JP2001077603A - Laminated filter, sharing unit and mobile object communication unit using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stack filter of high attenuation quantity, which can be applied to the stack filter used for a high-frequency unit of a portable tele phone or the like and which has a form similar to a conventional one. SOLUTION: The stack filter has plural resonator electrodes 102, an inter- stage coupling capacitor electrode 104 coupling adjacent resonators and two input/output coupling capacitor electrodes 105 which couple an input/output terminal electrode 108 and the resonator electrodes. A capacitor electrode 106, which electrically connects one input/output terminal and a part of the input/ output coupling capacitor electrode, is installed. A parallel circuit is constituted of the input/output coupling capacitor electrodes and the capacitor electrodes, and the parallel resonance circuit is formed between the input/output terminals. Thus, one other attenuation pole can be formed, in addition to the attenuation pole the one inter-resonator electromagnetic filed coupling and inter-stage capacity form. Then, the stack filter of high attenuation quantity can be realized having a form similar to the conventional types.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated filter and a duplexer mainly used for high-frequency equipment such as a portable telephone and a mobile communication device using the same.

[0002]

2. Description of the Related Art In general, a conventional multilayer filter has dielectric layers 1401a, 1401b and 1401 as shown in FIG.
1c, 1401d, 1401e, resonator electrode 1402
a, 1402b, load capacitor electrodes 1403a, 14
03b, an interstage coupling capacitor electrode 1404, input / output coupling capacitor electrodes 1405a and 1405b, and shield electrodes 1406a and 1406b.

One end of each of electrodes 1402a and 1402b and electrodes 1406a and 1406b are connected to a ground terminal electrode 1408a provided on the side surface of the dielectric, and electrodes 1403a and 1403a are connected to each other.
One end of 1403b and electrodes 1406a, 1406b are connected to ground terminal electrode 1408b on the side surface of the dielectric. The electrode 1405a is connected to an input / output terminal electrode 1407a provided on the dielectric side surface, and the electrode 1405b is connected to an input / output terminal electrode 1407b provided on the dielectric side surface. The electrodes 1408a and 1408b are configured to be grounded.

[0004] Since each electrode of the multilayer filter is formed in a dielectric, it operates as a strip line in a microwave band to be used. Therefore, the equivalent circuit of the multilayer filter in the microwave band is as shown in FIG.
In FIG. 16A, inductors 1613 and 1615
Indicates the inductance components of the electrodes 1403a and 1403b, respectively. The inductor 1606 is connected to the electrode 1404
Shows the inductance component of. Inductors 1603, 1
609 indicates an inductor component of each of the electrodes 1405a and 1405b.

In the above configuration, 1402a and 1402a
Since b has one end grounded, it functions as a quarter wavelength resonator. The electrode 1404 and the electrodes 1402a and 1402
2b, and electrodes 1405a, 1405b and electrode 140
2a and 1402b form a parallel plate capacitor between them, so that the input / output terminal and the resonator, and between the resonators, are capacitively coupled. Also, electrodes 1402a and 1402
b and the capacitance obtained by adjusting the parallel plate capacitor formed between the electrodes 1404, 1402a, and 1402b, the attenuation characteristic (passage between input and output terminals) At which the impedance becomes higher).

As a result, the high-frequency characteristic between the input and output terminals is a band-pass filter having an attenuation pole formed on one side of the pass band 1701 and an attenuation band 1702 near the pass band 1701, as shown in FIG. .

As shown in FIG. 17, the conventional duplexer comprises a reception filter 1501, a transmission filter 1502, and a phase shift circuit 1503. The other end of the reception filter 1501 is used as a reception terminal 1510 and the other end of the transmission filter 1502 is used for transmission. The terminal 1511 is configured.

The phase shift circuit 1503 is composed of an inductor 1504
, An inductor 1505, a capacitor 1506, a capacitor 1507, and a capacitor 1508. The duplexer is set so that the capacitor 1506, the inductor 1504, and the capacitor 1507 are equivalent to a transmission line having substantially a quarter wavelength at the pass band frequency of the transmission filter 1502.
05 and the capacitor 1508 are set so as to be equivalent to a transmission line having substantially a quarter wavelength at the pass band frequency of the reception filter 1501.

A transmission signal input from a transmission terminal 1511 passes only a signal component of a pass band frequency via a transmission filter 1502 and is input to a phase shift circuit 1503. At this time, the reception filter 1501 viewed from the common terminal 1509
Becomes high impedance, and the transmission signal is output from the common terminal 1509 without flowing into the reception filter 1501 side. The received signal input from the common terminal 1509 is input to the phase shift circuit 1503.
The impedance of the transmission filter 1502 from the side of the transmission filter 1502 becomes high impedance,
Input to the receiving filter 1501 without flowing into the
Only the signal component of the pass band frequency of the reception filter 1501 passes and is output to the reception terminal 1510.

As a result, the transmission signal input from the transmission terminal 1511 passes through the phase shift circuit 1503,
The signal is output from the common terminal 1509 without being affected by the 501 side, and the received signal input from the common terminal 1509 is output to the receiving terminal 1510 via the phase shift circuit 1503 without being affected by the transmission filter 1502 side. Acts as a duplexer.

[0011]

In the conventional laminated type filter, it is necessary to increase the number of resonators in order to obtain an attenuation, which causes a problem that the shape becomes large and the insertion loss of the pass band increases. Had.

Further, the conventional duplexer requires a phase shift circuit including an inductor and a capacitor as chip components.
There was a problem that the mounting area of the duplexer became large.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to realize a laminated filter having a simple structure, a low insertion loss and a high attenuation, and a duplexer having a small size and a small number of components.

[0014]

According to the present invention, there are provided a plurality of resonator electrodes, an interstage coupling capacitor electrode for coupling between adjacent resonators, and two input electrodes for coupling input / output terminals and resonator electrodes. In a multilayer filter having an output coupling capacitor electrode, a capacitor electrode for electrically connecting one input / output terminal and a part of the input / output coupling capacitor electrode is provided, and the input / output coupling capacitor electrode and the capacitor electrode constitute a parallel circuit. It was done.

With this configuration, a parallel resonance circuit is formed between the input and output terminals, and another attenuation pole can be formed in addition to the attenuation pole formed by the electromagnetic field coupling between the resonators and the interstage capacitance. A multilayer filter having the same shape as that of the related art and having a high attenuation can be realized.

Also, the parallel circuit is provided at one input / output terminal of a multilayer filter having a first band as a pass band and a second band as an attenuation band, and an attenuation pole formed by the parallel circuit is provided near the second band. Set to. Further, the first band is used as an attenuation band,
The parallel circuit is provided at one of the input / output terminals of the multilayer filter having the band as the pass band, and the attenuation pole formed by the parallel circuit is set near the first band. Furthermore, the duplexer of the present invention is configured by connecting the input / output terminals of the two laminated filters on the side where the parallel circuit is provided to form a common terminal.

According to this configuration, most of the signal components passing through one of the multilayer filters are input to the common terminal because the parallel circuit of the other multilayer filter has high impedance in terms of high frequency. A duplexer can be realized without using a circuit.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

(Embodiment 1) FIG. 1 is an exploded perspective view of a multilayer filter according to Embodiment 1 of the present invention.

In FIG. 1, the laminated filter is a dielectric layer 1.
01a, 101b, 101c, 101d, 101e, 1
01f, resonator electrodes 102a and 102b, load capacitor electrodes 103a and 103b, and interstage coupling capacitor electrode 1
04, input / output coupling capacitor electrodes 105a, 105b, capacitor electrode 106, and shield electrodes 107a, 107
b and has an integrated shape. Electrode 102
a and 102b and electrodes 107a and 107b are connected to a ground terminal electrode 109a provided on the side surface of the dielectric. One end of the electrode 103a, 103b and the electrode 107a, 1
07b is a ground terminal electrode 109b provided on the dielectric side surface.
Connected to One end of the electrode 105a and one end of the electrode 106 are connected to the input / output terminal electrode 108a provided on the dielectric side surface, and the electrode 105b is connected to the input / output terminal electrode 108 provided on the dielectric side surface.
b, and the ground terminal electrodes 109a and 109b are grounded.

The operation of the multilayer filter configured as described above will be described below.

Since each electrode of the multilayer filter is formed in a dielectric material, it operates as a strip line in a microwave band to be used. Therefore, the equivalent circuit of the multilayer filter in the microwave band is as shown in FIG. FIG.
14A, inductors 1813 and 1815 indicate inductance components of the electrodes 103a and 103b, respectively. An inductor 1806 indicates an inductance component of the electrode 104. Inductors 1803 and 1809 indicate inductor components of the electrodes 105a and 105b, respectively.

In the above configuration, the electrodes 102a, 102
Since b is grounded via the ground terminal electrode 109a, it functions as a quarter wavelength resonator.

The electrodes 103a and 103b are arranged so that a part thereof overlaps the open ends of the electrodes 102a and 102b, respectively.
A parallel plate capacitor is formed with 2a and 102b. Since the electrodes 103a and 103b are grounded via the ground terminal electrode 109b, this capacitor acts as a loading capacitor for adjusting the resonance frequency of the resonator.

Part of the electrode 104 is the electrodes 102a, 1
02b, the dielectric layer 10
A parallel plate capacitor is formed with the electrodes 102a and 102b via 1d. This capacitor acts as an interstage coupling capacitor between the resonators.

The electrodes 105a and 105b are arranged so that a part thereof overlaps a part of the electrodes 102a and 102b, respectively, so that a parallel plate capacitor is formed via the dielectric layer 101d. This capacitor acts as an input / output coupling capacitor.

As described above, the present laminate has a triplate structure sandwiched between the upper and lower shield electrodes, and has an electromagnetic field coupling between the two resonators and a capacitive coupling having one attenuation pole due to the interstage coupling capacitor. And acts as a two-stage single-sided polarized band-pass filter (hereinafter referred to as BPF).

Further, a capacitor electrode 106 is formed on the upper surface of the dielectric layer 101c, and one end is connected to an input / output terminal electrode 108.
a and the other end is arranged so as to overlap a part of the electrode 105a. At this time, the electrode 105a and the electrode 106 form a parallel plate capacitor via the dielectric layer 101c, and form a parallel circuit with the electrode 105a. In FIG. 2A, the electrode 106 has an inductance component 1810, and the parallel plate capacitor is represented by a capacitor 1811.

Here, the following simultaneous equations 1 / (jω ₀ L ₀ ) = jω ₀ C + 1 / (jω ₀ L) ω ² = 1 / (LC) Inductance (L) and capacitance ( By adjusting C), a resonance point is obtained at the frequency ω without disturbing the impedance near the pass band of the original BPF.

However, the electrode 1 before the electrode 106 is inserted
The inductance of the electrode 105a after inserting the electrode 106 is L, the capacitance of the parallel plate capacitor formed by the electrode 105a and the electrode 106 is C, and the inductance of the electrode 05a is L ₀ , the pass band frequency of the BPF is ω ₀ , and the capacitance of the electrode 105a is C. Let ω be the frequency of the attenuation pole.

Therefore, a parallel resonance circuit is provided between the input and output terminals, and a pass characteristic as shown in FIG. 2B is obtained by adding one new attenuation pole while maintaining the original filter characteristic.

With the above configuration, the present embodiment functions as a BPF that can realize a high attenuation with the same shape as the conventional one.

The capacitor electrode 10 of the present embodiment
6 is arranged so that one end is connected to the input / output terminal electrode and the other end is overlapped with the input / output coupling capacitor electrode.
As shown in FIG. 7, the transmission line electrode 210 may be branched from the electrode 105a, and a part thereof may be arranged so as to overlap the capacitor electrode 211 connected to the electrode 108a to form a parallel plate capacitor. In this case, since the disturbance of the impedance of the input / output coupling capacitor electrode is reduced, the design accuracy of the BPF and the newly formed attenuation pole is improved.

The electrode 106 is also formed on the lower surface of the dielectric layer 101d by utilizing the laminated structure of the present embodiment.
The electrode 105a or the electrode 210 may be sandwiched from above and below. In this case, since the capacity of the parallel plate capacitor can be increased with the same area, the degree of freedom in designing the parallel resonance circuit is improved.

In the BPF of this embodiment, the first
In the case where the band of the first band is an attenuation band and the second band is a pass band, the attenuation pole of the parallel circuit can be set arbitrarily near the first band. A laminated BPF having a conventional structure forms an attenuation pole by electromagnetic field coupling between resonators and an interstage coupling capacitor. Therefore, when the resonator has two stages, there is one attenuation pole in the attenuation band. In the case of this embodiment, since two attenuation poles can be configured, not only the attenuation amount in the attenuation band can be increased, but also the attenuation band can be broadened.

The parallel circuit in the present embodiment is only a portion formed by one input / output coupling capacitor electrode 105a and electrode 106, but this is the other portion as shown in FIG. A parallel circuit may be formed by providing the electrode 105b and the electrode 105b. In this case, there is an effect that two attenuation poles can be added. Since these two attenuation poles can be configured independently of each other, various settings are possible, such as setting them on both sides of the pass band or concentrating on the attenuation band.

It should be noted that the electrodes 108a, 10a of this embodiment
Although there is no other end surface electrode on the side surface forming 8b, a configuration may be adopted in which ground terminal electrodes are provided on both sides of the electrodes 108a and 108b and connected to the upper and lower shield electrodes and grounded. In this case, the ground of the laminate is strengthened and the BPF
The characteristics are improved.

Although there are various methods for forming each electrode in this embodiment, the effects of the present invention are not affected by the method. Similarly,
There are various types of electrode materials and dielectric materials that can be used in the present embodiment, and the effects of the present invention are not limited to specific materials.

By using the laminated filter of the present invention in a mobile communication device, most of unnecessary signals can be eliminated in the same shape, so that a high performance mobile communication device can be constructed.

(Embodiment 2) FIG. 5 is an exploded perspective view of a laminated filter according to Embodiment 2 of the present invention.

In FIG. 5, the laminated filter is a dielectric layer 4
01a, 401b, 401c, 401d, 401e, 4
01f, resonator electrodes 402a, 402b, transmission line electrodes 403a, 403b, 403c between input / output terminals, filter capacitor electrodes 404a, 404b, capacitor electrode 405, and shield electrodes 406a, 406b. I have. Electrodes 402a, 402
b and one of the electrodes 406a and 406b are connected to a ground terminal electrode 408a provided on the side surface of the dielectric. Electrode 40
The other ends of 2a and 402b are connected to frequency adjusting terminal electrodes 409a and 409b provided on the dielectric side surface, respectively. One end of the electrode 403a is connected to an input / output terminal electrode 407a provided on the side surface of the dielectric. The other end of the electrode 403a and one end of the electrode 403b are connected to the electrode 404a. The other end of the electrode 403b and one end of the electrode 403c are connected to the electrode 404b.
Connected to The other end of the electrode 403c and one end of the electrode 405 are connected to the electrode 407b. Electrodes 406a, 40
6b is connected to the electrode 408b, and the ground terminal electrode 408
a and 408b are configured to be grounded.

The operation of the multilayer filter configured as described above will be described below.

Since the electrodes 402a and 402b are grounded via the electrode 408a, they function as quarter-wave resonators. The electrodes 404a and 404b are
a, 402b are arranged so as to overlap a part of the
A parallel plate capacitor is formed via the dielectric layers 401 and 2a and 402b. Therefore, the two resonators are connected in series to the transmission line between the input and output terminals via the capacitor. As a result, the filter of the present embodiment
A two-stage notch filter (Band Elimi) having a high attenuation at the resonance frequency of the series resonance circuit composed of 2a and 402b
nation Filter: hereinafter referred to as BEF).

By adjusting the lengths and line widths of the electrodes 403a, 403b, 403c, the transmission line between the input and output terminals acts as a coupling element between the two resonator stages and the outer distributed constant line. I do. Therefore, this laminate has a triplate structure sandwiched between upper and lower shield electrodes,
The two resonators are connected in parallel via a transmission line, and a two-stage BEF having electrodes 407a and 407b as terminals
Act as

A capacitor electrode 405 is formed on the upper surface of the dielectric layer 401c, one end is connected to the electrode 407b, and the other end is arranged so as to overlap a part of the electrode 403c. At this time, the electrode 403c and the electrode 405 form a parallel plate capacitor via the dielectric layer 401c.
03c to form a parallel circuit.

Here, when L and C are adjusted so as to satisfy the following simultaneous equation 1 / (jω ₀ L ₀ ) = jω ₀ C + 1 / (jω ₀ L) ω ² = 1 / (LC) (Equation 2) Frequency ω without disturbing the impedance near the passband of the original BEF
, A resonance point is obtained.

However, the electrode 4 before the electrode 405 is inserted
The inductance of the electrode 03c was L ₀ , the pass band frequency of the BEF was ω ₀ , the inductance of the electrode 403c after the electrode 405 was inserted was L, the capacitance of the parallel plate capacitor formed by the electrode 403c and the electrode 405 was C, and a new capacitor was formed. Let ω be the frequency of the attenuation pole.

Accordingly, a parallel resonance circuit is provided between the input and output terminals, and a pass characteristic in which one new attenuation pole is added while maintaining the original filter characteristic can be obtained.

With the above-described configuration, the present embodiment functions as a BEF capable of realizing a high attenuation with the same shape as the conventional one.

The capacitor electrode 40 of the present embodiment
5 has one end connected to the electrode 407b and the other end connected to the electrode 403c.
The transmission line electrode 510 is branched from the electrode 403c as shown in FIG.
A part thereof may be arranged so as to overlap with the electrode 511 to form a parallel plate capacitor. In this case, the electrode 403c
Is reduced, and the design accuracy of the BEF and the newly formed attenuation pole is improved.

As in the case of the first embodiment, two capacitor electrodes are formed and the electrode 403c or the electrode 5 is formed.
10 may be sandwiched from above and below. In this case, since the capacitance value of the parallel plate capacitor can be increased with the same area, the degree of freedom in designing the parallel resonance circuit is improved.

In the BEF of this embodiment, the first
In the case where the band is a pass band and the second band is an attenuation band, the attenuation pole of the parallel circuit may be set near the second band. The conventional stacked BEF can form the same number of attenuation poles as the number of resonator stages. Therefore, when the number of resonators is two, the number of attenuation poles in the attenuation band is two. In the case of the present embodiment, three attenuation poles can be configured, so that the attenuation band can be increased in attenuation and the bandwidth can be broadened simultaneously. .

In this embodiment mode, one electrode 403 is used.
Although a parallel circuit is formed only for c, a parallel circuit may be formed on the other electrode 403a as shown in FIG. In this case, there is an effect that two attenuation poles can be added. Since these two attenuation poles are configured independently, various settings such as setting on both sides of the passband or concentrating on the attenuation band are possible.

Although there is no other end face electrode on the side face on which the input / output terminal electrode of this embodiment is formed, a ground terminal electrode is provided on both sides thereof and connected to upper and lower shield electrodes to ground. The configuration may be as follows. In this case, the ground of the laminate is strengthened, and the BEF characteristics are improved.

(Embodiment 3) FIG. 8 is an exploded perspective view of a multilayer filter according to Embodiment 3 of the present invention.

In FIG. 8, the laminated filter is a dielectric layer 7.
01a, 701b, 701c, 701d, 701e, 7
01f, capacitor electrodes 702a and 702b, transmission line electrodes 703a and 703b, capacitor electrode 704, and shield electrodes 705a and 705b, and have an integrated shape. One end of the electrode 702a and the electrode 705
a and 705b are ground terminal electrodes 7 provided on the side surfaces of the dielectric.
07a. One end of the electrode 703a is connected to an input / output terminal electrode 706a provided on the side surface of the dielectric. The other end of the electrode 703a and one end of the electrode 703b are connected to the electrode 702b.
To one end. The other end of the electrode 703b and the electrode 70
4 has an input / output terminal electrode 706b provided on the dielectric side surface.
Connected to Electrodes 705a and 705b are electrodes 707
b, and the electrodes 707a and 707b are grounded.

The operation of the multilayer filter configured as described above will be described below.

The electrodes 702a and 702b are arranged so that a part thereof overlaps, and forms a parallel plate capacitor via a dielectric layer 701d. The electrodes 703a and 703b act as inductors between the input and output terminals, and the capacitors act as capacitors inserted between the transmission line connecting the input and output terminals and the ground. Therefore, this laminate has a triplate structure sandwiched between upper and lower shield electrodes, and functions as a T-type three-stage low-pass filter (hereinafter, referred to as LPF) having electrodes 706a and 706b as terminals.

A capacitor electrode 704 is formed on the upper surface of the dielectric layer 701c, one end is connected to the electrode 706b, and the other end is arranged so as to overlap a part of the electrode 703b. At this time, the electrode 703b and the electrode 704 form a parallel plate capacitor via the dielectric layer 701c, and the electrode 704 and the electrode 7
03b to form a parallel circuit.

Here, when L and C are adjusted so as to satisfy the following simultaneous equations 1 / (jω ₀ L ₀ ) = jω ₀ C + 1 / (jω ₀ L) ω ² = 1 / (LC) (Equation 3) Frequency ω without disturbing the impedance near the pass band of the original LPF
, A resonance point is obtained.

However, the electrode 7 before the electrode 704 is inserted
The inductance of the electrode 03b is L ₀ , the pass band frequency of the LPF is ω ₀ , the inductance of the electrode 703b after the electrode 704 is inserted is L, the capacitance of the capacitor formed by the electrode 703b and the electrode 704 is C, and the newly formed attenuation pole Is ω.

Therefore, the laminate has a tri-plate structure sandwiched between the upper and lower shield electrodes and has a parallel resonance circuit between the input and output terminals, and a new attenuation pole is added while maintaining the original filter characteristics. Thus, an additional pass characteristic is obtained.

With the above-described configuration, the present embodiment functions as an LPF capable of realizing a high attenuation with the same shape as the conventional one.

The electrode 704 of this embodiment is arranged so that one end is connected to the electrode 706b and the other end is overlapped with the electrode 703b, but as shown in FIG.
, The transmission line electrode 808 may be branched, and a part thereof may be arranged so as to overlap the capacitor electrode 809 connected to the input / output terminal electrode 706b to form a parallel plate capacitor. In this case, since the disturbance of the impedance of the filter transmission line electrode is reduced, the design accuracy of the LPF and the newly formed attenuation pole is improved.

As in the first embodiment, two capacitor electrodes may be formed and the electrode 703b or the electrode 808 may be sandwiched from above and below. In this case, since the capacitance value of the parallel plate capacitor can be increased with the same area, the degree of freedom in designing the parallel resonance circuit is improved.

Although the parallel circuit of the present embodiment includes only one electrode 703b, a parallel circuit may be formed on the other electrode 703a as shown in FIG.
In this case, there is an effect that two attenuation poles can be added. Since these two attenuation poles are configured independently, various settings are possible.

Although there is no other end face electrode on the side face on which the input / output terminal electrode of the present embodiment is formed, a ground terminal electrode is provided on both sides thereof and connected to the upper and lower shield electrodes to ground. The configuration may be as follows. In this case, the ground of the laminate is strengthened, and the LPF characteristics are improved.

(Embodiment 4) FIG. 11 is an exploded perspective view of a multilayer filter according to Embodiment 4 of the present invention.

In FIG. 11, the laminated filter is composed of dielectric layers 1001a, 1001b, 1001c, 1001d, 1
001e, 1001f, transmission line electrode 10 between input and output terminals
02a, 1002b, 1002c, a filter transmission line electrode 1003, a capacitor electrode 1004, and shield electrodes 1005a, 1005b, and have an integrated shape. An electrode 10 is provided on the upper surface of the dielectric layer 1001d.
02a and an electrode 1002c are formed. Dielectric layer 1
An electrode 1002b and an electrode 1003 are formed on the upper surface of 001e. One end of the electrode 1002a and one end of the electrode 1004 are connected to an input / output terminal electrode 1006a provided on the side surface of the dielectric. The other end of the electrode 1002a and the electrode 1002b
Are arranged such that a part of them overlaps with each other via a dielectric layer 1001d. The other end of the electrode 1002b and one end of the electrode 1002c are arranged so as to partially overlap with each other via a dielectric layer 1001d. Electrode 1002
The other end of c is an input / output terminal electrode 1006 provided on the dielectric side surface.
b. The transmission line electrode 1003 branched from the electrode 1002b and the electrodes 1005a and 1005b are connected to a ground terminal electrode 1007a provided on the dielectric side surface. The ground terminal electrodes 1007a and 1007b are configured to be grounded.

The operation of the multilayer filter configured as described above will be described below.

The electrodes 1002a and 1002b are arranged so that a part thereof overlaps, and forms a parallel plate capacitor via the dielectric layer 1001d. The electrodes 1002b, 1
002c is arranged so that a part thereof overlaps, and forms a parallel plate capacitor via the dielectric layer 1001d. Therefore, the two capacitors are connected in series between the input and output terminals. Further, since the electrode 1003 acts as an inductor between the connection point of the two capacitors and the ground, the laminate has a triplate structure sandwiched between upper and lower shield electrodes, and has a T-type structure having the electrodes 1006a and 1006b as terminals. High Pass Filter (hereinafter, HP)
F).

The electrode 1004 is formed on the upper surface of the dielectric layer 1001c.
Is formed, one end is connected to the electrode 1006a, and the other end is arranged so as to overlap a part of the electrode 1002a. At this time, the electrode 1002a and the electrode 1004 form a capacitor via the dielectric layer 1001c.
2a and a parallel circuit.

Here, L and C are adjusted so as to satisfy the following simultaneous equations 1 / (jω ₀ L ₀ ) = jω ₀ C + 1 / (jω ₀ L) ω ² = 1 / (LC) (Equation 4) , Without disturbing the impedance near the passband of the original HPF
, A resonance point is obtained.

However, before the electrode 1004 is inserted, the inductance of the electrode 1002a is L ₀ , the pass band frequency of the HPF is ω ₀ , and the electrode 1002a after the electrode 1004 is inserted.
The inductance of a is L, the capacitance of the capacitor formed by the electrode 1002a and the capacitor electrode 1004 is C, and the frequency of the newly formed attenuation pole is ω.

Therefore, the filter according to the present embodiment has a parallel resonance circuit between the input and output terminals, and a pass characteristic in which one attenuation pole is newly added while maintaining the original filter characteristic can be obtained. With the above-described configuration, the present embodiment functions as an HPF capable of realizing a high attenuation with the same shape as the conventional one.

The electrode 1004 of this embodiment is arranged such that one end is connected to the electrode 1006a and the other end is overlapped with the electrode 1002a. However, as shown in FIG. Is branched, and a part of the capacitor electrode 11 is connected to the electrode 1006a.
09 to form a capacitor. In this case, since the disturbance of the impedance of the electrode 1002a is reduced, the design accuracy of the HPF and the newly formed attenuation pole is improved.

As in the case of the first embodiment, two capacitor electrodes may be formed and the electrode 1002a or the electrode 1108 may be sandwiched from above and below. In this case, since the capacitance value of the parallel plate capacitor can be increased with the same area, the degree of freedom in designing the parallel resonance circuit is improved.

Although the parallel circuit in this embodiment is formed only on the electrode 1002a connected to one electrode 1006a, the electrode 1002c connected to the other electrode 1006b as shown in FIG. May be configured as a parallel circuit. In this case, two attenuation poles can be added. Since these two attenuation poles are configured independently, various settings are possible.

Although there is no other end electrode on the side surface on which the input / output terminal electrode of this embodiment is formed, a ground terminal electrode is provided on both sides thereof and connected to the upper and lower shield electrodes to ground. The configuration may be as follows. In this case, the ground of the laminate is strengthened, and the HPF characteristics are improved.

(Embodiment 5) FIG. 14 is an exploded perspective view of a duplexer according to Embodiment 5 of the present invention.

In FIG. 14, the duplexer is a dielectric layer 130.
1a, 1301b, 1301c, 1301d, 1301
e, 1301f, resonator electrodes 1302a, 1302b,
1302c, 1302d and input / output terminal transmission line electrode 1
303a, 1303b, 1303c, filter capacitor electrodes 1304a, 1304b, transmission line electrode 130
5 and load capacitor electrodes 1306a, 1306b, inter-stage coupling capacitor electrode 1307, input / output coupling capacitor electrodes 1308a, 1308b, transmission line electrode 1309, capacitor electrode 1310, capacitor electrode 1311 and shield electrodes 1312a, 1312b. have. Electrodes 1302a, 1302b, 130
2c, 1302d and electrodes 1312a, 1312
b is connected to the ground terminal electrode 1314a provided on the side surface of the dielectric. The other ends of the electrodes 1302a and 1302b are connected to frequency adjustment terminal electrodes 1315a and 1315b provided on the side surfaces of the dielectric, respectively. Electrode 1306
a, 1306b and electrodes 1312a, 1312b are connected to a ground terminal electrode 1314c provided on the dielectric side surface. One end of the electrode 1303a is connected to the input / output terminal electrode 1313a provided on the dielectric side surface, and the other end of the electrode 1303a is connected to one end of the electrode 1303b and the electrode 1304a. The other end of the electrode 1303b and one end of the electrode 1303c are connected to the electrode 1304b. The other end of the electrode 1303c, one end of the electrode 1310, one end of the electrode 1308a, and one end of the electrode 1311 are connected to a common terminal electrode 1316 provided on a dielectric side surface. One end of the electrode 1308b is connected to the electrode 1313b. Electrodes 1312a, 1312
b is connected to the electrode 1314b and the electrodes 1314a, 131
4b and 1314c are grounded.

The duplexer configured as described above
The operation will be described below.

The electrodes 1302a and 1302b are electrodes 131
Since it is grounded via 4a, it functions as a quarter wavelength resonator. The electrodes 1304a and 1304b are arranged so as to overlap a part of the electrodes 1302a and 1302b, respectively, and form a capacitor through the dielectric layer 1301d. Therefore, the two resonators are connected in series to the transmission lines 1303a, 1303b, and 1303c between the input and output terminals via the capacitors, and the two BEFs having high attenuation at the resonance frequency of the series resonance circuit formed by the electrodes 1302a and 1302b. Act as Also, the lines 1303a, 1
By adjusting the lengths of the lines 303b and 1303c and the line widths, the lines 1303a, 1303b and 1303c act as coupling elements between the two resonator stages and the outer distributed constant lines. Therefore, the two resonators are connected in parallel via the transmission line, and the two-stage BEF using the electrode 1313a and the common terminal electrode 1316 as input / output terminals
Act as

The electrodes 1302c and 1302d are the electrodes 1
Since it is grounded via 314a, it acts as a quarter wavelength resonator. Since the electrodes 1306a and 1306b are arranged so that a part thereof overlaps the open ends of the electrodes 1302c and 1302d, the dielectric layer 1301d
To form a capacitor. The electrode 1306
Since a and 1306b are grounded via the ground terminal electrode 1314c, the capacitor functions as a loading capacitor for adjusting the resonance frequency of the resonator.
Part of the electrode 1307 is an electrode 1302c or 1302d.
And the dielectric layer 1301d
And the two capacitors act as interstage coupling capacitors between the resonators. Electrode 130
8a and 1308b each have a resonator electrode 13
02c and 1302d, a capacitor is formed via the dielectric layer 1301d to act as an input / output coupling capacitor. Therefore, the laminated body of the present embodiment has a triplate structure sandwiched between upper and lower shield electrodes, and has a two-stage capacitive coupling having one electromagnetic field coupling between two resonators and one attenuation pole by an inter-stage coupling capacitor. Acts as a unipolar BPF.

Further, the transmission line electrode 13 is connected to the electrode 1303c.
05 is branched and arranged so that a part thereof overlaps the electrode 1310. At this time, a capacitor is formed between the electrode 1305 and the electrode 1310 via the dielectric layer 1301c.
A parallel circuit is formed with the circuit 303c.

Further, the electrode 1309 is branched from the electrode 1308a, and is arranged so that a part thereof overlaps the electrode 1311. At this time, the electrode 1309 and the electrode 1311 form a capacitor via the dielectric layer 1301c, and the electrode 1308
and a is formed in parallel.

Here, the pass band of the BEF becomes the first band, and the attenuation band becomes the second band.
Each electrode of the present multilayer filter is set so that the attenuation band of the multilayer filter becomes the first band and the pass band becomes the second band.

[0088] As further satisfy the following simultaneous equations _{1 / (jω 1 L t0)} = jω 1 C t + 1 / (jω 1 L t) ω 2 2 = 1 / (L t C t) ( Equation 5) L _t, to adjust the C _t.

Here, the frequency in the first band is ω ₁ , the frequency in the second band is ω ₂ , the inductance of the electrode 1303c before the electrodes 1305 and 1310 are inserted is L _t0 , and the electrodes 1305 and 1310 are inserted. the inductance of the electrode 1303c after the L _t, electrodes 13
05 and the electrode 1310 are represented by C
_Let it be _t .

At this time, since the BEF obtains a resonance point in the second band without disturbing the impedance in the first band, a parallel resonance circuit is provided between the input and output terminals, and the original filter characteristics are maintained. 9 shows a pass characteristic in which one attenuation pole is added near the second band.

The inductance of the electrode 1308a before the electrode 1309 and the electrode 1311 are inserted is L _r0 , and the electrode 13308 after the electrode 1309 and the electrode 1311 are inserted.
The inductance of 08a L _r, electrode 1309 and the electrode 1
The capacitance of a parallel plate capacitor 311 to form a C _r,
The following simultaneous equations _{1 / (jω 2 L r0)} = jω 2 C r + 1 / (jω 2 L r) ω 1 2 = 1 / (L r C r) to satisfy (Equation 6) L _r, C _r To adjust. At this time, the BPF performs the first operation without disturbing the impedance in the second band.
Since the resonance point is obtained in the band, the parallel resonance circuit is provided between the input and output terminals, and a pass characteristic in which one attenuation pole is added near the first band while maintaining the original filter characteristics is exhibited.

When each electrode is set under the above conditions, the signal input to the electrode 1313a passes through the BEF, and only the signal component of the first band passes and is output to the electrode 1316. However, since the parallel circuit formed by the electrode 1308a, the electrode 1309, and the electrode 1311 has high impedance in a high frequency band in the first band, no signal flows from the electrode 1316 to the BPF side. A parallel circuit formed by the electrode 1303c, the electrode 1305, and the electrode 1310 is a second circuit.
The signal of the second band input to the electrode 1316 is BEF in order to have a high impedance at a high frequency in the band of BEF.
Most of the signal component does not flow to the side, but flows to the BPF side, and only the signal component of the second band is output to the electrode 1313b.

With the above configuration, the duplexer of this embodiment can separate the first band signal and the second band signal with one element without using a phase shift circuit. As a result, a duplexer useful for a system having a low loss in the first band and high attenuation in the second band and a system having a system requiring high attenuation on both sides of the second band is obtained.

In this embodiment, the duplexer is constituted by one element using the laminated body, but the duplexer does not necessarily have to be constituted by one element. BE in which the first band described in Embodiment 2 is a pass band and the second band is an attenuation band
F and the BPF having the first band as the attenuation band and the second band as the pass band described in the first embodiment, and the input / output terminal electrodes of the two elements on the side where the respective parallel circuits are formed. It may be configured to be connected. In this case, the mounting efficiency on the substrate is improved.

The duplexer according to the present embodiment has a BEF in which the first band is a pass band and the second band is an attenuation band, and a BPF in which the first band is an attenuation band and the second band is a pass band. This is composed of a BPF in which the first band described in the first embodiment is a pass band and a second band is an attenuation band, and the first band described in the second embodiment is an attenuation band. And a BEF having the second band as a pass band. In this case, it functions as a useful duplexer in a system having a system that requires high attenuation on both sides of the first band and a system that requires high attenuation in the first band and low loss in the second band.

The duplexer has a BPF in which the first band described in the first embodiment is a pass band and a second band is an attenuation band, and the first band described in the second embodiment is an attenuation band. A configuration in which the input / output terminal electrodes on the side where a parallel circuit is formed may be connected using a BEF having a pass band in the second band.

The duplexer has a first band described in the first embodiment as a pass band and a second band as an attenuation band, and the first band described in the first embodiment as an attenuation band. And a BPF having a pass band of the second band. In this case, it works as a useful duplexer for a system having a system requiring high attenuation on both sides of the first band and a system requiring high attenuation on both sides of the second band.

The duplexer includes a BPF having a first band as a pass band and a second band as an attenuation band described in the first embodiment, and a first band-pass filter described in the first embodiment.
A configuration in which the input / output terminal electrodes on the side where a parallel circuit is formed may be connected using a BPF having a band as an attenuation band and a pass band as a second band.

The duplexer has a BEF in which the first band described in the second embodiment is a pass band and a second band is an attenuation band, and a BEF in which the first band described in the second embodiment is an attenuation band. And a BEF having a pass band of the second band. This case is useful for a system having a system that requires low loss in the first band and high attenuation in the second band and a system that requires high attenuation in the first band and low loss in the second band. Acts as a duplexer.

The above-mentioned duplexer has a BEF in which the first band described in the second embodiment is a pass band and a second band is an attenuation band, and the first band described in the second embodiment is an attenuation band. A configuration may be used in which BEFs each having the second band as a pass band are individually used, and input / output terminal electrodes on the side where a parallel circuit is formed are connected.

The duplexer is an LPF in which the first band described in the third embodiment is a pass band and the second band is an attenuation band, and the first band described in the first embodiment is an attenuation band. And a BPF having a pass band of the second band. In this case, it works as a useful duplexer for a system having a system requiring low loss in the first band and a system requiring high attenuation on both sides of the second band.

Further, the duplexer has an LPF in which the first band described in the third embodiment is a pass band and a second band is an attenuation band, and the first band described in the first embodiment is an attenuation band. The configuration may be such that BPFs having a pass band in the second band are individually used, and input / output terminal electrodes on the side where a parallel circuit is formed are connected.

Note that the duplexer is a BPF in which the first band described in the first embodiment is a pass band and the second band is an attenuation band, and the first band described in the fourth embodiment is an attenuation band. And an HPF whose pass band is the second band. In this case, it acts as a useful duplexer for a system having a system requiring high attenuation on both sides of the first band and a system requiring low loss in the second band.

Further, the duplexer has a BPF in which the first band described in the first embodiment is a pass band and a second band is an attenuation band, and the first band described in the fourth embodiment is an attenuation band. A configuration may be used in which HPFs having a pass band in the second band are individually used, and input / output terminal electrodes on the side where a parallel circuit is formed are connected.

The duplexer has a BEF in which the first band described in the second embodiment is a pass band and a second band is an attenuation band, and the first band described in the fourth embodiment is an attenuation band. And an HPF whose pass band is the second band. In this case, it works as a useful duplexer for a system having a system requiring low loss in the first band and high attenuation in the second band and a system requiring a low loss in the second band.

The above-mentioned duplexer has a BEF in which the first band described in the second embodiment is a pass band and a second band is an attenuation band, and the first band described in the fourth embodiment is an attenuation band. A configuration may be used in which input and output terminal electrodes on the side where a parallel circuit is formed are connected using an HPF having a pass band in the second band.

Note that the duplexer is an LPF in which the first band described in the third embodiment is a pass band and the second band is an attenuation band, and the first band described in the second embodiment is an attenuation band. And a BEF having a pass band of the second band. In this case, it works as a useful duplexer in a system having a system requiring loss in the first band and a system having a system requiring high attenuation in the first band and low loss in the second band.

The duplexer includes an LPF having a first band as a pass band and a second band as an attenuation band described in the third embodiment, and a first band described in the second embodiment.
A configuration may be used in which the input / output terminal electrodes on the side where the parallel circuits are formed are connected using BEFs whose band is an attenuation band and whose band is a pass band.

Note that the duplexer is an LPF in which the first band described in the third embodiment is a pass band and the second band is an attenuation band, and the first band described in the fourth embodiment is an attenuation band. It may be configured using an HPF having a pass band of band 2. In this case, it works as a useful duplexer in a system having a system requiring low loss in the first band and a system requiring low loss in the second band.

Further, the duplexer is an LPF in which the first band described in the third embodiment is a pass band and the second band is an attenuation band, and the first band described in the fourth embodiment is an attenuation band. A configuration may be used in which input and output terminal electrodes on the side where a parallel circuit is formed are connected using an HPF having a pass band in the second band.

Further, by using the duplexer of the present invention in the mobile communication device, the phase shift circuit required so far can be eliminated, so that a small-sized mobile communication device can be configured.

[0112]

As described above, according to the present invention, it is possible to realize a multilayer filter having the same shape as the conventional one and having a high attenuation. Further, a duplexer can be realized without using a phase shift circuit.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a multilayer filter according to Embodiment 1 of the present invention.

2A is an equivalent circuit diagram at a frequency near a pass band of the multilayer filter according to the first embodiment of the present invention. FIG. 2B is a frequency characteristic diagram of the multilayer filter according to the first embodiment of the present invention.

FIG. 3 is an exploded perspective view showing another configuration example of the multilayer filter according to Embodiment 1 of the present invention.

FIG. 4 is an exploded perspective view showing still another configuration example of the multilayer filter according to Embodiment 1 of the present invention.

FIG. 5 is an exploded perspective view of a multilayer filter according to Embodiment 2 of the present invention.

FIG. 6 is an exploded perspective view showing another configuration example of the multilayer filter according to Embodiment 2 of the present invention.

FIG. 7 is an exploded perspective view showing still another configuration example of the multilayer filter according to the second embodiment of the present invention.

FIG. 8 is an exploded perspective view of a multilayer filter according to Embodiment 3 of the present invention.

FIG. 9 is an exploded perspective view showing another configuration example of the multilayer filter according to the third embodiment of the present invention.

FIG. 10 is an exploded perspective view showing still another configuration example of the multilayer filter according to Embodiment 3 of the present invention.

FIG. 11 is an exploded perspective view of a multilayer filter according to Embodiment 4 of the present invention.

FIG. 12 is an exploded perspective view showing another configuration example of the multilayer filter according to Embodiment 4 of the present invention.

FIG. 13 is an exploded perspective view showing still another configuration example of the multilayer filter according to Embodiment 4 of the present invention.

FIG. 14 is an exploded perspective view of a duplexer according to Embodiment 5 of the present invention.

FIG. 15 is an exploded perspective view of a conventional multilayer filter.

16A is an equivalent circuit diagram near the pass band of a conventional multilayer filter. FIG. 16B is a frequency characteristic diagram of the conventional multilayer filter.

FIG. 17 is a circuit diagram of a conventional duplexer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Dielectric layer 102 Resonator electrode 103 Load capacitor electrode 104 Interstage coupling capacitor electrode 105 Input / output coupling capacitor electrode 106 Capacitor electrode 107 Shield electrode 108 Input / output terminal electrode 109 Ground terminal electrode

Claims (43)

[Claims] An input / output terminal and at least a part of an electrode directly connected to the input / output terminal are used as one electrode, and the other electrode has at least one capacitor directly connected to the input / output terminal. An electrode directly connected to an input / output terminal and the capacitor form a parallel circuit. 2. A semiconductor device comprising: a plurality of resonators; an interstage coupling capacitor coupling between the resonators; and an input / output coupling capacitor coupling the resonator with the input / output terminal. Item 7. The multilayer filter according to Item 1. 3. The multilayer according to claim 2, wherein the capacitor has at least a part of a transmission line branched from an electrode directly connected to the input / output terminal of the input / output coupling capacitor as one electrode. filter. 4. The multilayer filter according to claim 2, wherein a resonance frequency of the parallel circuit is in an attenuation band of the multilayer filter. 5. The multilayer filter according to claim 2, wherein said parallel circuit is formed on both of said input / output terminals. 6. A transmission line connecting between both electrodes directly connected to the input / output terminal, a plurality of capacitors, and a plurality of resonators, wherein the transmission line and the resonator are respectively The multilayer filter according to claim 1, wherein the filter is connected by a capacitor. 7. The multilayer filter according to claim 6, wherein the capacitor has at least a part of a transmission line branched from the transmission line as one electrode. 8. The multilayer filter according to claim 6, wherein a resonance frequency of the parallel circuit is in an attenuation band of the multilayer filter. 9. The multilayer filter according to claim 6, wherein said parallel circuit is formed on both of said input / output terminals. 10. The multilayer filter according to claim 1, comprising: a transmission line connecting between both electrodes directly connected to the input / output terminal; and a capacitor coupling the transmission line to a ground. 11. The multilayer filter according to claim 10, wherein the capacitor has at least a part of a transmission line branched from the transmission line as one electrode. 12. The multilayer filter according to claim 10, wherein said parallel circuit is formed on both of said input / output terminals. 13. At least one transmission line arranged so as to partially overlap both electrodes directly connected to the input / output terminal, and a transmission line connecting between the transmission line and the ground. The multilayer filter according to claim 1, wherein: 14. The multilayer filter according to claim 13, wherein the capacitor has at least a part of a transmission line branched from an electrode directly connected to the input / output terminal as one electrode. 15. The multilayer filter according to claim 13, wherein said parallel circuit is formed on both of said input / output terminals. 16. One electrode is at least a part of an electrode directly connected to the input / output terminal or at least a part of a transmission line branched from the electrode directly connected to the input / output terminal, and the other electrode is the input / output terminal. A terminal connected to the input / output terminal and at least one capacitor connected directly to the input / output terminal, the capacitor and the capacitor comprising two laminated filters forming a parallel circuit; A duplexer characterized by connecting input / output terminals on the side forming a common terminal. 17. The method according to claim 17, wherein the two laminated filters include a first filter and a second filter, wherein the first filter includes a plurality of first resonators and a plurality of first resonators. And an input / output coupling capacitor for coupling the first resonator and the input / output terminal, wherein the second filter includes both electrodes directly connected to the input / output terminal. It has a transmission line connecting between them, a plurality of capacitors, and a plurality of second resonators, and has a structure in which the transmission line and the second resonator are respectively connected by the capacitors. 16. The duplexer according to 16. 18. The first filter according to claim 1, wherein a first band is an attenuation band, a second band is a pass band, and a resonance frequency of the parallel circuit of the first filter is the first band. , The second filter has a first band as a pass band, a second band as an attenuation band, and the resonance frequency of the parallel circuit of the second filter is the second band. The duplexer according to claim 17, wherein the duplexer is located in the vicinity of. 19. The first filter according to claim 1, wherein the first band is a pass band, the second band is an attenuation band, and the resonance frequency of the parallel circuit of the first filter is the second band. , The second filter has a first band as an attenuation band, a second band as a pass band, and the resonance frequency of the parallel circuit of the second filter is the first band. The duplexer according to claim 17, wherein the duplexer is located in the vicinity of. 20. The duplexer according to claim 17, wherein the duplexer has an integrated structure including the first and second filters in a dielectric. 21. A plurality of first resonators, a first inter-stage coupling capacitor for coupling between the first resonators, and a second coupling between the first resonator and the input / output terminal. A first filter including one input / output coupling capacitor, a plurality of second resonators, and a second filter for coupling between the second resonators.
17. The duplexer according to claim 16, comprising a second filter comprising: an inter-stage coupling capacitor; and a second input / output coupling capacitor coupling the second resonator and the input / output terminal. 22. The first filter or the second filter.
Is a filter in which the first band is an attenuation band, the second band is a pass band, and the resonance frequency of the parallel circuit is near the first band, and the other is the first band. 22. A duplexer according to claim 21, wherein the filter is a filter whose pass band is a pass band, a second band is an attenuation band, and a resonance frequency of the parallel circuit is near the second band. . 23. The duplexer according to claim 21, wherein the duplexer has an integrated structure including the first and second filters in a dielectric. 24. A semiconductor device comprising: a first transmission line connecting between both electrodes directly connected to the input / output terminal; a plurality of first capacitors; and a plurality of first resonators. A first filter having a structure in which one transmission line and the first resonator are connected by the first capacitor, respectively, and a second transmission connecting between both electrodes directly connected to the input / output terminal. A second line, a plurality of second capacitors, and a plurality of second resonators, wherein the second transmission line and the second
17. The duplexer according to claim 16, comprising a second filter having a structure in which the resonators are connected to each other by the second capacitor. 25. The first filter or the second filter
Is a filter in which the first band is an attenuation band, the second band is a pass band, and the resonance frequency of the parallel circuit is near the first band, and the other is the first band. 25. The duplexer according to claim 24, wherein the filter is a pass band, the second band is an attenuation band, and the resonance frequency of the parallel circuit is near the second band. . 26. The duplexer according to claim 24, wherein the duplexer has an integrated structure including the first and second filters in a dielectric. 27. A first circuit comprising: a plurality of resonators; an inter-stage coupling capacitor coupling between the resonators; and an input / output coupling capacitor coupling the resonator with the input / output terminal.
17. The shared filter according to claim 16, comprising a second filter comprising: a first filter; a transmission line connecting between the two electrodes directly connected to the input / output terminal; and a capacitor coupling the transmission line to the ground. vessel. 28. The first filter, wherein the first band is an attenuation band, the second band is a pass band, and the resonance frequency of the parallel circuit of the first filter is the first band. , The second filter has a first band as a pass band, and the resonance frequency of the parallel circuit of the second filter is near the second band. 28. The duplexer according to claim 27. 29. The duplexer according to claim 27, wherein the duplexer has an integrated structure including the first and second filters in a dielectric. 30. A first transmission line comprising: at least one transmission line disposed so as to partially overlap both electrodes directly connected to the input / output terminal; and a transmission line connecting between the transmission line and a ground. , A plurality of resonators, an inter-stage coupling capacitor coupling between the resonators, and an input / output coupling capacitor coupling the resonator with the input / output terminal. Claim 1
6. The duplexer according to 6. 31. The first filter has a second band as a pass band, the resonance frequency of the parallel circuit of the first filter is in a first band, and the second filter is a second band. The first band is a pass band, the second band is an attenuation band,
31. The duplexer according to claim 30, wherein the resonance frequency of the parallel circuit of the second filter is near the second band. 32. The duplexer according to claim 30, wherein the duplexer has an integrated structure including the first and second filters in a dielectric. 33. A first transmission line comprising: at least one transmission line disposed so as to partially overlap both electrodes directly connected to the input / output terminal; and a transmission line connecting between the transmission line and a ground. A filter, a transmission line connecting between both electrodes directly connected to the input / output terminal, a plurality of capacitors, and a plurality of resonators, wherein the transmission line and the resonator are each a capacitor. 17. The duplexer according to claim 16, comprising a second filter having a structure connected by. 34. The first filter has a second band as a pass band, and a resonance frequency of the parallel circuit of the first filter is in a first band, and the second filter is a second band. The first band is a pass band, the second band is an attenuation band,
34. The duplexer according to claim 33, wherein the resonance frequency of the parallel circuit of the second filter is near the second band. 35. The duplexer according to claim 33, wherein the duplexer has an integrated structure including the first and second filters in a dielectric. 36. A transmission line connecting between both electrodes directly connected to the input / output terminal, a plurality of capacitors,
A first filter comprising a plurality of resonators, wherein the transmission line and the resonators are each connected by the capacitor, and a transmission line connecting between both electrodes directly connected to the input / output terminal 17. The duplexer according to claim 16, comprising a second filter including a transmission line and a capacitor coupling the transmission line and a ground. 37. The first filter, wherein a first band is an attenuation band, a second band is a pass band, and a resonance frequency of the parallel circuit of the first filter is in a vicinity of a first band. Wherein the second filter has a first band as a pass band, and a resonance frequency of the parallel circuit of the second filter is in the vicinity of the second band. 36. The duplexer according to 36. 38. The duplexer according to claim 36, wherein the duplexer has an integrated structure including the first and second filters in a dielectric. 39. A first transmission line comprising: at least one transmission line disposed so as to partially overlap both electrodes directly connected to the input / output terminal; and a transmission line connecting between the transmission line and a ground. 17. The shared filter according to claim 16, comprising a second filter comprising: a first filter; a transmission line connecting between the two electrodes directly connected to the input / output terminal; and a capacitor coupling the transmission line to the ground. vessel. 40. The first filter, wherein a pass band is a second band, a resonance frequency of the parallel circuit of the first filter is in a band near a first band, and the second filter is 40. The duplexer according to claim 39, wherein a first band is a pass band, and a resonance frequency of the parallel circuit of the second filter is near the second band. 41. The duplexer according to claim 39, wherein the duplexer has an integrated structure including the first and second filters in a dielectric. 42. A mobile communication device using the multilayer filter according to claim 1. Description: 43. A mobile communication device using the duplexer according to any one of claims 16 to 41.