode 111 includes a pair of comb-tooth electrodes 1101a and a comb-tooth electrode 1101b arranged crosswise with each other, the comb-tooth electrode 1101a includes a plurality of electrode fingers 110a parallel to each other and a bus bar electrode 111a connecting the plurality of electrode fingers 110a, and the comb-tooth electrode 1101b includes a plurality of electrode fingers 110b parallel to each other and a bus bar electrode 111b connecting the plurality of electrode fingers 110b. The plurality of electrode fingers 110a and the plurality of electrode fingers 110b extend in directions perpendicular to the propagation direction of the surface acoustic wave, respectively. In an embodiment of the present application, the length direction of the resonator or the length direction of the resonant arm is the propagation direction of the surface acoustic wave, and the width direction of the resonator or the width direction of the resonant arm is the extension direction of the electrode fingers. The first end and the second end of the resonant arm are respectively the two ends in the width direction.

[0092] It should be noted that the SAW resonator in the embodiment of the present application can be any type of SAW resonator, such as a normal SAW resonator, a TC-SAW (Temperature Compensated-Surface Acoustic Wave) resonator or a TF-SAW (Thin film Surface Acoustic Wave) resonator, etc., and the embodiment of the present application does not limit this. A normal SAW resonator is a metal interdigital transducer and a reflection grating processed on the surface of a piezoelectric substrate; it is mainly used for frequencies below 2 GHz. The TC-SAW resonator improves the temperature drift phenomenon by coating the interdigital electrode structure with another layer of material whose stiffness increases with increasing temperature; it is mainly used for frequencies below 2 GHz. The TF-SAW resonator, in which a thin film including a piezoelectric material is arranged on the substrate as a piezoelectric layer, and a interdigital transducer structure is arranged on the piezoelectric layer, has an excellent quality factor; it is mainly used in the frequency range of 2 GHz to 3.5 GHz, and can also be used for frequencies below 2 GHz.

[0093] As an implementation mode, the series resonance unit and the parallel resonance unit in the filter circuit 100 are respectively integrated in the setting area 100a of the chip, and each series resonance arm in the series resonance unit and each parallel resonance arm in the parallel resonance unit respectively include at least one surface acoustic wave resonator; the length directions of each series resonance arm and each parallel resonance arm are respectively parallel, and the length direction is the propagation direction of the surface acoustic wave.

[0094] In some embodiments, see Fig.11As shown, the setting area 100a includes a first direction parallel to the length direction of the surface acoustic wave resonator and a second direction perpendicular to the first direction. The multiple nodes in the series resonance unit are multiple series bus bars 125 arranged in sequence along the second direction. Two adjacent series resonance arms SR in the series resonance unit are respectively connected to the two sides of the corresponding series bus bar 125, and the two adjacent series resonance arms SR are arranged diagonally relative to the corresponding series bus bar 125. In this embodiment, the series bus bars are arranged in sequence, which is conducive to saving the setting area; the arrangement path of each series resonance arm SR bends back and forth between the two sides of the first direction of the setting area 100a, which can avoid the arrangement of each series resonance arm or each parallel resonance arm on the same side of the setting area 100a, which is conducive to the flexible arrangement of terminals and other devices while saving area.

[0095] In some embodiments, see Fig.12 and Fig.13 As shown, the series resonant unit includes a first series resonant arm SR1, a second series resonant arm SR2, a third series resonant arm SR3 and a fourth series resonant arm SR4 which are connected in series in sequence, the first node is a first series bus bar 1251 arranged between the first series resonant arm SR1 and the second series resonant arm SR2, the second node is a second series bus bar 1252 arranged between the second series resonant arm SR2 and the third series resonant arm SR3, and the third node is a third series bus bar 1253 arranged between the third series resonant arm SR3 and the fourth series resonant arm SR4; the first series resonant arm SR1 and the second series resonant arm SR2 are arranged diagonally relative to the first series bus bar 1251, the second series resonant arm SR2 and the third series resonant arm SR3 are arranged diagonally relative to the second series bus bar 1252, and the third series resonant arm SR3 and the fourth series resonant arm SR4 are arranged diagonally relative to the third series bus bar 1253.

[0096] In some embodiments, see Fig.12 and Fig.13 As shown, the first terminal 11 is connected to the first series resonant arm SR1 through the fourth series bus bar 1254, and the first terminal 11 is arranged on a side of the first series resonant arm SR1 away from the first series bus bar 1251; the second terminal 12 is connected to the fourth series resonant arm SR4 through the fifth series bus bar 1255, and the second terminal 12 is arranged on a side of the fourth series resonant arm SR4 away from the third series bus bar 1253. In this embodiment, the first terminal 11 and the second terminal 12 are away from each other in the second direction, which is conducive to reducing signal interference.

[0097] In some embodiments, see Fig.12 and Fig.13As shown, the first parallel resonant arm PR1 and the first series resonant arm SR1 are respectively connected to the two sides of the first series bus bar 1251 and are arranged side by side in the second direction; the second parallel resonant arm PR2 and the second series resonant arm SR2 are respectively connected to the two sides of the first series bus bar 1251 and are arranged side by side in the second direction; the first series resonant arm SR1 and the second parallel resonant arm PR2 are arranged in sequence along the first direction, and the first parallel resonant arm PR1 and the second series resonant arm SR2 are arranged in sequence along the first direction. In this embodiment, the first parallel resonant arm PR1 and the second parallel resonant arm PR2 are arranged diagonally on both sides of the first series bus bar 1251, which is conducive to saving the layout area to achieve miniaturization of the filter circuit.

[0098] In some embodiments, see Fig.12 and Fig.13 As shown, the third parallel resonant arm PR3 and the fourth parallel resonant arm PR4 are arranged side by side in the second direction between the second serial bus bar 1252 and the third serial bus bar 1253, the third parallel resonant arm PR3 is connected to the second serial bus bar 1252, the fourth parallel resonant arm PR4 is connected to the third serial bus bar 1253, the third parallel resonant arm PR3 and the fourth parallel resonant arm PR4 are connected through the first parallel bus bar 1261, and the first parallel bus bar 1261 is arranged between the third parallel resonant arm PR3 and the fourth parallel resonant arm PR4. In this embodiment, the second parallel resonant arm PR2, the third parallel resonant arm PR3 and the fourth parallel resonant arm PR4 are respectively arranged on the same side of the setting area 100a in the first direction, which is conducive to saving the layout area to achieve miniaturization of the filter circuit.

[0099] Exemplarily, the first series resonant arm SR1, the second series resonant arm SR2, the third series resonant arm SR3 and the fourth series resonant arm SR4 may respectively include at least one surface acoustic wave resonator. On the premise that the comb-tooth electrodes of each surface acoustic wave resonator have the same length, the more surface acoustic wave resonators are included, the greater the width of the resonant arm. For example, Fig.12 In the embodiment, the first series resonant arm SR1 and the fourth series resonant arm SR4 include a surface acoustic wave resonator respectively, the second series resonant arm SR2 and the third series resonant arm SR3 include two surface acoustic wave resonators connected in series respectively, if it is assumed that the comb-teeth electrode lengths of the surface acoustic wave resonators are equal, the widths of the second series resonant arm SR2 and the third series resonant arm SR3 are equal, the widths of the first series resonant arm SR1 and the fourth series resonant arm SR4 are equal, and the width of the second series resonant arm SR2 is greater than the width of the first series resonant arm SR1.

[0100] In some embodiments, the RF front-end module 300 of this embodiment further includes a substrate (not shown), and the first inductor L1 and the second inductor L2 in the filter circuit 100 are respectively wound on the substrate. In this embodiment, by setting in a winding manner, the quality factor of the first inductor and the second inductor can be further improved, and the overall performance of the filter circuit can be improved. The filter circuit 100 also includes a third terminal 123 for connecting the first inductor L1 and a fourth terminal 124 for connecting the second inductor L2. The third terminal 123 and the fourth terminal 124 are far away from each other in the setting area 100a, and the third terminal 123 is set in the area between the first parallel resonant arm PR1 and the third series resonant arm SR3. The fourth terminal 124 and the third parallel resonant arm PR3 are arranged side by side in the first direction, and the fourth terminal 124 is located on the side of the third parallel resonant arm PR3 away from the third terminal 123. In this embodiment, the fourth terminal 124, the second parallel resonant arm PR2, the third parallel resonant arm PR3 and the fourth parallel resonant arm PR4 are respectively arranged on the same side of the setting area 100a in the first direction, the third terminal 123 and the first parallel resonant arm PR1 are located on the other side of the setting area 100a in the first direction, and the third terminal 123 and the fourth terminal 124 are far away from each other, which is beneficial to reducing the mutual interference between the first inductor L1 and the second inductor L2, thereby improving the performance of the filter circuit; and, by selecting the layout positions of the third terminal and the fourth terminal, the layout area is further saved to achieve miniaturization of the filter circuit.

[0101] In some embodiments, the fourth terminal 124 is a common node n0, the fourth terminal 124 is respectively connected to the third parallel resonant arm PR3 and the fourth parallel resonant arm PR4 through the first parallel bus bar 1261, the fourth terminal 124 is connected to the second parallel resonant arm PR2 through the second parallel bus bar 1262, and the fourth terminal 124 is connected to the side of the second parallel resonant arm PR2 away from the first series bus bar 1251. The second parallel bus bar 1262 is L-shaped, and the second parallel bus bar 1262 includes a first section 1262a extending along the first direction and a second section 1262b extending along the second direction, the first section 1262a is connected to the side of the second parallel resonant arm PR2 away from the first series bus bar 1251, and the second section 1262b is connected to the fourth terminal 124. In this embodiment, the fourth terminal 124, the second parallel resonant arm PR2, the third parallel resonant arm PR3 and the fourth parallel resonant arm PR4 are connected by the first parallel bus bar 1261 and the L-shaped second parallel bus bar 1262, which is beneficial to saving layout area to achieve miniaturization of the filter circuit.

[0102] In some embodiments, see Fig.13As shown, the setting area 100a is rectangular, and the first terminal 11 and the second terminal 12 are respectively arranged at the two ends of the diagonal of the rectangle. In this embodiment, the first terminal and the second terminal are distributed diagonally, which can further increase the distance between the first terminal and the second terminal and reduce signal interference.

[0103] The above is only an implementation method of the present application. It should be pointed out that a person skilled in the art can make improvements without departing from the creative concept of the present application, but these improvements are within the scope of protection of the present application.

Claims

1. A filter circuit, characterized in that: include: A series resonance unit connected in series between the first terminal and the second terminal, the series resonance unit comprising a plurality of series resonance arms connected in series and a plurality of nodes, the plurality of nodes being respectively arranged on a connection path between each two adjacent series resonance arms; a parallel resonance unit connected between the node and the ground terminal, the parallel resonance unit comprising a first parallel resonance arm, a second parallel resonance arm, a third parallel resonance arm and a fourth parallel resonance arm, the first end of the first parallel resonance arm and the first end of the second parallel resonance arm are respectively connected to the first node, the first end of the third parallel resonance arm is connected to the second node, and the first end of the fourth parallel resonance arm is connected to the third node, wherein the first node, the second node and the third node are respectively one of the plurality of nodes, and the first node, the second node and the third node are sequentially arranged on a connection path from the first terminal to the second terminal; a first inductor connected between the second end of the first parallel resonant arm and the ground end; A second inductor is connected between a common node and the ground terminal, wherein a second end of the second parallel resonant arm, a second end of the third parallel resonant arm and a second end of the fourth parallel resonant arm are respectively connected to the common node.

2. The filter circuit according to claim 1, characterized in that: The inductance value of the second inductor is smaller than the inductance value of the first inductor.

3. The filter circuit according to claim 1 or 2, characterized in that: A difference between the inductance value of the first inductor and the inductance value of the second inductor is a first difference value, and the first difference value is 0.1 nh to 0.3 nh.

4. The filter circuit according to claim 1, characterized in that: The first inductor and the first parallel resonant arm form a first adjustment unit, the second inductor, the second parallel resonant arm, the third parallel resonant arm and the fourth parallel resonant arm form a second adjustment unit, and the resonant frequency of the first adjustment unit is greater than the resonant frequency of the second adjustment unit.

5. The filter circuit according to claim 1, characterized in that: The second inductor is wound on a circuit substrate; the series resonance unit and the parallel resonance unit are respectively integrated into a chip, and the second parallel resonance arm, the third parallel resonance arm and the fourth parallel resonance arm are connected to the second inductor through bonding wires or metal bumps; And / or, the first inductor is wound on a circuit substrate; the first parallel resonant arm is connected to the first inductor via a bonding wire or a metal bump.

6. The filter circuit according to claim 1, characterized in that: The series resonant unit comprises a first series resonant arm, a second series resonant arm, a third series resonant arm and a fourth series resonant arm which are connected in series in sequence, wherein the first series resonant arm is connected to the first terminal, the fourth series resonant arm is connected to the second terminal, the first node is formed between the first series resonant arm and the second series resonant arm, the second node is formed between the second series resonant arm and the third series resonant arm, and the third node is formed between the third series resonant arm and the fourth series resonant arm; The number of resonators included in the second series resonant arm is the same as the number of resonators included in the third series resonant arm, the number of resonators included in the first series resonant arm is the same as the number of resonators included in the fourth series resonant arm, and the number of resonators included in the second series resonant arm is greater than the number of resonators included in the first series resonant arm.

7. The filter circuit according to claim 1, characterized in that: The first terminal is used to connect to an antenna, and the second terminal is used to connect to a power amplifier.

8. A radio frequency front-end module, characterized in that: The invention comprises the filter circuit as claimed in any one of claims 1 to 7.

9. The RF front-end module according to claim 8, characterized in that: It also includes a chip, wherein the first terminal and the second terminal in the filter circuit are respectively integrated into the chip, and in the setting area of ​​the filter circuit of the chip, the first terminal and the second terminal are set away from each other; the series resonance unit and the parallel resonance unit in the filter circuit are respectively integrated in the setting area of ​​the chip.

10. The RF front-end module according to claim 9, characterized in that: The setting area includes a first direction parallel to the propagation direction of the surface acoustic wave and a second direction perpendicular to the first direction. The multiple nodes in the series resonance unit are respectively multiple series bus bars arranged in sequence along the second direction. The two adjacent series resonance arms in the series resonance unit are respectively connected to the two sides of the corresponding series bus bars, and the two adjacent series resonance arms are arranged diagonally relative to the corresponding series bus bars.

11. The RF front-end module according to claim 10, characterized in that: The series resonance unit comprises a first series resonance arm, a second series resonance arm, a third series resonance arm and a fourth series resonance arm which are connected in series in sequence, the first node is a first series bus bar arranged between the first series resonance arm and the second series resonance arm, the second node is a second series bus bar arranged between the second series resonance arm and the third series resonance arm, and the third node is a third series bus bar arranged between the third series resonance arm and the fourth series resonance arm; The first terminal is connected to the first series resonant arm through the fourth series bus bar, and the first terminal is arranged on a side away from the first series bus bar, and the second terminal is connected to the fourth series resonant arm through the fifth series bus bar, and the second terminal is arranged on a side away from the third series bus bar.

12. The RF front-end module according to claim 11, characterized in that: The first parallel resonant arm and the first series resonant arm are respectively connected to two sides of the first series-connected bus bar and are arranged side by side in the second direction; The second parallel resonant arm and the second series resonant arm are respectively connected to two sides of the first series-connected bus bar and are arranged side by side in the second direction; The first series resonant arm and the second parallel resonant arm are arranged in sequence along a first direction, and the first parallel resonant arm and the second series resonant arm are arranged in sequence along the first direction.

13. The RF front-end module according to claim 12, characterized in that: The third parallel resonant arm and the fourth parallel resonant arm are arranged side by side between the second series bus bar and the third series bus bar in the second direction, and the third parallel resonant arm and the fourth parallel resonant arm are connected through a first parallel bus bar, and the first parallel bus bar is arranged between the third parallel resonant arm and the fourth parallel resonant arm.

14. The RF front-end module according to claim 13, characterized in that: The RF front-end module further includes a substrate, and the first inductor and the second inductor in the filter circuit are respectively wound on the substrate; The filter circuit also includes a third terminal for connecting the first inductor and a fourth terminal for connecting the second inductor, the third terminal and the fourth terminal are far away from each other in the setting area, the third terminal is set in the area between the first parallel resonant arm and the third series resonant arm, the fourth terminal and the third parallel resonant arm are arranged side by side in the first direction, and the fourth terminal is located on a side of the third parallel resonant arm away from the third terminal.

15. The RF front-end module according to claim 14, characterized in that: The fourth terminal is the common node, the fourth terminal is respectively connected to the third parallel resonant arm and the fourth parallel resonant arm through the first parallel bus bar, the fourth terminal is connected to the second parallel resonant arm through the second parallel bus bar, and the fourth terminal is connected to a side of the second parallel resonant arm away from the first series bus bar.

16. The radio frequency front-end module according to claim 15, characterized in that: The setting area is rectangular, and the first terminal and the second terminal are respectively arranged at two ends of a diagonal line of the rectangle.

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