Bandpass filter

Abstract

The bandpass filter (100) provided by the present invention includes filter circuits (FC1, FC2), intermediate circuits (MC1, MC2), and a capacitor (C51). The intermediate circuit (MC1) has an inductor (L31) connected between capacitors (C31 and C32). The intermediate circuit (MC2) has an inductor (L41) connected between capacitors (C41 and C42). The resonant circuits (RC1, RC2) included in the filter circuit (FC1) are grounded via a common capacitor (C61). The resonant circuits (RC3, RC4) included in the filter circuit (FC2) are grounded via a common capacitor (C62). The capacitor (C51) is connected between the intermediate circuits (MC1) and (MC2).

Description

Technical Field

[0001] This invention relates to bandpass filters, and more particularly to bandpass filters having multiple resonant circuits consisting of inductors and capacitors. Background Technology

[0002] Multiple resonant circuits with capacitors and inductors are formed within a stack comprising a dielectric layer, a patterned conductor, and a conductive conductor to construct a high-frequency bandpass filter suitable for miniaturization and low cost. As an example of such a bandpass filter, the bandpass filter described in Japanese Patent Application Publication No. 2014-57277 (Patent Document 1) can be cited.

[0003] Patent Document 1's bandpass filter has three or more resonant circuits composed of inductors and capacitors, and floating conductors configured not to contact other line conductors and spanning across each inductor. Furthermore, the electrostatic capacitance formed between the floating conductors and the specified line conductors is larger than the total resonant capacitance constituting the capacitors.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2014-57277

[0005] In bandpass filters, there are situations where it is necessary to simultaneously maintain the passband and change the attenuation of the attenuator. Here, in the bandpass filter of Patent Document 1, the above-described structure allows for capacitive coupling of non-adjacent resonant circuits, resulting in the desired passband. However, in this case, if the passband is changed, the attenuation of the attenuator also changes accordingly. That is, there is a concern that it is difficult to change the attenuation of the attenuator while maintaining the passband. Summary of the Invention

[0006] That is, the purpose of this invention is to provide a bandpass filter that can generate attenuation poles with the required attenuation on at least one of the high-frequency side and the low-frequency side of the passband while maintaining the passband.

[0007] The bandpass filter of this invention achieves an improvement in the coupling structure of multiple resonant circuits.

[0008] The first embodiment of the bandpass filter of the invention includes a first filter circuit, a second filter circuit, a first intermediate circuit, a second intermediate circuit, and a ninth capacitor.

[0009] The first filter circuit includes a first resonant circuit, a second resonant circuit, and a first common capacitor. The first resonant circuit has a first inductor, a third inductor, and a first capacitor. The second resonant circuit has a second inductor, a third inductor, and a second capacitor. The first and second resonant circuits are grounded via the first common capacitor.

[0010] The second filter circuit includes a third resonant circuit, a fourth resonant circuit, and a first common capacitor. The third resonant circuit has a fourth inductor, a sixth inductor, and a third capacitor. The fourth resonant circuit has a fifth inductor, a sixth inductor, and a fourth capacitor. The third and fourth resonant circuits are grounded via the second common capacitor.

[0011] The first intermediate circuit has a grounded fifth capacitor and a grounded sixth capacitor, and a seventh inductor connected between the fifth and sixth capacitors. The second intermediate circuit has a grounded seventh capacitor and a grounded eighth capacitor, and an eighth inductor connected between the seventh and eighth capacitors.

[0012] The seventh inductor is coupled to the electromagnetic fields of the first through third inductors. The eighth inductor is coupled to the electromagnetic fields of the fourth through seventh inductors.

[0013] Furthermore, the ninth capacitor is connected between the first intermediate circuit and the second intermediate circuit.

[0014] The second embodiment of the bandpass filter of the invention comprises multiple stacked dielectric layers, a first filter circuit and a second filter circuit, a first intermediate circuit and a second intermediate circuit, a first ground electrode, and a first intermediate capacitor electrode.

[0015] A first filter circuit and a second filter circuit are arranged in a direction orthogonal to the stacking direction of the multiple dielectric layers. A first intermediate circuit and a second intermediate circuit are arranged between the first filter circuit and the second filter circuit. Furthermore, the first intermediate circuit is electromagnetically coupled to the first filter circuit. The second intermediate circuit is electromagnetically coupled to both the second filter circuit and the first intermediate circuit.

[0016] The first filter circuit and the second filter circuit each include a first line electrode, a common electrode, a first capacitor electrode, a second capacitor electrode, a first conducting conductor, a second conducting conductor, and a common conducting conductor.

[0017] The first line electrode extends perpendicularly to the stacking direction of the dielectric layer. A first capacitor electrode and a second capacitor electrode are disposed opposite a common electrode. A first conducting conductor passes through the stacking direction and connects the first line electrode to the first capacitor electrode. A second conducting conductor passes through the stacking direction and connects the first line electrode to the second capacitor electrode. A common conducting conductor is disposed between the first and second conducting conductors, passes through the stacking direction, and connects the first line electrode to the common electrode.

[0018] The first intermediate circuit and the second intermediate circuit respectively include a second grounding electrode, a grounding conductor, a third capacitor electrode, a fourth capacitor electrode, a second line electrode, a third conductor, and a fourth conductor.

[0019] The second line electrode extends perpendicularly to the stacking direction of the dielectric layer. The third and fourth capacitor electrodes are positioned opposite the second ground electrode. A third conductive conductor passes through the stacking direction and connects the second line electrode to the third capacitor electrode. A fourth conductive conductor passes through the stacking direction and connects the second line electrode to the fourth capacitor electrode. A ground conductive conductor connects the first ground electrode to the second ground electrode.

[0020] Furthermore, the first intermediate capacitor electrode is configured opposite to the third capacitor electrode of the first intermediate circuit and the third capacitor electrode of the second intermediate circuit.

[0021] The bandpass filter of this invention can generate attenuation poles with the required attenuation on at least one of the high-frequency side and the low-frequency side of the passband while maintaining the passband. Attached Figure Description

[0022] Figure 1 This is the equivalent circuit diagram of the bandpass filter in the first example of this embodiment.

[0023] Figure 2 yes Figure 1 The decomposed stereo diagram of the bandpass filter.

[0024] Figure 3 yes Figure 1 The filtering characteristics of the bandpass filter are shown in the figure.

[0025] Figure 4 This is the equivalent circuit diagram of the bandpass filter in the second example of this embodiment.

[0026] Figure 5 yes Figure 4 A decomposed stereoscopic view of a portion of a bandpass filter.

[0027] Figure 6 yes Figure 4 The filtering characteristics of the bandpass filter are shown in the figure. Detailed Implementation

[0028] The following describes embodiments of the invention, and further details the features of the invention. Examples of bandpass filters using this invention include, for instance, stacked ceramic filters obtained by simultaneously firing low-temperature sintered ceramics, patterned conductors, and conductive conductors, but the invention is not limited to these.

[0029] The bandpass filter of this embodiment is related to the generation of attenuation poles on the high-frequency side of the passing frequency band, and is characterized by having a capacitor that connects the first intermediate circuit and the second intermediate circuit described later.

[0030] <First example>

[0031] use Figures 1-3 The bandpass filter 100, which is the first example of this embodiment, will be described.

[0032] Furthermore, the exploded perspective views described later are schematic diagrams. For example, the thickness of the dielectric layer and the patterned conductor, as well as the thickness of the conductive conductor, are schematic. In addition, deviations in the shape of the various components that occur during the manufacturing process are not necessarily reflected in the drawings. That is, even if the drawings used in this specification for illustrative purposes differ from the actual product, they can essentially be considered to represent the actual product.

[0033] Figure 1 This is the equivalent circuit diagram of a bandpass filter 100. The bandpass filter 100 includes a first filter circuit FC1, a second filter circuit FC2, a first intermediate circuit MC1, and a second intermediate circuit MC2.

[0034] The first filter circuit FC1 includes a first resonant circuit RC1, a second resonant circuit RC2, and a first common capacitor C61. The first resonant circuit RC1 has a first inductor L11, a third inductor L13, and a first capacitor C11. The second resonant circuit RC2 has a second inductor L12, a third inductor L13, and a second capacitor C12.

[0035] In the first resonant circuit RC1, the first inductor L11 and the third inductor L13, connected in series, are connected in parallel with the first capacitor C11. In the second resonant circuit RC2, the second inductor L12 and the third inductor L13, connected in series, are connected in parallel with the second capacitor C12. The third inductor L13 is a shared component in both the first resonant circuit RC1 and the second resonant circuit RC2.

[0036] In addition, the first filter circuit FC1 also includes a first port PT1 connected to the connection point of the first inductor L11 and the first capacitor C11. Furthermore, the connection point of the first capacitor C11, the second capacitor C12, and the third inductor L13 of the first filter circuit FC1 is grounded via a first common capacitor C61.

[0037] The second filter circuit FC2 includes a third resonant circuit RC3, a fourth resonant circuit RC4, and a second common capacitor C62. The third resonant circuit RC3 has a fourth inductor L21, a sixth inductor L23, and a third capacitor C21. The fourth resonant circuit RC4 has a fifth inductor L22, a sixth inductor L23, and a fourth capacitor C22.

[0038] In the third resonant circuit RC3, the fourth inductor L21 and the sixth inductor L23, connected in series, are connected in parallel with the third capacitor C21. In the fourth resonant circuit RC4, the fifth inductor L22 and the sixth inductor L23, connected in series, are connected in parallel with the fourth capacitor C22. The sixth inductor L23 is a shared component in both the third resonant circuit RC3 and the fourth resonant circuit RC4.

[0039] Furthermore, the second filter circuit FC2 also includes a second port PT2 connected to the connection point of the fourth inductor L21 and the third capacitor C21. Additionally, the connection point of the third capacitor C21, the fourth capacitor C22, and the sixth inductor L23 of the second filter circuit FC2 is grounded via a second common capacitor C62.

[0040] The first intermediate circuit MC1 includes a fifth capacitor C31, a sixth capacitor C32, and a seventh inductor L31. The fifth capacitor C31 and the sixth capacitor C32 are grounded. The seventh inductor L31 is connected between the fifth capacitor C31 and the sixth capacitor C32. That is, one electrode of the fifth capacitor C31 is grounded, and the other electrode is connected to one end of the seventh inductor L31. Similarly, one electrode of the sixth capacitor C32 is grounded, and the other electrode is connected to the other end of the seventh inductor L31. The first intermediate circuit MC1 functions as a resonant circuit, that is, it becomes the resonant circuit of the center stage of the bandpass filter 100.

[0041] The second intermediate circuit MC2 includes a seventh capacitor C41, an eighth capacitor C42, and an eighth inductor L41. The seventh capacitor C41 and the eighth capacitor C42 are grounded. The eighth inductor L41 is connected between the seventh capacitor C41 and the eighth capacitor C42. That is, one electrode of the seventh capacitor C41 is grounded, and the other electrode is connected to one end of the eighth inductor L41. Similarly, one electrode of the eighth capacitor C42 is grounded, and the other electrode is connected to the other end of the eighth inductor L41. The second intermediate circuit MC2 functions as a resonant circuit, that is, it becomes the resonant circuit of the center stage of the bandpass filter 100.

[0042] The seventh inductor L31 is electromagnetically coupled to the first inductor L11, the second inductor L12, and the third inductor L13. The eighth inductor L41 is electromagnetically coupled to the fourth inductor L21, the fifth inductor L22, and the sixth inductor L23. Furthermore, the seventh inductor L31 is also electromagnetically coupled to the eighth inductor L41.

[0043] Furthermore, the bandpass filter 100 also includes a ninth capacitor C51. The ninth capacitor C51 is connected between the connection point A1 of the fifth capacitor C31 and the seventh inductor L31, and the connection point B1 of the seventh capacitor C41 and the eighth inductor L41.

[0044] Figure 2 This is an exploded perspective view of the bandpass filter 100. The bandpass filter 100 includes stacked dielectric layers DL1-DL13, a first filter circuit and a second filter circuit, a first intermediate circuit and a second intermediate circuit, and a rectangular first intermediate capacitor electrode P16. Furthermore, although in Figure 2 In this case, a direction marker PM is configured on the dielectric layer DL1, but this is not required (the same applies below).

[0045] A first filter circuit and a second filter circuit are arranged in a direction orthogonal to the stacking direction of dielectric layers DL1 to DL13. A first intermediate circuit and a second intermediate circuit are arranged between the first filter circuit and the second filter circuit. Furthermore, the first intermediate circuit is electromagnetically coupled to the first filter circuit. The second intermediate circuit is electromagnetically coupled to both the second filter circuit and the first intermediate circuit.

[0046] The first filter circuit includes a first line electrode P1, a common electrode P2, a first capacitor electrode P3, a second capacitor electrode P4, a first conducting conductor V1, a second conducting conductor V2, and a common conducting conductor V3. The first line electrode P1 and the first capacitor electrode P3 are rectangular, the common electrode P2 is C-shaped, and the second capacitor electrode P4 is L-shaped. However, the shapes of the electrodes are not limited to these shapes. For example, the common electrode P2 can also be divided into a first part and a second part.

[0047] The first line electrode P1 is formed on the dielectric layer DL2. That is, it extends in a direction perpendicular to the stacking direction of the dielectric layers DL1 to DL13. When viewed from the stacking direction, the first capacitor electrode P3 and the second capacitor electrode P4 are arranged opposite to the common electrode P2 via the dielectric layer DL10, with at least a portion of each overlapping the common electrode P2.

[0048] That is, the first capacitor C11 described above is configured to include a first capacitor electrode P3 and a common electrode P2. The second capacitor C12 described above is configured to include a second capacitor electrode P4 and a common electrode P2. Furthermore, when the common electrode P2 is divided into a first part and a second part, the first capacitor C11 may include the first part and the second capacitor C12 may include the second part.

[0049] A first conducting conductor V1 extends through dielectric layers DL2 to DL9 and connects the first line electrode P1 to the first capacitor electrode P3. A second conducting conductor V2 extends through dielectric layers DL2 to DL9 and connects the first line electrode P1 to the second capacitor electrode P4. Furthermore, a common conducting conductor V3 is disposed between the first conducting conductor V1 and the second conducting conductor V2, extends through dielectric layers DL2 to DL10, and connects the first line electrode P1 to the common electrode P2.

[0050] Specifically, in Figure 2 When the lower surface of each electrode is designated as one main surface and the upper surface as the other main surface, one end of the first conducting conductor V1 is connected to one main surface of the first line electrode P1, and the other end is connected to the other main surface of the first capacitor electrode P3. One end of the second conducting conductor V2 is connected to one main surface of the first line electrode P1, and the other end is connected to the other main surface of the second capacitor electrode P4. Furthermore, one end of the common conducting conductor V3 is connected to one main surface of the first line electrode P1, and the other end is connected to the other main surface of the common electrode P2.

[0051] That is, the first inductor L11 is configured to include a first conducting conductor V1. The second inductor L12 is configured to include a second conducting conductor V2. The third inductor L13 is configured to include a common conducting conductor V3.

[0052] Furthermore, a lead-out electrode PL1 is connected to the first conductive conductor V1. Specifically, the lead-out electrode PL1 is provided to connect the first conductive conductor V1, located at the outer periphery of the dielectric layer, to the signal electrode PS1, located at the center of the dielectric layer. In the bandpass filter 100, the lead-out electrode PL1 is S-shaped, but its shape is not limited to this. The connection position between the first conductive conductor V1 and the lead-out electrode PL1 is determined according to the inductance design of the first inductor L11 described above. The lead-out electrode PL1 is connected to the signal electrode PS1, located on the outer surface of the dielectric layer DL13 (bottom of the drawing).

[0053] The second filter circuit includes a first line electrode P5, a common electrode P6, a first capacitor electrode P7, a second capacitor electrode P8, a first conducting conductor V4, a second conducting conductor V5, and a common conducting conductor V6. The first line electrode P5 and the first capacitor electrode P7 are rectangular, the common electrode P6 is C-shaped, and the second capacitor electrode P8 is L-shaped. However, the shapes of the electrodes are not limited to these shapes. For example, the common electrode P6 can also be divided into a first part and a second part.

[0054] The first line electrode P5 is formed in the dielectric layer DL2. That is, it extends in a direction perpendicular to the stacking direction of the dielectric layers DL1 to DL13. When viewed from the stacking direction, the first capacitor electrode P7 and the second capacitor electrode P8 are arranged opposite to the common electrode P2 via the dielectric layer DL10, with at least a portion of each overlapping the common electrode P6.

[0055] That is, the third capacitor C21 described above is configured to include a first capacitor electrode P7 and a common electrode P6. The fourth capacitor C22 described above is configured to include a second capacitor electrode P8 and a common electrode P6. Furthermore, if the common electrode P6 is divided into a first part and a second part, the third capacitor C21 may include the first part and the fourth capacitor C22 may include the second part.

[0056] A first conducting conductor V4 penetrates dielectric layers DL2 to DL9 and connects the first line electrode P5 to the first capacitor electrode P7. A second conducting conductor V5 penetrates dielectric layers DL2 to DL9 and connects the first line electrode P5 to the second capacitor electrode P8. A common conducting conductor V6 is disposed between the first conducting conductor V4 and the second conducting conductor V5, penetrates dielectric layers DL2 to DL10, and connects the first line electrode P5 to the common electrode P6.

[0057] Specifically, one end of the first conducting conductor V4 is connected to one main surface of the first line electrode P5, and the other end is connected to the other main surface of the first capacitor electrode P7. One end of the second conducting conductor V5 is connected to one main surface of the first line electrode P5, and the other end is connected to the other main surface of the second capacitor electrode P8. Furthermore, one end of the common conducting conductor V6 is connected to one main surface of the first line electrode P5, and the other end is connected to the other main surface of the common electrode P6.

[0058] That is, the fourth inductor L21 is configured to include a first conducting conductor V4. The fifth inductor L22 is configured to include a second conducting conductor V5. The sixth inductor L23 is configured to include a common conducting conductor V6.

[0059] Furthermore, a lead-out electrode PL2 is connected to the first conductive conductor V4. Specifically, the lead-out electrode PL2 is provided to connect the first conductive conductor V4, located on the outer periphery of the dielectric layer opposite to the outer periphery where the first conductive conductor V1 is located, to the signal electrode PS2 located in the central portion of the dielectric. In the bandpass filter 100, the lead-out electrode PL2 is S-shaped, but its shape is not limited to this. The connection position between the first conductive conductor V4 and the lead-out electrode PL2 is determined according to the inductance design of the fourth inductor L21 described above. The lead-out electrode PL2 is connected to the signal electrode PS2 located on the outer surface of the dielectric layer DL13 (bottom of the drawing).

[0060] The first intermediate circuit includes a second line electrode P9, a second ground electrode P10, a third capacitor electrode P11, a fourth capacitor electrode P12, a third conducting conductor V7, and a fourth conducting conductor V8. The second line electrode P9, the second ground electrode P10, the third capacitor electrode P11, and the fourth capacitor electrode P12 are all rectangular in shape. However, the shape of each electrode is not limited to this.

[0061] The second line electrode P9 is formed on the dielectric layer DL2. That is, it extends in a direction perpendicular to the stacking direction of the dielectric layers DL1 to DL13. When viewed from the stacking direction, the third capacitor electrode P11 and the fourth capacitor electrode P12 are arranged opposite to the second ground electrode P10 via the dielectric layer DL10, with at least a portion of each overlapping the second ground electrode P10.

[0062] That is, the fifth capacitor C31 described above is configured to include a third capacitor electrode P11 and a second ground electrode P10. The sixth capacitor C32 described above is configured to include a fourth capacitor electrode P12 and a second ground electrode P10.

[0063] The third conducting conductor V7 penetrates the dielectric layers DL2 to DL9 and connects the second line electrode P9 to the third capacitor electrode P11. The fourth conducting conductor V8 penetrates the dielectric layers DL2 to DL9 and connects the second line electrode P9 to the fourth capacitor electrode P12. Specifically, one end of the third conducting conductor V7 is connected to one main surface of the second line electrode P9, and the other end is connected to the other main surface of the third capacitor electrode P11. One end of the fourth conducting conductor V8 is connected to one main surface of the second line electrode P9, and the other end is connected to the other main surface of the fourth capacitor electrode P12.

[0064] That is, the aforementioned seventh inductor L31 is configured to include a second line electrode P9, a third conducting conductor V7, and a fourth conducting conductor V8.

[0065] The second intermediate circuit includes a second line electrode P13, a second ground electrode P10, a third capacitor electrode P14, a fourth capacitor electrode P15, a third conducting conductor V9, and a fourth conducting conductor V10. The second ground electrode P10 is a common component in both the first and second intermediate circuits. The second line electrode P13, the third capacitor electrode P14, and the fourth capacitor electrode P15 are all rectangular in shape. However, the shape of each electrode is not limited to this.

[0066] The second line electrode P13 is formed on the dielectric layer DL2. That is, it extends in a direction perpendicular to the stacking direction of the dielectric layers DL1 to DL13. When viewed from the stacking direction, the third capacitor electrode P14 and the fourth capacitor electrode P15 are arranged opposite to the second ground electrode P10 via the dielectric layer DL10, with at least a portion of each overlapping the second ground electrode P10.

[0067] That is, the seventh capacitor C41 described above is configured to include a third capacitor electrode P14 and a second ground electrode P10. The eighth capacitor C42 described above is configured to include a fourth capacitor electrode P15 and a second ground electrode P10.

[0068] The third conductive conductor V9 penetrates the dielectric layers DL2 to DL9 and connects the second line electrode P13 to the third capacitor electrode P14. The fourth conductive conductor V10 penetrates the dielectric layers DL2 to DL9 and connects the second line electrode P13 to the fourth capacitor electrode P15. Specifically, one end of the third conductive conductor V9 is connected to one main surface of the second line electrode P13, and the other end is connected to the other main surface of the third capacitor electrode P14. One end of the fourth conductive conductor V10 is connected to one main surface of the second line electrode P13, and the other end is connected to the other main surface of the fourth capacitor electrode P15.

[0069] That is, the eighth inductor L41 described above is configured to include a second line electrode P13, a third conducting conductor V9, and a fourth conducting conductor V10.

[0070] Furthermore, the first intermediate capacitor electrode P16 is disposed opposite to the third capacitor electrode P11 of the first intermediate circuit and the third capacitor electrode P14 of the second intermediate circuit via the dielectric layer DL9. Specifically, one main surface of the first intermediate capacitor electrode P16 and the other main surface of the third capacitor electrode P11 of the first intermediate circuit are disposed opposite to each other via the dielectric layer DL9. Additionally, one main surface of the first intermediate capacitor electrode P16 and the other main surface of the third capacitor electrode P14 of the second intermediate circuit are disposed opposite to each other via the dielectric layer DL9.

[0071] Furthermore, the second ground electrode P10 can also be divided into multiple parts. In this case, the fifth capacitor C31, the sixth capacitor C32, the seventh capacitor C41, and the eighth capacitor C42 described above may each include a portion of the divided second ground electrode P10.

[0072] exist Figure 3The filtering characteristics of the bandpass filter 100 are shown when the capacitance of each capacitor and the inductance of each inductor are set to predetermined values. Considering the filtering characteristics in S21, when the passband is defined as the frequency at which the insertion loss decreases by 3 dB from the flat portion, the bandpass filter 100 can consider approximately 6.3 GHz to approximately 8.7 GHz as the passband. Furthermore, there is a sharp attenuation of approximately -55 dB at approximately 5.7 GHz on the low-frequency side of the passband, and a sharp attenuation of approximately -60 dB at approximately 9.4 GHz on the high-frequency side. The high-frequency attenuation is achieved because an intermediate circuit, different from the ground lines of each of the first and second filter circuits, is arranged between the first and second filter circuits, thus minimizing signal propagation via the ground lines. Furthermore, by providing the first intermediate capacitor electrode P16, a larger attenuation can be set at the desired frequency.

[0073] <Second Example>

[0074] use Figures 4-6 The bandpass filter 100A, which is the second example of this embodiment, will be described.

[0075] Figure 4 This is the equivalent circuit diagram of bandpass filter 100A. Bandpass filter 100A also includes a tenth capacitor C52. In bandpass filter 100A, the ninth capacitor C51 is connected between the aforementioned connection point A1 and connection point B1. Furthermore, the tenth capacitor C52 is connected between the connection point A2 of the sixth capacitor C32 and the seventh inductor L31, and the aforementioned connection point B2. Other than these components are the same as those of bandpass filter 100.

[0076] Figure 5 This is an exploded perspective view of a portion of a bandpass filter 100A. Specifically, the diagram shows dielectric layers DL9 and DL10, first capacitor electrodes P3 and P7, second capacitor electrodes P4 and P8, third capacitor electrodes P11 and P14, fourth capacitor electrodes P12 and P15, a first intermediate capacitor electrode P16, and a second intermediate capacitor electrode P18. That is, the bandpass filter 100A also includes a rectangular second intermediate capacitor electrode P18. However, the shape is not limited to this. In the bandpass filter 100A, the first intermediate capacitor electrode P16 is arranged in the same manner as in the bandpass filter 100.

[0077] Furthermore, the second intermediate capacitor electrode P18 is disposed opposite to the fourth capacitor electrode P12 of the first intermediate circuit and the fourth capacitor electrode P15 of the second intermediate circuit via the dielectric layer DL9. Specifically, one main surface of the second intermediate capacitor electrode P18 and the other main surface of the fourth capacitor electrode P12 of the first intermediate circuit are disposed opposite to each other via the dielectric layer DL9. Additionally, one main surface of the second intermediate capacitor electrode P18 and the other main surface of the fourth capacitor electrode P15 of the second intermediate circuit are disposed opposite to each other via the dielectric layer DL9. Other than these components, they are the same as those of the bandpass filter 100.

[0078] exist Figure 6 The filtering characteristics of the bandpass filter 100A are shown when the capacitance of each capacitor and the inductance of each inductor are set to predetermined values. Considering the filtering characteristics in S21, the passband of the bandpass filter 100A is approximately 6.3 GHz to approximately 8.7 GHz, which can be considered practically unchanged compared to the passband of the bandpass filter 100. Furthermore, there is a sharp attenuation to approximately -50 dB at approximately 5.7 GHz on the low-frequency side of the passband, and a sharp attenuation to approximately -55 dB at approximately 9.4 GHz on the high-frequency side.

[0079] Based on the first and second examples described above, in the bandpass filter of this embodiment, it is possible to generate an attenuation pole with the required attenuation amount on the high-frequency side of the passband while maintaining the passband.

[0080] Furthermore, in the case of having a ninth capacitor C51 and a tenth capacitor C52, as in the second example, the degree T of the reduction in attenuation on the higher frequency side relative to the attenuation electrode on the high frequency side can be reduced, and the attenuation on the high frequency side passing through the frequency band can be increased (see reference). Figure 3 , Figure 6 ).

[0081] Furthermore, bandpass filters 100 and 100A each have a first ground electrode P17 and a grounding conductor V13. Additionally, the common electrode P2 and the second ground electrode P10 are configured to be separate from each other. The first ground electrode P17 is connected to external ground electrodes PG1 to PG4.

[0082] Furthermore, the common electrode P2 and the first ground electrode P17 in the first filter circuit FC1 are configured such that at least a portion of each electrode is opposite to the other. A first common capacitor C61 is formed through the common electrode P2 and the first ground electrode P17. By grounding the first resonant circuit RC1 and the second resonant circuit RC2 via the first common capacitor C61, even when a DC component signal is input to the first port PT1, the DC component signal can be suppressed from flowing to the first filter circuit FC1.

[0083] Similarly, in the second filter circuit FC2, the common electrode P6 and the first ground electrode P17 are configured such that at least a portion of each electrode is opposite to the other. A second common capacitor C62 is formed through the common electrode P6 and the first ground electrode P17. By grounding the third resonant circuit RC3 and the fourth resonant circuit RC4 via the second common capacitor C62, even when a DC component signal is input to the second port PT2, the flow of that DC component signal to the second filter circuit FC12 can be suppressed.

[0084] That is, the first common capacitor C61 and the second common capacitor C62 function as DC cutoff filters. Furthermore, it is not necessary to have both the first common capacitor C61 and the second common capacitor C62; it is sufficient to configure at least one of them as needed.

[0085] The second grounding electrode P10 in the first intermediate circuit MC1 and the second intermediate circuit MC2 are connected to the first grounding electrode P17 through a grounding conductor V13. Figure 2 In this configuration, multiple grounding conductors V13 are formed, but the number of grounding conductors V13 can also be singular.

[0086] With the above-described structure, the inductance between the first filter circuit and the ground wire can be adjusted independently. Similarly, the inductance between the second filter circuit and the ground wire, as well as the inductance between the first intermediate circuit and the second intermediate circuit and the ground wire, can also be adjusted independently.

[0087] The embodiments described in this specification are illustrative embodiments. The invention is not limited to the above-described embodiments and variations, and various applications and variations can be added within the scope of the invention.

[0088] It is also intended that the various embodiments disclosed herein be appropriately combined and implemented within a non-contradictory scope. It should be understood that the embodiments disclosed herein are illustrative in all respects and not restrictive. The scope of the invention is not shown based on the foregoing description but as defined in the claims, and includes all modifications equivalent to and within the scope of the claims.

[0089] Explanation of reference numerals in the attached figures

[0090] 100, 100A~100H, 100J… bandpass filters, A1, A2, B1, B2… connection points, C11… first capacitor, C12… second capacitor, C21… third capacitor, C22… fourth capacitor, C31… fifth capacitor, C32… sixth capacitor, C41… seventh capacitor, C42… eighth capacitor, C51… ninth capacitor, C52… tenth capacitor, C61… first common capacitor, C62… second common capacitor, DL1~DL1 3…Dielectric layer, FC1…First filter circuit, FC2…Second filter circuit, P9, P13, P19…Second line electrodes, IL1, IL2…Imaginary lines, L11…First inductor, L12…Second inductor, L13…Third inductor, L21…Fourth inductor, L22…Fifth inductor, L23…Sixth inductor, L31…Seventh inductor, L41…Eighth inductor, MC1…First intermediate circuit, MC2…Second intermediate circuit, P1a…First section, P1 b…Part Two, P1, P5…First line electrodes, P1c, P1e, P1d, P5c, P5e, P5d…partial, P2, P6…Common electrode, P3, P7…First capacitor electrode, P4, P8…Second capacitor electrode, P10…Second ground electrode, P11, P14…Third capacitor electrode, P12, P15…Fourth capacitor electrode, P16…First intermediate capacitor electrode, P17…First ground electrode, P18…Second intermediate capacitor electrode, PG1… External grounding electrode, PL1, PL2…leading electrodes, PS1, PS2…signal electrodes, PT1…first port, PT2…second port, RC1…first resonant circuit, RC2…second resonant circuit, RC3…third resonant circuit, RC4…fourth resonant circuit, V1, V4…first conducting conductor, V2, V5…second conducting conductor, V3, V6…common conducting conductor, V7, V9…third conducting conductor, V8, V10…fourth conducting conductor, V13…grounding conducting conductor.

Claims

1. A bandpass filter, wherein, have: The first filter circuit includes a first resonant circuit, a second resonant circuit, and a first common capacitor. The first resonant circuit has a first inductor, a third inductor, and a first capacitor. The second resonant circuit has a second inductor, the third inductor, and a second capacitor. The second filter circuit includes a third resonant circuit, a fourth resonant circuit, and a second common capacitor. The third resonant circuit has a fourth inductor, a sixth inductor, and a third capacitor. The fourth resonant circuit has a fifth inductor, the sixth inductor, and a fourth capacitor. The first intermediate circuit has a grounded fifth capacitor and a grounded sixth capacitor, and a seventh inductor connected between the fifth capacitor and the sixth capacitor. The second intermediate circuit has a grounded seventh capacitor and a grounded eighth capacitor, and an eighth inductor connected between the seventh capacitor and the eighth capacitor. as well as Ninth capacitor, The aforementioned first resonant circuit and the aforementioned second resonant circuit are grounded via the aforementioned first common capacitor. The aforementioned third resonant circuit and the aforementioned fourth resonant circuit are grounded via the aforementioned second common capacitor. The seventh inductor is coupled to the electromagnetic fields of the first through third inductors, and the eighth inductor is coupled to the electromagnetic fields of the fourth through seventh inductors. The aforementioned ninth capacitor is connected between the aforementioned first intermediate circuit and the aforementioned second intermediate circuit. The ninth capacitor is connected between the connection point of the fifth capacitor and the seventh inductor, and between the connection point of the seventh capacitor and the eighth inductor.

2. The bandpass filter according to claim 1, wherein, It also has a tenth capacitor. The tenth capacitor is connected between the connection point of the sixth capacitor and the seventh inductor, and between the connection point of the eighth capacitor and the eighth inductor.

3. A bandpass filter, wherein, have: Multiple dielectric layers stacked together; The first filter circuit and the second filter circuit are arranged in a direction orthogonal to the stacking direction of the plurality of dielectric layers. The first intermediate circuit and the second intermediate circuit are arranged between the first filter circuit and the second filter circuit. The first intermediate circuit is electromagnetically coupled to the first filter circuit, and the second intermediate circuit is electromagnetically coupled to both the second filter circuit and the first intermediate circuit. First grounding electrode; and First intermediate capacitor electrode The first filter circuit and the second filter circuit mentioned above each include: The first line electrode extends in a perpendicular direction relative to the aforementioned stacking direction; A common electrode is configured opposite to the first grounding electrode mentioned above; The first capacitor electrode is disposed opposite to the aforementioned common electrode; The second capacitor electrode is disposed opposite to the aforementioned common electrode; A first conductive conductor passes through the aforementioned stacking direction and connects the aforementioned first line electrode to the aforementioned first capacitor electrode; The second conductive conductor passes through the aforementioned stacking direction and connects the aforementioned first line electrode to the aforementioned second capacitor electrode; as well as A common conductive conductor is disposed between the first conductive conductor and the second conductive conductor, passes through in the stacking direction, and connects the first line electrode to the common electrode. The first intermediate circuit and the second intermediate circuit mentioned above each include: The second line electrode extends in the aforementioned vertical direction; Second grounding electrode; A grounding conductor is used to connect the first grounding electrode to the second grounding electrode. The third capacitor electrode is disposed opposite to the second grounding electrode mentioned above; The fourth capacitor electrode is positioned opposite the second grounding electrode described above; The third conductive conductor passes through the aforementioned stacking direction and connects the aforementioned second line electrode to the aforementioned third capacitor electrode; as well as The fourth conducting conductor passes through the aforementioned stacking direction and connects the second line electrode to the fourth capacitor electrode. The first intermediate capacitor electrode is disposed opposite to the third capacitor electrode of the first intermediate circuit and the third capacitor electrode of the second intermediate circuit.

4. The bandpass filter according to claim 3, wherein, It also has a second intermediate capacitor electrode. The second intermediate capacitor electrode is disposed opposite to the fourth capacitor electrode of the first intermediate circuit and the fourth capacitor electrode of the second intermediate circuit.

5. The bandpass filter according to claim 3 or 4, wherein, The aforementioned common electrode and the aforementioned second grounding electrode are configured to be separate from each other.

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