Bandpass Filter

Abstract

To achieve a bandpass filter capable of increasing a pass attenuation amount at a high-pass side of a passband.SOLUTION: A bandpass filter 1 comprises: a first input-output port 2; a second input-output port 3; a first high-pass filter 12; a first low-pass filter 11; and a first stub type resonator 41. The first stub type resonator 41 includes a first distribution constant line 41A. The first low-pass filter 11 is provided between the first input-output port 2 and the first high-pass filter 12 in constituting a circuit. The first distribution constant line 41A has: a first end 41Aa connected with a first path 5 for connecting between the first input-output port 2 and the first low-pass filter 11; and a second end 41Ab closest to the ground in constituting a circuit.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a bandpass filter, including a highpass filter and a lowpass filter. [Background technology]

[0002] In recent years, there has been a market demand for miniaturization and space saving of small mobile communication devices, and there is also a demand for miniaturization of bandpass filters used in such communication devices. As a bandpass filter suitable for miniaturization, a laminate including a plurality of laminated dielectric layers and a plurality of laminated conductor layers is known.

[0003] A bandpass filter can be constructed by connecting in series a highpass filter that forms an attenuation pole on the low-frequency side of the passband of the bandpass filter and a lowpass filter that forms an attenuation pole on the high-frequency side of the passband of the bandpass filter. Each of the highpass filter and the lowpass filter can be a filter including at least one inductor and at least one capacitor.

[0004] Patent Documents 1 and 2 disclose a bandpass filter in which a highpass filter and a lowpass filter are connected in series. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 9-181549 [Patent Document 2] JP 2009-267811 A Summary of the Invention [Problem to be solved by the invention]

[0006] Currently, communication services using the fifth generation mobile communication system (hereinafter referred to as 5G) are beginning to be provided. In 5G, it is expected that frequency bands of 10 GHz or more, particularly the quasi-millimeter wave band of 10 to 30 GHz and the millimeter wave band of 30 to 300 GHz, will be used. As higher frequency bands than conventional ones are used in this way, bandpass filters are also required to satisfy characteristics in higher frequency bands than conventional ones. For example, it is required to increase the passing attenuation of the bandpass filter on the high frequency side of the passband of the bandpass filter.

[0007] The present invention has been made in view of the above problems, and an object of the present invention is to provide a bandpass filter that can increase the amount of passing attenuation on the high-frequency side of the passband. [Means for solving the problem]

[0008] The bandpass filter of the present invention is a bandpass filter that selectively passes signals of frequencies within a predetermined passband. The bandpass filter includes a first input / output port, a second input / output port, and a first highpass filter, a first lowpass filter, and a first stub-type resonator that are provided between the first input / output port and the second input / output port in terms of a circuit configuration. Each of the first highpass filter and the first lowpass filter includes at least one first inductor and at least one first capacitor. The first stub-type resonator includes a first distributed constant line.

[0009] The first low-pass filter is provided between the first input / output port and the first high-pass filter in terms of the circuit configuration. The first distributed constant line has a first end connected to a first path that connects the first input / output port and the first low-pass filter, and a second end closest to ground in the circuit configuration.

[0010] In the bandpass filter of the present invention, the first stub resonator may further include, in terms of circuit configuration, a second capacitor provided between the first distributed constant line and ground.

[0011] In the bandpass filter of the present invention, each of the first lowpass filter and the first stub resonator may form an attenuation pole on the high-frequency side of the passband.

[0012] In the bandpass filter of the present invention, the first distributed constant line may be a quarter-wave line.

[0013] The bandpass filter of the present invention may further include a laminate including a plurality of laminated dielectric layers and a plurality of laminated conductor layers, and for integrating the first input / output port, the second input / output port, the first high-pass filter, the first low-pass filter, and the first stub-type resonator. In this case, the plurality of conductor layers may include a first conductor line constituting the first distributed constant line, and a ground conductor layer connected to ground. A part of the first conductor line may face the ground conductor layer.

[0014] The bandpass filter of the present invention may further include a second high-pass filter, a second low-pass filter, and a second stub-type resonator provided between the first high-pass filter and the second input / output port in terms of the circuit configuration. In this case, each of the second high-pass filter and the second low-pass filter may include at least one second inductor and at least one third capacitor, and the second stub-type resonator may include a second distributed constant line. The second low-pass filter may be provided between the second input / output port and the second high-pass filter in terms of the circuit configuration. The second distributed constant line may have a third end connected to a second path connecting the second input / output port and the second low-pass filter, and a fourth end closest to the ground in terms of the circuit configuration.

[0015] In the bandpass filter of the present invention, the second stub resonator may further include a fourth capacitor provided between the second distributed constant line and ground in terms of the circuit configuration.

[0016] In the bandpass filter of the present invention, the second distributed constant line may be a quarter-wave line.

[0017] The bandpass filter of the present invention may further include a laminate including a plurality of laminated dielectric layers and a plurality of laminated conductor layers, and for integrating the first input / output port, the second input / output port, the first high-pass filter, the first low-pass filter, the first stub-type resonator, the second high-pass filter, the second low-pass filter, and the second stub-type resonator. In this case, the plurality of conductor layers may include a first conductor line constituting the first distributed constant line, a second conductor line constituting the second distributed constant line, and a ground conductor layer connected to ground. A part of the first conductor line and a part of the second conductor line may face the ground.

[0018] The bandpass filter of the present invention may further include at least one resonator provided between the first and second highpass filters in terms of the circuit configuration. In this case, the at least one resonator may include a third inductor provided between a third path connecting the first and second highpass filters in terms of the circuit configuration and ground. Effect of the Invention

[0019] The bandpass filter of the present invention includes a first highpass filter, a first lowpass filter, and a first stub-type resonator. The first stub-type resonator includes a first distributed constant line. In terms of the circuit configuration, the first lowpass filter is provided between a first input / output port and the first highpass filter. The first distributed constant line is connected to a first path connecting the first input / output port and the first lowpass filter. As a result, according to the present invention, it is possible to achieve an effect of increasing the passing attenuation on the high-frequency side of the passband. [Brief description of the drawings]

[0020] [Figure 1]1 is a circuit diagram showing a circuit configuration of a bandpass filter according to an embodiment of the present invention. [Diagram 2] 1 is a perspective view showing an external appearance of a bandpass filter according to an embodiment of the present invention; [Diagram 3] 1 is an explanatory diagram showing a pattern formation surface of first to third dielectric layers in a laminate of a bandpass filter according to an embodiment of the present invention. FIG. [Figure 4] 2 is an explanatory diagram showing pattern formation surfaces of fourth to sixth dielectric layers in a laminate of a bandpass filter according to an embodiment of the present invention. FIG. [Diagram 5] 2 is an explanatory diagram showing pattern formation surfaces of seventh to ninth dielectric layers in a laminate of a bandpass filter according to an embodiment of the present invention. FIG. [Figure 6] 1 is an explanatory diagram showing pattern formation surfaces of 10th to 12th dielectric layers in a laminate of a bandpass filter according to an embodiment of the present invention. FIG. [Figure 7] 2 is an explanatory diagram showing pattern formation surfaces of 13th to 15th dielectric layers in a laminate of a bandpass filter according to an embodiment of the present invention. FIG. [Figure 8] 2 is an explanatory diagram showing the pattern formation surfaces of 16th to 18th dielectric layers in a laminate of a bandpass filter according to an embodiment of the present invention. FIG. [Figure 9] 2 is an explanatory diagram showing pattern formation surfaces of the 19th and 20th dielectric layers in a laminate of a bandpass filter according to an embodiment of the present invention. FIG. [Figure 10] 1 is a perspective view showing an inside of a laminate of a bandpass filter according to an embodiment of the present invention; [Figure 11] 11 is a perspective view showing a part of the inside of the laminate shown in FIG. [Figure 12] 11 is a cross-sectional view showing a part of the inside of the laminate shown in FIG. [Figure 13] FIG. 13 is a characteristic diagram showing an example of pass attenuation characteristics of a model of an embodiment and a model of a comparative example. [Figure 14]FIG. 13 is a characteristic diagram showing insertion loss of a model of an embodiment and a model of a comparative example. [Figure 15] FIG. 13 is a characteristic diagram showing the return loss at the first input / output port of each of the model of the embodiment and the model of the comparative example. [Figure 16] FIG. 13 is a characteristic diagram showing the return loss at the second input / output port of each of the model of the embodiment and the model of the comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. First, an outline of the configuration of a bandpass filter 1 according to an embodiment of the present invention will be described with reference to FIG. 1. The bandpass filter 1 according to this embodiment selectively passes signals of frequencies within a predetermined passband. The bandpass filter 1 includes a first input / output port 2, a second input / output port 3, a first highpass filter 12, a first lowpass filter 11, a second highpass filter 22, a second lowpass filter 21, a resonator 31, a first stub-type resonator 41, and a second stub-type resonator 42. The first highpass filter 12, the first lowpass filter 11, the second highpass filter 22, the second lowpass filter 21, the resonator 31, the first stub-type resonator 41, and the second stub-type resonator 42 are provided between the first input / output port 2 and the second input / output port 3 in terms of the circuit configuration.

[0022] In this application, the expression "in terms of a circuit configuration" is used to indicate a layout on a circuit diagram, not a layout in a physical configuration.

[0023] In terms of the circuit configuration, the first low-pass filter 11 is provided between the first input / output port 2 and the first high-pass filter 12. The first low-pass filter 11 is also connected to the first input / output port 2.

[0024] In terms of the circuit configuration, the second high-pass filter 22 is provided between the first high-pass filter 12 and the second input / output port 3. In terms of the circuit configuration, the second low-pass filter 21 is provided between the second input / output port 3 and the second high-pass filter 22. In addition, the second low-pass filter 21 is connected to the second input / output port 3.

[0025] The resonator 31 is provided between the first high-pass filter 12 and the second high-pass filter 22 in terms of the circuit configuration.

[0026] Each of the first high-pass filter 12, the first low-pass filter 11, the second high-pass filter 22, and the second low-pass filter 21 is configured by an LC resonant circuit including an inductor and a capacitor.

[0027] The resonator 31 includes, in terms of its circuit configuration, an inductor provided between the path 4 that connects the first high-pass filter 12 and the second low-pass filter 21 and the ground.

[0028] The first stub resonator 41 includes a first distributed constant line 41A and a capacitor C41. The first distributed constant line 41A is a quarter-wavelength line. The first distributed constant line 41A has a first end 41Aa connected to a first path 5 that connects the first input / output port 2 and the first low-pass filter 11, and a second end 41Ab that is closest to the ground in terms of the circuit configuration. The capacitor C41 is provided between the first distributed constant line 41A and the ground in terms of the circuit configuration.

[0029] The second stub resonator 42 includes a second distributed constant line 42A and a capacitor C42. The second distributed constant line 42A is a quarter-wavelength line. The second distributed constant line 42A has a first end 42Aa connected to a second path 6 that connects the second input / output port 3 and the second low-pass filter 21, and a second end 42Ab that is closest to the ground in terms of the circuit configuration. The capacitor C42 is provided between the second distributed constant line 42A and the ground in terms of the circuit configuration.

[0030] Next, an example of the configuration of the first high-pass filter 12, the first low-pass filter 11, the second high-pass filter 22, the second low-pass filter 21, and the resonator 31 will be described with reference to FIG.

[0031] The first low-pass filter 11 includes an inductor L11 and capacitors C11 and C12. One end of the inductor L11 is connected to the first input / output port 2. The capacitor C11 is connected in parallel to the inductor L11. One end of the capacitor C12 is connected to the other end of the inductor L11. The other end of the capacitor C12 is connected to ground.

[0032] The first high-pass filter 12 includes an inductor L12 and capacitors C13, C14, C15, and C16. One end of the capacitor C13 is connected to the other end of the inductor L11 of the first low-pass filter 11. One end of the capacitor C14 is connected to the other end of the capacitor C13. One end of the capacitor C15 is connected to one end of the capacitor C13. The other end of the capacitor C15 is connected to the other end of the capacitor C14.

[0033] One end of the inductor L12 is connected to the connection point between the capacitors C13 and C14. The other end of the inductor L12 is connected to the ground. The capacitor C16 is connected in parallel to the inductor L12.

[0034] The second low-pass filter 21 includes an inductor L21 and a capacitor C21. One end of the inductor L21 is connected to the second input / output port 3. The capacitor C21 is connected in parallel to the inductor L21.

[0035] The second high-pass filter 22 includes an inductor L22 and capacitors C23, C24, C25, and C26. One end of the capacitor C23 is connected to the other end of the inductor L21 of the second low-pass filter 21. One end of the capacitor C24 is connected to the other end of the capacitor C23. One end of the capacitor C25 is connected to one end of the capacitor C23. The other end of the capacitor C25 is connected to the other end of the capacitor C24.

[0036] One end of the inductor L22 is connected to the connection point between the capacitors C23 and C24. The other end of the inductor L22 is connected to the ground. The capacitor C26 is connected in parallel to the inductor L22.

[0037] A path 4 connecting the first high-pass filter 12 and the second high-pass filter 22 connects the other end of the capacitor C14 of the first high-pass filter 12 to the other end of the capacitor C24 of the second high-pass filter 22.

[0038] The resonator 31 includes an inductor L31 and a capacitor C31. One end of the inductor L31 is connected to the path 4 at a position closer to the first high-pass filter 12 than to the second high-pass filter 22 in terms of the circuit configuration. One end of the capacitor C31 is connected to the other end of the inductor L31. The other end of the capacitor C31 is connected to ground.

[0039] Next, other configurations of the bandpass filter 1 will be described with reference to Fig. 2. Fig. 2 is a perspective view showing the external appearance of the bandpass filter 1.

[0040] The bandpass filter 1 further includes a laminate 50 including a plurality of laminated dielectric layers and a plurality of laminated conductor layers. The laminate 50 is for integrating the first input / output port 2, the second input / output port 3, the first high-pass filter 12, the first low-pass filter 11, the second high-pass filter 22, the second low-pass filter 21, the resonator 31, the first stub-type resonator 41, and the second stub-type resonator 42. The first high-pass filter 12, the first low-pass filter 11, the second high-pass filter 22, the second low-pass filter 21, the resonator 31, the first stub-type resonator 41, and the second stub-type resonator 42 are configured using a plurality of conductor layers.

[0041] The laminate 50 has a bottom surface 50A and a top surface 50B located at both ends in the stacking direction T of the multiple dielectric layers, and four side surfaces 50C to 50F connecting the bottom surface 50A and the top surface 50B. The side surfaces 50C and 50D face in opposite directions to each other, and the side surfaces 50E and 50F also face in opposite directions to each other. The side surfaces 50C to 50F are perpendicular to the top surface 50B and the bottom surface 50A.

[0042] Here, the X direction, Y direction, and Z direction are defined as shown in FIG. 2. The X direction, Y direction, and Z direction are mutually perpendicular. In this embodiment, a direction parallel to the stacking direction T is defined as the Z direction. Also, the direction opposite to the X direction is defined as the -X direction, the direction opposite to the Y direction is defined as the -Y direction, and the direction opposite to the Z direction is defined as the -Z direction.

[0043] As shown in FIG. 2, the bottom surface 50A is located at the end of the laminate 50 in the -Z direction. The top surface 50B is located at the end of the laminate 50 in the Z direction. The bottom surface 50A and the top surface 50B each have a rectangular shape that is elongated in the X direction. The side surface 50C is located at the end of the laminate 50 in the -X direction. The side surface 50D is located at the end of the laminate 50 in the X direction. The side surface 50E is located at the end of the laminate 50 in the -Y direction. The side surface 50F is located at the end of the laminate 50 in the Y direction.

[0044] The bandpass filter 1 further includes a plurality of terminals 111, 112, 113, 114, 115, and 116 provided on the bottom surface 50A of the laminate 50. The terminal 111 extends in the Y direction near the side surface 50C. The terminal 112 extends in the Y direction near the side surface 50D. The terminals 113 to 116 are disposed between the terminals 111 and 112. The terminals 113 and 114 are arranged in this order in the X direction at a position closer to the side surface 50E than the side surface 50F. The terminals 115 and 116 are arranged in this order in the X direction at a position closer to the side surface 50F than the side surface 50E.

[0045] Terminal 111 corresponds to the first input / output port 2, and terminal 112 corresponds to the second input / output port 3. Therefore, the first and second input / output ports 2, 3 are provided on the bottom surface 50A of the laminate 50. Each of terminals 113 to 116 is connected to ground.

[0046] Next, an example of the plurality of dielectric layers and the plurality of conductor layers constituting the laminate 50 will be described with reference to Figs. 3 to 9. In this example, the laminate 50 has 20 laminated dielectric layers. Hereinafter, these 20 dielectric layers will be referred to as the 1st to 20th dielectric layers from the bottom up. The 1st to 20th dielectric layers will be denoted by reference numerals 51 to 70.

[0047] 3(a) shows the pattern-formed surface of the first dielectric layer 51. Terminals 111, 112, 113, 114, 115, and 116 are formed on the pattern-formed surface of the dielectric layer 51. Furthermore, through holes 51T1, 51T2, 51T3, 51T4, 51T5, 51T6, and 51T7 are formed in the dielectric layer 51. The through hole 51T1 is connected to the terminal 111. The through holes 51T2 and 51T3 are connected to the terminal 112. The through holes 51T4 to 51T7 are connected to the terminals 113 to 116, respectively.

[0048] 3(b) shows the pattern-formed surface of the second dielectric layer 52. Conductor layers 521 and 522 and a ground conductor layer 523 are formed on the pattern-formed surface of the dielectric layer 52. Through holes 52T1, 52T2, 52T3, 52T4, and 52T5 are formed on the dielectric layer 52. The through holes 51T1 and 52T1 formed on the dielectric layer 51 are connected to the conductor layer 521. The through holes 51T2 and 51T3 and 52T2 and 52T5 formed on the dielectric layer 51 are connected to the conductor layer 522. The through holes 51T4 to 51T7 and 52T3 and 52T4 formed on the dielectric layer 51 are connected to the ground conductor layer 523.

[0049] FIG. 3(c) shows the pattern-formed surface of the third dielectric layer 53. On the pattern-formed surface of the dielectric layer 53, a first conductor line 531 constituting the first distributed constant line and a second conductor line 532 constituting the second distributed constant line are formed. In addition, through holes 53T1, 53T2, 53T3, and 53T4 are formed in the dielectric layer 53. The through holes 52T1 and 53T2 formed in the dielectric layer 52 are connected to the first conductor line 531. The through holes 52T2 to 52T4 formed in the dielectric layer 52 are connected to the through holes 53T2 to 53T4, respectively. The through hole 52T5 formed in the dielectric layer 52 is connected to the second conductor line 532.

[0050] FIG. 4(a) shows the pattern-formed surface of the fourth dielectric layer 54. Conductor layers 541, 542, and 543 are formed on the pattern-formed surface of the dielectric layer 54. Through holes 54T1, 54T2, 54T3, 54T4, 54T5, 54T6, and 54T7 are also formed in the dielectric layer 54. The through holes 53T1 to 53T4 formed in the dielectric layer 53 are connected to the through holes 54T1 to 54T4, respectively. The through hole 54T5 is connected to the conductor layer 541. The through hole 54T6 is connected to the conductor layer 543. The through hole 54T7 is connected to the conductor layer 542.

[0051] FIG. 4(b) shows the pattern-formed surface of the fifth dielectric layer 55. Conductor layers 551 and 552 are formed on the pattern-formed surface of the dielectric layer 55. Through holes 55T1, 55T2, 55T3, 55T4, 55T5, 55T6, 55T7, 55T8, and 55T9 are formed in the dielectric layer 55. The through holes 54T1 to 54T7 formed in the dielectric layer 54 are connected to the through holes 55T1 to 55T7, respectively. The through hole 55T8 is connected to the conductive layer 552. The through hole 55T9 is connected to the conductive layer 551.

[0052] FIG. 4(c) shows the pattern-formed surface of the sixth dielectric layer 56. Conductor layers 561, 562, and 563 are formed on the pattern-formed surface of the dielectric layer 56. Through holes 56T1, 56T2, 56T3, 56T4, 56T5, 56T6, 56T7, 56T8, 56T9, and 56T10 are formed on the dielectric layer 56. The through holes 55T1 to 55T5, 55T8, and 55T9 formed on the dielectric layer 55 are connected to the through holes 56T1 to 56T5, 56T8, and 56T9, respectively. The through hole 55T6 and the through hole 56T6 formed on the dielectric layer 55 are connected to the conductor layer 562. The through hole 55T7 and the through hole 56T7 formed on the dielectric layer 55 are connected to the conductor layer 561. The through hole 56T10 is connected to the conductor layer 563.

[0053] FIG. 5(a) shows the pattern-formed surface of the seventh dielectric layer 57. Conductive layers 571 and 572 are formed on the pattern-formed surface of the dielectric layer 57. The conductive layer 571 has a first end and a second end located on opposite sides. The dielectric layer 57 also has through holes 57T1, 57T2, 57T3, 57T4, 57T5, 57T6, 57T7, 57T8, 57T9, and 57T10. ,57T10 The through holes 56T1 to 56T4, 56T7, 56T8, and 56T10 formed in the dielectric layer 56 correspond to the through holes 57T1 to 57T4, 57T7, 57T8, and 57T10. The through hole 56T6 formed in the dielectric layer 56 is connected to the through hole 57T9. The through hole 56T9 formed in the dielectric layer 56 is connected to the conductor layer 572. The through hole 56T5 and the through hole 57T5 formed in the dielectric layer 56 are connected to a portion of the conductor layer 571 in the vicinity of a first end. The through hole 57T6 is connected to a portion of the conductor layer 571 in the vicinity of a second end.

[0054] FIG. 5(b) shows the pattern-formed surface of the eighth dielectric layer 58. Conductor layers 581 and 582 are formed on the pattern-formed surface of the dielectric layer 58. The conductor layer 581 has a first end and a second end located opposite to each other. The dielectric layer 58 also has through holes 58T1, 58T2, 58T3, 58T4, 58T5, 58T6, 58T7, and 58T8 formed therein. The through holes 57T1 to 57T4 and 57T7 formed in the dielectric layer 57 are connected to the through holes 58T1 to 58T4 and 58T7, respectively. The through hole 57T5 formed in the dielectric layer 57 is connected to a portion of the conductor layer 581 near the first end. The through hole 57T6 and the through hole 58T6 formed in the dielectric layer 57 are connected to a portion of the conductor layer 581 near the second end. The through hole 57T9 formed in the dielectric layer 57 is connected to the through hole 58T5. The through hole 57T10 formed in the dielectric layer 57 is connected to the conductor layer 582.

[0055] FIG. 5(c) shows the pattern-formed surface of the ninth dielectric layer 59. Conductor layers 591 and 592 are formed on the pattern-formed surface of the dielectric layer 59. Each of the conductor layers 591 and 592 has a first end and a second end located opposite to each other. Through holes 59T1, 59T2, 59T3, 59T4, 59T5, 59T6, 59T7, 59T8, and 59T9 are formed in the dielectric layer 59. The through hole 58T1 formed in the dielectric layer 58 and the through hole 59T1 are connected to a portion near the first end of the conductor layer 591. The through holes 58T2 to 58T4, 58T7, and 58T8 formed in the dielectric layer 58 are connected to the through holes 59T2 to 59T4, 59T7, and 59T8, respectively. Through hole 58T5 and through hole 59T5 formed in dielectric layer 58 are connected to a portion near the first end of conductor layer 592. Through hole 58T6 and through hole 59T6 formed in dielectric layer 58 are connected to a portion near the second end of conductor layer 591. Through hole 59T9 is connected to a portion near the second end of conductor layer 592.

[0056] FIG. 6(a) shows the pattern-formed surface of the 10th dielectric layer 60. Conductor layers 601 and 602 are formed on the pattern-formed surface of the dielectric layer 60. The conductive layers 601 and 602 each have a first end and a second end located opposite to each other. The dielectric layer 60 also has through holes 60T1, 60T2, 60T3, 60T4, 60T5, and 60T6. The through hole 59T1 formed in the dielectric layer 59 is connected to a portion near the first end of the conductive layer 601. The through holes 59T2 to 59T4 formed in the dielectric layer 59 are connected to the through holes 60T2 to 60T4, respectively. The through hole 59T5 formed in the dielectric layer 59 is connected to a portion near the first end of the conductive layer 602. The through hole 59T6 formed in the dielectric layer 59 is connected to a portion near the second end of the conductive layer 601. The through hole 59T7 formed in the dielectric layer 59 is connected to the through hole 60T1. The through hole 59T8 formed in the dielectric layer 59 is connected to the through hole 60T6. The through hole 59T9 and the through hole 60T5 formed in the dielectric layer 59 are connected to a portion of the conductor layer 602 near the second end.

[0057] FIG. 6(b) shows the pattern-formed surface of the eleventh dielectric layer 61. A conductor layer 611 is formed on the pattern-formed surface of the dielectric layer 61. The conductor layer 611 has a first end and a second end located on opposite sides. In addition, through holes 61T1, 61T2, 61T3, 61T4, 61T5, and 61T6 are formed in the dielectric layer 61. The through holes 60T1, 60T3, 60T4, and 60T6 formed in the dielectric layer 60 are connected to the through holes 61T1, 61T3, 61T4, and 61T6, respectively. The through holes 60T2 and 61T2 formed in the dielectric layer 60 are connected to the vicinity of the first end of the conductor layer 611. The through holes 60T5 and 61T5 formed in the dielectric layer 60 are connected to the vicinity of the second end of the conductor layer 611.

[0058] FIG. 6(c) shows the pattern-formed surface of the twelfth dielectric layer 62. A conductor layer 621 is formed on the pattern-formed surface of the dielectric layer 62. The conductor layer 621 has a first end and a second end located on opposite sides. In addition, through holes 62T1, 62T2, 62T3, and 62T4 are formed in the dielectric layer 62. The through holes 61T1, 61T3, and 61T4 formed in the dielectric layer 61 are connected to the through holes 62T1, 62T3, and 62T4, respectively. The through hole 61T2 formed in the dielectric layer 61 is connected to a portion near the first end of the conductor layer 621. The through hole 61T5 formed in the dielectric layer 61 is connected to a portion near the second end of the conductor layer 621. The through hole 61T6 formed in the dielectric layer 61 is connected to the through hole 62T2.

[0059] 7(a) shows a pattern-formed surface of the 13th dielectric layer 63. Through holes 63T1, 63T2, 63T3, and 63T4 are formed in the dielectric layer 63. Through holes 62T1 to 62T4 formed in the dielectric layer 62 are connected to through holes 63T1 to 63T4, respectively.

[0060] FIG. 7(b) shows the pattern-formed surface of the 14th dielectric layer 64. A conductor layer 641 is formed on the pattern-formed surface of the dielectric layer 64. The conductor layer 641 has a first end and a second end located on opposite sides. The dielectric layer 64 also has through holes 64T1, 64T2, 64T3, 64T4, and 64T5. The through holes 63T1 and 64T2 formed in the dielectric layer 63 are connected to the vicinity of the first end of the conductor layer 641. The through holes 63T2 to 63T4 formed in the dielectric layer 63 are connected to the through holes 64T2 to 64T4, respectively. The through hole 64T5 is connected to the vicinity of the second end of the conductor layer 641.

[0061] FIG. 7(c) shows the pattern-formed surface of the 15th dielectric layer 65. A conductor layer 651 is formed on the pattern-formed surface of the dielectric layer 65. The conductor layer 651 has a first end and a second end located on opposite sides. The dielectric layer 65 also has through holes 65T1, 65T2, 65T3, and 65T4 formed therein. The through hole 64T1 formed in the dielectric layer 64 is connected to a portion near the first end of the conductor layer 651. The through holes 64T2 to 64T4 formed in the dielectric layer 64 are connected to the through holes 65T2 to 65T4, respectively. The through hole 64T5 and the through hole 65T1 formed in the dielectric layer 64 are connected to a portion near the second end of the conductor layer 651.

[0062] FIG. 8(a) shows the pattern-formed surface of the 16th dielectric layer 66. A conductor layer 661 is formed on the pattern-formed surface of the dielectric layer 66. The conductor layer 661 has a first end and a second end located on opposite sides. In addition, through holes 66T1, 66T2, 66T3, 66T4, and 66T5 are formed in the dielectric layer 66. The through holes 65T1, 65T3, and 65T4 formed in the dielectric layer 65 are connected to the through holes 66T1, 66T3, and 66T4, respectively. The through holes 65T2 and 66T2 formed in the dielectric layer 65 are connected to the vicinity of the first end of the conductor layer 661. The through hole 66T5 is connected to the vicinity of the second end of the conductor layer 661.

[0063] FIG. 8(b) shows the pattern-formed surface of the 17th dielectric layer 67. A conductor layer 671 is formed on the pattern-formed surface of the dielectric layer 67. The conductor layer 671 has a first end and a second end located on opposite sides. The dielectric layer 67 also has through holes 67T1, 67T2, 67T3, and 67T4 formed therein. The through holes 66T1, 66T3, and 66T4 formed in the dielectric layer 66 are connected to the through holes 67T1, 67T3, and 67T4, respectively. The through hole 66T2 formed in the dielectric layer 66 is connected to a portion near the first end of the conductor layer 671. The through holes 66T5 and 67T2 formed in the dielectric layer 66 are connected to a portion near the second end of the conductor layer 671.

[0064] FIG. 8(c) shows the pattern-formed surface of the 18th dielectric layer 68. Conductor layers 681 and 682 are formed on the pattern-formed surface of the dielectric layer 68. Each of the conductor layers 681 and 682 has a first end and a second end located opposite to each other. In addition, through holes 68T1, 68T2, 68T3, and 68T4 are formed in the dielectric layer 68. The through holes 67T1 and 68T1 formed in the dielectric layer 67 are connected to a portion near the first end of the conductor layer 681. The through holes 67T2 and 68T2 formed in the dielectric layer 67 are connected to a portion near the first end of the conductor layer 682. The through holes 67T3 and 68T3 formed in the dielectric layer 67 are connected to a portion near the second end of the conductor layer 681. The through hole 67T4 and the through hole 68T4 formed in the dielectric layer 67 are connected to a portion of the conductor layer 682 in the vicinity of the second end thereof.

[0065] FIG. 9(a) shows the pattern-formed surface of the 19th dielectric layer 69. Conductor layers 691 and 692 are formed on the pattern-formed surface of the dielectric layer 69. Each of the conductor layers 691 and 692 has a first end and a second end located opposite to each other. A through hole 68T1 formed in the dielectric layer 68 is connected to a portion near the first end of the conductor layer 691. A through hole 68T2 formed in the dielectric layer 68 is connected to a portion near the first end of the conductor layer 692. A through hole 68T3 formed in the dielectric layer 68 is connected to a portion near the second end of the conductor layer 691. A through hole 68T4 formed in the dielectric layer 68 is connected to a portion near the second end of the conductor layer 692.

[0066] 9(b) shows the pattern-formed surface of the twentieth dielectric layer 70. On the pattern-formed surface of the dielectric layer 70, a mark 701 made of a conductor layer is formed.

[0067] The laminate 50 shown in Figure 2 is formed by stacking the first to twentieth dielectric layers 51-70 such that the pattern-forming surface of the first dielectric layer 51 becomes the bottom surface 50A of the laminate 50, and the surface opposite the pattern-forming surface of the twentieth dielectric layer 70 becomes the top surface 50B of the laminate 50.

[0068] Fig. 10 shows the inside of the laminate 50 formed by laminating the first to twentieth dielectric layers 51-70. As shown in Fig. 10, the inside of the laminate 50 has a plurality of conductor layers and a plurality of through holes as shown in Figs. 3 to 9 laminated therein. Note that the mark 701 is omitted in Fig. 10. Fig. 11 shows a part of the inside of the laminate 50 shown in Fig. 10. Specifically, Fig. 11 mainly shows the ground conductor layer 523, the first conductor line 531, and the second conductor line 532.

[0069] The following describes the correspondence between the components of the circuit of the bandpass filter 1 shown in FIG. 1 and the components inside the laminate 50 shown in FIG. 3 to FIG. 9. First, the components of the first low-pass filter 11 are described. The inductor L11 is composed of the conductor layers 571, 581, 591, and 601 shown in FIG. 5(a) to FIG. 6(a) and a plurality of through holes connected to these conductor layers. Here, the shape of the conductor layer when viewed from a direction parallel to the lamination direction T (Z direction) is called the planar shape of the conductor layer. In particular, in this embodiment, the planar shape of the conductor layer 571 and the planar shape of the conductor layer 581 are the same or almost the same. Also, the planar shape of the conductor layer 591 and the planar shape of the conductor layer 601 are the same or almost the same. The conductor layers 571 and 581 are connected in parallel by the through holes 57T5 and 57T6. The conductor layers 591 and 601 are connected in parallel by the through holes 59T1 and 59T6.

[0070] The capacitor C11 includes the terminal 111 shown in FIG. 3(a), the conductor layer 541 shown in FIG. 4(a), Terminal 111 and Conductive Layer 541 and and dielectric layers 51 to 53 therebetween.

[0071] The capacitor C12 is composed of the ground conductor layer 523 shown in FIG. 3(b), the conductor layer 541 shown in FIG. 4(a), and dielectric layers 52 and 53 between these conductor layers.

[0072] Next, the components of the first high-pass filter 12 will be described. The inductor L12 is composed of the conductor layers 641, 651, 681, and 691 shown in FIG. 7(b), FIG. 7(c), FIG. 8(c), and FIG. 9(a), and a plurality of through holes connected to these conductor layers. In particular, in this embodiment, the planar shape of the conductor layer 641 and the planar shape of the conductor layer 651 are the same or almost the same. Also, the planar shape of the conductor layer 681 and the planar shape of the conductor layer 691 are the same or almost the same. The conductor layers 641 and 651 are connected in parallel by the through holes 64T1 and 64T5. The conductor layers 681 and 691 are connected in parallel by the through holes 68T1 and 68T3.

[0073] The capacitor C13 is composed of the conductor layers 541 and 542 shown in FIG.

[0074] The capacitor C14 is composed of the conductor layers 551, 561, and 572 shown in FIGS. 4(b) to 5(a), and the dielectric layers 55 and 56 between these conductor layers.

[0075] The capacitor C15 is composed of the conductor layers 541 and 551 shown in FIGS. 4(a) and 4(b) and a dielectric layer 54 between these conductor layers.

[0076] The capacitor C16 is composed of the ground conductor layer 523 shown in FIG. 3(b), the conductor layer 542 shown in FIG. 4(a), and dielectric layers 52 and 53 between these conductor layers.

[0077] Next, the components of the second low-pass filter 21 will be described. The inductor L21 is composed of the conductor layers 592, 602, 611, and 621 shown in FIG. 5(c) to FIG. 6(c) and a plurality of through holes connected to these conductor layers. In particular, in this embodiment, the planar shape of the conductor layer 592 and the planar shape of the conductor layer 602 are the same or almost the same. Also, the planar shape of the conductor layer 611 and the planar shape of the conductor layer 621 are the same or almost the same. The conductor layers 592 and 602 are connected in parallel by the through holes 59T5 and 59T9. The conductor layers 611 and 621 are connected in parallel by the through holes 61T2 and 61T5.

[0078] The capacitor C21 is composed of the conductor layers 522 and 543 shown in FIG. 3(b) and FIG. 4(a), and the dielectric layers 52 and 53 between these conductor layers.

[0079] Next, the components of the second high-pass filter 22 will be described. The inductor L22 is composed of the conductor layers 661, 671, 682, and 692 shown in Figs. 8(a) to 9(a) and a plurality of through holes connected to these conductor layers. In particular, in this embodiment, the planar shape of the conductor layer 661 and the planar shape of the conductor layer 671 are the same or almost the same. Also, the planar shape of the conductor layer 682 and the planar shape of the conductor layer 692 are the same or almost the same. The conductor layers 661 and 671 are connected in parallel by the through holes 66T2 and 66T5. The conductor layers 682 and 692 are connected in parallel by the through holes 66T2 and 66T5. 692 are connected in parallel by through holes 68T2 and 68T4.

[0080] The capacitor C23 is composed of the conductor layers 543, 552, 562, 582, and 592 shown in FIGS. 4(a) to 5(c) and the dielectric layers 54 to 58 between these conductor layers.

[0081] The capacitor C24 is composed of the conductor layers 551, 563, 572, and 582 shown in FIG. 4(b) to FIG. 5(b), and the dielectric layers 55 to 57 between these conductor layers.

[0082] The capacitor C25 is composed of the conductor layers 543, 551, 562, and 572 shown in FIGS. 4(a) to 5(a), and the dielectric layers 54 to 56 between these conductor layers.

[0083] The capacitor C26 is composed of the conductor layers 671 and 682 shown in FIGS. 8(b) and 8(c) and a dielectric layer 68 between these conductor layers.

[0084] Next, a description will be given of the components of the resonator 31. The inductor L31 is formed by the conductor layer 551 and the through holes 55T9 and 56T9 shown in Fig. 4(b) and Fig. 4(c).

[0085] The capacitor C31 is composed of the ground conductor layer 523 shown in FIG. 3(b), the conductor layer 551 shown in FIG. 4(b), and the dielectric layers 52 to 54 between these conductor layers.

[0086] Next, components of the first stub-type resonator 41 will be described. The first distributed constant line 41A is composed of the first conductor line 531 shown in Fig. 3(c). As shown in Fig. 11, a part of the first conductor line 531 faces the ground conductor layer 523 shown in Fig. 3(b). The capacitor C41 is composed of the ground conductor layer 523, the first conductor line 531, and the dielectric layer 52.

[0087] Next, components of the second stub-type resonator 42 will be described. The second distributed constant line 42A is composed of the second conductor line 532 shown in FIG. 3(c). As shown in FIG. 11, a part of the second conductor line 532 faces the ground conductor layer 523 shown in FIG. 3(b). The capacitor C42 is composed of the ground conductor layer 523, the second conductor line 532, and the dielectric layer 52.

[0088] Next, structural features of the bandpass filter 1 according to this embodiment will be described with reference to Fig. 1 to Fig. 12. Fig. 12 is a cross-sectional view showing a part of the inside of the laminate 50 shown in Fig. 10. The multiple conductor layers of the laminate 50 include at least one first conductor layer constituting the inductor L12 of the first highpass filter 12, at least one second conductor layer constituting the inductor L11 of the first lowpass filter 11, at least one third conductor layer constituting the inductor L22 of the second highpass filter 22, at least one fourth conductor layer constituting the inductor L21 of the second lowpass filter 21, and a ground conductor layer 523 connected to ground. In the laminate 50 shown in Figures 3 to 10, the conductor layers 641, 651, 681, and 691 correspond to the first conductor layer, the conductor layers 571, 581, 591, and 601 correspond to the second conductor layer, the conductor layers 661, 671, 682, and 692 correspond to the third conductor layer, and the conductor layers 592, 602, 611, and 621 correspond to the fourth conductor layer.

[0089] The group of the first conductor layers 641, 651, 681, 691, the group of the second conductor layers 571, 581, 591, 601, and the ground conductor layer 523 are disposed at different positions from each other in the stacking direction T. The second conductor layers 571, 581, 591, 601 are disposed between the first conductor layers 641, 651, 681, 691 and the ground conductor layer 523 in the stacking direction T. In addition, the first conductor layers 641, 651, 681, 691 and the second conductor layers 571, 581, 591, 601 are disposed between the ground conductor layer 523 and the upper surface 50B of the laminate 50 in the stacking direction T.

[0090] The inductor L12 of the first high-pass filter 12 includes a first portion L12a composed of first conductor layers 641, 651, 681, and 691. The first portion L12a has a first end E12a that is closest to the terminal 112 constituting the second input / output port 3 in terms of the circuit configuration, and a second end E12b that is farthest from the terminal 112 in terms of the circuit configuration. As shown in FIG. 7(b), the portion of the first conductor layer 641 to which the through hole 63T1 is connected corresponds to the first end E12a. As shown in FIG. 8(c), the portion of the first conductor layer 681 to which the through hole 67T3 is connected corresponds to the second end E12b. The first portion L12a is wound in a first winding direction D1 (see FIG. 8(c)) from the first end E12a to the second end E12b when viewed from a direction parallel to the lamination direction T (Z direction).

[0091] The inductor L11 of the first low-pass filter 11 includes a second portion L11a including second conductor layers 571, 581, 591, and 601. The second portion L11a has a third end E11a that is closest to the terminal 112 constituting the second input / output port 3 in terms of the circuit configuration, and a fourth end E11b that is farthest from the terminal 112 in terms of the circuit configuration. As shown in FIG. 5(a), the portion of the second conductor layer 571 to which the through hole 56T5 is connected corresponds to the third end E11a. As shown in FIG. 5(c), the portion of the second conductor layer 591 to which the through hole 58T1 is connected corresponds to the fourth end E11b. The second portion L11a is wound in a second winding direction D2 (see Figure 5(c)) opposite to the first winding direction D1 from the third end E11a to the fourth end E11b when viewed from a direction parallel to the stacking direction T (Z direction).

[0092] Figure 12 , the center of the group of first conductor layers 641, 651, 681, and 691 in the stacking direction T is indicated by symbol C1, and the center of the group of second conductor layers 571, 581, 591, and 601 in the stacking direction T is indicated by symbol C2. The distance from center C2 to center C1 is greater than the distance from center C2 to ground conductor layer 523.

[0093] The group of the third conductor layers 661, 671, 682, 692, the group of the fourth conductor layers 592, 602, 611, 621, and the ground conductor layer 523 are disposed at different positions from each other in the stacking direction T. The fourth conductor layers 592, 602, 611, 621 are disposed between the third conductor layers 661, 671, 682, 692 and the ground conductor layer 523 in the stacking direction T. In addition, the third conductor layers 661, 671, 682, 692 and the fourth conductor layers 592, 602, 611, 621 are disposed between the ground conductor layer 523 and the upper surface 50B of the laminate 50 in the stacking direction T.

[0094] The inductor L22 of the second high-pass filter 22 includes a third portion L22a composed of third conductor layers 661, 671, 682, and 692. The third portion L22a has a fifth end E22a that is closest to the terminal 112 constituting the second input / output port 3 in terms of the circuit configuration, and a sixth end E22b that is farthest from the terminal 112 in terms of the circuit configuration. As shown in FIG. 8(a), the portion of the third conductor layer 661 to which the through hole 65T2 is connected corresponds to the fifth end E22a. As shown in FIG. 8(c), the portion of the third conductor layer 682 to which the through hole 67T4 is connected corresponds to the sixth end E22b. The third portion L22a is wound in a third winding direction D3 (see FIG. 8(c)) from the fifth end E22a toward the sixth end E22b when viewed from a direction parallel to the stacking direction T (Z direction).

[0095] The inductor L21 of the second low-pass filter 21 includes a fourth portion L21a including the fourth conductor layers 592, 602, 611, and 621. The fourth portion L21a has a seventh end E21a that is closest to the terminal 112 constituting the second input / output port 3 in terms of the circuit configuration, and an eighth end E21b that is farthest from the terminal 112 in terms of the circuit configuration. As shown in FIG. 6(b), the portion of the fourth conductor layer 611 to which the through hole 60T2 is connected corresponds to the seventh end E21a. As shown in FIG. 5(c), the portion of the fourth conductor layer 592 to which the through hole 58T5 is connected corresponds to the eighth end E21b. The fourth portion L21a is wound in a fourth winding direction D4 (see FIG. 6(b)) opposite to the third winding direction D3 from the seventh end E21a to the eighth end E21b when viewed from a direction parallel to the stacking direction T (Z direction).

[0096] The first conductor layers 641, 651 constituting the inductor L12 of the first high-pass filter 12 and the third conductor layers 661, 671 constituting the inductor L22 of the second high-pass filter 22 are disposed at different positions from each other in the stacking direction T. The second conductor layers 571, 581 constituting the inductor L11 of the first low-pass filter 11 and the fourth conductor layers 611, 621 constituting the inductor L21 of the second low-pass filter 21 are disposed at different positions from each other in the stacking direction T.

[0097] Next, the operation and effect of the bandpass filter 1 according to the present embodiment will be described. The bandpass filter 1 according to the present embodiment includes first and second highpass filters 12, 22, first and second lowpass filters 11, 21, and first and second stub-type resonators 41, . The first and second lowpass filters 11, 21 and the first and second stub-type resonators 41, , respectively, form attenuation poles on the high-frequency side of the passband of the bandpass filter 1. According to the present embodiment, by providing the first and second stub-type resonators 41, , it is possible to increase the pass attenuation on the high-frequency side of the passband.

[0098] The operation and effect of the first and second stub-type resonators 41, 42 will be described below with reference to the results of a simulation. In the simulation, a model of the bandpass filter 1 according to this embodiment (hereinafter referred to as the model of the embodiment) and a model of a bandpass filter of a comparative example not provided with the first and second stub-type resonators 41, 42 (hereinafter referred to as the model of the comparative example) were used. The configuration of the bandpass filter of the comparative example is the same as that of the bandpass filter 1 according to this embodiment, except that the first and second stub-type resonators 41, 42 are not provided.

[0099] FIG. 13 is a characteristic diagram showing the pass attenuation characteristics of the model of the embodiment and the model of the comparative example. FIG. 14 is a characteristic diagram showing an example of insertion loss in the vicinity of the pass band. FIG. 15 is a characteristic diagram showing the return loss of the first input / output port 2. FIG. 16 is a characteristic diagram showing the return loss of the second input / output port 3. In FIGS. 13 to 16, the curve marked with reference numeral 91 shows the characteristics of the model of the embodiment, and the curve marked with reference numeral 92 shows the characteristics of the model of the comparative example. In FIGS. 13 to 16, the horizontal axis shows the frequency. In FIG. 13, the vertical axis shows the amount of attenuation. In FIG. 14, the vertical axis shows the insertion loss. In FIGS. 15 and 16, the vertical axis shows the return loss.

[0100] From the simulation results shown in FIG. 13, it is understood that, according to this embodiment, by providing the first and second stub-type resonators 41 and 42, it is possible to increase the amount of transmission attenuation in the vicinity of 20 GHz.

[0101] Next, other effects of the bandpass filter 1 according to the present embodiment will be described. As described above, in the present embodiment, the second conductor layers 571, 581, 591, and 601 constituting the inductor L11 of the first lowpass filter 11 are disposed between the first conductor layers 641, 651, 681, and 691 constituting the inductor L12 of the first highpass filter 12 and the ground conductor layer 523 in the stacking direction T. As a result, according to the present embodiment, the areas of the bottom surface 50A and the top surface 50B of the laminate 50 can be made smaller than when the first conductor layer constituting the inductor L12 of the first highpass filter 12 and the second conductor layer constituting the inductor L11 of the first lowpass filter 11 are disposed at the same position in the stacking direction T.

[0102] Incidentally, when the second conductor layer constituting the inductor L11 of the first low-pass filter 11 is disposed between the ground conductor layer connected to the ground and the bottom surface 50A of the laminate on which the multiple terminals 111 to 116 are disposed, if the dimension of the laminate 50 in the stacking direction T is reduced, electromagnetic fields interact with each other between the second conductor layer and the ground conductor layer and between the second conductor layer and the multiple terminals 111 to 116, resulting in a decrease in the Q value of the first low-pass filter 11. To prevent this, the distance between the second conductor layer and the ground conductor layer and the distance between the second conductor layer and the multiple terminals 111 to 116 must be increased to some extent. In contrast, in this embodiment, the second conductor layers 571, 581, 591, and 601 are disposed between the ground conductor layer 523 and the top surface 50B of the laminate 50 in the stacking direction T. As a result, according to this embodiment, it is possible to reduce the dimension of the laminate 50 in the stacking direction T by the distance between the second conductor layer and the multiple terminals 111-116 in the above case, while preventing a decrease in the Q value of the first low-pass filter 11.

[0103] Furthermore, in this embodiment, the distance from the center C2 of the group of the second conductor layers 571, 581, 591, 601 in the stacking direction T to the center C1 of the group of the first conductor layers 641, 651, 681, 691 in the stacking direction T is greater than the distance from the center C2 to the ground conductor layer 523. As a result, according to this embodiment, it is possible to suppress interaction of electromagnetic fields between the second conductor layers 571, 581, 591, 601 and the first conductor layers 641, 651, 681, 691, compared to the case where the distance from the center C2 to the center C1 is smaller than the distance from the center C2 to the ground conductor layer 523.

[0104] Similarly, in the present embodiment, the fourth conductor layers 592, 602, 611, and 621 constituting the inductor L21 of the second low-pass filter 21 are disposed between the third conductor layers 661, 671, 682, and 692 constituting the inductor L22 of the second high-pass filter 22 and the ground conductor layer 523 in the stacking direction T. Also, the fourth conductor layers 592, 602, 611, and 621 are disposed between the ground conductor layer 523 and the top surface 50B of the laminate 50 in the stacking direction T. As a result, according to the present embodiment, the areas of the bottom surface 50A and the top surface 50B of the laminate 50 can be reduced, and the dimension of the laminate 50 in the stacking direction T can be reduced while preventing a decrease in the Q value of the second low-pass filter 21.

[0105] As described above, according to this embodiment, it is possible to suppress the interaction between the conductor layers, thereby achieving miniaturization and desired characteristics.

[0106] In addition, in this embodiment, as described above, each of the inductors L11, L12, L21, and L22 includes a pair of two conductor layers having the same or almost the same planar shape and connected in parallel by a through hole. For example, the inductor L11 includes a pair of conductor layers 571 and 581 connected in parallel and a pair of conductor layers 591 and 601 connected in parallel. As a result, according to this embodiment, the DC resistance of each of the inductors L11, L12, L21, and L22 can be reduced, and the Q value of each of the inductors L11, L12, L21, and L22 can be increased.

[0107] The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, as long as the requirements of the claims are met, the configurations of the high-pass filter and the low-pass filter in the present invention are not limited to the examples shown in the embodiment, and may be arbitrary. [Explanation of symbols]

[0108] 1...bandpass filter, 2...first input / output port, 3...second input / output port, 11...first low-pass filter, 12...first high-pass filter, 21...second low-pass filter, 22...second high-pass filter, 31...resonator, 41...first stub-type resonator, 41A...first distributed constant line, 42...second stub-type resonator, 42A...second distributed constant line, 50...laminated body, 50A...bottom surface, 50B...top surface, 50C to 50F...side surfaces, 51 to 70...dielectric layer.

Claims

1. A bandpass filter that selectively passes signals having frequencies within a predetermined passband, a first input / output port; a second input / output port; a first high-pass filter, a first low-pass filter, and a first stub-type resonator provided between the first input / output port and the second input / output port in terms of a circuit configuration; a laminate including a plurality of laminated dielectric layers and a plurality of laminated conductor layers, for integrating the first input / output port, the second input / output port, the first high-pass filter, the first low-pass filter, and the first stub-type resonator; a plurality of terminals provided on a bottom surface of the laminate; each of the first high-pass filter and the first low-pass filter includes at least one first inductor and at least one first capacitor; the first stub resonator includes a first distributed constant line, the first low-pass filter is provided between the first input / output port and the first high-pass filter in terms of a circuit configuration; the first distributed constant line has a first end connected to a first path connecting the first input / output port and the first low-pass filter, and a second end closest to ground in a circuit configuration; the plurality of conductor layers include a first conductor line constituting the first distributed constant line and a ground conductor layer connected to the ground, the plurality of terminals includes a first terminal corresponding to the first input / output port; the first conductor line is connected to the first terminal; the first stub-type resonator further includes, in terms of a circuit configuration, a second capacitor provided between the first distributed constant line and the ground; a portion of the first conductor line faces the ground conductor layer so as to define the second capacitor; the ground conductor layer is disposed between the first conductor line and the plurality of terminals in a stacking direction of the plurality of dielectric layers.

2. 2. The bandpass filter according to claim 1, wherein the first lowpass filter and the first stub-type resonator each form an attenuation pole on the high-frequency side of the passband.

3. 3. The bandpass filter according to claim 1, wherein the first distributed constant line is a quarter-wavelength line.

4. 4. The bandpass filter according to claim 1, wherein the at least one first inductor of the first lowpass filter is directly connected to the first end of the first distributed constant line.

5. the circuit configuration further includes a second high-pass filter, a second low-pass filter, and a second stub-type resonator provided between the first high-pass filter and the second input / output port; each of the second high-pass filter and the second low-pass filter includes at least one second inductor and at least one third capacitor; the second stub resonator includes a second distributed constant line, the second low-pass filter is provided between the second input / output port and the second high-pass filter in terms of a circuit configuration; 5. The bandpass filter according to claim 1, wherein the second distributed constant line has a third end connected to a second path connecting the second input / output port and the second low-pass filter, and a fourth end closest to the ground in the circuit configuration.

6. 6. The bandpass filter according to claim 5, wherein the second stub-type resonator further comprises a fourth capacitor provided between the second distributed constant line and the ground in terms of a circuit configuration.

7. 7. The bandpass filter according to claim 5, wherein the second lowpass filter and the second stub-type resonator each form an attenuation pole on the high-frequency side of the passband.

8. 8. The bandpass filter according to claim 5, wherein the second distributed constant line is a quarter-wavelength line.

9. the plurality of conductor layers further include a second conductor line constituting the second distributed constant line, 9. The bandpass filter according to claim 5, wherein a portion of the first conductor line and a portion of the second conductor line each face the ground conductor layer.

10. each of the first conductor line and the second conductor line has a shape that is long in one direction perpendicular to the lamination direction; 10. The bandpass filter according to claim 9, wherein the ground conductor layer is disposed between another part of the first conductor line and another part of the second conductor line in the one direction when viewed from the stacking direction.

11. 11. The bandpass filter according to claim 5, further comprising at least one resonator disposed between the first highpass filter and the second highpass filter in terms of a circuit configuration.

12. 12. The bandpass filter according to claim 11, wherein the at least one resonator includes a third inductor provided between a third path that connects the first highpass filter and the second highpass filter in a circuit configuration and the ground.

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