JP2012019443A - Filter circuit and electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a filter circuit which can make the frequency characteristics broadband for common mode signals while reducing removal of effective normal mode signals, and to provide an electronic component.SOLUTION: Ground paths G1, G2 connect an external electrode 14e (ground), respectively, with signal paths Sig1, Sig2. The signal path Sig1 includes a coil L1. The signal path Sig2 includes a coil L2 which constitutes a common mode choke coil L101 in conjunction with the coil L1. The ground path G1 includes a coil L3 and a capacitor C1 connected in series with the coil L3. The ground path G2 includes a coil L4 which constitutes a common mode choke coil L102 in conjunction with the coil L3, and a capacitor C2 connected in series with the coil L4.

Description

  The present invention relates to a filter circuit and an electronic component, and more particularly, to a filter circuit and an electronic component having a built-in common mode choke coil.

  A common mode choke coil is used to remove noise in a differential transmission type signal line. The common mode choke coil is configured by electromagnetically coupling two coils. The common mode choke coil has a characteristic of acting as a filter for a common mode signal and not acting as a filter for a normal mode signal. Thereby, the common mode choke coil can remove common mode noise generated in the differential transmission type signal line.

  By the way, the common mode choke coil needs to effectively remove common mode noise in a frequency band used in an electronic device (for example, a mobile phone) used. Therefore, in order to obtain a filter circuit having a desired frequency characteristic, the common mode choke coil is used in combination with an electronic component such as a coil or a capacitor. FIG. 12 is a circuit diagram of a filter circuit 500 including a common mode choke coil. 13A shows the frequency characteristics of the filter circuit 500 and the common mode choke coil L500 of the filter circuit 500 with respect to the common mode signal. FIG. 13B shows the common mode of the filter circuit 500 and the filter circuit 500. The frequency characteristic with respect to the signal of the normal mode of the choke coil L500 is shown. In FIG. 13, the vertical axis indicates insertion loss, and the horizontal axis indicates frequency. In FIG. 13, the dotted line indicates the frequency characteristic of the common mode choke coil L500, and the solid line indicates the frequency characteristic of the filter circuit 500. The filter circuit 500 will be described below with reference to the drawings.

  As shown in FIG. 12, the filter circuit 500 includes signal paths Sig501 and Sig502, ground paths G501 and G502, and external electrodes 514 (514a to 514d). The signal paths Sig501 and Sig502 are signal paths through which, for example, a differential transmission signal is transmitted, and include coils L501 and L502. The coils L501 and L502 are provided on the signal paths Sig501 and Sig502, respectively, and constitute a common mode choke coil L500 by being electromagnetically coupled to each other. The common mode choke coil L500 is configured by a chip-type electronic component.

  The external electrodes 514a and 514b are provided at both ends of the signal path Sig501, and function as an input terminal and an output terminal. The external electrodes 514c and 514d are provided at both ends of the signal path Sig502, and function as an input terminal and an output terminal.

  The ground paths G501 and G502 are respectively connected between the coils L501 and L502 and the external electrodes 514a and 514c and between the ground. The ground paths G501 and G502 include capacitors C501 and C502, respectively. Capacitors C501 and C502 are configured by chip-type electronic components different from common mode choke coil L500, for example. Therefore, there are signal line and terminal connection portions between the common mode choke coil L500 and the capacitors C501 and C502. Therefore, as shown in FIG. 12, residual inductors L503 and L504 are generated in the ground paths G501 and G502, respectively. Therefore, a filter is constituted by the capacitors C501 and C502 and the residual inductors L503 and L504.

  In the filter circuit 500 as described above, it can be seen that the insertion loss for the common mode signal in the high frequency band is large as shown in FIG. More specifically, the insertion loss of the common mode choke coil L500 is maximum in the vicinity of 600 MHz. On the other hand, in the filter circuit 500, a filter including capacitors C501 and C502 and residual inductors L503 and L504 is provided in each of the ground paths G501 and G502, so that a high-frequency signal is sent to the ground via the ground paths G501 and G502. It flows. Therefore, the insertion loss of the filter circuit 500 is maximum in the vicinity of 2 GHz, which is higher than 600 MHz.

  Here, the frequency at which the insertion loss of the common mode choke coil L500 and the filter insertion loss of the capacitors C501 and C502 and the residual inductors L503 and L504 are maximized (that is, the resonance frequency) are the common mode choke coil L, the capacitor C501, Setting at any frequency is possible by changing the constants of C502 and residual inductors L503 and L504. When the two resonance frequencies are brought close to each other, an extremely large insertion loss can be provided at the specific frequency. Conversely, when the two resonance frequencies are separated from each other, the filtering frequency can be widened.

  However, as described below, the filter circuit 500 has a problem that insertion loss for an effective normal mode signal increases. More specifically, in the filter circuit 500, the insertion loss is maximized in the vicinity of 2 GHz for a normal mode signal due to the filter composed of the capacitors C501 and C502 and the residual inductors L503 and L504. However, the normal mode signal is not a noise but an effective signal used for differential transmission. Therefore, in the filter circuit 500, an effective normal mode signal is removed.

  As a conventional filter circuit, for example, a multilayer common mode filter described in Patent Document 1 is known. In the filter circuit, a capacitor is connected in parallel to each of the coils constituting the common mode choke coil. However, Patent Document 1 does not mention reducing the removal of an effective normal mode signal.

JP 2007-159069 A

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a filter circuit and an electronic component that can broaden the frequency characteristics of common mode signals and reduce the removal of effective normal mode signals. .

  A filter circuit according to an aspect of the present invention includes a first signal path and a second signal path, and a first ground path that connects a ground and each of the first signal path and the second signal path. And a second ground path, wherein the first signal path includes a first coil, and the second signal path includes the first coil and a first common mode choke. A second coil constituting a coil, and the first ground path includes a third coil and a first capacitor connected in series to the third coil; The second ground path includes a fourth coil constituting the third coil and the second common mode choke coil, and a second capacitor connected in series to the fourth coil; It is characterized by.

  An electronic component according to an aspect of the present invention incorporates the filter circuit.

  According to the present invention, it is possible to broaden the frequency characteristics of a common mode signal and to reduce the removal of an effective normal mode signal.

It is a circuit diagram of a filter circuit concerning one embodiment of the present invention. It is an external appearance perspective view of the electronic component which concerns on one Embodiment. It is a disassembled perspective view of the laminated body of the electronic component which concerns on one Embodiment. It is a circuit diagram of a filter circuit concerning the 1st modification. It is a disassembled perspective view of the laminated body of the electronic component incorporating the filter circuit which concerns on a 1st modification. It is a circuit diagram of the filter circuit concerning the 2nd modification. It is a disassembled perspective view of the laminated body of the electronic component incorporating the filter circuit which concerns on a 2nd modification. It is a circuit diagram of the filter circuit which concerns on a 3rd modification. It is a disassembled perspective view of the laminated body of the electronic component incorporating the filter circuit which concerns on a 3rd modification. It is a circuit diagram of a filter circuit concerning the 4th modification. It is a disassembled perspective view of the laminated body of the electronic component incorporating the filter circuit which concerns on a 4th modification. It is a circuit diagram of a filter circuit including a common mode choke coil. FIG. 13A shows the frequency characteristics for the common mode signal of the filter circuit and the common mode choke coil of the filter circuit, and FIG. 13B shows the normal mode of the common mode choke coil of the filter circuit and the filter circuit. The frequency characteristic for the signal is shown.

  The filter circuit and the electronic component according to the embodiment of the present invention will be described below.

(Configuration of filter circuit)
A configuration of a filter circuit according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram of a filter circuit 10a according to an embodiment of the present invention.

  As shown in FIG. 1, the filter circuit 10a includes signal paths Sig1 and Sig2, ground paths G1 and G2, and external electrodes 14 (14a to 14e).

  Each of the signal paths Sig1 and Sig2 is, for example, a signal path through which a differential transmission signal is transmitted, and includes coils L1 and L2. The coils L1 and L2 are provided on the signal paths Sig1 and Sig2, respectively, and constitute a common mode choke coil L101 by being electromagnetically coupled to each other.

  The external electrode 14a is provided at the input side end of the signal path Sig1 and functions as an input terminal. The external electrode 14b is provided at the output side end of the signal path Sig1, and functions as an output terminal. The external electrode 14c is provided at the input side end of the signal path Sig2 and functions as an input terminal. The external electrode 14d is provided at the output side end of the signal path Sig2, and functions as an output terminal.

  The ground paths G1 and G2 connect the ground and the signal paths Sig1 and Sig2, respectively. Specifically, one end of the ground path G1 is connected between the external electrode 14a (that is, the input side end of the signal path Sig1) and the coil L1. The other end of the ground path G1 is connected to the external electrode 14e. One end of the ground path G2 is connected between the external electrode 14c (that is, the end on the input side of the signal path Sig2) and the coil L2. The other end of the ground path G2 is connected to the external electrode 14e. The external electrode 14e functions as a ground terminal.

  The ground path G1 includes a capacitor C1 and a coil L3. The capacitor C1 and the coil L3 are connected in series. The coil L3 is provided between the capacitor C1 and the external electrode 14e (ie, ground).

  The ground path G2 includes a capacitor C2 and a coil L4. The capacitor C2 and the coil L4 are connected in series. The coil L4 is provided between the capacitor C2 and the external electrode 14e (ie, ground).

  The coils L3 and L4 constitute a common mode choke coil L102 by being electromagnetically coupled to each other.

(Configuration of electronic parts)
Next, the configuration of the electronic component 11a incorporating the filter circuit 10a will be described with reference to the drawings. FIG. 2 is an external perspective view of the electronic component 11a according to the embodiment. FIG. 3 is an exploded perspective view of the multilayer body 12 of the electronic component 11a according to the embodiment. Hereinafter, the stacking direction of the stacked body 12 of the electronic component 11a is defined as the z-axis direction. In addition, the direction in which the long side of the stacked body 12 extends when viewed in plan from the z-axis direction is defined as the x-axis direction, and the short side of the stacked body 12 extends when viewed in plan from the z-axis direction. This direction is defined as the y-axis direction.

  As shown in FIGS. 2 and 3, the electronic component 11a includes a multilayer body 12, external electrodes 14 (14a to 14e), signal paths Sig1 and Sig2, and ground paths G1 and G2.

  The laminated body 12 has a rectangular parallelepiped shape, and is configured by laminating insulator layers 16 (16a to 16k) as shown in FIG. The insulator layer 16 has a rectangular shape and is made of a dielectric material, a magnetic material, or a glass material. The insulator layers 16a to 16k are stacked so as to be arranged in this order from the positive direction side to the negative direction side in the z-axis direction. Hereinafter, the surface on the positive side in the z-axis direction of the insulator layer 16 is referred to as a front surface, and the surface on the negative direction side in the z-axis direction of the insulator layer 16 is referred to as a back surface.

  As shown in FIG. 2, the external electrodes 14 a and 14 c are provided on the side surface on the positive side in the y-axis direction of the multilayer body 12, and are arranged in this order from the negative direction side to the positive direction side in the x-axis direction. Yes. The external electrodes 14b and 14d are provided on the side surface on the negative direction side in the y-axis direction of the multilayer body 12, and are arranged in this order from the negative direction side in the x-axis direction to the positive direction side. The external electrode 14e is provided on the side surface of the laminate 12 on the negative direction side in the x-axis direction. The external electrodes 14a and 14c function as input terminals, and the external electrodes 14b and 14d function as output terminals. The external electrode 14e functions as a ground terminal.

  As shown in FIG. 3, the signal path Sig1 includes a coil conductor 18a, a lead conductor 20a, and a via-hole conductor v1. The coil conductor 18a constitutes the coil L1 provided on the signal path Sig1, and is a conductor layer provided on the surface of the insulator layer 16c. The coil conductor 18a is formed by bending a linear conductor, and has a spiral shape that turns clockwise toward the center when viewed from the positive side in the z-axis direction. One end of the coil conductor 18a is located near the center (intersection of diagonal lines) of the insulator layer 16c. The other end of the coil conductor 18a is drawn out to the long side of the insulator layer 16c on the negative side in the y-axis direction, and is connected to the external electrode 14b.

  The lead conductor 20a is a linear conductor and is a conductor layer provided on the surface of the insulator layer 16b. One end of the lead conductor 20a overlaps with one end of the coil conductor 18a when viewed in plan from the z-axis direction, and is positioned near the center (intersection of diagonal lines) of the insulator layer 16b. The other end of the lead conductor 20a is drawn to the long side of the insulator layer 16b on the positive side in the y-axis direction, and is connected to the external electrode 14a.

  The via-hole conductor v1 passes through the insulator layer 16b in the z-axis direction, and connects one end of the coil conductor 18a and one end of the lead conductor 20a. Thereby, the signal path Sig1 having the coil L1 is provided between the external electrodes 14a and 14b.

  As shown in FIG. 3, the signal path Sig2 includes a coil conductor 18b, a lead conductor 20b, and a via-hole conductor v2. The coil conductor 18b constitutes the coil L2 provided on the signal path Sig2, and is a conductor layer provided on the surface of the insulator layer 16d. The coil conductor 18b is formed by bending a linear conductor, and has a spiral shape that turns clockwise toward the center when viewed from the positive side in the z-axis direction. When viewed in plan from the z-axis direction, the coil conductor 18b overlaps the coil conductor 18a and is electromagnetically coupled to the coil conductor 18a. Thus, the coil L1 and the coil L2 constitute a common mode choke coil L101. One end of the coil conductor 18b is located near the center (intersection of diagonal lines) of the insulator layer 16d. The other end of the coil conductor 18b is drawn to the long side of the insulator layer 16d on the negative side in the y-axis direction, and is connected to the external electrode 14d.

  The lead conductor 20b is a linear conductor and is a conductor layer provided on the surface of the insulator layer 16e. One end of the lead conductor 20b overlaps with one end of the coil conductor 18b when viewed in plan from the z-axis direction, and is located near the center (intersection of diagonal lines) of the insulator layer 16e. The other end of the lead conductor 20b is drawn to the long side on the positive side in the y-axis direction of the insulator layer 16e, and is connected to the external electrode 14c.

  The via-hole conductor v2 passes through the insulator layer 16d in the z-axis direction, and connects one end of the coil conductor 18b and one end of the lead conductor 20b. Thereby, the signal path Sig2 having the coil L2 is provided between the external electrodes 14c and 14d.

  As shown in FIG. 3, the ground path G1 includes a coil conductor 18c, capacitor conductors 22a and 22b, and a via-hole conductor v3. Each of the capacitor conductors 22a and 22b constitutes a capacitor C1 provided on the ground path G1, and is a conductor layer provided on the surfaces of the insulator layers 16f and 16g. Capacitor conductors 22a and 22b each have a rectangular shape and overlap each other when viewed in plan from the z-axis direction. The capacitor conductor 22a is drawn out to the long side of the insulator layer 16f on the positive side in the y-axis direction, and is connected to the external electrode 14a. Thereby, the ground path G1 is connected between the external electrode 14a and the coil L1 (in this embodiment, the external electrode 14a).

  The coil conductor 18c constitutes a coil L3 provided on the ground path G1, and is a conductor layer provided on the surface of the insulator layer 16h. The coil conductor 18c is formed by bending a linear conductor, and has a spiral shape that turns clockwise toward the center when viewed from the positive side in the z-axis direction. One end of the coil conductor 18c is located near the center (intersection of diagonal lines) of the insulator layer 16h. The other end of the coil conductor 18c is drawn out to the short side of the insulator layer 16h on the negative side in the x-axis direction, and is connected to the external electrode 14e.

  The via-hole conductor v3 passes through the insulator layer 16g in the z-axis direction, and connects the capacitor conductor 22b and one end of the coil conductor 18c. Thus, the coil L3 and the capacitor C1 are connected in series. Further, a ground path G1 having a coil L3 and a capacitor C1 is provided between the external electrodes 14a and 14e.

  As shown in FIG. 3, the ground path G2 includes a coil conductor 18d, capacitor conductors 22c and 22d, and a via-hole conductor v4. Capacitor conductors 22c and 22d constitute a capacitor C2 provided on the ground path G2, and are conductor layers provided on the surfaces of the insulator layers 16j and 16k. Capacitor conductors 22c and 22d each have a rectangular shape and overlap each other when viewed in plan from the z-axis direction. The capacitor conductor 22d is led out to the long side of the insulator layer 16k on the positive side in the y-axis direction, and is connected to the external electrode 14c. Thus, the ground path G2 is connected between the external electrode 14c and the coil L2 (in this embodiment, the external electrode 14c).

  The coil conductor 18d constitutes a coil L4 provided on the ground path G2, and is a conductor layer provided on the surface of the insulator layer 16i. The coil conductor 18d is formed by bending a linear conductor, and has a spiral shape that turns clockwise toward the center when viewed from the positive side in the z-axis direction. That is, the coil conductor 18c and the coil conductor 18d have the same shape, and overlap in a matched state when viewed in plan from the z-axis direction. Thereby, the coil L3 and the coil L4 are magnetically coupled to each other to constitute a common mode choke coil L102. One end of the coil conductor 18d is located near the center (intersection of diagonal lines) of the insulator layer 16i. The other end of the coil conductor 18d is drawn out to the short side of the insulator layer 16i on the negative side in the x-axis direction, and is connected to the external electrode 14e.

  The via-hole conductor v4 passes through the insulator layer 16i in the z-axis direction, and connects the capacitor conductor 22c and one end of the coil conductor 18d. Thereby, the coil L4 and the capacitor C2 are connected in series. Further, a ground path G2 having a coil L4 and a capacitor C2 is connected between the external electrodes 14c and 14e.

  In the electronic component 11a configured as described above, the capacitor C1 is sandwiched between the coils L1 and L2 and the coils L3 and L4 in the z-axis direction.

  Here, the operation of the electronic component 11a will be described. The electronic component 11a is used by being mounted on a circuit board. At this time, the external electrodes 14a and 14c are used as input terminals, the external electrodes 14b and 14d are used as output terminals, and the external electrode 14e is used as a ground terminal. Since the electronic component 11a includes the common mode choke coil L101 composed of the coils L1 and L2, the signal path Sig1 and Sig2 have a large insertion loss with respect to the common mode signal as described below. Insertion loss is small.

  Since the common mode signal is an in-phase signal, when it flows from the external electrode 14a to the external electrode 14b in the signal path Sig1 and from the external electrode 14c to the external electrode 14d in the signal path Sig2, the coil conductors 18a and 18b It flows to turn in the same direction. Therefore, in the coil conductors 18a and 18b, magnetic flux is generated in the same direction, and inductance for a common mode signal is generated. Therefore, the common mode signal is prevented from passing through the signal paths Sig1 and Sig2. That is, the insertion loss for the common mode signal is large in the signal paths Sig1 and Sig2.

  On the other hand, since the signal in the normal mode is a reverse-phase signal, when the signal flows from the external electrode 14a to the external electrode 14b in the signal path Sig1, and flows from the external electrode 14d to the external electrode 14c in the signal path Sig2, the coil conductors 18a, In 18b, it flows so as to turn in opposite directions. Therefore, magnetic flux is generated in the opposite direction in the coil conductors 18a and 18b. Therefore, the magnetic flux generated in the coil conductors 18a and 18b is canceled out. Therefore, the coils L1 and L2 hardly function as a coil for signals in the normal mode (that is, the inductance value is extremely small), and thus the passage through the signal paths Sig1 and Sig2 is not hindered. That is, the insertion loss for the normal mode signal is small in the signal paths Sig1 and Sig2.

  Furthermore, the electronic component 11a has a ground path G1 having a capacitor C1 and a coil L3, and a ground path G2 having a capacitor C2 and a coil L3. Therefore, as will be described below, the frequency characteristic for the common mode signal can be broadened by the filter constituted by the capacitor C1 and the coil L3 and the filter constituted by the capacitor C2 and the coil L4, and an effective normal mode can be obtained. It can reduce that a signal is removed.

  The coils L3 and L4 constitute a common mode choke coil L102. The common mode choke coil L102 exhibits a large inductance value for a common mode signal and a small inductance value for a normal mode signal. A resonance frequency f of a filter composed of a coil having an inductance value L and a capacitor having a capacitance C is represented by f = 1 / 2π√ (LC). Therefore, the resonance frequency of the filter composed of the coils L3 and L4 and the capacitors C1 and C2 is relatively low in the common mode signal and relatively high in the normal mode. That is, by using the common mode choke coil L102 as the coils L3 and L4, the resonance frequency for the normal mode signal and the resonance frequency for the common mode signal can be made different.

  Therefore, in the electronic component 11a, the resonance frequency for the common mode signal of the filter composed of the coils L3 and L4 and the capacitors C1 and C2 may be designed in accordance with the frequency band used in the electronic device in which the electronic component 11a is used. . As a result, it is possible to widen the frequency characteristics for the common mode signal.

  Further, the resonance frequency for the normal mode signal of the filter comprising the coils L3 and L4 and the capacitors C1 and C2 is higher than the resonance frequency for the common mode signal of the filter comprising the coils L3 and L4 and the capacitors C1 and C2. Therefore, it is possible to suppress the removal of an effective normal mode signal in the electronic component 11a.

(Method for manufacturing electronic parts)
Below, the manufacturing method of the electronic component 11a is demonstrated, referring drawings. In the following, a method for manufacturing the electronic component 11a when simultaneously creating the plurality of electronic components 11a will be described.

  A ceramic green sheet to be the insulator layer 16 in FIG. 3 is prepared. As shown in FIG. 3, via-hole conductors v1 to v4 are formed in each of the ceramic green sheets to be the insulator layers 16b, 16d, 16g, and 16i. Specifically, a via hole is formed by irradiating a ceramic green sheet to be the insulator layers 16b, 16d, 16g, and 16i with a laser beam. Next, the via hole is filled with a conductive paste such as Ag, Pd, Cu, Au or an alloy thereof by a method such as printing.

  Next, as shown in FIG. 3, the coil conductor 18, the lead conductor 20, and the capacitor conductor 22 are formed on the surface of the ceramic green sheet to be the insulator layers 16 b to 16 k. Specifically, a conductive paste mainly composed of Ag, Pd, Cu, Au, or an alloy thereof is screen-printed or photolithography-processed on the surface of the ceramic green sheet to be the insulator layers 16b to 16k. The coil conductor 18, the lead conductor 20, and the capacitor conductor 22 are formed by application by a method such as the above. Note that the step of forming the coil conductor 18, the lead conductor 20, and the capacitor conductor 22 and the step of filling the via hole with the conductive paste may be performed in the same step.

  Next, as shown in FIG. 3, ceramic green sheets to be the insulator layers 16a to 16k are laminated and pressure-bonded so as to be arranged in this order to obtain an unfired mother laminated body. Lamination and pressure bonding of the ceramic green sheets to be the insulator layers 16a to 16k are carried out one by one and temporarily bonded to obtain a mother laminated body, and then the unfired mother laminated body is pressed by a hydrostatic pressure press or the like. To perform final crimping.

  Next, the mother laminated body is cut into a laminated body 12 having a predetermined size with a cutting blade. Thereafter, the unfired laminate 12 is subjected to binder removal processing and firing.

  Next, an electrode paste made of a conductive material containing Ag as a main component is applied to the laminate 12 to form a silver electrode to be the external electrode 14. Further, the external electrode 14 is formed by performing Ni plating / Sn plating on the surface of the silver electrode to be the external electrode 14. Through the above steps, the electronic component 11a as shown in FIG. 2 is completed.

(effect)
According to the filter circuit 10a and the electronic component 11a, it is possible to broaden the frequency characteristic for the common mode signal and reduce the removal of an effective normal mode signal. Since this effect has already been described in the operation of the electronic component 11a, further description is omitted.

(First modification)
The filter circuit 10b according to the first modification will be described below with reference to the drawings. FIG. 4 is a circuit diagram of the filter circuit 10b according to the first modification.

  The difference between the filter circuit 10b and the filter circuit 10a is that the capacitors C1 and C2 and the coils L3 and L4 are interchanged. More specifically, as shown in FIG. 4, in the filter circuit 10b, the capacitors C1 and C2 are provided between the external electrode 14e (ground) and the coils L3 and L4, respectively. Since the other configuration of the filter circuit 10b is the same as that of the filter circuit 10a, description thereof is omitted.

  Next, the configuration of the electronic component 11b incorporating the filter circuit 10b according to the first modification will be described with reference to the drawings. FIG. 5 is an exploded perspective view of the multilayer body 12 of the electronic component 11b incorporating the filter circuit 10b according to the first modification.

  In the electronic component 11b, the capacitor conductors 22a and 22d are connected to the external electrode 14e. The coil conductors 18c and 18d are connected to the external electrodes 14a and 14c, respectively. Accordingly, the capacitors C1 and C2 are provided between the external electrode 14e (ground) and the coils L3 and L4, respectively.

  Similarly to the filter circuit 10a and the electronic component 11a, the filter circuit 10b and the electronic component 11b can widen the frequency characteristic for the common mode signal, and the effective normal mode signal can be removed. Can be reduced.

(Second modification)
Hereinafter, a filter circuit 10c according to a second modification will be described with reference to the drawings. FIG. 6 is a circuit diagram of a filter circuit 10c according to the second modification.

  The difference between the filter circuit 10c and the filter circuit 10a is that the ground paths G1 and G2 are branched into branch portions G1a, G1b, G2a, and G2b, respectively, and capacitors C3 and C4 are provided. is there.

  The branch portion G1a is connected between the external electrode 14a (the end portion on the input side of the signal path Sig1) and the coil L1. The branch part G1b is connected between the external electrode 14b (end part on the output side of the signal path Sig1) and the coil L1.

  The branch portion G2a is connected between the external electrode 14c (the end portion on the input side of the signal path Sig2) and the coil L2. The branch part G2b is connected between the external electrode 14d (the output side end of the signal path Sig2) and the coil L2.

  The coil L3 is provided between a connection portion between the branch part G1a and the branch part G2a on the ground path G1 and the external electrode 14e (ground). Further, the coil L4 is provided between a connection portion between the branch portion G2a and the branch portion G2b on the ground path G2 and the external electrode 14e (ground).

  The capacitor C1 is provided on the branch part G1a. The capacitor C2 is provided on the branch part G2a. The capacitor C3 is provided on the branch part G1b. The capacitor C4 is provided on the branch part G2b.

  Next, the configuration of the electronic component 11c incorporating the filter circuit 10c according to the second modification will be described with reference to the drawings. FIG. 7 is an exploded perspective view of the multilayer body 12 of the electronic component 11c incorporating the filter circuit 10c according to the second modification.

  In the electronic component 11c, capacitor conductors 122a and 122b are provided on the surface of the insulator layer 16f instead of the capacitor conductor 22a. The capacitor conductors 122a and 122b overlap the capacitor conductor 22b when viewed in plan from the z-axis direction. Thus, the capacitor conductor 122a and the capacitor conductor 22b constitute a capacitor C1, and the capacitor conductor 122b and the capacitor conductor 22b constitute a capacitor C3.

  The capacitor conductors 122a and 122b are connected to the external electrodes 14a and 14b, respectively. Accordingly, the capacitors C1 and C3 are provided between the external electrodes 14a and 14b and the coil L3, respectively.

  Further, in the electronic component 11c, capacitor conductors 122c and 122d are provided on the surface of the insulator layer 16k instead of the capacitor conductor 22d. The capacitor conductors 122c and 122d overlap the capacitor conductor 22c when viewed in plan from the z-axis direction. Accordingly, the capacitor conductor 122c and the capacitor conductor 22c constitute a capacitor C2, and the capacitor conductor 122d and the capacitor conductor 22c constitute a capacitor C4.

  The capacitor conductors 122c and 122d are connected to the external electrodes 14c and 14d, respectively. Accordingly, the capacitors C2 and C4 are provided between the external electrodes 14c and 14d and the coil L4, respectively.

  Similarly to the filter circuit 10a and the electronic component 11a, the filter circuit 10c and the electronic component 11c can widen the frequency characteristic for the common mode signal and can eliminate the effective normal mode signal. Can be reduced.

  In addition, in the filter circuit 10c and the electronic component 11c, by providing the capacitors C3 and C4, a change in insertion loss near the resonance frequency with respect to a normal mode signal can be sharpened. As a result, the filter circuit 10c and the electronic component 11c are less likely to affect the normal mode signal in the frequency band used in the electronic device in which the filter circuit 10c and the electronic component 11c are used. Therefore, the filter circuit 10c and the electronic component 11c can further reduce the removal of an effective normal mode signal.

(Third Modification)
Hereinafter, a filter circuit 10d according to a third modification will be described with reference to the drawings. FIG. 8 is a circuit diagram of a filter circuit 10d according to a third modification.

  The difference between the filter circuit 10d and the filter circuit 10c is the connection position of the branch portions G1a, G1b, G2a, and G2b.

  The branch portion G1a is connected between the external electrode 14a (the end portion on the input side of the signal path Sig1) and the coil L1. The branch portion G1b is connected between the external electrode 14d (the end portion on the output side of the signal path Sig2) and the coil L2.

  The branch portion G2a is connected between the external electrode 14c (the end portion on the input side of the signal path Sig2) and the coil L2. The branch part G2b is connected between the external electrode 14b (end part on the output side of the signal path Sig2) and the coil L1. Since the other configuration of the filter circuit 10d is the same as that of the filter circuit 10c, description thereof is omitted.

  Next, the configuration of the electronic component 11d incorporating the filter circuit 10d according to the third modification will be described with reference to the drawings. FIG. 9 is an exploded perspective view of the multilayer body 12 of the electronic component 11d incorporating the filter circuit 10d according to the third modification.

  In the electronic component 11d, the capacitor conductors 122a and 122b are connected to the external electrodes 14a and 14d, respectively. Thereby, the capacitors C1 and C3 are provided between the external electrodes 14a and 14d and the coil L3, respectively.

  The capacitor conductors 122c and 122d are connected to the external electrodes 14c and 14b, respectively. Accordingly, the capacitors C2 and C4 are provided between the external electrodes 14c and 14b and the coil L4, respectively.

  Similarly to the filter circuit 10a and the electronic component 11a, the filter circuit 10d and the electronic component 11d can broaden the frequency characteristic for the common mode signal and can eliminate the effective normal mode signal. Can be reduced.

  Further, in the filter circuit 10d and the electronic component 11d, by providing the capacitors C3 and C4, a change in insertion loss near the resonance frequency with respect to a normal mode signal can be made steep. As a result, the filter circuit 10d and the electronic component 11d are less likely to affect the normal mode signal in the frequency band used in the electronic device in which the filter circuit 10d and the electronic component 11d are used. Therefore, the filter circuit 10d and the electronic component 11d can further reduce the removal of an effective normal mode signal.

(Fourth modification)
Hereinafter, a filter circuit 10e according to a fourth modification will be described with reference to the drawings. FIG. 10 is a circuit diagram of a filter circuit 10e according to a fourth modification.

  The difference between the filter circuit 10e and the filter circuit 10c is the connection position of the branch portions G1a, G1b, G2a, and G2b.

  The branch part G1a is connected between the external electrode 14b (end part on the output side of the signal path Sig1) and the coil L1. The branch portion G1b is connected between the external electrode 14d (the end portion on the output side of the signal path Sig2) and the coil L2.

  The branch portion G2a is connected between the external electrode 14c (the end portion on the input side of the signal path Sig2) and the coil L2. The branch portion G2b is connected between the external electrode 14a (the end portion on the output side of the signal path Sig2) and the coil L1. Since the other configuration of the filter circuit 10e is the same as that of the filter circuit 10c, description thereof is omitted.

  Next, the configuration of the electronic component 11e incorporating the filter circuit 10e according to the fourth modification will be described with reference to the drawings. FIG. 11 is an exploded perspective view of the multilayer body 12 of the electronic component 11e incorporating the filter circuit 10e according to the fourth modification.

  In the electronic component 11e, the capacitor conductors 122a and 122b are connected to the external electrodes 14b and 14d, respectively. Thereby, the capacitors C1 and C3 are provided between the external electrodes 14b and 14d and the coil L3, respectively.

  The capacitor conductors 122c and 122d are connected to the external electrodes 14c and 14a, respectively. Thereby, the capacitors C2 and C4 are provided between the external electrodes 14c and 14a and the coil L4, respectively.

  Similarly to the filter circuit 10a and the electronic component 11a, the filter circuit 10e and the electronic component 11e can widen the frequency characteristic for the common mode signal and can eliminate the effective normal mode signal. Can be reduced.

  Further, in the filter circuit 10e and the electronic component 11e, by providing the capacitors C3 and C4, a change in insertion loss near the resonance frequency with respect to a normal mode signal can be made sharp. As a result, the filter circuit 10e and the electronic component 11e are less likely to affect the normal mode signal in the frequency band used in the electronic device in which the filter circuit 10e and the electronic component 11e are used. Therefore, the filter circuit 10e and the electronic component 11e can further reduce the removal of an effective normal mode signal.

  Although the filter circuits 10a to 10e are realized by the electronic components 11a to 11e, for example, a plurality of electronic components may be mounted on a circuit board.

  As described above, the present invention is useful for filter circuits and electronic components. In particular, the present invention is capable of widening the frequency characteristics for common mode signals and removing effective normal mode signals. It is excellent in that it can be reduced.

C1 to C4 capacitors G1 and G2 Ground paths G1a, G1b, G2a and G2b Branch portions L1 to L4 Coils L101 and L102 Common mode choke coils Sig1 and Sig2 Signal paths 10a to 10e Filter circuits 11a to 11e Electronic components 12 Laminated bodies 14a to 14e External electrodes 16a to 16k Insulator layers 18a to 18d Coil conductors 20a and 20b Lead conductors 22a to 22d, 122a to 122d Capacitor conductors

Claims (10)

A first signal path and a second signal path;
A first ground path and a second ground path connecting a ground and each of the first signal path and the second signal path;
With
The first signal path includes a first coil;
The second signal path includes a second coil that constitutes the first common mode choke coil with the first coil;
The first ground path includes a third coil and a first capacitor connected in series to the third coil;
The second ground path includes a fourth coil constituting the third coil and a second common mode choke coil, and a second capacitor connected in series to the fourth coil. thing,
A filter circuit characterized by the above. The first ground path is connected between an input side end of the first signal path and the first coil;
The second ground path is connected between an input side end of the second signal path and the second coil;
The filter circuit according to claim 1. The third coil and the fourth coil are respectively provided between a ground and the first capacitor and the second capacitor;
The filter circuit according to claim 1, wherein: The first capacitor and the second capacitor are respectively provided between a ground and the third coil and the fourth coil;
The filter circuit according to claim 1, wherein: The first ground path includes a first branch connected between an input side end of the first signal path and the first coil, and an output of the first signal path. Branching into a second branch connected between the first end and the first coil;
The second ground path includes a third branch connected between an input side end of the second signal path and the second coil, and an output of the second signal path. Branching into a fourth branch connected between the second end and the second coil;
The third coil is provided between a connection portion between the first branch portion and the second branch portion on the first ground path and a ground,
The fourth coil is provided between a connection portion between the third branch portion and the fourth branch portion on the second ground path and a ground.
The first capacitor and the second capacitor are provided on the first branch and the third branch, respectively.
The first ground path includes a third capacitor provided on the second branch;
The second ground path includes a fourth capacitor provided on the fourth branch;
The filter circuit according to claim 1. The first ground path includes a first branch connected between an input side end of the first signal path and the first coil, and an output of the second signal path. Branching into a second branch connected between the side end and the second coil;
The second ground path includes a third branch connected between an input side end of the second signal path and the second coil, and an output of the first signal path. Branching into a fourth branch connected between the side end and the first coil;
The third coil is provided between a connection portion between the first branch portion and the second branch portion on the first ground path and a ground,
The fourth coil is provided between a connection portion between the third branch portion and the fourth branch portion on the second ground path and a ground.
The first capacitor and the second capacitor are provided on the first branch and the third branch, respectively.
The first ground path includes a third capacitor provided on the second branch;
The second ground path includes a fourth capacitor provided on each of the fourth branches;
The filter circuit according to claim 1. The first ground path includes a first branch connected between an output side end of the first signal path and the first coil, and an output of the second signal path. Branching into a second branch connected between the side end and the second coil;
The second ground path includes a third branch connected between an input side end of the second signal path and the second coil, and an input of the first signal path. Branching into a fourth branch connected between the side end and the first coil;
The third coil is provided between a connection portion between the first branch portion and the second branch portion on the first ground path and a ground,
The fourth coil is provided between a connection portion between the third branch portion and the fourth branch portion on the second ground path and a ground.
The first capacitor and the second capacitor are provided on the first branch and the third branch, respectively.
The first ground path includes a third capacitor provided on the second branch;
The second ground path includes a fourth capacitor provided on the fourth branch;
The filter circuit according to claim 1.   An electronic component comprising the filter circuit according to any one of claims 1 to 7. A laminate in which a plurality of insulator layers are laminated,
Has
The first signal path, the second signal path, the first ground path, and the second ground path are configured by a conductor layer and a via-hole conductor provided in the insulator layer;
The electronic component according to claim 8. The first capacitor or the second capacitor is sandwiched between the first coil and the second coil, the third coil and the fourth coil in the stacking direction;
The electronic component according to claim 9.

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