JPH11225034A - Lamination type band pass filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the lamination type band pass filter with a small size and a low loss. SOLUTION: The band pass filter has earth electrodes 31, 32 on and under a lamination structure, and an L section (line electrodes 21, 22) and a C section (capacitor electrodes 47, 48) being components of an LC resonator are formed as a continuous electrode pattern on one side of a dielectric layer 14 in the middle of the laminator structure. Then capacitor electrodes 45, 46 for input output coupling capacitor are formed between the L section (line electrodes 21, 22) and the C section (capacitor electrodes 47, 48). Then the electrode patterns of the L section, the coupling resistance and the C section are placed straight and connected electrically. The electrode pattern opposed to the coupling capacitor and connecting to input output terminals and an electrode pattern opposed to the C section and connecting to the earth electrodes are configured via a dielectric layer on and under the electrode pattern above and the input output capacitor electrode pattern is configured via a dielectric layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a band-pass filter used for a communication device such as a portable telephone, and more particularly to a small-sized laminated band-pass filter.

[0002]

2. Description of the Related Art Conventionally, various configurations have been proposed for a laminated band-pass filter used in microwave communication equipment and the like. For example, JP-A-8-31603
There is one shown in FIG. This conventional example is shown in FIG. In this conventional example, ground electrodes (ground electrodes) 3a, 3b and 3c are formed on three dielectric layers 2, respectively, and capacitor electrodes 4a and 4b and a capacitor electrode 5a are provided between the two ground electrodes 3a and 3b. , 5b,
The common electrode 6 is formed. Further, between the two ground electrodes 3b and 3c, two inductance electrodes 7a,
7b is formed. This conventional example has the equivalent circuit shown in FIG. 6, and it is described that two resonators each composed of an inductance and a capacitance are coupled via another capacitance.

[0003]

The multilayer bandpass filter of the present invention is used, for example, in a portable telephone. With respect to this mobile phone, studies on reduction in size and weight have been constantly made, and there is a strong demand for reduction in size and weight of components used. Needless to say, the demand for small and lightweight components is not limited to mobile phones.

In the conventional structure shown in FIG. 5, the inductance electrodes 7a and 7b have a coil shape of about one turn. In order to maintain such a coil shape,
It requires a certain space and is not suitable for miniaturization. Further, as described above, since the coil-shaped inductance electrodes 7a and 7b are formed adjacent to each other, the resonator is strongly magnetically coupled.
It has the disadvantage that the attenuation outside the passband is relatively small. In order to improve such filter characteristics, a shield electrode is formed between the inductance electrodes. Also in this regard, the structure is against the miniaturization.

SUMMARY OF THE INVENTION An object of the present invention is to provide a laminated bandpass filter which has good filter characteristics and can be miniaturized.

[0006]

Means for Solving the Problems A first invention of the present invention is:
A first and a second resonator constituted by an LC resonance circuit; a coupling capacitance between the first resonator and an input terminal; and a coupling capacitance between the second resonator and an output terminal. And a laminated band-pass filter comprising a laminated structure of a dielectric layer and an electrode pattern, wherein the L part and the C part of the resonator are composed of separate electrode patterns, and the L part is a linear electrode. This is a multilayer bandpass filter that is configured by a pattern, is arranged for the first resonator and the second resonator side by side, and is M-coupled to each other.

According to a second aspect of the present invention, in the first aspect, the electrode pattern of the L portion is connected to ground on one side surface of the dielectric layer and extends in the longitudinal direction of the dielectric layer. It is a bandpass filter.

According to a third aspect of the present invention, there is provided a first and a second resonator comprising an LC resonance circuit, a coupling capacitance between the first resonator and an input terminal, and a second resonator. A small laminated band-pass filter having a coupling capacitance between a capacitor and an output end, and having a laminated structure of a dielectric layer and an electrode pattern, wherein the L portion and the C portion constituting the resonator are: The electrode pattern for the coupling capacitance is formed between the electrode pattern of the L part and the electrode pattern of the C part, and is formed by separate electrode patterns, and the electrodes for the L part, the coupling capacitance, and the C part are arranged. The pattern is a laminated bandpass filter arranged linearly and electrically connected.

According to a fourth aspect of the present invention, in the third aspect of the invention, the series of electrode patterns for the L portion, the coupling capacitor, and the C portion are different for the first resonator and the second resonator. It is a stacked bandpass filter arranged side by side.

According to a fifth aspect of the present invention, in the third or fourth aspect, the series of electrode patterns for the L portion, the coupling capacitor, and the C portion are arranged at an intermediate portion of the laminated structure. A capacitor forming electrode pattern for forming a capacitance, the capacitor forming electrode pattern being opposed to the C portion and the coupling capacitor electrode pattern with a dielectric layer interposed therebetween; Is a multilayer bandpass filter connected to the input terminal or the output terminal.

According to a sixth aspect of the present invention, in the fifth aspect, the capacitor forming electrode pattern for the coupling capacitor is opposed to the capacitor forming electrode pattern by interposing a dielectric layer above and below the capacitor forming electrode pattern. , A multilayer band-pass filter in which an electrode pattern constituting a capacitance connected between an input terminal and an output terminal is configured.

In the first to sixth aspects of the present invention, it is preferable that ground electrodes are provided above and below the laminated structure.

According to a seventh aspect of the present invention, there is provided a first and a second resonator constituted by an LC resonance circuit, a coupling capacitance between the first resonator and an input terminal, and the second resonator. And a coupling capacitor between the output terminal and the output terminal, a laminated band-pass filter having a laminated structure of a dielectric layer and an electrode pattern, having a ground electrode above and below the laminated structure, In the center, L1 which constitutes the LC resonator on one surface of the dielectric layer
Section and C21 section are constituted by a continuous electrode pattern,
The C11 electrode pattern for input / output coupling capacitance is integrally formed between the first part and the C21 part, and a dielectric layer is interposed above and below the electrode pattern to face the C11 part and connect to the input / output terminal. And a C22 part electrode pattern facing the C21 part and connected to the ground terminal. Further, the C12 part electrode pattern faces the C12 part with a dielectric layer interposed therebetween. This is a multilayer bandpass filter having a C3 part electrode pattern.

According to an eighth aspect of the present invention, in the seventh aspect, the L1 portion, the C11 portion, and the C21 portion are connected to the ground on one side surface, and extend linearly in the L1 portion electrode pattern.
A C11 portion electrode pattern which is continuous with the portion and a wide C11 portion electrode pattern and a C21 portion electrode pattern which is connected to the C11 portion by a thin connection electrode are formed on a dielectric layer, and the L1 portion, C11 portion, C
Reference numeral 21 denotes a laminated band-pass filter in which two filters are formed side by side.

A ninth invention of the present invention is the multilayer bandpass filter according to the eighth invention, wherein the L1 portions formed side by side are M-coupled.

According to the present invention, the inductance L of the LC resonator is constituted by a straight line. In addition, since the size is small, the inductance L does not have a very large value. For this reason, it is necessary to increase the C portion to some extent. In order to configure this large C portion, two C portions for the resonator, a coupling capacitance portion at the input / output end portion, or two capacitance portions between the input and output are formed and connected in parallel to form a large portion. The capacity is increasing.

Further, according to the present invention, the L portions formed side by side
Are combined. With this M-coupling, a compact laminated bandpass filter having sufficient characteristics as a bandpass filter could be formed. The M-coupling needs to be strengthened or weakened depending on the required characteristics. In the present invention, the strength of the M-coupling is adjusted by the distance between adjacent L portions.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an internal electrode pattern of a laminated bandpass filter according to an embodiment of the present invention, FIG. 2 is a perspective view, and FIG. 3 is an equivalent circuit diagram. In FIGS. 1 and 2, the hatched portions are conductor portions. The thickness between the internal electrode patterns is appropriately set, and a plain dielectric layer on which no electrode pattern is formed can be inserted therebetween.

In this embodiment, a dielectric material that can be fired at a low temperature of 900 ° C. or less is used. This dielectric material is formed into a sheet shape by a doctor blade, and Ag is appropriately formed on the sheet.
An electrode pattern and a ground electrode were formed by screen printing on a conductor made of, and they were laminated, pressed, cut, and fired. After firing, the external terminal electrodes were printed and baked, and further plated to form a laminated bandpass filter. In the present embodiment, a dielectric material having a dielectric constant of about 30 is used. However, in the present invention, the dielectric constant is desirably about 20 to 50. Further, the present invention is not limited to the above manufacturing steps.

The laminated structure of the embodiment will be described. An electrode pattern for an LC resonator (resonator constituted by an LC resonance circuit) is formed on the dielectric layer 14 disposed at the center. In this dielectric layer 14, two electrode patterns for the LC resonator are formed side by side. This LC resonator L portion (L1 of the equivalent circuit) is composed of a linear electrode 2 extending from one end surface to the other end surface.
1,22. The linear electrodes 21 and 22 are connected at one end to the external terminal electrode T4 and to the ground.
The two electrodes 21 and 22 are connected to the common electrode 33 on one end surface side. The purpose of this common electrode is to displace the electrode pattern in the left-right direction in the figure due to lamination displacement, and if there is no common electrode, the length of the linear electrode will vary, but this common electrode is provided. By keeping
This is for obtaining the effect that the length of the linear electrode can be maintained at a predetermined length. For this reason, it is preferable that the linear electrodes 21 and 22 are connected to the common electrode 33.

Wide capacitor electrodes 45 and 46 are formed on the other ends of the linear electrodes 21 and 22, respectively.
The capacitor electrodes 45 and 46 are for forming a coupling capacitance (C1 in an equivalent circuit) between the resonator (LC resonator) and the input terminal and between the resonator and the output terminal. On the other ends of the capacitor electrodes 45 and 46, capacitor electrodes 47 and 48 connected by thin connection electrodes 23 and 24 are formed. The capacitor electrodes 47 and 48 are for forming a C portion (C2 of an equivalent circuit) for the resonator.

The common electrode 34 is also formed on the other end face side where the capacitor electrodes 47 and 48 are formed. This common electrode 34 is connected to the external terminal electrode T3. The common electrode 34 is also formed in order to keep the space between the capacitor electrodes 47 and 48 and the ground electrode (the external terminal electrode T3 and the common electrode 34) even if a lamination shift occurs.
Therefore, it is preferable to provide such a resonance electrode 34.

As described above, the L portion (the linear electrodes 21 and 22) and the C portion (the capacitor electrode 4) constituting the LC resonator are formed.
7, 48) are formed in a continuous electrode pattern on one dielectric layer. Moreover, capacitor electrodes 45 and 46 for input / output coupling capacitance are formed between the L portion (the linear electrodes 21 and 22) and the C portion (the capacitor electrodes 47 and 48). The electrode patterns of the L portion, the coupling capacitor, and the C portion are arranged linearly and electrically connected.

The linear electrodes 21 and 22 are formed separately on both sides of the dielectric layer 14. This is because the M-coupling between the linear electrodes 21 and 22 is performed in order to optimize the degree of the coupling. In the present embodiment, it is preferable that the electrodes are separated from each other on both sides. Was. Thus, the electrode pattern of the dielectric layer 14 has a shape symmetric with respect to the center line of the dielectric layer 14.

The dielectric layers 15 above and below the dielectric layer 14,
13, electrode patterns having the same shape are formed. The dielectric layer 13 has a capacitor electrode 42 (C12) which is opposed to the capacitor electrode 45 of the dielectric layer 14 and constitutes the coupling capacitance (C1) at the input / output end, and is also opposed to the capacitor electrode 46 of the dielectric layer 14. And the coupling capacitance at the input / output end (C
A capacitor electrode 43 (C12) constituting 1) is formed, and the capacitor electrodes 42 and 43 are connected to the external terminal electrodes T
1 and T2. For example, external terminal electrode T
1 is an input terminal, and the external terminal electrode T2 is an output terminal.
Further, on the dielectric layer 13, a capacitor electrode 44 (C 22) is formed facing the capacitor electrodes 47 and 48 of the dielectric layer 14 and constituting a portion C (C 2) for a resonator. This capacitor electrode 44 is connected to the external terminal electrode T3 and is grounded.

Similarly, capacitor electrodes 49, 50 and 51 are formed on the dielectric layer 15. The portion C (C2) for the resonator includes a capacitor electrode 47 (C21) and a capacitor electrode 44 (C22) for one resonator.
And the capacitor electrode 47 (C2
1) and a capacitor formed by the capacitor electrode 51 (C22) are connected in parallel. This constitutes a large capacity. Similarly, for the other resonator, the capacitor electrode 48 (C21) and the capacitor electrode 4
4 (C22) and a capacitor formed by the capacitor electrode 48 (C21) and the capacitor electrode 51 (C22) are connected in parallel.

As for the coupling capacitance (C1) at the input / output end, the one corresponding to one of the resonators has the capacitor electrode 4
5 (C11) and the capacitor electrode 42 (C12), and the capacitor formed by the capacitor electrode 45 (C11) and the capacitor electrode 49 (C12) are connected in parallel. The one corresponding to the container is the capacitor electrode 46 (C11) and the capacitor electrode 4
3 (C12) and a capacitor formed by the capacitor electrode 46 (C11) and the capacitor electrode 50 (C12) are connected in parallel. This constitutes a large capacity.

The dielectric layer 12 below the dielectric layer 13 includes:
A capacitor electrode 41 for capacitance (C3 in an equivalent circuit) connected between the input and output is formed. The capacitor electrode 41 corresponds to the capacitor electrodes 42 and 43 for the coupling capacitance at the input / output end of the dielectric layer 13 and is formed of one electrode pattern. The electrode 41 is not connected to the external terminal electrode, and has a constricted portion at the center.

The capacitor electrode 52 for capacitance (C3) connected between the input and output is also formed on the dielectric layer 16 above the dielectric layer 15. This capacitor electrode 5
Numeral 2 corresponds to the capacitor electrodes 49 and 50 for the coupling capacitance at the input / output end of the dielectric layer 15 and is constituted by one electrode pattern. The electrode 52 is not connected to the external terminal electrode, and has a constricted portion at the center. The narrow portions of the capacitor electrodes 41 and 52 may not be provided.

An earth electrode 31 is provided on the lower dielectric layer 11.
Are formed. The ground electrode 31 is formed on almost the entire surface, and is connected to the external terminal electrodes T3 and T4 at both ends. A similar earth electrode 3 is also provided on the upper dielectric layer 17.
2 are formed. The ground electrode 32 is also formed on almost the entire surface, and is connected to the external terminal electrodes T3 and T4 at both ends. Dielectric layer 1 as a protective layer on dielectric layer 17
8 are stacked.

According to this embodiment, a multilayer bandpass filter having the equivalent circuit shown in FIG. 3 was obtained.
The external shape of this example was 3.2 mm × 1.6 mm × 1.3 mm in height, and could be configured extremely small. The conventional laminated bandpass filter is 4.5 mm ×
The mainstream is 3.2 mm × 1.7 mm in height, and according to the embodiment of the present invention, the area is reduced to 36% in a plane area and to 27% in volume. Of course, the height has also been reduced, achieving a reduction in size and thickness.

FIG. 4 shows the attenuation characteristics of this embodiment. According to this embodiment, the center frequency f0 is 1950M
A good filter characteristic with an insertion loss of 3 dB or less at Hz and an attenuation of 25 dB or more at f0 + 190 MHz was obtained. In addition to achieving this small size and thickness, it has sufficient characteristics. In particular, the attenuation at f0 + 190 MHz is sufficient, and the insertion loss is also good. In this embodiment, the band-pass filter passes the transmission frequency (1920 to 1980 MHz) and blocks the reception frequency (2110 to 2170 MHz). The frequency to be blocked is close to the frequency to be passed. This embodiment is characterized in that a sufficient amount of attenuation is obtained.
Generally, rejection characteristics (increase the amount of attenuation) of adjacent frequencies and insertion loss are deteriorated, but in the present invention, sufficient characteristics can be obtained. According to the invention, 1
This is effective when a bandpass filter corresponding to a frequency of GHz or more is configured. Further, the characteristics can be adjusted by changing the dimensions of each pattern, the thickness of the dielectric layer (interval between the patterns), the dielectric constant of the dielectric, and the like.

[0033]

According to the present invention, a laminated band-pass filter having good insertion loss, sufficient attenuation at frequencies to be rejected, good filter characteristics, and extremely small size is constructed. can do. Therefore, it contributes to downsizing of communication devices such as mobile phones.

[Brief description of the drawings]

FIG. 1 is an internal electrode pattern diagram showing a laminated structure of one embodiment according to the present invention.

FIG. 2 is a perspective view of one embodiment according to the present invention.

FIG. 3 is an equivalent circuit diagram of one embodiment according to the present invention.

FIG. 4 is a diagram showing attenuation characteristics of an example according to the present invention.

FIG. 5 is a diagram showing a conventional laminated structure.

FIG. 6 is an equivalent circuit diagram of a conventional example.

[Explanation of symbols]

11, 12, 13, 14, 15, 16, 17, 18 Dielectric layer 31, 32 Ground electrode 33, 34 Common electrode 41, 42, 43, 44, 45, 46, 47, 48, 4
9, 50, 51, 52 Capacitor electrodes 21, 22 Linear electrodes for L1

Continued on the front page (72) Inventor, Takeshi Takeda 70-2, Minamisakaemachi, Tottori-shi, Tottori Hitachi Metals Co., Ltd. Inside the Tottori Plant (72) Inventor Toshihiko Tanaka 70-2, Minamisakaemachi, Tottori-shi, Tottori Hitachi Metals, Ltd. In company Tottori factory

Claims (9)

[Claims] 1. A first and a second resonator constituted by an LC resonance circuit, a coupling capacitance between the first resonator and an input terminal, and a coupling capacitance between the second resonator and an output terminal. A laminated bandpass filter having a coupling capacitance and comprising them in a laminated structure of a dielectric layer and an electrode pattern, wherein the L portion and the C portion of the resonator are composed of separate electrode patterns, Is a laminated band-pass filter comprising a linear electrode pattern, wherein the first resonator and the second resonator are arranged side by side and M-coupled to each other. 2. The multilayer bandpass filter according to claim 1, wherein the electrode pattern of the L portion is grounded on one side surface of the dielectric layer and extends in the longitudinal direction of the dielectric layer. 3. A first and second resonator constituted by an LC resonance circuit, a coupling capacitance between the first resonator and an input terminal, and a coupling capacitance between the second resonator and an output terminal. A small laminated bandpass filter having a coupling capacitance and having a laminated structure of a dielectric layer and an electrode pattern, wherein the L portion and the C portion constituting the resonator are formed by separate electrode patterns. An electrode pattern for the coupling capacitance is disposed between the electrode pattern of the L portion and the electrode pattern of the C portion;
The laminated band-pass filter, wherein the electrode patterns for the L portion, the coupling capacitor, and the C portion are arranged linearly and electrically connected. 4. A series of electrode patterns for the L portion, the coupling capacitor, and the C portion, wherein a series of electrode patterns for a first resonator and a series of electrodes for a second resonator are arranged. 4. The multilayer bandpass filter according to 3. 5. A series of electrode patterns for the L portion, the coupling capacitor, and the C portion are disposed in an intermediate portion of the laminated structure, and a dielectric layer is interposed between the electrode patterns for the C portion and the L portion. It has a capacitance forming electrode pattern that is opposed to the capacitance electrode pattern and constitutes a capacitance, and the coupling capacitance capacitance formation electrode pattern is connected to an input terminal or an output terminal. The multilayer band-pass filter according to claim 3 or 4, wherein: 6. A capacitance-forming electrode pattern for a coupling capacitor is further disposed above and below the capacitance-forming electrode pattern with a dielectric layer interposed therebetween, and is connected between an input terminal and an output terminal. The multilayer band-pass filter according to claim 5, wherein an electrode pattern forming a capacitance is formed. 7. A first and second resonator constituted by an LC resonance circuit, a coupling capacitance between the first resonator and an input terminal, and a coupling capacitance between the second resonator and an output terminal. A laminated bandpass filter having a coupling capacitance and a laminated structure of a dielectric layer and an electrode pattern, wherein ground electrodes are provided above and below the laminated structure, and a dielectric layer is provided at the center of the laminated structure. The L1 portion and the C21 portion constituting the LC resonator are formed by a continuous electrode pattern on one side of the surface, and the C11 portion electrode pattern for input / output coupling capacitance is integrally formed between the L1 portion and the C21 portion. C is connected to the input / output terminal, facing the C11 portion with a dielectric layer interposed above and below the pattern.
A C12 portion electrode pattern, a C22 portion electrode pattern facing the C21 portion and connected to the ground terminal, and further facing the C12 portion with a dielectric layer interposed, and a C3 portion for input / output capacitance A multilayer band-pass filter comprising an electrode pattern. 8. The L1 part, the C11 part, and the C21 part are a L1 part electrode pattern that is connected to ground on one side and extends linearly, a C11 part electrode pattern that is continuous with the L1 part and has a wide shape,
An electrode pattern of a C21 portion connected to the C11 portion by a thin connection electrode is formed on a dielectric layer, and the L1 portion, a C
8. The multilayer bandpass filter according to claim 7, wherein two 11 parts and two C21 parts are formed side by side. 9. The multilayer bandpass filter according to claim 8, wherein the L1 portions formed side by side are M-coupled.