JPH06152202A - Laminated dielectric filter - Google Patents

Abstract

PURPOSE:To obtain a laminated dielectric filter having structure in which induction coupling between resonance elements is adjusted without disturbing the miniaturization of the laminated dielectric filter. CONSTITUTION:Resonance elements 21, 23 whose one terminal is respectively connected to an earth electrode 50 to form a 1/4 wavelength strip line resonator and electrodes 31, 33 whose one terminal is connected to the earth electrode 50 and whose other terminal is opposite to the open terminal of the resonance elements 21, 23 respectively at a prescribed distance from the open terminal of the resonance elements 21, 23 are formed on a dielectric layer 14. Furthermore, electrodes 61, 62, 63 whose both ends are connected to the earth electrode 50 at a front side and the rear side of the laminated dielectric filter are formed respectively on dielectric layers 12, 14, 16 between the resonance elements 21 and 23. The inductive coupling among the resonance elements is suppressed through the presence of the electrodes 61-63.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated dielectric filter, and more particularly to a laminated dielectric filter used for a high frequency circuit filter used in a high frequency circuit radio equipment such as a mobile phone.

[0002]

Prior Art and Problems to be Solved by the Invention FIG.
1 and 12 are a schematic development view and a perspective view of a laminated dielectric filter devised by the present inventors.

In this laminated dielectric filter, one end is connected to the ground electrode 50 and one end is connected to the resonance elements 21, 22 and 23 constituting the quarter-wavelength stripline resonator and the ground electrode 50. And forming the electrodes 31, 32 and 33 on the dielectric layer 511, the other ends of which are spaced apart from the open ends of the resonant elements 21, 22 and 23 by a predetermined distance to face the resonant elements 21, 22 and 23, respectively. An input / output electrode 41 overlapping part of the element 21 with the dielectric layer 512 sandwiched therebetween and an input / output electrode 42 overlapping with part of the resonant element 23 sandwiching the dielectric layer 512 with each other are formed on the dielectric layer 512, A dielectric layer 513 on the surface of which the ground electrode 51 is formed is laminated on the dielectric layer 512, the dielectric layers 511, 512 and 513 are integrally formed, and then fired to form a laminated body 1. To form a 0.

Next, as shown in FIG. 12, a laminated body 100 is formed.
The ground electrode 50 is formed on the upper and lower surfaces and the side surfaces except the input / output terminal portions 43 and 45. Further, in the input / output terminal portion 43 on the side surface of the laminated body 100, the input / output terminal 44 insulated from the ground electrode 50 and connected to the input / output electrode 41 is formed. Ground electrode 50
An input / output terminal 46 is formed that is insulated from and connected to the input / output electrode 42.

An equivalent circuit of the above-mentioned laminated dielectric filter is shown in FIG. In FIG. 13, a capacitance 301 is a capacitance formed between the resonance element 21 and the input / output electrode 41, and a capacitance 302 is the resonance element 2.
3 is the capacitance formed between the electrode 3 and the input / output electrode 42. The capacitances 211, 221, and 231 and the inductances 212, 222, and 232 are the resonance element 21,
22 and 23 are capacitance and inductance when equivalent conversion is performed on 22 and 23, respectively. Capacitance 213,223
And 233 are resonant elements 21, 22 and 2 respectively.
3 is an electrostatic capacitance formed between the open end of the electrode 3 and the electrodes 31, 32 and 33.
And 233 exist, the resonance element 21 and the resonance element 22 are inductively coupled with each other by the inductance 314, and the resonance element 22 and the resonance element 23 are inductively coupled with each other by the inductance 315, thereby forming a combline type bandpass filter. .

Then, these capacitances 213, 223
And 233 are respectively added to the capacitances 211, 221, and 231 of the parallel resonant circuit when the resonant elements 21, 22 and 23 are equivalently converted. Therefore,
When the resonance frequencies are the same, the inductance of the parallel resonance circuit can be small, the lengths of the resonance elements 21, 22 and 23 can be shortened, and the entire length of the laminated dielectric filter can be shortened.

However, the resonance element 21,
When the lengths of 22 and 23 become short, the resonance elements 21, 22
Also, the electrical lengths of Nos. 23 and 23 are shortened, and the resonant elements are strongly inductively coupled to each other, which causes a problem that the characteristics of the filter are broadened to a wide band.

It is possible to increase the distance between the resonance elements to weaken the inductive coupling between the resonance elements, thereby narrowing the band of the filter characteristic, but the lateral width of the dielectric filter becomes large, which hinders downsizing of the filter. The problem arises.

When it is desired to use capacitive coupling as the coupling between the resonant elements, it is necessary to cancel the inductive coupling between the resonant elements by the capacitive coupling. However, such inductive coupling between the resonant elements is offset by the capacitive coupling. Therefore, it is necessary to add a large capacitance between the resonant elements, which also hinders the miniaturization of the filter.

Further, as shown in FIGS. 11 and 12, the outer periphery of the laminated dielectric filter is surrounded by the ground electrode 50, and the casing of this laminated dielectric filter acts as another resonator. Therefore, as shown in FIG. 14, propagation of higher-order modes such as TE and TM waves in the waveguide occurs at a high frequency that is twice or more than three times the center frequency of the filter, and attenuation in the high frequency band occurs. However, there was a problem that it deteriorated significantly.

The present inventors have also devised a duplexer whose schematic developed view is shown in FIG. 15 and its perspective view is shown in FIG. This duplexer includes a dielectric filter 600 constituted by the resonance elements 21 and 23 and the resonance elements 24 and 25.
Is a laminated dielectric filter having a dielectric filter 700 having a center frequency different from that of the dielectric filter 600.

In this duplexer, one end is connected to the ground electrode 50 and one end is connected to the resonance elements 21, 23, 24-26 and the ground electrode 50 which form a quarter-wave stripline resonator. The electrodes 31, 33, 34 to 36 facing the resonant elements 21, 23, 24 to 26 with the other ends separated from the open ends of the resonant elements 21, 23, 24 to 26 by a predetermined distance are provided on the dielectric layer 14. Formed into
The dielectric layer 14 is provided on a part of the resonance element 26 and the input / output electrode 41 which is overlapped with the dielectric layer 14 on a part of the resonance element 21.
An input / output electrode 42 is formed on the dielectric layer 13 so as to overlap with the common electrode 9 with one end 91 overlapping part of the resonant element 23 and the other end 92 overlapping part of the resonant element 24.
0 is formed on the dielectric layer 15, the dielectric layers 11 to 17 are integrally formed, and then fired to form the laminated body 100.

Next, as shown in FIG. 16, a laminate 100 is formed.
The ground electrode 50 is formed on the upper and lower surfaces and the side surfaces except the input / output terminal portions 43, 45 and 47. Further, the laminated body 100
An input / output terminal 44 that is insulated from the ground electrode 50 and connected to the input / output electrode 41 is formed in the input / output terminal portion 43 on the side surface of the ground electrode 50. An input / output terminal 46 that is insulated and connected to the input / output electrode 42 is formed, and an input / output terminal 48 that is insulated from the ground electrode 50 and connected to the common electrode 90 is formed in the input / output terminal portion 47 on the side surface of the laminated body 100. Form.

An equivalent circuit of the above-mentioned laminated dielectric filter is as shown in FIG. In FIG. 17, a capacitance 301 is a capacitance formed between the resonance element 21 and the input / output electrode 41, and a capacitance 302 is a resonance element 2.
3 and the input / output electrode 42, and the electrostatic capacitance 303 is the electrostatic capacitance formed between the end 91 of the shared electrode 90 and the resonance element 23. Electric capacity 3
Reference numeral 04 denotes an electrostatic capacitance formed between the end portion 92 of the shared electrode 90 and the resonance element 24. Capacitance 211, 231,
241, 251, and 261 and the inductance 21
2, 232, 242, 252 and 262 are resonant elements 2
It is the electrostatic capacitance and the inductance when 1, 23, 24, 25 and 26 are equivalently converted. The capacitances 213, 233, 243, 253 and 263 are capacitances formed between the open ends of the resonant elements 21, 23, 24, 25 and 26 and the electrodes 31, 33, 34, 35 and 36, respectively. Yes, these capacitances 213, 2
Due to the presence of 33, 243, 253 and 263, the resonance element 21 and the resonance element 23 are connected by the inductance 311, the resonance elements 24 and 25 are connected by the inductance 312, and the resonance element 25 and the resonance element 2 are arranged.
6 is inductively coupled to each other by an inductance 313, and the resonance element 21 and the resonance element 23 constitute a combline bandpass filter 600.
4, the resonance element 25 and the resonance element 26 constitute a combline type bandpass filter 700 having a center frequency different from that of the bandpass filter 600.

In a duplexer in which two dielectric filters 600 and 700 having different center frequencies are integrally formed in one dielectric substrate, the resonance elements of the two dielectric filters interfere with each other. There is a problem in that good separation characteristics cannot be obtained.

Therefore, an object of the present invention is to provide a laminated dielectric filter having a structure capable of adjusting inductive coupling between resonant elements without hindering downsizing of the laminated dielectric filter.

Another object of the present invention is to prevent the propagation of higher order modes at a high frequency which is twice or more than three times the center frequency of the filter and prevent deterioration of the attenuation in the high frequency band. An object is to provide a laminated dielectric filter that can be suppressed.

Still another object of the present invention is to use a laminated dielectric filter as a duplexer in which dielectric filters having different center frequencies are integrally formed in one dielectric substrate. It is an object of the present invention to provide a laminated dielectric filter in which resonant elements of a dielectric filter are suppressed from interfering with each other and good isolation characteristics are obtained.

[0019]

According to the present invention, in a laminated dielectric filter having a triplate structure in which a plurality of resonant elements are integrally provided in a dielectric substrate, a predetermined number of the plurality of resonant elements are provided. A laminated type having at least one electrode formed between the pair of closest resonance elements and other than the surface on which the predetermined pair of closest resonance elements are formed and short-circuited to ground. A dielectric filter is obtained.

It is preferable that the electrode short-circuited to the ground is a via hole formed in a direction substantially perpendicular to the surface on which the predetermined closest pair of resonant elements are formed.

In this case, it is more preferable that the via hole is short-circuited to the ground on both main surfaces of the laminated dielectric filter in a direction parallel to the main surface of the resonant element.

The electrode short-circuited to the ground may be an electrode formed in a predetermined plane parallel to the plane on which the predetermined closest set of resonant elements is formed.

In this case, it is more preferable that the electrode short-circuited to the ground is short-circuited to the ground on both side surfaces of the laminated dielectric filter facing each other in the direction perpendicular to the main surface of the resonant element. .

Preferably, one end of the electrode short-circuited to the ground is short-circuited on the side surface of the dielectric filter in a direction perpendicular to the main surface of the resonant element, and the other end is parallel to the main surface of the resonant element. It is also possible to short-circuit by a via hole connected to the main surface of the multilayer dielectric filter in any direction.

Further, the electrode short-circuited to the ground is
A via hole formed in a direction substantially perpendicular to the surface on which the predetermined closest pair of resonant elements is formed and a predetermined direction parallel to the surface on which the predetermined closest pair of resonant elements is formed. It can also be constituted by an electrode formed in the plane of.

[0026]

According to the present invention, in a laminated dielectric filter having a tri-plate structure in which a plurality of resonant elements are integrally provided in a dielectric substrate, a set of the most recent closest resonance of the plurality of resonant elements is provided. It is possible to suppress the inductive coupling between the resonance elements by having at least one electrode formed between the elements and on a surface other than the surface on which the predetermined closest set of resonance elements is formed and shorted to the ground. it can.

That is, the distributed coupling between the resonant elements is caused by the distributed coupling between the resonant elements closest to each other, but the inductive coupling between the resonant elements closest to each other is an even mode impedance and an odd mode between the two resonant elements. The larger the impedance difference is, the larger it becomes. Two resonant elements 27,
The even mode impedance between the two resonant elements 2
Inversely proportional to the capacitance Cop (= C1 + C2) (see FIG. 18B) between the resonance element 27 (or 28) and the ground when the symmetry plane 800 of 7 and 28 (see FIG. 18A) is considered as an open plane, and The odd mode impedance is the capacitance Csh (= C1 + C2 + C3) between the resonance element 27 (or 28) and the ground when the symmetry plane 800 is considered as the ground plane (FIG. 1).
8C)).

As described above, the difference between the even mode impedance and the odd mode impedance is caused by the difference in the capacitance formed between the resonant element and the ground in each case. And this difference in capacitance is the symmetry plane 800 in the even mode.
Between the resonance element 27 (or 28) and the resonance element 27 (or 28), the capacitance C3 between the symmetry plane 800 and the resonance element 27 (or 28) occurs in the odd mode. There is.

Therefore, as in the present invention, by providing an electrode short-circuited to the ground between the pair of closest resonance elements and on a surface other than the surface where the pair of closest resonance elements is formed, Capacitance is formed between the electrode short-circuited to the ground and each of the two closest resonance elements in both the even mode and the odd mode. As a result, in the case of the even mode, capacitance is formed. The difference between the capacitance formed between the resonant element and the ground and the capacitance formed between the resonant element and the ground in the case of the odd mode becomes small, and the difference between the even mode impedance and the odd mode impedance also becomes small. As a result, it is possible to suppress the inductive coupling between the resonance elements.

Furthermore, in a duplexer in which two dielectric filters having different center frequencies are integrally formed in one dielectric substrate, the resonance element of one of the two dielectric filters and the resonance element Coupling with the resonance element of the other dielectric filter closest to the resonance element is the most problematic, and the cause is the same as in the case of inductive coupling between the resonance elements described above. The same problem can be solved by providing an electrode that is formed between the resonance elements and other than the surface on which the set of the closest resonance elements is formed and is short-circuited to the ground.

Further, an electrode short-circuited to the ground, which is formed between the pair of closest resonant elements and other than the surface where the pair of closest resonant elements is formed, is connected to the pair of closest resonant elements. By forming a via hole formed in a direction substantially perpendicular to the surface on which is formed, high-order mode propagation is prevented from occurring at a high frequency that is twice or more than the center frequency of the filter, and high frequency It is possible to suppress deterioration of attenuation in the band.

In a general waveguide, a signal propagates at a certain frequency (cutoff frequency) or more, and this frequency is mainly determined by the length of the long side of the cross section of the waveguide. To be done. That is, when the length of the long side is long, the signal of lower frequency is propagated, and when the length of the long side is short, only the signal of higher frequency is propagated.

On the other hand, also in the present invention, a via hole is provided between the resonant elements in a direction substantially perpendicular to the surface on which the resonant element is formed, and the via hole is parallel to the main surface of the resonant element. It can be considered that the long side of the cross section of the casing formed by the ground electrode surrounding the outer periphery of the multilayer dielectric filter is divided into two rectangles by the via hole by short-circuiting to the ground on both main surfaces. become able to. In this way, when the length of the long side of the cross section becomes short, only a high frequency signal can be propagated, that is, the frequency at which the signal starts to be propagated can be shifted to a high level, as in the case of the waveguide. become. As a result, the attenuation characteristic of the filter in the high frequency band can be improved.

[0034]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic development view of the first embodiment of the present invention, and FIG. 2 is a perspective view of this embodiment.

As shown in FIG. 1, a resonance element 21 and a resonance element 23, which have electrodes 61 respectively connected to front and rear surfaces of a laminate 100, the front and rear ends of which are respectively connected to a ground electrode 50, which will be described later, will be described later. And on the dielectric layer 12 between.

A dielectric layer 1 is formed on a part of a resonance element 21 described later.
4, the input / output electrode 41 and the input / output electrode 42 overlapping with the dielectric layer 14 are formed on the dielectric layer 13 at a part of the resonance element 23 described later.

One end of each of the resonance electrodes 21 and 23 is connected to a ground electrode 50, which will be described later, to form a quarter-wave strip line resonator, and one end thereof is connected to the ground electrode 50, which will be described later. Are resonant elements 21, 2
The electrodes 31 and 33 facing the open ends of the resonant elements 21 and 23 at a predetermined distance from the open end of the dielectric layer 3 are formed on the dielectric layer 1.
4 on the front surface and the rear surface of the laminated body 100, which will be described later, respectively. It is formed on the dielectric layer 14.

Resonant element 2 having electrodes 63 whose front and rear ends are respectively connected to a ground electrode 50 which will be described later on a front surface and a rear surface of a laminate 100 which will be described later.
1 and the resonance element 23 on the dielectric layer 16.

A ground electrode 50 is provided on the surface of the dielectric layer 16.
Of the dielectric layers 11 to 11
17 is integrally formed and then fired to form the laminated body 100.

Ground electrodes 50 are formed on the upper and lower surfaces of the laminate 100 and on the side surfaces excluding the input / output terminal portions 43 and 45, as shown in FIG. Further, an input / output terminal 44 insulated from the ground electrode 50 and connected to the input / output electrode 41 is formed in the input / output terminal portion 43 on one side surface of the stacked body 100. An input / output terminal 46 insulated from the ground electrode 50 and connected to the input / output electrode 42 is formed in the input / output terminal portion 45 on the other side surface of the.

The equivalent circuit of the laminated dielectric filter of this embodiment having the above-described structure is shown in FIG. In FIG. 3, the electrostatic capacitance 301 is the resonance element 21 and the input / output electrode 4
1 is an electrostatic capacitance formed between the electrostatic capacitance 302 and
Is an electrostatic capacitance formed between the resonance element 23 and the input / output electrode 42. The capacitances 211 and 231 and the inductances 212 and 232 are capacitance and inductance when the resonant elements 21 and 23 are equivalently converted, respectively. The capacitances 213 and 233 are capacitances formed between the open ends of the resonant elements 21 and 23 and the electrodes 31 and 33, respectively. Due to the presence of these capacitances 213 and 233, the resonant elements are 21 and the resonance element 23 are inductively coupled by the inductance 311 to form a combline type bandpass filter.

Then, these capacitances 213 and 2
33 is added to the capacitances 211 and 231 of the parallel resonance circuit when the resonance elements 21 and 23 are equivalently converted. Therefore, if the resonance frequencies are the same, the inductance of the parallel resonance circuit can be small, the lengths of the resonance elements 21 and 23 can be shortened, and the entire length of the laminated dielectric filter can be shortened.

Further, in this embodiment, the resonance element 2
Since the electrodes 61 to 63 whose both ends are short-circuited to the ground electrodes 50 provided on the front surface and the rear surface of the laminated body 100 between 1 and 23 respectively, these electrodes 61 to 6 are provided.
3 and the resonant elements 21 and 23 form capacitances in the even mode and the odd mode, respectively, and as a result, in the even mode, the resonant elements 21 and 23 and the ground are connected. The difference between the capacitance formed between the resonant elements 21 and 23 and the ground in the case of an odd mode is small, and the difference between the even mode impedance and the odd mode impedance is also small. As a result, inductive coupling between the resonant elements 21 and 23 can be suppressed. Next, a method of manufacturing the laminated dielectric filter according to the first embodiment will be described.

The laminated dielectric filter of this embodiment comprises the resonant elements 21 and 23, the electrodes 31 and 33, the input / output electrodes 41 and 4.
2 and the electrodes 61 to 63 are completely contained in the dielectric, the resonant elements 21 and 23, the electrodes 31 and 33, the input / output electrodes 41 and 42, and the electrodes 61 to 63 have low loss and low specific resistance. It is desirable to use a conductor, and it is preferable to use a low resistance Ag-based or Cu-based conductor.

As the dielectric to be used, a ceramic dielectric which is highly reliable and has a large permittivity εγ and thus can be miniaturized is preferable.

As a manufacturing method, a conductor paste is applied to a ceramic powder compact to form an electrode pattern, the compacts are laminated and fired to densify, and a conductor is laminated therein. It is desirable to integrate the ceramic dielectric with the ceramic dielectric.

When Ag-based or Cu-based conductors are used, the melting points of these conductors are low and it is difficult to co-fire with ordinary dielectric materials. Therefore, their melting points (1100 ° C. or less) are used. It is necessary to use a dielectric material that can be fired at lower temperatures. Also, due to the nature of the device as a microwave filter, the temperature characteristic (temperature coefficient) of the resonance frequency of the formed parallel resonance circuit is ± 50 ppm / ° C.
The following dielectric materials are preferred. Examples of such a dielectric material include glass-based materials such as a mixture of cordierite-based glass powder, TiO ₂ powder and Nd ₂ Ti ₂ O ₇ powder, and BaO—TiO ₂ —Re ₂ O.
_3- Bi ₂ O ₃ composition (Re: rare earth component) with some glass-forming components or glass powder added, barium oxide-titanium oxide-neodymium oxide dielectric magnetic composition powder with some glass powder added There is something I did.

As an example, MgO: 18 wt% -Al _{7
O 3: 37wt% -SiO 2:} 37wt% -B 2 O 3:
5 wt% -TiO _2: and 73 wt% of glass powder 3 wt% a composition, and 17 wt% of a commercially available TiO ₂ powder, N
10 wt% of the d ₂ Ti ₂ O ₇ powder was thoroughly mixed to obtain a mixed powder. The Nd ₂ Ti ₂ O ₇ powder is Nd ₂ O.
₃ powder and TiO ₂ powder were calcined at 1200 ° C. and then pulverized to be used. Next, an acrylic organic binder, a plasticizer, toluene and an alcohol solvent were added to this mixed powder, and the mixture was thoroughly mixed with alumina cobblestone to form a slurry. Then, using this slurry, a green tape having a thickness of 0.2 mm to 0.5 mm was prepared by a doctor blade method.

Next, in the case of the first embodiment, the conductor patterns shown in FIG. 1 are printed using silver paste as the conductor paste, and then the thickness of the green tape on which these conductor patterns are printed is adjusted. Therefore, necessary green tapes were stacked and stacked so as to have the structure shown in FIG. 1, stacked and then fired at 900 ° C. to prepare a stacked body 100.

As shown in FIG. 2, a ground electrode 50 made of a silver electrode is printed on the upper surface and the lower surface of the laminated body 100 having the above-described structure and the side surfaces excluding the input / output terminal portions 43 and 45. The silver electrode which is insulated and is connected to the input / output electrodes 41 and 42 separately is used as the input / output terminal portion
Printed as input / output terminals 44 and 46 in 3, 45 and printed electrodes were baked at 850 ° C.

Next, a second embodiment of the present invention will be described.
FIG. 4 is a schematic development view of this embodiment.

In the above-described first embodiment, both ends of the dielectric layers 12, 14 and 16 between the resonant elements 21 and 23 are short-circuited to the ground electrode 50 on the front surface and the rear surface of the laminate 100, respectively. Although the electrodes 61 to 63 are provided respectively, in the present embodiment, the resonance elements 21 and 23 are provided.
The front ends of the electrodes 64, 65, 66 provided on the dielectric layers 12, 14 and 16 between and are short-circuited to the ground electrode 50 on the front surface of the laminate 100, respectively.
The first embodiment is that the rear ends of 65 and 66 are short-circuited to the ground electrodes 50 provided on the upper surface and the lower surface of the laminated body 100 through via holes 71 to 77 provided in the dielectric layers 11 to 17, respectively. Although different from the example, the other configurations are similar to those of the first embodiment. The materials used and the manufacturing method are also the same as in the first embodiment. Also in this embodiment, the inductive coupling between the resonant elements 21 and 23 can be suppressed as in the case of the first embodiment, but the suppressing effect is weaker than that of the first embodiment. .

Next, a third embodiment of the present invention will be described.
FIG. 5 is a schematic development view of this embodiment, and FIG. 6 is a perspective view of this embodiment.

Although the first and second embodiments relate to a laminated dielectric filter having two resonance elements, this embodiment has dielectric filters 600 and 3 each composed of two resonance elements. The present invention relates to a duplexer including a dielectric filter 700 having a center frequency different from that of the dielectric filter 600, which is composed of individual resonance elements.

In this embodiment, as shown in FIG.
A dielectric layer 12 between a resonance element 23 and a resonance element 24, which have electrodes 81 and 82 whose front and rear ends are connected to a ground electrode 50, which will be described later, respectively on the front surface and the rear surface of a laminate 100, which will be described later. Form on top.

A dielectric layer 1 is formed on a part of a resonance element 21 described later.
4, the input / output electrode 41 and the input / output electrode 42 overlapping with the dielectric layer 14 are formed on the dielectric layer 13 at a part of the resonance element 26 described later.

One end of the ground electrode 50 is connected to
Resonant element 2 constituting a four-wavelength stripline resonator
1, 23, 24-26 and the ground electrode 50 are connected at one end to the resonance elements 21, 23, 24-26 at the other end.
A predetermined distance away from the open end of the resonant elements 21, 23, 2
4 to 26, electrodes 31, 33, 34 to 3 facing each other
6 is formed on the dielectric layer 14. A combline type bandpass filter 6 is formed by the resonance element 21 and the resonance element 23.
00, and the comb line type band pass filter 7 is constituted by the resonance element 24, the resonance element 25 and the resonance element 26.
00 is configured.

A common electrode 90 is formed on the dielectric layer 15 so that its one end 91 overlaps part of the resonance element 23 and the other end 92 overlaps part of the resonance element 24.

Dielectric between a resonance element 23 and a resonance element 24, which have electrodes 83 and 84, whose front and rear ends are connected to a ground electrode 50, which will be described later, on a front surface and a rear surface of a laminate 100, which will be described later, respectively. It is formed on the body layer 16.

The dielectric layer 17 having the ground electrode 50 formed on the surface thereof is laminated on the dielectric layer 16 to form the dielectric layers 11 to 1
7 are integrally formed and then fired to form the laminated body 100.

Next, as shown in FIG. 6, the ground electrode 50 is formed on the upper and lower surfaces of the laminated body 100 and the side surfaces except the input / output terminal portions 43, 45 and 47. Further, in the input / output terminal portion 43 on the side surface of the laminated body 100, the input / output terminal 44 insulated from the ground electrode 50 and connected to the input / output electrode 41 is formed. Is formed with an input / output terminal 46 that is insulated from the ground electrode 50 and connected to the input / output electrode 42, and is insulated from the ground electrode 50 in the input / output terminal portion 47 on the side surface of the laminated body 100 and is the common electrode 9
An input / output terminal 48 connected to 0 is formed.

The materials and manufacturing method used in this embodiment are the same as the materials and manufacturing method used in the first embodiment.

The equivalent circuit of the above-mentioned laminated dielectric filter is as shown in FIG. In FIG. 7, the capacitance 3
Reference numeral 01 is an electrostatic capacitance formed between the resonant element 21 and the input / output electrode 41, and electrostatic capacitance 302 is an electrostatic capacitance formed between the resonant element 23 and the input / output electrode 42. ,
The capacitance 303 is formed by the end 91 of the common electrode 90 and the resonance element 2
3 is an electrostatic capacitance formed between the electrostatic capacitance 304 and
Is a capacitance formed between the end portion 92 of the shared electrode 90 and the resonance element 24. Capacitance 211, 231, 24
1, 251 and 261, and the inductance 212,
222, 242, 252 and 262 are resonant elements 21,
23 and 24 are capacitance and inductance when equivalent conversion is performed on 23, 24, 25, and 26, respectively. Capacitance 2
Reference numerals 13, 233, 243, 253 and 263 denote capacitances formed between the open ends of the resonant elements 21, 23, 24, 25 and 26 and the electrodes 31, 33, 34, 35 and 36, respectively. Capacitance 213, 23
Due to the presence of 3, 243, 253, and 263, the resonance element 21 and the resonance element 23 have an inductance of 3
11, the resonance element 24 and the resonance element 25 are connected to each other by the inductance 312, and the resonance element 25 and the resonance element 26 are connected to each other.
Are inductively coupled by an inductance 313, and the resonance element 21 and the resonance element 23 constitute a combline type bandpass filter 600.
4, the resonance element 25 and the resonance element 26 constitute a combline type bandpass filter 700 having a center frequency different from that of the bandpass filter 600.

In the present embodiment, both ends are short-circuited to the ground electrodes 50 provided on the front surface and the rear surface of the laminated body 100 between the resonance element 23 forming the filter 600 and the resonance element 24 forming the filter 700. Since the electrodes 81 to 84 are provided, the electrodes 81 to 84 are
As a result, the filters 600 and 700 can be prevented from interfering with each other, and good separation characteristics can be obtained.

Next, a fourth embodiment of the present invention will be described.
FIG. 8 is a schematic development view of this embodiment, and FIG. 2 is a perspective view of this embodiment.

In the first and second embodiments, the case where the electrodes whose both ends are respectively connected to the ground electrode 50 on the front surface and the rear surface of the laminated body 100 is provided on the dielectric layer between the resonance elements. However, in this embodiment, via holes short-circuited to the ground electrodes 50 provided on the upper surface and the lower surface of the laminated body 100 are provided between the resonant elements.

In this embodiment, as shown in FIG.
Via holes 11 connected to a ground electrode 50, which will be described later, on the upper surface and the lower surface of a laminate 100, which will be described later.
1a and 112a, which will be described later, are a resonance element 21 and a resonance element 22.
Between the resonance element 22 and the resonance element 23 which will be described later, via holes 113a and 114a which are formed in the dielectric layer 11 between Dielectric layer 1
It is formed within 1.

On the dielectric layer 12, an inner-layer earth electrode 181 is formed on the open end side of the resonant elements 21, 22, 23 described later with the dielectric layers 13, 14 sandwiched therebetween and the end portion of which is connected to the earth electrode 50 described later. Ground electrode 5 to be formed and described later
The dielectric layer 12 between the resonant element 21 and the resonant element 22 described later has via holes 111b and 112b connected to the upper surface and the lower surface of the laminated body 100 described later, respectively.
Via holes 113b and 114b, which are formed inside and are connected to a ground electrode 50 described later on the upper surface and the lower surface of a laminated body 100 described later, respectively, are formed in the dielectric layer 12 between the resonance element 22 and the resonance element 23 described later. To do.

The dielectric layer 1 is formed on a part of the resonance element 23 described later.
4, an input / output electrode 42 overlapping each other is formed on the dielectric layer 13, and via electrodes 111c, 112c, which will be described later, are connected to an earth electrode 50, which will be described later, respectively connected to the upper surface and the lower surface of a laminate 100, which will be described later. 21
Via hole 113 formed in the dielectric layer 13 between the resonator element 22 and the resonance element 22 and connected to the ground electrode 50 described later on the upper surface and the lower surface of the laminated body 100 described later, respectively.
c and 114c are formed in the dielectric layer 13 between the resonance element 22 and the resonance element 23, which will be described later.

One end is connected to a ground electrode 50, which will be described later, and one end is connected to the resonance elements 21 to 23 and the ground electrode 50 which form a quarter-wavelength stripline resonator, and the other end is the resonance element 21. Electrodes 23 to 33 respectively facing the resonance elements 21 to 23 at a predetermined distance from the open ends of the dielectric layers 14 to 23 on the dielectric layer 14, and further to the earth electrode 50 described later, the upper surface and the lower surface of the laminated body 100 described later. Via holes 111d respectively connected at
112d is formed in the dielectric layer 14 between the resonance element 21 and the resonance element 22 which will be described later, and via holes 113d and 114d which will be respectively connected to the ground electrode 50 which will be described later are respectively connected to the upper surface and the lower surface of the laminate 100 which will be described later. Is formed in the dielectric layer 14 between the resonance element 22 and the resonance element 23.

An input / output electrode 41 is formed on the dielectric layer 15 so as to overlap a part of the resonant element 21 with the dielectric layer 15 interposed therebetween.
Further, a laminated body 100 described later is added to a ground electrode 50 described later.
Via holes 111e and 112e, which are respectively connected to the upper and lower surfaces of the resonator, are formed in the dielectric layer 15 between the resonant element 21 and the resonant element 22, and the ground electrode 5 to be described later is formed.
Via holes 113e and 114e connected to the upper surface and the lower surface of the laminated body 100, which will be described later, are formed in the dielectric layer 15 between the resonant element 22 and the resonant element 23.

An inner layer ground electrode 182 is formed on the dielectric layer 16 on the open end side of the resonant elements 21, 22, and 23 with the dielectric layers 15 and 16 sandwiched therebetween, and the overlapping end portion is connected to a ground electrode 50 described later. Further, via holes 111f and 112f connected to an earth electrode 50, which will be described later, respectively on the upper surface and the lower surface of a laminate 100, which will be described later, are connected to the resonance element 21.
Via hole 113 formed in the dielectric layer 16 between the resonator element 22 and the resonance element 22 and connected to the ground electrode 50 described later on the upper surface and the lower surface of the laminated body 100 described later, respectively.
f and 114f are formed in the dielectric layer 16 between the resonant element 22 and the resonant element 23.

The dielectric layer 17 having the ground electrode 50 formed on the surface thereof is laminated on the dielectric layer 16 to form the dielectric layers 11 to 1.
7 is integrally formed and then fired to form the laminated body 100. The via hole 111 connected to the ground electrode 50 on the upper surface and the lower surface of the laminated body 100, respectively.
g and 112 g are formed in the dielectric layer 17 between the resonance element 21 and the resonance element 22, and are stacked on the ground electrode 50.
Via holes 113g and 114g connected to the upper surface and the lower surface of the resonance element 22 and the resonance element 23, respectively.
Is formed in the dielectric layer 17 between and.

As shown in FIG. 2, the ground electrode 50 is formed on the upper and lower surfaces of the laminated body 100 and the side surfaces excluding the input / output terminal portions 43 and 45. Further, an input / output terminal 44 insulated from the ground electrode 50 and connected to the input / output electrode 41 is formed in the input / output terminal portion 43 on one side surface of the stacked body 100. An input / output terminal 46 insulated from the ground electrode 50 and connected to the input / output electrode 42 is formed in the input / output terminal portion 45 on the other side surface of the.

The materials and manufacturing method used in this embodiment are the same as the materials and manufacturing method used in the first embodiment.

An equivalent circuit of the laminated dielectric filter of the present embodiment constructed as above is shown in FIG. In FIG. 9, the electrostatic capacitance 301 is the resonance element 21 and the input / output electrode 4
1 is an electrostatic capacitance formed between the electrostatic capacitance 302 and
Is an electrostatic capacitance formed between the resonance element 23 and the input / output electrode 42. Capacitances 211, 221, and 231
Also, the inductances 212, 222 and 232 are capacitance and inductance when the resonant elements 21, 22 and 23 are equivalently converted, respectively. Capacitance 2
13, 223 and 233 are resonant elements 21, 2 respectively.
It is the capacitance formed between the open ends of 2 and 23 and the electrodes 31, 32 and 33. Further, the inductance 314 is an inductance indicating the inductive coupling between the resonance element 21 and the resonance element 22, and the inductance 315 is an inductance indicating the inductive coupling between the resonance element 22 and the resonance element 23.

Further, in the laminated dielectric filter of this embodiment, inner layer ground electrodes 181 and 182 facing the open ends of the resonant elements 21, 22 and 23 are provided. Therefore, the open end portions of the resonance elements 21, 22, 23 facing the inner layer ground electrodes 181, 182 are closer to the ground, and the open end sides of the resonance elements 21, 22, 23 and the inner layer ground electrodes 181, 182 are connected to each other. Between the capacitances 214, 2
15, 224, 225, 234, and 235 are formed, and these capacitances 214, 215, 224, and 22 are formed.
5, 234 and 235 are also capacitances 211 and 22 of the parallel resonant circuit when the resonant elements 21, 22 and 23 are equivalently converted.
1 and 231, respectively. Therefore,
If the resonance frequencies are the same, the inductance of the parallel resonance circuit can be small, and the resonance elements 21, 22,
The length of 23 is also shortened, and the length of the whole laminated dielectric filter can be shortened.

Further, in this embodiment, the resonance element 21 is used.
And the resonant element 22 between the ground electrode 50 and the laminated body 100.
Via holes 111a to 111g and via holes 112a to 11g connected to the upper and lower surfaces of the
2g is provided, and via holes 113a to 113g and via holes 114a to 114g connected to the ground electrode 50 on the upper surface and the lower surface of the laminated body 100 are provided between the resonant element 22 and the resonant element 23. The long side of the cross section of the casing formed by the ground electrode 50 surrounding the outer circumference is the via holes 111a.
~ 111g, 112a-112g, 113a-113
It can be considered that the rectangle is divided into three rectangles by g and 114a to 114g. In this way, when the length of the long side of the cross section becomes short, as in the case of the waveguide,
Only high frequency signals can be propagated, that is, the frequencies at which signals start to propagate can be shifted higher. As a result, the attenuation characteristic of the filter in the high frequency band can be improved. Next, a fifth embodiment of the present invention will be described. FIG. 10 is a schematic development view of this embodiment.

In the above-described fourth embodiment, the via hole 1 connected between the resonance elements 21 and 22 to the ground electrode 50 on the upper surface and the lower surface of the laminated body 100, respectively.
11a to 111g and via holes 112a to 112g
And the via holes 113a to 113g and the via holes 114a to 114g connected to the ground electrode 50 on the upper surface and the lower surface of the stacked body 100, respectively, are provided between the resonant element 22 and the resonant element 23. Via holes 111a-111g, 112a
~ 112g, 113a-113g, 114a-114g
In addition to the dielectric layers 13 and 1 between the resonant elements 21 and 22,
Electrodes 40 on both ends of which are short-circuited to the ground electrode 50 on the front surface and the rear surface of the laminate 100, respectively.
1, 403 and 405 are provided on the dielectric layers 13, 14 and 15 between the resonant elements 22 and 23, and both ends are short-circuited to the ground electrode 50 on the front surface and the rear surface of the laminated body 100, respectively. And 406 are respectively different from the fourth embodiment, but the other configurations are the same as the fourth embodiment. The materials used and the manufacturing method are also the same as in the fourth embodiment.

Also in this embodiment, as in the case of the fourth embodiment, the via holes 111a to 111g are connected between the resonant element 21 and the resonant element 22 to the ground electrode 50 on the upper surface and the lower surface of the laminated body 100, respectively. And via holes 112a to 112g, and the via hole 11 is connected between the resonance element 22 and the resonance element 23 to the ground electrode 50 on the upper surface and the lower surface of the laminated body 100, respectively.
Since 3a to 113g and via holes 114a to 114g are provided, the attenuation characteristic in the high frequency band of the filter can be improved.

Further, in this embodiment, these via holes 111a to 111g, 112a to 112g, 11 are formed.
3a to 113g and 114a to 114g, and an electrode 401 whose both ends are short-circuited to the ground electrode 50 on the front surface and the rear surface of the laminated body 100 on the dielectric layers 13, 14 and 15 between the resonant elements 21 and 22, respectively. , 403 and 4
05 are provided on the dielectric layers 13, 14 and 15 between the resonance elements 22 and 23, and electrodes 402, 404 and 406 whose both ends are short-circuited to the ground electrode 50 on the front surface and the rear surface of the laminate 100, respectively. Since the electrodes 401, 403, and 405 are provided, the resonance element 2 is provided.
Inductive coupling between the electrodes 1 and 22 is connected to the electrodes 402, 404 and 406.
Thus, inductive coupling between the resonance elements 22 and 23 can be suppressed.

In particular, as in this embodiment, the inner layer ground electrode 18
When the elements 1, 182 are provided so as to face the open ends of the resonant elements 21, 22, 23, the resonant elements are more strongly inductively coupled to each other. However, as in the present embodiment, the resonant elements 21 and 22 are connected to each other. Electrodes 401 and 40 whose both ends are short-circuited to the earth electrode 50 on the front surface and the rear surface of the laminated body 100, respectively.
3 and 405 are provided respectively, and both ends between the resonant elements 22 and 23 are short-circuited to the ground electrode 50 on the front surface and the rear surface of the laminated body 100, respectively.
And 406 respectively, it is possible to effectively suppress the inductive coupling between the resonance elements and prevent the characteristics of the filter from being broadened.

That is, the inner layer ground electrodes 181 and 182
Is provided so as to face the open ends of the resonant elements 21, 22, and 23, the open end sides of the resonant elements 21 to 23 facing the inner-layer ground electrodes 181 and 182 are closer to the ground, and are coupled to the ground. The inner layer ground electrode 18
The coupling between the resonant elements on the open end side facing the first and the second 182 weakens. Therefore, the resonance elements are mainly coupled to each other at a portion which does not overlap the inner layer ground electrodes 181 and 182. This means that the electrical length of the resonant element is substantially reduced. Then, when the electrical length is shortened, the reactance of the distributed constant element that couples the resonant elements is also reduced, and the resonant elements are more strongly inductively coupled to each other, and the characteristics of the filter are further broadened. If the inner layer ground electrode facing the open ends of the resonant elements 21, 22, and 23 is provided in this way, the length of the multilayer dielectric filter can be shortened, but the problem that the half-plane filter characteristic becomes too wide band occurs. In this embodiment, electrodes 401, 403 and 405, both ends of which are short-circuited to the ground electrode 50, are provided between the resonance elements 21 and 22, and both ends of the ground electrode 50 are provided between the resonance elements 22 and 23.
By providing the electrodes 402, 404 and 406 which are short-circuited with each other, it is possible to effectively suppress the inductive coupling between the resonance elements and prevent the characteristics of the filter from being broadened.

[0085]

According to the present invention, in a laminated dielectric filter having a tri-plate structure in which a plurality of resonant elements are integrally provided in a dielectric substrate, a set of a plurality of the resonant elements which is closest to a predetermined one is provided. Suppressing inductive coupling between the resonance elements by having at least one electrode formed between the resonance elements other than the surface on which the predetermined closest set of resonance elements is formed and short-circuited to ground. be able to.

Further, in a duplexer in which two dielectric filters having different center frequencies are integrally formed in one dielectric substrate, the resonance element of one of the two dielectric filters and the resonance element Coupling with the resonance element of the other dielectric filter closest to the resonance element is the most problematic, and the cause is the same as in the case of inductive coupling between the resonance elements described above. The same problem can be solved by providing an electrode that is formed between the resonance elements and other than the surface on which the set of the closest resonance elements is formed and is short-circuited to the ground.

Further, an electrode short-circuited to the ground, which is formed on a surface other than the surface on which the pair of closest resonance elements is formed, between the pair of closest resonance elements, is connected to the pair of closest resonance elements. By forming a via hole formed in a direction substantially perpendicular to the surface on which is formed, high-order mode propagation is prevented from occurring at a high frequency that is twice or more than the center frequency of the filter, and high frequency It is possible to suppress deterioration of attenuation in the band.

[Brief description of drawings]

FIG. 1 is a schematic development view of a laminated dielectric filter according to a first embodiment of the present invention.

FIG. 2 is a perspective view of the laminated dielectric filter according to the first embodiment of the present invention.

FIG. 3 is an equivalent circuit diagram of the laminated dielectric filter according to the first embodiment of the present invention.

FIG. 4 is a schematic development view of a laminated dielectric filter according to a second embodiment of the present invention.

FIG. 5 is a schematic development view of a duplexer according to a third embodiment of the present invention.

FIG. 6 is a perspective view of a duplexer according to a third embodiment of the present invention.

FIG. 7 is an equivalent circuit diagram of a duplexer according to a third embodiment of the present invention.

FIG. 8 is a schematic development view of a laminated dielectric filter according to a fourth embodiment of the present invention.

FIG. 9 is an equivalent circuit diagram of a multilayer dielectric filter according to a fourth embodiment of the present invention.

FIG. 10 is a schematic development view of a laminated dielectric filter according to a fifth embodiment of the present invention.

FIG. 11 is a schematic development view of a conventional laminated dielectric filter devised by the present inventors.

FIG. 12 is a perspective view of a conventional laminated dielectric filter devised by the present inventors.

FIG. 13 is an equivalent circuit diagram of a conventional laminated dielectric filter devised by the present inventors.

FIG. 14 is a diagram for explaining an attenuation characteristic of a multilayer dielectric filter in a high frequency band.

FIG. 15 is a schematic development view of a conventional duplexer devised by the present inventors.

FIG. 16 is a perspective view of a conventional duplexer devised by the present inventors.

FIG. 17 is an equivalent circuit diagram of a conventional duplexer devised by the present inventors.

FIG. 18 is a diagram for explaining a difference between an even mode impedance and an odd mode impedance between resonance elements.

[Explanation of symbols]

11-17 ... Dielectric layer 21-26 ... Resonance element 31-36 ... Electrode 41, 42 ... Input / output electrode 43, 45, 47 ... Input / output terminal part 44, 46, 48 ... Input / output terminal 50 ... Ground electrode 61 -66 ... Electrode 71-77 ... Via hole 81-84 ... Electrode 90 ... Shared electrode 100 ... Laminated body 111a-111g, 112a-112g, 113a-.
113g, 114a-114g ... Via holes 181, 182 ... Inner layer ground electrodes 401-406 ... Electrodes

Claims (7)

[Claims] 1. A laminated dielectric filter having a triplate structure in which a plurality of resonant elements are integrally provided in a dielectric substrate, and between a predetermined closest set of resonant elements among the plurality of resonant elements. A multilayered dielectric filter having at least one electrode formed on a surface other than the surface on which the predetermined closest set of resonant elements is formed and shorted to ground. 2. The multilayer dielectric filter according to claim 1, wherein the electrode short-circuited to the ground is formed in a direction substantially perpendicular to a surface on which the predetermined closest pair of resonant elements are formed. Laminated dielectric filter, which is a formed via hole. 3. The laminated dielectric filter according to claim 2, wherein the via hole is short-circuited to ground on both main surfaces of the laminated dielectric filter in a direction parallel to the main surface of the resonant element. A laminated dielectric filter characterized by: 4. The multilayer dielectric filter according to claim 1, wherein the electrode short-circuited to the ground is within a predetermined plane parallel to the plane on which the predetermined closest pair of resonant elements are formed. A laminated dielectric filter, which is a formed electrode. 5. The multilayer dielectric filter according to claim 4, wherein the electrodes short-circuited to the ground are provided on opposite side surfaces of the multilayer dielectric filter in a direction perpendicular to the main surface of the resonant element. A laminated dielectric filter comprising an electrode short-circuited to the ground. 6. The laminated dielectric filter according to claim 4, wherein the electrode short-circuited to the ground is short-circuited at one end thereof on a side surface of the dielectric filter in a direction perpendicular to the main surface of the resonant element. The laminated dielectric filter, wherein the other end is short-circuited by a via hole connected to the principal surface of the laminated dielectric filter in a direction parallel to the principal surface of the resonant element. 7. The multilayer dielectric filter according to claim 1, wherein the electrode short-circuited to the ground is formed in a direction substantially perpendicular to a surface on which the predetermined closest pair of resonant elements are formed. A multilayer dielectric filter, which is an electrode formed in a predetermined surface in a direction parallel to a surface on which the formed via hole and the predetermined closest set of resonant elements are formed.