TW201742375A - LC filter - Google Patents

Abstract

Provided is an LC filter in which an attenuation pole is formed near a pass band and in which impedance matching between input and output is performed. The LC filter is provided with an input terminal 1, an output terminal 2, a signal line 3, a first LC series resonator LC1, and a second LC series resonator LC2. The first LC series resonator LC1 has an inductor L1 and a capacitor C1 connected in series, and the second LC series resonator LC2 has an inductor L2 and a capacitor C2 connected in series. The first LC series resonator LC1 is connected between the signal line and the ground. The second LC series resonator LC2 is connected between the signal line and a point at which the inductor L1 and the capacitor C1 of the first LC series resonator LC1 are connected to each other.

Description

LC filter

The present invention relates to an LC filter, and more particularly to an LC filter that forms a fading pole near the pass band and integrates the impedance between the input and the input.

An LC filter that forms a circuit network by an inductor or a capacitor and transmits only a signal of a desired frequency through a signal line connecting the input terminal and the output terminal is widely used in an electronic circuit.

Such an LC filter is disclosed in Patent Document 1 (JP-A-2002-94349). FIG. 12 shows an equivalent circuit of an LC filter (LC filter circuit) 1000 disclosed in Patent Document 1. However, the LC filter 1000 is disclosed in the patent document 1 as a conventional technique (refer to FIG. 4 of Patent Document 1).

In the LC filter 1000, an LC parallel resonator (LC resonance circuit) in which an inductor (inductor) L1 and a capacitor (capacitor) C1 are connected in parallel is connected between the input terminal P1 and the ground (ground terminal). Further, an LC parallel resonator (LC resonance circuit) in which an inductor (inductor) L2 and a capacitor (capacitor) C2 are connected in parallel is connected between the output terminal P2 and the ground (ground terminal). In the LC filter 1000, the inductor L1 is magnetically coupled to the inductor L2. Further, a coupling capacitor (coupling capacitor) C5 is connected between the input terminal P1 and the output terminal P2.

Further, in the LC filter 1000, an LC series resonance in which an inductor (inductor) L3 and a capacitor (capacitor) C3 are connected in series is connected between the input terminal P1 and the ground (ground terminal). (Series resonance notch circuit). Similarly, an LC series resonator (series resonance trap circuit) in which an inductor (inductor) L4 and a capacitor (capacitor) C4 are connected in series is connected between the output terminal P2 and the ground (ground terminal). These LC series resonators are used to form a fading pole near the pass band.

[Previous Technical Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2002-94349

In the LC filter 1000, in order to achieve integration of the impedance between the input and the input, it is necessary to insert another impedance integrated circuit formed by an inductor or a capacitor on the circuit. However, when the impedance integration circuit is added, there is a problem that the number of necessary components is increased, or when the LC filter 1000 is configured as a module, for example, a problem arises in that the LC filter module is enlarged.

The present invention has been made to solve the above-mentioned conventional problems. An LC filter according to the present invention includes an input terminal, an output terminal, a signal line, an input terminal and an output terminal, a first LC series resonator, a second LC series resonator, a first LC series resonator, and the foregoing 2LC series resonators, respectively connected in series with an inductor and a capacitor; a first LC series resonator connected between the signal line and the ground; and a second LC series resonator connected to the signal line and the inductor and capacitor of the first LC series resonator Between the points.

In the above, for example, the first LC series resonator can form a fading pole mainly in the vicinity of the low frequency side of the pass band, and the second LC series resonator can form the fading pole mainly in the vicinity of the high frequency side of the pass band.

A connection point and a signal line of the first LC series resonator are connected to the signal line Between the connection points to which the second LC series resonator is connected, a capacitor or an LC circuit composed of an inductor and a capacitor may be connected. This capacitor or LC circuit primarily contributes to the formation of a pass band. Further, for example, an LC series resonator in which an inductor and a capacitor are connected in series may be connected as an LC circuit. Alternatively, an LC parallel resonator in which an inductor and a capacitor are connected in parallel may be connected as an LC circuit.

Further, when the LC circuit is an LC parallel resonator, the inductor of the LC parallel resonator may be divided into at least a first split inductor and a second split inductor, and the second LC series resonator may be first. The connection point between the split inductor and the second split inductor is connected to the signal line.

At least one capacitor may be further connected to at least one of an input terminal of the signal line and the LC circuit and an output terminal of the LC circuit of the signal line. This capacitor can be used as a coupling capacitor or the like.

The type of the LC filter may be, for example, a band pass filter, a high pass filter, a low pass filter, or the like.

The LC filter can be configured, for example, as a laminated LC filter. More specifically, an LC filter includes: a laminate body in which a plurality of dielectric layers are laminated; a plurality of inductor electrodes are formed between the layers of the laminate; and a plurality of capacitor electrodes are formed between the layers of the laminate; a plurality of via electrodes are formed through the dielectric layer; a plurality of capacitor electrodes are formed between the layers of the laminate; an input terminal is formed on the surface of the laminate; and an output terminal is formed on the surface of the laminate; The inductor electrodes constitute an inductor; a capacitor is formed by a plurality of capacitor electrodes.

The LC filter of the present invention is connected to the signal by connecting the first LC series resonator Between the line and the ground, the second LC series resonator is connected between the signal line and the connection point between the inductor and the capacitor of the first LC series resonator to form a fading pole in the vicinity of the pass band, and to achieve integration of the input-output impedance.

Further, since the LC filter of the present invention has the above-described connection relationship, only the number of components connected to the capacitor or inductor connected between the connection point of the second LC series resonator and the ground of the first LC series resonator is adjusted (selected). The integration of impedance can be easily sought.

1‧‧‧Input terminal

2‧‧‧Output terminal

3‧‧‧ signal line

4a, 4b‧‧‧ grounding terminal

5a~5h‧‧‧ capacitor electrode

6a~6n‧‧‧ relay electrode

7a~7k‧‧‧Inductor electrodes

8a‧‧‧ lead electrode

9a~9p‧‧‧through hole electrode

10‧‧‧Layer

10a~10r‧‧‧ dielectric layer

LC1‧‧‧1LC series resonator

LC2‧‧‧2LC series resonator

LC3‧‧‧LC circuit (LC series circuit)

LC13, LC23‧‧‧LC circuit (LC parallel circuit)

L1~L3, L13‧‧‧ inductors

L23A‧‧‧First Split Inductor

L23B‧‧‧Second split inductor

C1~C5, C13, C23‧‧‧ capacitors

Fig. 1 is an equivalent circuit diagram showing an LC filter 100 of the first embodiment.

FIG. 2 is a graph showing the frequency characteristics of the LC filter 100.

Fig. 3 is an equivalent circuit diagram showing an LC filter 1100 of a comparative example.

FIG. 4 is a graph showing the frequency characteristics of the LC filter 1100.

Fig. 5 is an equivalent circuit diagram showing the LC filter 200 of the second embodiment.

Fig. 6 is an equivalent circuit diagram showing the LC filter 300 of the third embodiment.

Fig. 7 is an equivalent circuit diagram showing the LC filter 400 of the fourth embodiment.

Fig. 8 is an equivalent circuit diagram showing the LC filter 500 of the fifth embodiment.

FIG. 9 is a perspective view showing a laminated LC filter 500.

FIG. 10 is an exploded perspective view showing the laminated LC filter 500.

Fig. 11 is an equivalent circuit diagram showing the LC filter 600 of the sixth embodiment.

FIG. 12 is an equivalent circuit diagram showing the LC filter 1000 disclosed in Patent Document 1.

Hereinafter, the drawings and the modes for carrying out the invention will be described. In addition, Each embodiment exemplarily shows an embodiment of the present invention, and the present invention is not limited to the embodiment. Further, the contents described in the different embodiments can be combined and implemented, and the implementation in this case is also included in the present invention. Moreover, the drawings are intended to help the understanding of the embodiment, and may not be drawn rigorously. For example, the ratio of the dimensions of the constituent elements or constituent elements depicted may not match the ratio of the dimensions described in the specification. Further, the constituent elements described in the specification may be omitted or omitted in the drawings, and may be drawn.

[First Embodiment]

Fig. 1 is an equivalent circuit diagram showing an LC filter 100 of the first embodiment.

The LC filter 100 includes a signal line 3 that connects the input terminal 1 and the output terminal 2.

In the LC filter 100, a series resonator LC3 in series with an inductor L3 and a capacitor C3 as an LC circuit for forming a pass band is connected to the signal line 3.

Further, the LC filter 100 includes a first LC series resonator LC1 in which an inductor L1 and a capacitor C1 are connected in series. In the first LC series resonator LC1, the inductor L1 side is connected to the signal line 3 at the connection point X shown in FIG. 1, and the capacitor C1 side is grounded. The first LC series resonator LC1 mainly contributes to the formation of a fading pole near the low frequency side of the pass band. Further, the first LC series resonator LC1 may also replace the position of the inductor L1 and the capacitor C1, and the capacitor C1 side is connected to the signal line 3 and the inductor L1 side is grounded.

Further, the LC filter 100 includes a second LC series resonator LC2 in which an inductor L2 and a capacitor C2 are connected in series. In the second LC series resonator LC2, the inductor L2 side is connected to the signal line 3 at the connection point Y shown in FIG. 1, and the capacitor C2 side is connected to the first LC series resonator LC1. The connection point between the inductor L1 and the capacitor C1. The 2LC series resonator LC2 mainly contributes to the formation of a fading pole near the high frequency side of the pass band. Further, the second LC series resonator LC2 may also replace the position of the inductor L2 and the capacitor C2, the capacitor C2 side is connected to the signal line 3, and the inductor L2 side is connected to the connection of the inductor L1 of the first LC series resonator LC1 and the capacitor C1. point.

The LC filter 100 appropriately selects the number of components of the inductors L1 to L3 and the capacitors C1 to C3, and forms only the desired passband of the above-mentioned circuit, and forms a vicinity of the low-frequency side and the high-frequency side of the passband. The attenuation is reduced and the impedance between the input and the input is integrated. Table 1 shows the number of parts of the LC filter 100.

The frequency characteristics of the LC filter 100 of the first embodiment are shown in Fig. 2 .

The LC filter 1100 of the comparative example was fabricated for comparison. An equivalent circuit showing the LC filter 1100 is shown in FIG.

The LC filter 1100 applies a change to the equivalent circuit of the LC filter 100. In the LC filter, the capacitor C1 side and the second LC string of the first LC series resonator LC1 are used. The capacitor C2 side of the coupled resonator LC2 is connected to each other and then grounded at its connection point. The number of components of the inductors L1 to L3 and the capacitors C1 to C3 of the LC filter 1100 are the same as those of the LC filter 100, respectively.

The frequency characteristics of the LC filter 1100 of the comparative example are shown in FIG.

As shown in FIG. 2, the LC filter 100 of the first embodiment forms a fading electrode in the vicinity of both the low frequency side and the high frequency side of the pass band, and integrates the impedance between the input and the output. On the other hand, the LC filter 1100 of the comparative example does not integrate the impedance between the input and the output as shown in FIG. Further, although the LC filter 1100 has a fading electrode formed in the vicinity of both the low frequency side and the high frequency side of the pass band, the balance between the two attenuation amounts is poor. Although it is attempted to adjust the number of parts of the inductors L1 to L3 and the capacitors C1 to C3 within the realistic range of the LC filter 1100 circuit to take into account the integration of the fading pole near the pass band and the impedance between the input and the input, it is still difficult to Optimized at the same time.

As described above, the LC filter 100 of the first embodiment has a desired pass band, and forms a fading pole in the vicinity of both the low frequency side and the high frequency side of the pass band, and integrates the impedance between the input and the output.

[Second Embodiment]

The equivalent circuit of the LC filter 200 of the second embodiment is shown in Fig. 5 .

The LC filter 200 is modified in the equivalent circuit of the LC filter 100 of the first embodiment. Specifically, in the LC filter 100, an LC series resonator LC3 as an LC circuit is connected between the connection point X of the signal line 3 and the connection point Y. In place of this, the LC filter 200 is connected to the LC parallel resonator LC13 in which the resistor L13 and the capacitor C13 are connected in parallel between the connection point X of the signal line 3 and the connection point Y as an LC circuit.

The LC filter 200 of the second embodiment is also compatible with the LC filter of the first embodiment. Similarly, the wave device 100 has a desired pass band and forms a fading electrode in the vicinity of both the low frequency side and the high frequency side of the pass band, and integrates the impedance between the input and the output.

[Third embodiment]

An equivalent circuit diagram of the LC filter 300 of the third embodiment is shown in Fig. 6.

The LC filter 300 is modified in the equivalent circuit of the LC filter 200 of the second embodiment. Specifically, the LC filter 300 is a capacitor C4 that mainly functions as a coupling capacitor between the connection point X of the signal line 3 of the LC filter 200 and the LC parallel resonator LC13.

In the LC filter 300 of the third embodiment, the impedance is integrated more easily than the LC filter 200 by adding the capacitor C4.

[Fourth embodiment]

An equivalent circuit diagram of the LC filter 400 of the fourth embodiment is shown in FIG.

The LC filter 400 is modified in the equivalent circuit of the LC filter 300 of the third embodiment. Specifically, the LC filter 400 divides the inductor L13 of the LC parallel resonator LC13 of the LC filter 300 into a first split inductor L23A and a second split inductor at a connection point Z as shown in FIG. L23B, and these are connected in parallel to capacitor C23 to form LC parallel resonator LC23. In addition, the term "integrated inductor" is originally designed to function as one inductor, but it is specifically divided into a plurality of inductors (L23A, L23B).

Further, the LC filter 400 changes the inductor of the second series resonator LC2. The L2 side is at the connection position of the signal line 3. In the LC filter 300, the inductor L2 side of the second LC series resonator LC2 is connected to the connection point Y of the signal line 3, but in the LC filter 400, the second LC series resonator LC2 is replaced by this. The inductor L2 side is connected to the connection point Z between the first split inductor L23A and the second split inductor L23B.

In the LC filter of the fourth embodiment, for example, the second split inductor L23 of the LC parallel resonator 23 and the inductor 2 of the second LC series resonator LC2 are magnetically coupled, even if the inductance is not increased compared to the LC filter 300. The inductance value of the device L2 can still form a fading pole having the same amount of attenuation as the LC filter 300 in the vicinity of the high frequency side of the pass band.

[Fifth Embodiment]

The LC filter 500 of the fifth embodiment is shown in Figs. 8 to 10, and Fig. 8 is an equivalent circuit diagram of the LC filter 500. Moreover, FIG. 9 is a perspective view showing a laminated LC filter 500 in which a laminated body in which a plurality of dielectric layers are laminated is realized. FIG. 10 is an exploded perspective view of the laminated LC filter 500.

The LC filter 500 is modified in the equivalent circuit of the LC filter 400 of the fourth embodiment. Specifically, as shown in FIG. 8, the LC filter 500 adds a capacitor C5 between the input terminal 1 of the signal line 3 of the LC filter 400 and the connection point X. Capacitor C5 mainly functions as a capacitor of a high-pass filter.

Next, a laminated LC filter 500 in which a laminate having a plurality of dielectric layers is laminated will be described.

As shown in FIG. 9, the laminated LC filter 500 is, for example, a laminated body 10 having a rectangular parallelepiped made of ceramic.

An input terminal 1 is formed on one end surface of one of the laminated bodies 10, and an output terminal 2 is formed on the other end surface. Further, a pair of ground terminals 4a and 4b are formed on both side faces of the laminated body 10. The output terminal 1, the output terminal 2, and the ground terminals 4a and 4b are formed to extend to the lower main surface and the upper main surface of the laminated body 10, respectively.

The input terminal 1, the output terminal 2, and the ground terminals 4a, 4b can be formed of a metal containing, for example, Ag, Cu, or the like as an essential component. On the surface of the terminals, a plating layer containing Ni, Sn, Au or the like as a main component may be formed in one layer or a plurality of layers as necessary.

The laminated body 10 is composed of a structure in which the dielectric layers 10a to 10r are sequentially stacked from the bottom as shown in FIG.

The capacitor electrodes 5a to 5h, the relay electrodes 6a to 6n, the inductor electrodes 7a to 7k, and the extraction electrode 8a are formed between the layers of the dielectric layers 10a to 10r. Further, through-hole electrodes 9a to 9p are formed through the dielectric layers 10b to 10q. Further, the relay electrodes 6a to 6n are electrodes for making the connection between the via-hole conductor provided in the upper dielectric layer and the via-hole conductor provided in the lower dielectric layer more reliable. Further, the extraction electrode 8a is an electrode for connection to a terminal.

The capacitor electrodes 5a to 5h, the relay electrodes 6a to 6n, the inductor electrodes 7a to 7k, and the extraction electrode 8a formed in the dielectric layer will be described below for each of the dielectric layers 10a to 10r. Moreover, the input terminal 1, the output terminal 2, and the ground terminals 4a and 4b formed in the dielectric layer will be described as necessary.

An input terminal 1 is formed on one end surface of the dielectric layer 10a, and an output terminal 2 is formed on the other end surface. Further, a pair of ground terminals 4a and 4b are formed on both side faces of the dielectric layer 10a. The input terminal 1, the output terminal 2, and the ground terminals 4a and 4b are formed so as to extend to the lower main surface of the dielectric layer 10a.

A capacitor electrode 5a is formed on the upper main surface of the dielectric layer 10a. The capacitor electrode 5a also functions as a ground electrode. The capacitor electrode 5a is connected to the ground terminals 4a and 4b.

A capacitor electrode 5b is formed on the upper main surface of the dielectric layer 10b.

A capacitor electrode 5c and a relay electrode 6a are formed on the upper main surface of the dielectric layer 10c.

A relay electrode 6b and an inductor electrode 7a are formed on the upper main surface of the dielectric layer 10d.

Relay electrodes 6c and 6d and extraction electrodes 8a are formed on the upper main surface of the dielectric layer 10e. The extraction electrode 8a is connected to the output terminal 2.

Relay electrodes 6e and 6f and an inductor electrode 7b are formed on the upper main surface of the dielectric layer 10f.

A relay electrode 6g and an inductor electrode 7c are formed on the upper main surface of the dielectric layer 10g.

Inductor electrodes 7d and 7e are formed on the upper main surface of the dielectric layer 10h.

Inductor electrodes 7f and 7g are formed on the upper main surface of the dielectric layer 10i.

Inductor electrodes 7h and 7i are formed on the upper main surface of the dielectric layer 10j.

An inductor electrode 7j and a relay electrode 6h are formed on the upper main surface of the dielectric layer 10k.

An inductor electrode 7k and a relay electrode 6i are formed on the upper main surface of the dielectric layer 10l.

Relay electrodes 6j and 6k and a capacitor electrode 5d are formed on the upper main surface of the dielectric layer 10m. The capacitor electrode 5d is connected to the output terminal 2.

A relay electrode 61 and a capacitor electrode 5e are formed on the upper main surface of the dielectric layer 10n.

A relay electrode 6m and a capacitor electrode 5f are formed on the upper main surface of the dielectric layer 10o.

A relay electrode 6n and a capacitor electrode 5g are formed on the upper main surface of the dielectric layer 10p. The capacitor electrode 5g is connected to the input terminal 1.

A capacitor electrode 5h is formed on the upper main surface of the dielectric layer 10q.

An input terminal 1 is formed on one end surface of the dielectric layer 10r, and an output terminal 2 is formed on the other end surface. Further, a pair of ground terminals 4a and 4b are formed on both side surfaces of the dielectric layer 1a. The input terminal 1, the output terminal 2, and the ground terminals 4a, 4b are formed to extend to the upper main surface of the dielectric layer 10a, respectively.

Next, the via electrodes 9a to 9p formed by penetrating the dielectric layers 10b to 10q will be described.

The via electrode 9a connects the capacitor electrode 5b and the relay electrode 6a.

The via electrode 9b connects one end of the capacitor electrode 5c and the inductor electrode 7a.

The via electrode 9c is connected to one end of the extraction electrode 8a and the inductor electrode 7b.

The via electrode 9d is connected to the other end of the inductor electrode 7b and one end of the inductor electrode 7c.

The via electrode 9e is connected to the other end of the inductor electrode 7a and the other end of the inductor electrode 7d via the relay electrodes 6d and 6f.

The via electrode 9f connects one end of the relay electrode 6a and the inductor electrode 7d via the relay electrodes 6b, 6c, 6e, and 6g.

The via electrode 9g is connected to one end of the connection point Z and the inductor electrode 7e provided in the middle of the inductor electrode 7c. Further, the connection point Z is a connection point Z on the equivalent circuit of the LC filter 500 shown in FIG.

The via electrode 9h is connected to the other end of the inductor electrode 7d and one end of the inductor electrode 7f.

The via electrode 9i is connected to the other end of the inductor electrode 7e and one end of the inductor electrode 7g.

The via electrode 9j is connected to the other end of the inductor electrode 7f and one end of the inductor electrode 7h.

The via electrode 9k is connected to the other end of the inductor electrode 7g and one end of the inductor electrode 7i.

The via electrode 91 is connected to the other end of the inductor electrode 7h and one end of the inductor electrode 7j.

The via electrode 9m is connected to the other end of the inductor electrode 7j and one end of the inductor electrode 7k.

The via electrode 9n is connected to the other end of the inductor electrode 7i and the capacitor electrode 5e via the relay electrodes 6h, 6i, and 6k.

The via electrode 90 is connected to the capacitor electrode 5e and the capacitor electrode 5f.

The via electrode 9p is connected to the other end of the inductor electrode 7k and the capacitor electrode 5h via the relay electrodes 6j, 61, 6m, and 6n.

The capacitor electrodes 5a to 5h, the relay electrodes 6a to 6n, the inductor electrodes 7a to 7k, and the extraction electrode 8a may be formed of a metal such as silver (Ag), copper (Cu), or the like as a main component. to make.

The multilayer LC filter 500 according to the fifth embodiment of the above configuration can be manufactured by a general manufacturing method for manufacturing a laminated LC filter.

Next, the relationship between the equivalent circuit of the LC filter 500 shown in FIG. 8 and the internal structure of the laminated LC filter 500 shown in FIG. 10 will be described.

The capacitor C5 is mainly constituted by a capacitance formed between the capacitor electrode 5g and the capacitor electrode 5h. Further, the capacitor electrode 5g is connected to the input terminal 1.

The capacitor C4 is mainly constituted by a capacitance formed between the capacitor electrode 5h and the capacitor electrode 5f.

The capacitor C23 of the LC parallel resonator LC23 is mainly constituted by a capacitance formed between the capacitor electrode 5e and the capacitor electrode 5d. Further, the capacitor electrode 5e is connected to the capacitor electrode 5f of the capacitor C4 via the via electrode 90. Further, the capacitor electrode 5d is connected to the output terminal 2.

The first split inductor L23A of the LC parallel resonator LC23 is connected to the via electrode 9n, the inductor electrode 7i, the via electrode 9k, the inductor electrode 7g, the via electrode 9i, the inductor electrode 7e, and the via electrode 9g. The line consists of. Further, the via electrode 9n is connected to the capacitor electrode 5e of the capacitor C23 of the LC parallel resonator LC23. Further, the via electrode 9g is connected to the connection point Z of the inductor electrode 7c.

The second split inductor L23B of the LC parallel resonator LC23 is connected by a line connecting the connection point Z from the inductor electrode 7c to the one end, the via electrode 9d, the inductor electrode 7b, the via electrode 9c, and the extraction electrode 8a. Composition. Further, the extraction electrode 8a is connected to the output terminal 2.

The inductor L1 of the first LC series resonator LC1 is connected to the via electrode 9p, the inductor electrode 7k, the via electrode 9m, the inductor electrode 7j, the via electrode 91, the inductor electrode 7h, the via electrode 9j, and the inductor. The circuit of the electrode 7f, the via electrode 9h, the inductor electrode 7d, the via electrode 9f, the relay electrode 6a, and the via electrode 9a is formed. Further, the via electrode 9p is connected to the capacitor electrode 5h of the capacitor C5. Further, the via electrode 9a is connected to the capacitor electrode 5b of the capacitor C1 of the first LC series resonator LC1 to be described below.

The capacitor C1 of the first LC series resonator is mainly constituted by a capacitor formed between the capacitor electrode 5b and the capacitor electrode 5a. Further, the capacitor electrode 5a also has a function as a ground electrode and is connected to the ground terminals 4a, 4b.

The inductor L2 of the second LC series resonator LC2 is constituted by a line connecting the connection point Z from the inductor electrode 7c to the other end, the via electrode 9e, the inductor electrode 7a, and the via electrode 9b. Further, the via electrode 9b is connected to the capacitor electrode 5c of the capacitor C2 of the second LC series resonator LC2 which will be described later.

The capacitor C2 of the second LC series resonator LC2 is mainly constituted by a capacitor formed between the capacitor electrode 5c and the capacitor electrode 5b. Further, the capacitor electrode 5b is also an electrode of the capacitor C1 of the first LC series resonator LC1.

The multilayer LC filter 500 of the fifth embodiment which is constituted by the equivalent circuit and structure as described above has the following features.

In the laminated LC filter 500, when the laminated body 10 is seen in the lamination direction, LC parallel resonance is performed by the inductor electrode 7c, the via electrode 9d, the inductor electrode 7b, the via electrode 9c, and the extraction electrode 8a. The spiral pattern of the second split inductor L23B of the LC 25 and the inductor electrode 7c, the via electrode 9e, the inductor electrode 7a, and the via electrode 9b The spiral pattern of the inductor L2 of the 2LC series resonator LC2 partially overlaps. Further, the winding direction of the spiral pattern of the second split inductor L23B and the winding direction of the spiral pattern of the inductor L2 are opposite directions. This result makes the second split inductor L23B and the inductor L2 strongly magnetically coupled, and in the LC filter 500, even if the spiral pattern of the inductor L2 is not increased to increase the inductance value, the passband can be high. A fading pole having a sufficient amount of attenuation is formed near the frequency side. Since the LC filter 500 does not increase the spiral pattern of the inductor L2 formed in the laminated body 10, it is possible to reduce the size thereof.

[Sixth embodiment]

The equivalent circuit of the LC filter 600 of the sixth embodiment is shown in Fig. 11 .

In the LC filters 100 to 500 of the first to fifth embodiments described above, between the first LC series resonator LC1 (connection point X) of the signal line 3 and the second LC series resonator LC2 (connection point Y) An LC circuit (LC series resonator LC3, LC parallel resonator LC13, LC23) including an inductor and a capacitor is connected. However, in the simplest circuit configuration, this part is only necessary to connect a capacitor.

In the LC filter 600, a capacitor C6 is connected between the first LC series resonator LC1 (connection point X) of the signal line 3 and the second LC series resonator LC2 (connection point Y). In the LC filter 600, a fading pole is also formed in the vicinity of the pass band, and impedance integration can be obtained between the input and the output.

The LC filters 100 to 600 of the first to sixth embodiments have been described above. However, the present invention is not limited to the above, and various modifications can be made in accordance with the gist of the invention.

For example, the LC filter can be of any kind and can form a bandpass filter, Qualcomm Various LC filters such as filters and low-pass filters. Further, the circuit configuration can be any configuration other than the specifically defined portion, and various circuit configurations can be employed.

Further, in the LC filter of the fifth embodiment, although the LC filter is realized as the laminated body 10 in which a plurality of dielectric layers 10a to 10r are laminated, the LC filter of the present invention is not limited to having a plurality of dielectric layers laminated. The layer body of the body layer. For example, an LC element of the present invention may be constructed by arranging an inductance element or a capacitance element on a substrate.

1‧‧‧Input terminal

2‧‧‧Output terminal

3‧‧‧ signal line

LC1‧‧‧1LC series resonator

LC2‧‧‧2LC series resonator

LC3‧‧‧LC circuit (LC series circuit)

L1~L3‧‧‧Inductors

C1~C3‧‧‧ capacitor

Claims (10)

An LC filter comprising: an input terminal; an output terminal; a signal line connecting the input terminal and the output terminal; a first LC series resonator; and a second LC series resonator; the first LC series resonator and the second LC series The resonator has an inductor and a capacitor connected in series; the first LC series resonator is connected between the signal line and the ground; and the second LC series resonator is connected to the signal line and the inductor of the first LC series resonator And between the connection points of the capacitor. The LC filter according to claim 1, wherein the first LC series resonator mainly forms a fading pole near a low frequency side of the pass band; and the second LC series resonator is formed mainly near a high frequency side of the pass band. Reduce the aging. The LC filter according to claim 1 or 2, wherein a connection point between the signal line to which the first LC series resonator is connected and a connection point between the signal line to which the second LC series resonator is connected is A capacitor is connected. The LC filter according to claim 1 or 2, wherein a connection point between the signal line to which the first LC series resonator is connected and a connection point between the signal line to which the second LC series resonator is connected is An LC circuit composed of an inductor and a capacitor is connected. The LC filter of claim 4, wherein the LC circuit is an LC series resonator in which an inductor and a capacitor are connected in series. An LC filter according to claim 4, wherein the LC circuit is an LC parallel resonator in which an inductor and a capacitor are connected in parallel. The LC filter according to claim 6, wherein the inductor of the LC parallel resonator is divided into at least a first split inductor and a second split inductor; and the second LC series resonator is in the first split A connection point between the inductor and the second split inductor is connected to the signal line. The LC filter according to claim 4, wherein at least one of the input terminal of the signal line and the LC circuit and the LC circuit and the output terminal of the signal line is further connected At least 1 capacitor. An LC filter according to claim 1 or 2, which constitutes any one of a band pass filter, a high pass filter, and a low pass filter. A laminated LC filter comprising: a laminate body in which a plurality of dielectric layers are laminated; a plurality of inductor electrodes formed between the layers of the laminate; a plurality of capacitor electrodes formed between the layers of the laminate; a plurality of a via electrode is formed through the dielectric layer; an input terminal is formed on a surface of the laminated body; and an output terminal is formed on a surface of the laminated body; The inductor is formed by a plurality of the plurality of inductor electrodes; and the capacitor is formed by a plurality of the capacitor electrodes, wherein the laminated LC filter constitutes the LC filter according to any one of claims 1 to 9. .