Filter circuit

Abstract

The present application provides a filter circuit, which comprises two ports, a first resonant circuit and a second resonant circuit. The first resonant circuit is arranged between the two ports in circuit structure and coupled with both of the two ports. The second resonant circuit is arranged between the two ports in circuit structure and coupled with at least one of the two ports. The coupling between the second resonant circuit and the two ports is weaker than the coupling between the first resonant circuit and the two ports.

Description

Technical Field

[0001] This invention relates to a filter circuit having two resonant circuits. Background Technology

[0002] A bandpass filter is an electronic component used in communication devices. For a bandpass filter, it is required that the insertion loss in the passband be low and the insertion loss outside the passband be high.

[0003] Chinese Patent Application Publication No. 111710941A describes a filtering device obtained by combining a bandpass filter and a band-stop filter. In this filtering device, the band-stop filter is used to increase the insertion loss in the frequency domain above the passband.

[0004] Currently, communication services using the 5th generation mobile communication system (hereinafter referred to as 5G) are being offered. In 5G, the utilization of frequency bands above 10 GHz is envisioned, particularly the 10–30 GHz quasi-millimeter wave band or the 30–300 GHz millimeter wave band. Similar to the frequency bands used in 4th generation mobile communication systems, several specifications exist within these bands, with relatively close band sizes. Therefore, the bandpass filters used in 5G also require a rapid change in insertion loss in the frequency domain close to the passband.

[0005] Traditionally, in bandpass filters, the number of resonators used to construct the filter has been increased to achieve a rapid change in insertion loss near the passband. However, comparing the Q values ​​of the resonators with the same value reveals that as the number of resonators increases, the insertion loss in the passband also increases.

[0006] Here, in a bandpass filter, to obtain the characteristic of a rapid change in frequency domain insertion loss close to the passband, a bandstop filter is considered. In this case, the center frequency of the stopband of the bandstop filter needs to be close to the frequency of the passband. However, this will result in an increase in the insertion loss of the passband of the bandpass filter.

[0007] The above-mentioned problems are not limited to filter circuits with bandpass and bandstop filters, but apply to all filter circuits that use slave resonant circuits in order to adjust the characteristics of the master resonant circuit. Summary of the Invention

[0008] The object of the present invention is to provide a filter circuit having a main resonant circuit and a slave resonant circuit, which can suppress the degradation of the characteristics of the filter circuit obtained by using the main resonant circuit and achieve the desired characteristics.

[0009] The filter circuit of the present invention includes: two ports; a first resonant circuit comprising a plurality of first resonators, disposed between the two ports and coupled to both ports; and a second resonant circuit comprising a plurality of second resonators, disposed between the two ports and coupled to at least one of the two ports. The coupling between the second resonant circuit and the two ports is weaker than the coupling between the first resonant circuit and the two ports.

[0010] The filter circuit of the present invention may further include: two first capacitors coupling the first resonant circuit to the two-port capacitor; and at least one second capacitor coupling the second resonant circuit to the two-port capacitor. Alternatively, the capacitance of the at least one second capacitor may be smaller than the capacitance of each of the two first capacitors. Or, the filter circuit of the present invention may further include at least one second capacitor coupling the second resonant circuit to the two-port capacitor, with the first resonant circuit directly connected to at least one of the two ports.

[0011] Furthermore, in the filter circuit of the present invention, multiple second resonators may include a first specific resonator and a second specific resonator. The first specific resonator may be coupled to one port of the two-port circuit. The second specific resonator may be coupled to the other port of the two-port circuit. Alternatively, the first specific resonator and the second specific resonator may be coupled to each other.

[0012] Furthermore, in the filter circuit of the present invention, the multiple second resonators can each be an open-ended resonator.

[0013] Furthermore, in the filter circuit of the present invention, the first resonant circuit can also be configured as a bandpass filter.

[0014] Furthermore, in the filter circuit of the present invention, the second resonant circuit can also be configured as a band-stop filter.

[0015] In the filter circuit of the present invention, the coupling between the second resonant circuit and the two ports is weaker than that between the first resonant circuit and the two ports. Therefore, according to the present invention, a filter circuit that suppresses the degradation of the characteristics of the filter circuit obtained using the first resonant circuit and achieves the desired characteristics can be realized.

[0016] Other objects, features and benefits of the present invention will become fully apparent from the following description. Attached Figure Description

[0017] Figure 1 This is a circuit diagram showing the circuit structure of the filter circuit according to the first embodiment of the present invention.

[0018] Figure 2 This is a perspective view showing the appearance of a stacked filter device including the filter circuit of the first embodiment of the present invention.

[0019] Figure 3 This is an explanatory diagram showing the pattern formation surface of the first dielectric layer of the stacked body of the stacked filter device in the first embodiment of the present invention.

[0020] Figure 4 This is an explanatory diagram showing the pattern formation surfaces of the second to seventh dielectric layers of the stacked body of the stacked filter device in the first embodiment of the present invention.

[0021] Figure 5 This is an explanatory diagram showing the pattern formation surface of the eighth dielectric layer of the stacked body of the stacked filter device in the first embodiment of the present invention.

[0022] Figure 6 This is an explanatory diagram showing the pattern formation surface of the 9th dielectric layer of the stacked body of the stacked filter device in the first embodiment of the present invention.

[0023] Figure 7 This is an explanatory diagram showing the pattern formation surface of the 10th dielectric layer of the stacked body of the stacked filter device in the first embodiment of the present invention.

[0024] Figure 8 This is an explanatory diagram showing the pattern formation surface of the 11th to 16th dielectric layers of the stacked body of the stacked filter device in the first embodiment of the present invention.

[0025] Figure 9 This is an explanatory diagram showing the terminal forming surface of the 16th dielectric layer of the stacked body of the stacked filter device in the first embodiment of the present invention.

[0026] Figure 10 This is a perspective view showing the interior of the stacked body of the stacked filter device in the first embodiment of the present invention.

[0027] Figure 11 This is a characteristic diagram illustrating an example of the frequency characteristics of the filter circuit according to the first embodiment of the present invention.

[0028] Figure 12 It is Figure 11 The frequency response shown is a magnified representation of a portion of the frequency response.

[0029] Figure 13 This is a circuit diagram showing the circuit structure of the filter circuit according to the second embodiment of the present invention.

[0030] Figure 14 This is an explanatory diagram showing the pattern formation surface of the first dielectric layer of the stacked body of the stacked filter device in the second embodiment of the present invention.

[0031] Figure 15This is an explanatory diagram showing the pattern formation surfaces of the second to seventh dielectric layers of the stacked body of the stacked filter device in the second embodiment of the present invention.

[0032] Figure 16 This is an explanatory diagram showing the pattern formation surface of the eighth dielectric layer of the stacked body of the stacked filter device in the second embodiment of the present invention.

[0033] Figure 17 This is an explanatory diagram showing the pattern formation surface of the 9th dielectric layer of the stacked body of the stacked filter device in the second embodiment of the present invention.

[0034] Figure 18 This is an explanatory diagram showing the pattern formation surface of the 10th dielectric layer of the stacked body of the stacked filter device in the second embodiment of the present invention.

[0035] Figure 19 This is an explanatory diagram showing the pattern formation surfaces of the 11th to 16th dielectric layers of the stacked body of the stacked filter device in the second embodiment of the present invention.

[0036] Figure 20 This is an explanatory diagram showing the terminal forming surface of the 16th dielectric layer of the stacked body of the stacked filter device in the second embodiment of the present invention.

[0037] Figure 21 This is a perspective view showing the interior of the stacked body of the stacked filter device in the second embodiment of the present invention.

[0038] Figure 22 This is a characteristic diagram illustrating an example of the frequency characteristics of the filter circuit according to the second embodiment of the present invention.

[0039] Figure 23 It is Figure 22 The frequency response shown is a magnified representation of a portion of the frequency response.

[0040] Figure 24 This is a circuit diagram showing the circuit structure of the filter circuit according to the second embodiment of the present invention.

[0041] Figure 25 This is a circuit diagram showing the circuit structure of the filter circuit according to the third embodiment of the present invention. Detailed Implementation

[0042] [First Implementation Method]

[0043] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, referring to... Figure 1The following describes a general outline of the structure of the filter circuit 1 according to the first embodiment of the present invention. The filter circuit 1 includes two ports 3 and 4, a first resonant circuit 10, and a second resonant circuit 20. Ports 3 and 4 are respectively used for signal input or output.

[0044] In this embodiment, the first resonant circuit 10 constitutes a bandpass filter, and the second resonant circuit 20 constitutes a bandstop filter. Specifically, in this embodiment, the first resonant circuit 10 is the master resonant circuit, and the second resonant circuit 20 is the slave resonant circuit. The filter circuit 1 as a whole functions as a bandpass filter.

[0045] The first resonant circuit 10 is arranged in the circuit structure between two ports 3 and 4. Furthermore, the first resonant circuit 10 is coupled to both ports 3 and 4. Additionally, in this application, the expression "in the circuit structure" refers to the arrangement in the circuit diagram, not the physical structure.

[0046] The second resonant circuit 20 is disposed between the two ports 3 and 4 in the circuit structure. Furthermore, the second resonant circuit 20 is coupled to at least one of the two ports 3 and 4. Specifically, in this embodiment, the second resonant circuit 20 is coupled to both ports 3 and 4. Additionally, in this embodiment, the second resonant circuit 20 is disposed in parallel with the first resonant circuit 10 between the two ports 3 and 4, and is not disposed between the first resonant circuit 10 and either port 3 or port 4.

[0047] The filter circuit 1 further includes two first capacitors C11 and C12 that couple the first resonant circuit 10 to the capacitors at ports 3 and 4. First capacitor C11 couples the first resonant circuit 10 to port 3. First capacitor C12 couples the first resonant circuit 10 to port 4.

[0048] The filter circuit 1 further includes at least one second capacitor that couples the second resonant circuit 20 to the capacitors at ports 3 and 4. Specifically, in this embodiment, the filter circuit 1, as at least one second capacitor, includes two second capacitors C21 and C22. Second capacitor C21 couples the second resonant circuit 20 to port 3. Second capacitor C22 couples the second resonant circuit 20 to port 4.

[0049] The coupling between the second resonant circuit 20 and the two ports 3 and 4 is weaker than the coupling between the first resonant circuit 10 and the two ports 3 and 4. In this embodiment, where the coupling between the resonant circuit and the ports is capacitive coupling, the coupling becomes stronger as the capacitance of the capacitor that capacitively couples the resonant circuit to the ports increases. That is, the coupling between the resonant circuit and the ports weakens as the capacitance decreases.

[0050] In this embodiment, the capacitances of the second capacitors C21 and C22 are each smaller than the capacitances of the first capacitors C11 and C12. Therefore, the couplings between the second resonant circuit 20 and port 3, and between the second resonant circuit 20 and port 4, become weaker than the couplings between the first resonant circuit 10 and port 3, and between the first resonant circuit 10 and port 4. In one example, the capacitances of the second capacitors C21 and C22 are each 0.03 pF, and the capacitances of the first capacitors C11 and C12 are each 0.14 pF.

[0051] Next, refer to Figure 1 This section describes an example of the structure of the first and second resonant circuits 10 and 20. First, the first resonant circuit 10 will be described. The first resonant circuit 10 includes a plurality of first resonators. In this embodiment, specifically, the first resonant circuit 10, as a plurality of first resonators, includes two first resonators 11 and 12 arranged sequentially from the port 3 side in the circuit structure. The first resonators 11 and 12 are both open-ended half-wavelength resonators. The first resonators 11 and 12 are magnetically coupled to each other.

[0052] The first resonator 11 is coupled to port 3. The first resonator 11 has a first end 11a closest to port 3 and a second end 11b furthest from port 3. The first capacitor C11 is disposed in the circuit structure between the first end 11a of the first resonator 11 and port 3.

[0053] The first resonator 12 is coupled to port 4. The first resonator 12 has a first terminal 12a closest to port 4 and a second terminal 12b furthest from port 4. The first capacitor C12 is disposed in the circuit structure between the first terminal 12a of the first resonator 12 and port 4.

[0054] The first resonant circuit 10 further includes a capacitor C13 connecting the second terminal 11b of the first resonator 11 and the second terminal 12b of the first resonator 12. The first resonator 11 and the first resonator 12 are magnetically coupled and capacitively coupled through the capacitor C13.

[0055] Next, the second resonant circuit 20 will be described. The second resonant circuit 20 includes a plurality of second resonators. In this embodiment, specifically, the second resonant circuit 20, as a plurality of second resonators, includes two second resonators 21 and 22 arranged sequentially from the port 3 side in terms of circuit structure. The second resonators 21 and 22 are both open-ended half-wavelength resonators. The second resonators 21 and 22 are magnetically coupled to each other. The second resonators 21 and 22 correspond to the "first specific resonator" and "second specific resonator" in this invention, respectively.

[0056] The second resonator 21 is coupled to port 3. The second resonator 21 has a first end 21a closest to port 3 and a second end 21b farthest from port 3. The second capacitor C21 is arranged in the circuit structure between the first end 21a of the second resonator 21 and port 3.

[0057] The second resonator 22 is coupled to port 4. The second resonator 22 has a first end 22a closest to port 4 and a second end 22b furthest from port 4. The second capacitor C22 is arranged in the circuit structure between the first end 22a of the second resonator 22 and port 4.

[0058] Next, the structure of the cascaded filter device (hereinafter simply referred to as the filter device) 2 in this embodiment will be described. Figure 2 This is a perspective view showing the appearance of filter device 2. Filter device 2 includes... Figure 1 The filtering device of the filter circuit 1 shown.

[0059] Filter device 2 includes a reference Figure 1 The filter circuit 1 is described, including its constituent elements and a laminate 50 for integrating these elements. The laminate 50 includes multiple stacked dielectric layers, multiple conductor layers formed on the dielectric layers, and multiple vias.

[0060] The laminate 50 has a bottom surface 50A and a top surface 50B located at both ends of the lamination direction T of the plurality of dielectric layers, and four side surfaces 50C to 50F connecting the bottom surface 50A and the top surface 50B. Side surfaces 50C and 50D face opposite sides to each other, and side surfaces 50E and 50F also face opposite sides to each other. Side surfaces 50C to 50F are perpendicular to the top surface 50B and the bottom surface 50A.

[0061] Here, as Figure 2 The X, Y, and Z directions are defined as shown. The X, Y, and Z directions are orthogonal to each other. In this embodiment, the Z direction is defined as the direction parallel to the stacking direction T. Furthermore, the direction opposite to the X direction is defined as the -X direction, the direction opposite to the Y direction as the -Y direction, and the direction opposite to the Z direction as the -Z direction.

[0062] like Figure 2 As shown, bottom surface 50A is located at the end of laminate 50 in the -Z direction. Top surface 50B is located at the end of laminate 50 in the Z direction. Side surface 50C is located at the end of laminate 50 in the -X direction. Side surface 50D is located at the end of laminate 50 in the X direction. Side surface 50E is located at the end of laminate 50 in the -Y direction. Side surface 50F is located at the end of laminate 50 in the Y direction.

[0063] The filter device 2 further includes terminals 511 and 661 and grounding conductor layers 512 and 662. Terminals 511 and grounding conductor layer 512 are disposed on the bottom surface 50A. In particular, in this embodiment, the grounding conductor layer 512 covers almost the entire bottom surface 50A. A gap is formed between the terminals 511 and the grounding conductor layer 512.

[0064] Terminal 661 and grounding conductor layer 662 are disposed on the upper surface 50B. In this embodiment, in particular, the grounding conductor layer 662 covers almost the entire upper surface 50B. A gap is formed between terminal 661 and grounding conductor layer 662.

[0065] Terminal 511 corresponds to port 3, and terminal 661 corresponds to port 4. Grounding conductor layers 512 and 662 are connected to the grounding part respectively.

[0066] Next, refer to Figures 3 to 9 This illustrates an example of multiple dielectric layers and multiple conductor layers constituting a laminate 50. In this example, the laminate 50 has 16 stacked dielectric layers. Hereinafter, these 16 dielectric layers will be referred to sequentially from bottom to top as dielectric layers 1 to 16. Furthermore, reference numerals 51 to 66 will be used to denote dielectric layers 1 to 16. Figures 3 to 9 In the diagram, multiple circles represent multiple through holes.

[0067] Figure 3 This indicates the patterned surface of the first dielectric layer 51. Terminals 511 and a grounding conductor layer 512 are formed on the patterned surface of the dielectric layer 51. Furthermore, specific through-holes 51T1 connected to the terminals 511 are formed in the dielectric layer 51. Multiple through-holes formed in the dielectric layer 51, excluding the specific through-holes 51T1, are connected to the grounding conductor layer 512.

[0068] Figure 4 This indicates the patterned surfaces of dielectric layers 52 to 57, from layer 2 to layer 7. Specific vias 52T1 are formed in each of dielectric layers 52 to 57. Specific vias 51T1 formed in dielectric layer 51 are connected to specific vias 52T1 formed in dielectric layer 52. Furthermore, adjacent specific vias 52T1 in dielectric layers 52 to 57 are interconnected.

[0069] Figure 5 This indicates the patterned surface of the 8th dielectric layer 58. Conductor layers 581, 582, and 583 are formed on the patterned surface of the dielectric layer 58. Furthermore, a specific via 58T1 is formed in the dielectric layer 58. A specific via 52T1 formed in the dielectric layer 57 is connected to the specific via 58T1.

[0070] Figure 6This indicates the patterning surface of the 9th dielectric layer 59. Conductor layers 591, 592, 593, and 594 for resonators, conductor layers 595 and 596, and a grounding conductor layer 597 are formed on the patterning surface of the dielectric layer 59. Conductor layers 591 to 596 each have a first end and a second end located on opposite sides of each other.

[0071] Conductor layer 591 includes a portion extending from a first end along the Y direction and a portion extending from a second end along the X direction. Conductor layer 592 includes a portion extending from a first end along the Y direction and a portion extending from a second end along the -X direction. Conductor layer 593 includes a portion extending from a first end along the -Y direction and a portion extending from a second end along the X direction. Conductor layer 594 includes a portion extending from a first end along the -Y direction and a portion extending from a second end along the -X direction. Conductor layer 595 extends from the first end to the second end along the -X direction. Conductor layer 596 extends from the first end to the second end along the X direction.

[0072] Furthermore, a specific via 59T1 is formed in the dielectric layer 59. The specific via 59T1 is connected to a portion near the first end of the conductor layer 596. A specific via 58T1 formed in the dielectric layer 58 is connected to a portion near the first end of the conductor layer 595. A portion of a plurality of vias formed in the dielectric layer 58 (excluding the specific via 58T1) and a portion of a plurality of vias formed in the dielectric layer 59 (excluding the specific via 59T1) are connected to the grounding conductor layer 597.

[0073] The first end of conductor layer 591 is adjacent to the near portion of the second end of conductor layer 595 at a predetermined interval. The first end of conductor layer 592 is adjacent to the near portion of the second end of conductor layer 596 at a predetermined interval. The second end of conductor layer 591 is adjacent to the second end of conductor layer 592 at a predetermined interval.

[0074] The first end of conductor layer 593 is adjacent to the vicinity of the second end of conductor layer 595 at a predetermined interval. The first end of conductor layer 594 is adjacent to the vicinity of the second end of conductor layer 596 at a predetermined interval. The second end of conductor layer 593 is adjacent to the second end of conductor layer 594 at a predetermined interval. The interval between the second end of conductor layer 593 and the second end of conductor layer 594 is greater than the interval between the second ends of conductor layer 591 and the second ends of conductor layer 592.

[0075] Figure 7 This indicates the patterned surface of the 10th dielectric layer 60. Conductor layers 601 and 602 are formed on the patterned surface of the dielectric layer 60. Furthermore, a specific via 60T1 is formed in the dielectric layer 60. The specific via 59T1 formed in the dielectric layer 59 is connected to the specific via 60T1.

[0076] Figure 8 This indicates the patterned surfaces of dielectric layers 61 to 66, layers 11 to 16. Specific vias 61T1 are formed in each of dielectric layers 61 to 66. Specific vias 60T1 formed in dielectric layer 60 are connected to specific vias 61T1 formed in dielectric layer 61. Furthermore, adjacent specific vias 61T1 in dielectric layers 61 to 66 are interconnected.

[0077] Figure 9 This refers to the terminal forming surface of the 16th dielectric layer 66, which is opposite to the pattern forming surface. Terminals 661 and a grounding conductor layer 662 are formed on the terminal forming surface of the dielectric layer 66. A specific through-hole 61T1 formed in the dielectric layer 66 is connected to the terminal 661. Multiple through-holes formed in the dielectric layer 66, excluding the specific through-hole 61T1, are connected to the grounding conductor layer 662.

[0078] Figure 2 The stack 50 shown is constructed by stacking the first to sixteenth dielectric layers 51 to 66 in such a way that the pattern forming surface of the first dielectric layer 51 becomes the bottom surface 50A of the stack 50 and the terminal forming surface of the sixteenth dielectric layer 66 becomes the upper surface 50B of the stack 50.

[0079] Figure 10 This refers to the interior of the laminate 50, which consists of 1 to 16 dielectric layers 51 to 66. For example... Figure 10 As shown, the following are stacked inside the laminate 50: Figures 3 to 9 The diagram shows multiple conductor layers and multiple through-holes. Conductor layer 595 is connected to terminal 511 via specific through-holes 51T1, 52T1, and 58T1. Conductor layer 596 is connected to terminal 661 via specific through-holes 59T1, 60T1, and 61T1. Grounding conductor layers 512, 597, and 662 are interconnected via multiple through-holes other than the specific through-holes 51T1, 52T1, 58T1, 59T1, 60T1, and 61T1.

[0080] The following is about Figure 1 The components of the filter circuit 1 shown are the same as Figures 4 to 8 The correspondence of the internal components of the stacked body 50 shown is explained. The first resonator 11 of the first resonant circuit 10 is composed of a resonator conductor layer 591. The first resonator 12 of the first resonant circuit 10 is composed of a resonator conductor layer 592. The second resonator 21 of the second resonant circuit 20 is composed of a resonator conductor layer 593. The second resonator 22 of the second resonant circuit 20 is composed of a resonator conductor layer 594.

[0081] The first capacitor C11 is composed of conductor layers 581, 591, and 595 and a dielectric layer 58 between these conductor layers. The first capacitor C12 is composed of conductor layers 582, 592, and 596 and a dielectric layer 58 between these conductor layers. The second capacitor C21 is composed of conductor layers 593, 595, and 601 and a dielectric layer 59 between these conductor layers. The second capacitor C22 is composed of conductor layers 594, 596, and 602 and a dielectric layer 59 between these conductor layers.

[0082] The capacitor C13 is composed of conductor layers 583, 591, 592 and a dielectric layer 58 between these conductor layers.

[0083] Next, the structural features of the filter device 2 in this embodiment will be briefly described. In the filter device 2, the resonator conductor layers 591 to 594 are disposed within the space enclosed by the ground conductor layers 512 and 662 and a plurality of through holes.

[0084] Furthermore, in the filter device 2, the areas of the conductor layers 601 and 602 constituting the second capacitors C21 and C22 are smaller than the areas of the conductor layers 581 and 582 constituting the first capacitors C11 and C12.

[0085] Next, the function and effect of the filter circuit 1 in this embodiment will be explained. As described above, in this embodiment, the coupling between the second resonant circuit 20 and the two ports 3 and 4 is weaker than the coupling between the first resonant circuit 10 and the two ports 3 and 4. Therefore, according to this embodiment, the effect caused by the second resonant circuit 20 can be suppressed and the second resonant circuit 20 can be assembled into the filter circuit 1.

[0086] In this embodiment, specifically, the first resonant circuit 10 constitutes a bandpass filter, and the second resonant circuit 20 constitutes a bandstop filter. Specifically, the effect caused by the second resonant circuit 20 is to increase the insertion loss in the frequency domain near the center frequency of the stopband of the bandstop filter formed by the second resonant circuit 20, in the frequency characteristics of the insertion loss of the filter circuit 1 (the frequency characteristics of the insertion loss of the bandpass filter). Therefore, according to this embodiment, the insertion loss in the frequency domain can be reduced to a desired level, and the second resonant circuit 20 can be assembled into the filter circuit 1. Therefore, according to this embodiment, by making the center frequency of the stopband of the bandstop filter formed by the second resonant circuit 20 close to the frequency of the passband of the bandpass filter formed by the first resonant circuit 10, the increase in the insertion loss of the passband of the filter circuit 1 can be suppressed, and the characteristic of a sharp change in the frequency domain insertion loss near the passband of the filter circuit 1 can be obtained.

[0087] Furthermore, by increasing the number of resonators constituting the bandpass filter, it is also possible to obtain a characteristic where the insertion loss changes drastically in the frequency domain close to the passband. However, comparing the resonators with identical Q values ​​reveals that as the number of resonators increases, the insertion loss in the passband increases.

[0088] In contrast, in this embodiment, the first resonant circuit 10 includes only two resonators. According to this embodiment, without increasing the number of resonators constituting the bandpass filter, a characteristic of a sharp change in insertion loss in the frequency domain close to the passband can be obtained. Therefore, according to this embodiment, the increase in passband insertion loss can be suppressed. Furthermore, according to this embodiment, the filter circuit 1 and the filter device 2 can be miniaturized.

[0089] The center frequency of the stopband of the band-stop filter formed by the second resonant circuit 20 can exist in the frequency domain of the low-frequency side of the passband of the band-pass filter formed by the first resonant circuit 10, or it can exist in the frequency domain of the high-frequency side of the passband.

[0090] Next, an example of the frequency characteristics of the filter circuit 1 in this embodiment will be described. Figure 11 This is a characteristic diagram representing an example of the frequency characteristics of filter circuit 1. Figure 12 It is Figure 11 The frequency response shown is a portion of the frequency characteristics, specifically a magnified representation of the frequency domain near the passband. Figure 11 and Figure 12 In the diagram, the horizontal axis represents frequency, and the vertical axis represents attenuation. Furthermore, in... Figure 11 and Figure 12 In the figure, the curve labeled 91 represents the insertion loss, and the curve labeled 92 represents the reflection loss.

[0091] exist Figure 11 and Figure 12 In the example shown, the center frequency of the stopband of the band-stop filter formed by the second resonant circuit 20 exists in the frequency domain of the low-frequency side of the passband of the band-pass filter formed by the first resonant circuit 10. For example... Figure 11 and Figure 12 As shown, according to this embodiment, it is possible to obtain a characteristic where the insertion loss (attenuation) changes drastically in the frequency domain close to the passband. Furthermore, the magnitude of the insertion loss (the absolute value of the attenuation) in the passband becomes a very small value.

[0092] [Second Implementation]

[0093] Next, the second embodiment of the present invention will be described. First, referring to... Figure 13 This section briefly explains the differences between the filter circuit 1 in this embodiment and the first embodiment. Figure 13This is a circuit diagram showing the circuit structure of the filter circuit 1 in this embodiment.

[0094] In this embodiment, the first resonators 11 and 12 of the first resonant circuit 10 are quarter-wavelength resonators with one end short-circuited and the other end open. The second terminal 11b of the first resonator 11 and the second terminal 12b of the first resonator 12 are respectively connected to the ground. Figure 13 In the figure, reference numeral L11 indicates the inductive component of the line connecting the first resonators 11 and 12 to the ground.

[0095] Next, refer to Figures 14 to 20 This section describes the filter device 2 in this embodiment. The structure of the filter device 2 in this embodiment is the same as that of the filter device 2 in the first embodiment, except for the plurality of dielectric layers constituting the laminate 50. In this embodiment, the laminate 50 replaces the dielectric layers 51 to 66 in the first embodiment and has 16 stacked dielectric layers 71 to 86. Hereinafter, these 16 dielectric layers 71 to 86 will be referred to sequentially from bottom to top as the 1st to the 16th dielectric layers 71 to 86. Figures 14 to 20 In the diagram, multiple circles represent multiple through holes.

[0096] Figure 14 This indicates the patterned surface of the first dielectric layer 71. Terminals 511 and a grounding conductor layer 512 are formed on the patterned surface of the dielectric layer 71. Furthermore, a specific through-hole 71T1 connected to the terminal 511 is formed in the dielectric layer 71. Multiple through-holes formed in the dielectric layer 71, excluding the specific through-hole 71T1, are connected to the grounding conductor layer 512. The multiple through-holes connected to the grounding conductor layer 512 include specific through-holes 71T2 and 71T3.

[0097] Figure 15 The diagram indicates the patterned surfaces of dielectric layers 72 to 77, from layer 2 to layer 77. Specific vias 72T1, 72T2, and 72T3 are formed in dielectric layers 72 to 77, respectively. Specific vias 71T1 to 71T3 formed in dielectric layer 71 are connected to specific vias 72T1 to 72T3 formed in dielectric layer 72, respectively. Furthermore, in dielectric layers 72 to 77, adjacent vias with the same reference numerals are interconnected.

[0098] Figure 16 This indicates the patterned surface of the 8th dielectric layer 78. Conductor layers 781 and 782 are formed on the patterned surface of the dielectric layer 78. Furthermore, specific vias 78T1, 78T2, and 78T3 are formed in the dielectric layer 78. Specific vias 72T1 to 72T3 formed in the dielectric layer 77 are connected to specific vias 78T1 to 78T3, respectively.

[0099] Figure 17 This indicates the patterning surface of the 9th dielectric layer 79. Resonator conductor layers 791, 792, 793, and 794, conductor layers 795 and 796, and a grounding conductor layer 797 are formed on the patterning surface of the dielectric layer 79. Conductor layers 791 to 796 each have a first end and a second end located on opposite sides of each other.

[0100] Conductor layers 791 and 795 extend from the first end to the second end along the -X direction. Conductor layers 792 and 796 extend from the first end to the second end along the X direction. Conductor layers 793 and 794 extend from the first end to the second end along the -Y direction.

[0101] Furthermore, specific vias 79T1, 79T2, and 79T3 are formed in the dielectric layer 79. Specific via 79T1 is connected to a portion near the first end of the conductor layer 796. Specific via 78T1 formed in the dielectric layer 78 is connected to a portion near the first end of the conductor layer 795. Specific vias 78T2, 78T3 and 79T2, 79T3 formed in the dielectric layer 78 are connected to the grounding conductor layer 797.

[0102] The portion near the first end of conductor layer 791 is adjacent to the portion near the second end of conductor layer 795 at a predetermined interval. The portion near the first end of conductor layer 792 is adjacent to the portion near the second end of conductor layer 796 at a predetermined interval. The second end of each of conductor layers 791 and 792 is connected to grounding conductor layer 797. Figure 17 In the diagram, dashed lines represent the boundaries between conductor layers 791 and 792 and grounding conductor layer 797.

[0103] The first end of conductor layer 793 is adjacent to the near portion of the second end of conductor layer 795 at a predetermined interval. The first end of conductor layer 794 is adjacent to the near portion of the second end of conductor layer 796 at a predetermined interval.

[0104] Figure 18 This indicates the patterned surface of the 10th dielectric layer 80. Conductor layers 801 and 802 are formed on the patterned surface of the dielectric layer 80. Furthermore, specific vias 80T1, 80T2, and 80T3 are formed in the dielectric layer 80. Specific vias 79T1 to 79T3 formed in the dielectric layer 79 are connected to specific vias 80T1 to 80T3, respectively.

[0105] Figure 19The diagram indicates the patterned surfaces of dielectric layers 81 to 86, layers 11 through 16. Specific vias 81T1, 81T2, and 81T3 are formed in dielectric layers 81 to 86, respectively. Specific vias 80T1 to 80T3 formed in dielectric layer 80 are connected to specific vias 81T1 to 81T3 formed in dielectric layer 81, respectively. Furthermore, in dielectric layers 81 to 86, adjacent vias with the same reference numerals are interconnected.

[0106] Figure 20 This refers to the terminal forming surface, which is the side opposite to the pattern forming surface of the 16th dielectric layer 86. A terminal 861 and a grounding conductor layer 862 are formed on the terminal forming surface of the dielectric layer 86. A specific through-hole 81T1 formed in the dielectric layer 86 is connected to the terminal 661. Multiple through-holes formed in the dielectric layer 86, including the specific through-holes 81T2 and 81T3 (excluding the specific through-hole 81T1), are connected to the grounding conductor layer 662.

[0107] In this embodiment, the stack 50 is constructed by stacking the first to the sixteenth dielectric layers 71 to 86 in such a way that the pattern forming surface of the first dielectric layer 71 becomes the bottom surface 50A of the stack 50 and the terminal forming surface of the sixteenth dielectric layer 86 becomes the upper surface 50B of the stack 50.

[0108] Figure 21 This refers to the interior of the laminate 50, which consists of 1 to 16 dielectric layers 71 to 86. For example... Figure 21 As shown, inside the laminate 50, there are laminated... Figures 14 to 20 The diagram shows multiple conductor layers and multiple through-holes. Conductor layer 795 is connected to terminal 511 via specific through-holes 71T1, 72T1, and 78T1. Conductor layer 796 is connected to terminal 661 via specific through-holes 79T1, 80T1, and 81T1. Grounding conductor layers 512, 662, and 797 are interconnected via multiple through-holes other than the specific through-holes 51T1, 52T1, 58T1, 59T1, 60T1, and 61T1. In particular, grounding conductor layer 797 is connected to grounding conductor layer 512 via specific through-holes 71T2, 71T3, 72T2, 72T3, 78T2, and 78T3, and to grounding conductor layer 662 via specific through-holes 79T2, 79T3, 80T2, 80T3, 81T2, and 81T3.

[0109] The following is about Figure 13 The components of the filter circuit 1 shown are the same as Figures 15 to 19The correspondence of the internal components of the stacked body 50 shown is explained. The first resonator 11 of the first resonant circuit 10 is composed of a resonator conductor layer 791. The first resonator 12 of the first resonant circuit 10 is composed of a resonator conductor layer 792. The second resonator 21 of the second resonant circuit 20 is composed of a resonator conductor layer 793. The second resonator 22 of the second resonant circuit 20 is composed of a resonator conductor layer 794.

[0110] The first capacitor C11 is composed of conductor layers 781, 791, and 795 and a dielectric layer 78 between these conductor layers. The first capacitor C12 is composed of conductor layers 782, 792, and 796 and a dielectric layer 78 between these conductor layers. The second capacitor C21 is composed of conductor layers 793, 795, and 801 and a dielectric layer 79 between these conductor layers. The second capacitor C22 is composed of conductor layers 794, 796, and 802 and a dielectric layer 79 between these conductor layers.

[0111] Next, the structural features of the filter device 2 in this embodiment will be briefly described. In the filter device 2, the resonator conductor layers 791 to 794 are disposed within the space enclosed by the ground conductor layers 512 and 662 and a plurality of through holes.

[0112] Furthermore, in the filter device 2, the areas of the conductor layers 801 and 802 constituting the second capacitors C21 and C22 are smaller than the areas of the conductor layers 781 and 782 constituting the first capacitors C11 and C12.

[0113] Specific through holes 71T2, 71T3, 72T2, 72T3, 78T2, 78T3, 79T2, 79T3, 80T2, 80T3, 81T2, and 81T3 are electrically connected to grounding conductor layers 512, 662, and 797. Grounding conductor layers 512, 662, and 797 are electrically connected to the grounding portion. Hereinafter, the specific through holes 71T2, 71T3, 72T2, 72T3, 78T2, 78T3, 79T2, 79T3, 80T2, 80T3, 81T2, and 81T3 will be referred to as multiple specific through holes connected to the grounding portion.

[0114] The grounding connection includes multiple specific vias comprising two vias arranged in a direction orthogonal to the stacking direction T. Specifically, these two vias are groups of specific vias 71T2 and 71T3, groups of specific vias 72T2 and 72T3, groups of specific vias 78T2 and 78T3, groups of specific vias 79T2 and 79T3, groups of specific vias 80T2 and 80T3, and groups of specific vias 81T2 and 81T3. The two specific vias in these groups are arranged in a direction orthogonal to at least one of the directions in which the resonator conductor layer 791 and the resonator conductor layer 792 extend (described later). In this embodiment, the two specific vias in these groups are arranged in a direction parallel to the Y direction.

[0115] The resonator conductor layer 791 extends along a first direction from a plurality of specific vias connected to the ground portion. The resonator conductor layer 792 extends along a second direction from the plurality of specific vias connected to the ground portion. In particular, in this embodiment, the resonator conductor layers 791 and 792 are electrically connected to the plurality of specific vias connected to the ground portion.

[0116] The first and second directions are directions orthogonal to the stacking direction T. In this embodiment, specifically, the first direction is the X direction and the second direction is the -X direction. Therefore, the first and second directions are opposite to each other.

[0117] The resonator conductor layers 793 and 794 each include a narrow amplitude section and two wide amplitude sections located on both sides of the narrow amplitude section. The second resonators 21 and 22, which are composed of the resonator conductor layers 793 and 794, are both step impedance resonators.

[0118] Next, the unique function and effect of the filter device 2 in this embodiment will be explained. In this embodiment, as described above, the resonator conductor layers 791 and 792 extend in a direction away from the plurality of specific vias connected to the ground portion. Therefore, in this embodiment, if the resonator conductor layers 791 and 792, or the plurality of specific vias connected to them, deviate in a direction parallel to the X direction due to manufacturing deviations, one of the resonator conductor layers 791 and 792 becomes longer and the other becomes shorter. Thus, according to this embodiment, the change in the characteristics of the resonator caused by the change in the length of the resonator conductor layers can be offset. As a result, according to this embodiment, the change in the characteristics of the first resonant circuit 10, i.e., the bandpass filter, caused by manufacturing deviations can be suppressed.

[0119] Furthermore, in this embodiment, as described above, the plurality of specific vias connected to the ground portion include two vias arranged in a direction orthogonal to the stacking direction T and orthogonal to at least one of the directions in which the resonator conductor layer 791 and the resonator conductor layer 792 extend. Specifically, in this embodiment, the two vias are arranged in a direction orthogonal to both the directions in which the resonator conductor layer 791 and the resonator conductor layer 792 extend. Therefore, even if the resonator conductor layers 791 and 792, or the plurality of specific vias connected thereto, deviate in a direction parallel to the Y direction, the lengths of the resonator conductor layers 791 and 792 remain almost unchanged. Thus, according to this embodiment, changes in the characteristics of the first resonant circuit 10, i.e., the bandpass filter, caused by manufacturing deviations, can also be suppressed.

[0120] Hereinafter, the effects described above in this embodiment will be explained with reference to the simulation results. In the simulation, the models of the embodiment and the comparative examples are used. Both the model of the embodiment and the model of the comparative examples are bandpass filters having a grounding conductor layer and two resonator conductor layers extending from the grounding conductor layer.

[0121] In the embodiment model, similar to filter device 2 in this embodiment, the two resonator conductor layers are arranged to sandwich the ground conductor layer and extend in opposite directions. In the comparative example model, the two resonator conductor layers extend from the ground conductor layer in the same direction. Furthermore, in the simulation, the length direction of the resonator conductor layers (the direction parallel to the extension direction) is the same in both the embodiment and comparative example models. In the simulation, the length of each of the two resonator conductor layers in the embodiment model is 700 μm, and the length of each of the two resonator conductor layers in the comparative example model is 855 μm.

[0122] In the simulation, the deviations of the two resonator conductor layers by 15 μm along their length direction were determined, including the deviation of the low-frequency cutoff frequency (lower limit of the passband) and the deviation of the high-frequency cutoff frequency (upper limit of the passband). In the example model, when the two resonator conductor layers were deviated by 15 μm along their length direction, one resonator conductor layer became 15 μm shorter and the other became 15 μm longer. In the comparative example model, when the two resonator conductor layers were deviated by 15 μm along their length direction, both resonator conductor layers either became 15 μm shorter or 15 μm longer. In the simulation, the two resonator conductor layers were deviated in such a way that both resonator conductor layers became longer.

[0123] When the two resonators are offset by the conductor layer as described above, in the comparative example model, the deviation of the low-frequency cutoff frequency is 0.80%, and the deviation of the high-frequency cutoff frequency is 1.25%. Furthermore, in the embodiment model, the deviation of the low-frequency cutoff frequency is 0.11%, and the deviation of the high-frequency cutoff frequency is 0.11%. The simulation results show that, according to this embodiment, variations in the low-frequency and high-frequency cutoff frequencies caused by manufacturing deviations can be suppressed.

[0124] Next, an example of the frequency characteristics of the filter circuit 1 in this embodiment will be described. Figure 22 This is a characteristic diagram representing an example of the frequency characteristics of filter circuit 1. Figure 23 It is Figure 22 The frequency response shown is a portion of the frequency characteristics, specifically a magnified representation of the frequency domain near the passband. Figure 22 and Figure 23 In the diagram, the horizontal axis represents frequency, and the vertical axis represents attenuation. Furthermore, in... Figure 22 and Figure 23 In the figure, the curve marked with reference numeral 93 represents the insertion loss, and the curve marked with reference numeral 94 represents the reflection loss.

[0125] exist Figure 22 and Figure 23 In the example shown, the center frequency of the stopband of the band-stop filter formed by the second resonant circuit 20 exists in the frequency domain of the low-frequency side of the passband of the band-pass filter formed by the first resonant circuit 10. For example... Figure 22 and Figure 23 As shown, according to this embodiment, it is possible to obtain a characteristic where the insertion loss (attenuation) changes drastically in the frequency domain close to the passband. Furthermore, the magnitude of the insertion loss (the absolute value of the attenuation) in the passband becomes a very small value.

[0126] The other structures, functions, and effects in this embodiment are the same as in the first embodiment.

[0127] [Third Implementation Method]

[0128] Next, refer to Figure 24 The third embodiment of the present invention will be described below. Figure 24 This is a circuit diagram showing the circuit structure of the filter circuit 1 in this embodiment.

[0129] The structure of the filter circuit 1 in this embodiment differs from that in the first embodiment in the following aspects. In this embodiment, the first capacitors C11 and C12 in the first embodiment are not provided. Therefore, the first resonant circuit 10 is directly connected to ports 3 and 4, respectively. Specifically, the first terminal 11a of the first resonator 11 of the first resonant circuit 10 is directly connected to port 3, and the first terminal 12a of the first resonator 12 of the first resonant circuit 10 is directly connected to port 4.

[0130] As explained in the first embodiment, when the coupling between the resonant circuit and the port is capacitive coupling, the coupling becomes stronger as the capacitance of the capacitor that capacitively couples the resonant circuit to the port increases. Here, when the resonant circuit is directly connected to the port, in the high-frequency region, it is essentially the same as the case of capacitive coupling through an infinitely large capacitor. Therefore, in this embodiment, the coupling between the first resonant circuit 10 and port 3 and between the first resonant circuit 10 and port 4 is stronger than in the first embodiment. Furthermore, the coupling between the first resonant circuit 10 and both ports 3 and 4 is also stronger than the coupling between the second resonant circuit 20 and only one port 3 and 4.

[0131] Alternatively, the structure of the first resonant circuit 10 can be the same as that in the second embodiment. Other structures, functions, and effects in this embodiment are the same as those in the first or second embodiment.

[0132] [Fourth Implementation]

[0133] Next, refer to Figure 25 The fourth embodiment of the present invention will be described below. Figure 25 This is a circuit diagram showing the circuit structure of the filter circuit 1 in this embodiment.

[0134] The structure of the filter circuit 1 in this embodiment differs from that in the first embodiment in the following aspects. In this embodiment, the second resonators 21 and 22 of the second resonant circuit 20 are not magnetically coupled to each other. Such a structure can be achieved, for example, by increasing the distance between the two conductor layers constituting the second resonators 21 and 22.

[0135] Alternatively, in this embodiment, either the second resonator 21 or 22 may be omitted. For example, with only the second resonator 21, the second resonant circuit 20 is coupled only to port 3. Furthermore, with only the second resonator 22, the second resonant circuit 20 is coupled only to port 4.

[0136] The structure of the first resonant circuit 10 can also be the same as in the second embodiment. Furthermore, similar to the third embodiment, the first resonant circuit 10 can also be directly connected to ports 3 and 4 respectively. Other structures, functions, and effects in this embodiment are the same as in any of the first to third embodiments.

[0137] Furthermore, the present invention is not limited to the embodiments described above, and various modifications are possible. For example, the number and structure of the first and second resonators are not limited to those shown in the embodiments, but are subject to the scope of the claims. The number of the first and second resonators may also be three or more.

[0138] Furthermore, the first resonant circuit 10 is not limited to forming a bandpass filter; it can also be a resonant circuit that forms other filters such as low-pass filters and high-pass filters.

[0139] As can be seen from the above description, various methods and variations of the present invention can be implemented. Therefore, the present invention can be implemented in ways other than the preferred method described above, within the equivalent scope of the application.

Claims

1. A filter circuit, characterized in that, include: 2 ports; The first resonant circuit includes a plurality of first resonators, which are arranged in the circuit structure between the two ports and coupled to both ports. The second resonant circuit includes a plurality of second resonators, which are arranged in the circuit structure between the two ports and coupled to at least one of the two ports; and A stack for integrating the two ports, the first resonant circuit, and the second resonant circuit comprises multiple stacked dielectric layers, multiple conductor layers formed on the multiple dielectric layers, and multiple vias. The plurality of conductor layers includes a plurality of conductor layers for resonators. The plurality of first resonators and the plurality of second resonators are formed by the plurality of resonators using a conductor layer. The coupling between the second resonant circuit and the two ports is weaker than the coupling between the first resonant circuit and the two ports. The first resonant circuit constitutes a bandpass filter. The plurality of resonator conductor layers include a first resonator conductor layer constituting one of the plurality of first resonators and a second resonator conductor layer constituting another of the plurality of first resonators. The plurality of vias includes a plurality of specific vias that are grounded. The first resonator conductor layer and the second resonator conductor layer are each electrically connected to the plurality of specific vias. The first resonator uses a conductor layer that extends along a first direction away from the plurality of specific vias. The second resonator uses a conductor layer that extends along a second direction away from the plurality of specific vias. The first direction and the second direction are opposite to each other. The plurality of specific through holes includes at least two through holes arranged along at least one of the directions orthogonal to the first direction and the second direction. The plurality of second resonators are open-ended resonators. The second resonant circuit constitutes a band-stop filter.

2. The filter circuit as described in claim 1, characterized in that, Also includes: Two first capacitors that couple the first resonant circuit to the two port capacitors; and At least one second capacitor couples the second resonant circuit to the two port capacitors. The capacitance of the at least one second capacitor is smaller than the capacitance of each of the two first capacitors.

3. The filter circuit as described in claim 1, characterized in that: It also includes at least one second capacitor that couples the second resonant circuit to the two port capacitors. The first resonant circuit is directly connected to at least one of the two ports.

4. The filter circuit as described in claim 1, characterized in that: The plurality of second resonators includes a first specific resonator and a second specific resonator. The first specific resonator is coupled to one of the two ports. The second specific resonator is coupled to the other port of the two ports.

5. The filter circuit as described in claim 4, characterized in that: The first specific resonator is coupled to the second specific resonator.

Images