JPH07226603A - Laminated dielectric filter - Google Patents

Abstract

PURPOSE:To provide a laminated dielectric filter capable of adjusting the degree of inductive coupling between resonance elements and obtaining a desired band width while satisfying a request to miniaturize a filter. CONSTITUTION:An electrode 41 for input and the electrode 42 for output are formed on a dielectric layer 13. The resonance elements 21 and 23 whose one end parts are respectively connected to a grounding electrode 70 for constituting a 1/4 wavelength type strip line resonator are formed on the dielectric layer 14. A coupling electrode 91 superimposed both on a part of the resonance element 21 and a part of the resonance element 23 is formed on the dielectric layer 15 and a dielectric exposure part 75 for exposing a dielectric from the grounding electrode 70 is provided on the front side face 501 of the laminated body of the dielectric layers 11-17. As a result, the desired band width is obtained, an attenuation electrode is formed separately from a passing band and attenuation characteristics are improved.

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 high frequency circuit filter used for a high frequency circuit radio equipment such as a mobile phone and a laminated dielectric filter used for an antenna duplexer.

[0002]

2. Description of the Related Art FIGS. 14 and 15 are a schematic development view and a perspective view, respectively, of a laminated dielectric filter devised by the present inventors.

In this laminated dielectric filter, an output electrode 42 which overlaps a part of the resonant element 23 on the output end side with the dielectric layer 14 sandwiched is provided on the dielectric layer 13 on the dielectric layer 11. , One end of each of which is connected to the ground electrode 70 to form a quarter-wave stripline resonator is formed on the dielectric layer 14, and one end of which is connected to the ground electrode 70. And the other ends of the electrodes are separated from the open ends of the resonant elements 21 to 23 for a predetermined period of time, and electrodes 31 to 33 facing the resonant elements 21 to 23 are formed on the dielectric layer 14, and on the dielectric layer 15, An input electrode 41 is formed on a part of the resonance element 21 on the input end side so as to overlap with the dielectric layer 15 interposed therebetween, and a dielectric layer 17 having a ground electrode 70 formed on the surface thereof is laminated on the dielectric layer 15. And the dielectric layers 11, 13-15 Preliminary 17 integrally constructed, and then fired to form a laminate 500.

Next, as shown in FIG. 15, a laminated body 500.
The ground electrode 70 is formed on the upper and lower surfaces and the side surface excluding the input terminal portion 61 and the output terminal portion 62. Further, the laminated body 50
0 into the input terminal portion 61 on one side surface of the ground electrode 70
Forming an input terminal 51 that is insulated from the input electrode 41 and is also insulated from the ground electrode 70 in the output terminal portion 62 on the other side surface of the laminated body 500.
Moreover, the output terminal 52 connected to the output electrode 42 is formed.

An equivalent circuit of the above-mentioned laminated dielectric filter is shown in FIG. In FIG. 16, reference numeral 111
Is the capacitance between the resonance element 21 and the input electrode 41,
Reference numeral 112 is a capacitance between the resonance element 23 and the output electrode 42, and reference numerals 121 to 123 are the resonance element 21 respectively.
Between the resonance element 22 and the electrode 32, the capacitance between the resonance element 22 and the electrode 32, and the capacitance between the resonance element 23 and the electrode 33. Reference numeral 132 indicates induction between the resonance element 21 and the resonance element 22. Reference numeral 133 is an inductance indicating coupling, and reference numeral 133 is an inductance indicating inductive coupling between the resonance element 22 and the resonance element 23, which constitutes a bandpass filter. The capacitances 211, 221, 2 of the parallel resonance circuit are
31 and the inductances 212, 222, 232 are
These are capacitance and inductance when the resonant elements 21, 22, and 23 are equivalently converted.

In this laminated dielectric filter, electrodes 31, 32 and 33 are provided which face the open ends of the resonant elements 21, 22 and 23, respectively. Therefore, capacitances 121, 122 and 123 are formed between the open ends of the resonance elements 21, 22 and 23 and the electrodes 31, 32 and 33, respectively, and these capacitances 121 to 123 are also the resonance elements 21 and 123.
It is added to the electrostatic capacitances 211, 221, and 231 of the parallel resonant circuit when 22 and 23 are equivalently converted. Therefore, if the resonance frequencies are the same, the inductance of the parallel resonance circuit can be small, and the resonance element 21,
The lengths of 22 and 23 are also shortened, and the length of the whole laminated dielectric filter can be shortened.

[0007]

However, when the electric length of the resonant elements is shortened in order to reduce the size of the laminated dielectric filter as described above, the resonant elements are more strongly inductively coupled to each other and the characteristics of the filter are improved. There is a problem that the band tends to be too wide and a filter having a desired bandwidth cannot be obtained.

Even if the electrodes 31, 32 and 33 facing the open ends of the resonant elements 21, 22 and 23 are not provided, the resonant elements are too strongly coupled to each other and the filter characteristics are broadened. In some cases, it is difficult to obtain a filter that is downsized and has a desired bandwidth.

Therefore, an object of the present invention is to provide a laminated dielectric filter which can adjust the degree of inductive coupling between resonance elements and obtain a desired bandwidth while satisfying the demand for miniaturization of the filter. is there.

[0010]

According to the present invention, a dielectric having an upper surface, a lower surface and a side surface, a first ground electrode provided on the upper surface of the dielectric, and the lower surface of the dielectric. A second ground electrode provided on the side surface of the dielectric body, a third ground electrode provided on the side surface of the dielectric body, and a third ground electrode provided inside the dielectric body, one end of which is located in the first short circuit region of the side surface. One-side short-circuit type first short-circuited to the earth electrode of
Second resonance element provided adjacent to the first resonance element in the dielectric body, and one end of which is short-circuited to the third ground electrode in the second short-circuit region of the side surface. And a coupling electrode facing a part of the first resonant element and a part of the second resonant element in the dielectric layer. And a dielectric exposed portion for exposing the dielectric from the third ground electrode is provided between the first short-circuited region and the second short-circuited region. Provided.

[0011]

In the present invention, the one-side short-circuit type first resonance element and the second resonance element are provided adjacent to each other, and a part of the first resonance element and a part of the second resonance element are opposed to each other. Since the coupling electrode is provided, a capacitance is formed between the coupling electrode and each of the first resonant element and the second resonant element. Since the combined capacitance of these capacitances is connected in parallel with the inductive coupling formed between the first resonant element and the second resonant element, these capacitances cause the first resonant element and the The inductive coupling formed between the two resonant elements can be suppressed. Therefore, by adjusting the value of this capacitance, the degree of inductive coupling between the first resonant element and the second resonant element can be adjusted, and a filter having a desired bandwidth can be obtained. The capacitance can be easily adjusted by changing the overlapping area between the first resonant element and the coupling electrode and the distance between them, and the overlapping area between the second resonant element and the coupling electrode and the distance between them. Can be done.

Further, as described above, in the present invention,
By providing the coupling electrodes facing both the first and second resonant elements adjacent to each other, the combined capacitance of the electrostatic capacitances formed between the first and second resonant elements and the coupling electrode becomes the first and the second resonant elements, respectively. Since it is connected in parallel with the inductive coupling formed between the second resonant elements, a parallel resonant circuit composed of an electrostatic capacitance and an inductance is inserted between the adjacent first and second resonant elements. It will be. And
Since the impedance of the parallel resonant circuit composed of the electrostatic capacity and the inductance changes from inductive to capacitive before and after the parallel resonant point, it is respectively connected between the adjacent first and second resonant elements and the coupling electrode. By adjusting the value of the formed capacitance, the coupling between the resonant elements can be made inductive or capacitive. Considering the case where the coupling between the resonance elements is inductive, a filter having an attenuation pole on the high frequency side of the pass band is obtained because the parallel resonance point exists on the high frequency side of the pass band. If the coupling between them is made capacitive, there will be a parallel resonance point on the low frequency side of the pass band, and a filter with an attenuation pole on the low frequency side of the pass band will be obtained. Can be improved.

Furthermore, in the present invention, the first short-circuit region in which the first resonance element is short-circuited to the third ground electrode and the second short-circuit region in which the second resonance element is short-circuited to the third ground electrode are provided. Since the dielectric exposed portion where the dielectric is exposed from the third ground electrode is provided between the short-circuited area and the short-circuited area, the third ground electrode is not provided in this dielectric exposed portion. The first short circuit area and the second
It is possible to prevent the third ground electrode from acting as an inductance due to the flow of a current between the short circuit area and the short circuit area, and as a result, the inductive coupling between the first resonant element and the second resonant element is weakened. be able to. The inductive coupling between the first resonant element and the second resonant element can be weakened by increasing the distance between the first resonant element and the second resonant element. This is not preferable because the size of the dielectric filter becomes large and it goes against the demand for miniaturization.

As described above, in the present invention, not only the coupling electrodes facing the part of the first resonant element and the part of the second resonant element which are adjacent to each other are provided, but also the first resonant element is provided. The dielectric is exposed from the third ground electrode between the first short-circuited region short-circuited to the third ground electrode and the second short-circuited region where the second resonant element is short-circuited to the third ground electrode. Since the dielectric exposed portion is provided, the parallel resonant circuit including the capacitance and the inductance is inserted between the first and second resonant elements to inductively couple the first resonant element and the second resonant element. Not only can the strength of the filter be adjusted by the capacitance, but also the strength of the inductive coupling itself between the first resonant element and the second resonant element can be adjusted. As a result, the bandwidth of the filter and the position of the attenuation pole can be adjusted. And can be changed separately and the desired filter It can be obtained sex easily.

The bandwidth of the filter is determined by the magnitude of the absolute value of the admittance of the coupling circuit between the first and second resonant elements at the center frequency of the filter.
In the present invention, since the coupling electrodes facing the part of the first resonance element and the part of the second resonance element which are adjacent to each other are provided, the capacitance between the first and second resonance elements is increased. A parallel resonant circuit consisting of an inductance will be inserted. Therefore, the coupling circuit between the first and second resonant elements is a parallel resonant circuit of capacitance and inductance, and its admittance jY is jY = j (ωC-1 / ωL) (1) (here Where C is the coupling capacitance between the first and second resonant elements, and L is the inductance when the inductive coupling between the first and second resonant elements is equivalently converted).

Now, by providing capacitances on the open end sides of the first and second resonant elements, the lengths of the first and second resonant elements are shortened, resulting in the first and second resonant elements. If the inductive coupling due to the distributed coupling between the resonant elements of (1) becomes large (that is, the inductance L becomes small), the coupling capacitance C is correspondingly increased, so that the first and second
The admittance jY between the resonant elements can be set to a desired value, and the coupling degree between the first and second resonant elements can be set to a desired value.

As described above, even if the inductive coupling of the coupling circuit becomes large, the coupling degree between the first and second resonant elements can be adjusted by increasing the coupling capacitance of the coupling circuit.
As a result, a filter having a desired bandwidth can be obtained. However, when the inductive coupling of the coupling circuit increases and the inductance L decreases, the frequency of the attenuation pole of the filter generated by the parallel resonant circuit of the capacitance and the inductance approaches the center frequency of the filter. As a result, the attenuation characteristic of the region on the side opposite to the pass band with respect to the attenuation pole (see region C in FIG. 10) deteriorates.

That is, when the coupling between the first and second resonant elements is capacitively coupled (Y> 0) and an attenuation pole occurs on the low frequency side of the pass band, the first and second resonant elements are present. Assuming that the inductive coupling between the elements becomes strong and the value of the inductance L becomes 1/2, the capacitance C ′ required to keep the value of Y constant and the width of the pass band constant is (1) the equation, ωC '= 2ωC-Y ...... (2) , and the parallel resonance frequency omega _p of this _{time, ω p = 1 / √ {} L (C-Y / 2ω)} ...... (3) , and the now Since Y> 0, the parallel resonance frequency ω ₀ before the inductive coupling between the first and second resonance elements becomes strong, ω ₀ = 1 / √ (LC) (4), which is higher than the parallel resonance frequency and passes through the filter. It approaches the center frequency of the band.

Further, when the coupling between the first and second resonant elements is inductively coupled (Y <0) and an attenuation pole is generated on the high frequency side of the pass band, the first and second resonant elements. The inductive coupling between them becomes stronger, and the value of the inductance L becomes 1 /
If it becomes 2, the capacitance C ′ required to keep the value of Y constant and the width of the pass band constant is ωC ′ = 2ωC−Y (5) from equation (1) The parallel resonance frequency ω _{p at this time} is ω _p = 1 / √ {L (C−Y / 2ω)} (6), and since Y <0 now, the inductive coupling between the first and second resonant elements is Becomes lower than the parallel resonance frequency ω ₀ , ω ₀ = 1 / √ (LC) (7) before becoming stronger, and also approaches the center frequency of the pass band of the filter.

As the frequency characteristic required for the filter, not only the frequency characteristic in the vicinity of the pass band but also a predetermined amount of attenuation in the frequency region away from the pass band is required. Therefore, the attenuation pole is the center frequency of the pass band. If too close to, it may be difficult to form a filter that satisfies the standard.

In the present invention, the first resonant element is the third
And a second short-circuit region in which the second resonant element is short-circuited to the third ground electrode, the dielectric being exposed from the third ground electrode. Since the exposed portion is provided, the inductive coupling itself between the first and second resonant elements can be reduced, and as a result, the attenuation pole is separated from the pass band of the filter, and the region on the opposite side of the pass band from the attenuation pole is provided. The amount of attenuation in (see the area C in FIG. 10) is increased, and the attenuation characteristic is improved.

That is, if the third ground electrode exists continuously between the first short-circuited region where the first resonant element is short-circuited and the second short-circuited region where the second resonant element is short-circuited. Since the third ground electrode also has a certain impedance, a current flows between the first short-circuited region and the second short-circuited region and acts as an inductance, and as a result, the first resonant element and the Inductive coupling is generated between the second resonance element and the third ground electrode. Therefore, this inductive coupling is added between the first and second resonant elements, the inductive coupling between the first and second resonant elements increases, and the attenuation pole approaches the center frequency of the pass band. There is a case where the damping characteristic deteriorates and the standard is not satisfied.

In such a case, as in the present invention, the third
And a second short circuit in which a first resonance element is short-circuited to a third ground electrode and a second resonance element is short-circuited to a third ground electrode. By providing a dielectric exposed portion where the dielectric is exposed from the third ground electrode between the first resonance element and the second resonance element, induction is provided between the first resonance element and the second resonance element through the third ground electrode. It is possible to prevent the addition of sexual coupling, and as a result, it is possible to reduce the inductive coupling between the first and second resonant elements. Therefore, the attenuation pole is separated from the pass band of the filter, the amount of attenuation in the region opposite to the pass band with respect to the attenuation pole is increased, and the attenuation characteristic is improved.

The amount of suppression of the inductive coupling added between the first resonant element and the second resonant element via the third ground electrode is determined by the first short circuit area and the second short circuit area. This can be adjusted by changing the width and shape of the exposed dielectric portion provided between the first and second resonant elements, and as a result, the inductive coupling between the first and second resonant elements can be adjusted. The width and shape of the exposed dielectric part can be easily changed by changing the shape of the third ground electrode provided on the side surface of the dielectric.

[0025]

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

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

An inner layer ground electrode 81, which overlaps the open ends of the resonant elements 21 and 23 with the dielectric layers 13 and 14 sandwiched therebetween and whose end is connected to the ground electrode 70, is laminated on the dielectric layer 11. It is formed on the body layer 12.

On the dielectric layer 13, the resonance element 2 on the input end side is formed.
1. An input electrode 41 that overlaps with a part of the dielectric layer 14 with the dielectric layer 14 interposed therebetween
Also, an output electrode 42 is formed so as to overlap the part of the resonance element 23 on the output end side with the dielectric layer 14 in between.

One end of the ground electrode 70 has a short circuit area 201.
And 203, which are connected to each other to form a quarter-wave type stripline resonator, respectively.
Are formed on the dielectric layer 14 to form a combline type filter. Further, electrodes 31 and 33, one end of which is connected to the ground electrode 70 and the other end of which is separated from the open ends of the resonant elements 21 and 23 for a predetermined period and which oppose the open ends of the resonant elements, respectively, on the dielectric layer 14. To form.

A coupling electrode 91 is formed on the dielectric layer 15 so as to overlap the resonance element 21 and the resonance element 23 with the dielectric layer 15 in between.

An inner layer ground electrode 82 is formed on the dielectric layer 16 so as to overlap the open ends of the resonant elements 21 and 23 with the dielectric layers 15 and 16 sandwiched therebetween and the ends of which are connected to the ground electrode 70.

A ground electrode 70 is formed on the surface of the dielectric layer 16.
Of the dielectric layers 11 to 11
17 is integrally configured and then fired to form the laminated body 500.

The upper surface 503, the lower surface 505 of the laminated body 500,
Input terminal portion 61, output terminal portion 62 and dielectric exposed portion 7
As shown in FIG. 2, a ground electrode 70 is formed on the side surface except for 5. The dielectric exposed portion 75 is the front side surface 5 of the laminated body 500.
01, the upper surface of which is the upper surface 503 of the stack 500.
And the lower part thereof reaches the lower surface 505 of the laminated body 500. The left end of the dielectric exposed portion 75 matches the right end of the resonant element 21, and the right end of the exposed dielectric portion 75 is the resonant element 23.
The width of the dielectric exposed portion 75 is the same as the left end of the resonant element 2 and
Equal to the distance between 1 and the resonant element 23.

Further, an input terminal 51, which is insulated from the ground electrode 70 and connected to the input electrode 41, is formed in the input terminal portion 61 on one side surface of the laminate 500, and similarly, the laminate 500. An output terminal 52, which is insulated from the ground electrode 70 and connected to the output electrode 42, is formed in the output terminal portion 62 on the other side surface of the.

In the present embodiment configured as described above,
Resonant elements 21, 23, electrodes 31, 33, input electrode 4
1, a plan view of the spatial configuration of the output electrode 42, the inner-layer ground electrodes 81 and 82, the coupling electrode 91, the ground electrode 70, and the dielectric exposed portion 75, a cross-sectional view taken along the line XX, and YY.
The sectional views taken along the lines are as shown in FIGS. 3, 4 and 5.

The lengths of the resonance elements 21 and 23 are such that their electric lengths are each not more than 1/4 wavelength,
There is an inductive coupling between 1 and 23. The inductance 131 is an equivalent representation of this inductive coupling.

The open ends of the resonant elements 21 and 23 and the electrode 31,
Capacitances 121 and 123 are formed between the electrodes 33 and 33, respectively.

A capacitance 111 is formed between the input electrode 41 and the resonance element 21, and a capacitance 112 is formed between the output electrode 42 and the resonance element 23.

A capacitance 151 is formed between the resonance element 21 and the coupling electrode 91, and the resonance element 23 and the coupling electrode 91 are formed.
A capacitance 152 is formed between and.

The open end of the resonant element 21 and the inner layer ground electrode 8
Capacitances 141 and 142 are respectively formed between the open ends of the resonance element 23 and the inner-layer earth electrode 8.
Capacitances 145 and 146 are formed between the electrodes 1 and 82, respectively.

The equivalent circuit of the laminated dielectric filter configured as described above is as shown in FIG. 6 and exhibits bandpass characteristics.

In this embodiment, since the capacitances 151 and 152 are connected in parallel with the inductance 131 formed between the resonance element 21 and the resonance element 23, the capacitances 151 and 152 are connected. Thus, the inductive coupling formed between the resonance element 21 and the resonance element 23 and represented by the inductance 131 here can be suppressed. Therefore, the degree of inductive coupling between the resonance element 21 and the resonance element 23 can be adjusted by adjusting the values of the electrostatic capacitances 151 and 152, and a filter having a desired bandwidth can be obtained. The capacitance values of the electrostatic capacitances 151 and 152 are adjusted by adjusting the overlapping area of the resonant element 21 and the coupling electrode 91 and the distance between them, and the overlapping area of the resonant element 23 and the coupling electrode 91 and the distance between them. Can be easily performed by changing

Further, as described above, in the present embodiment, by providing the coupling electrodes 91 facing the resonance elements 21 and 23 together, the static electrodes formed between the resonance elements 21 and 23 and the coupling electrode 91 respectively. Inductance 131 in which capacitances 151 and 152 are formed between the resonance elements 21 and 23
And the resonance elements 21 and 2 are connected in parallel.
A parallel resonance circuit including the electrostatic capacitances 151 and 152 and the inductance 131 is inserted between the three. Since the impedance of the parallel resonant circuit formed of the electrostatic capacitances 151 and 152 and the inductance 131 changes from inductive to capacitive before and after the parallel resonant point, the resonant elements 21 and 23 and the coupling electrode 91 are connected. The coupling between the resonant elements 21 and 23 can be made inductive or capacitive by adjusting the capacitance values of the electrostatic capacitances 151 and 152 formed between them. Now, the resonance element 2
Considering the case where the coupling between 1 and 23 is inductive, a parallel resonance point exists on the high frequency side of the pass band, so that a filter having an attenuation pole on the high frequency side of the pass band can be obtained. If the coupling between No. 23 and No. 23 is made capacitive, a parallel resonance point exists on the low frequency side of the pass band, and a filter having an attenuation pole on the low frequency side of the pass band is obtained. The damping characteristics can be improved.

Furthermore, in this embodiment, the ground electrode 70 is not provided on the front side surface 501 of the laminated body 500 between the resonance element 21 and the resonance element 23, and the resonance element 21 is not provided. Since the front side surface 501 of the dielectric 500 between the resonant element 23 and the resonant element 23 is the dielectric exposed portion 75 exposed from the ground electrode 70, the inductive coupling between the resonant element 21 and the resonant element 23 via the ground electrode 70. Can be prevented, and as a result, inductive coupling between the resonant elements 21 and 23 can be reduced. Therefore, the attenuation pole is separated from the pass band of the filter, the amount of attenuation in the region opposite to the pass band with respect to the attenuation pole is increased, and the attenuation characteristic is improved.

FIG. 7 is a perspective view showing a laminated dielectric filter in which the ground electrode 70 is provided on the entire front surface 501 of the laminated body 500 and the dielectric exposed portion 75 is not provided in this embodiment. 8 is the resonance element 2 in this case
1 is a plan view showing the spatial configuration of 1, 23, electrodes 31, 33, input electrode 41, output electrode 42, inner layer ground electrodes 81, 82, coupling electrode 91, and ground electrode 70.

A short-circuit area 201 where the resonance element 21 is short-circuited.
The ground electrode 70 continuously exists also between the short circuit area 203 where the resonance element 23 is short-circuited.
Since it also has a certain constant impedance, a current flows between the short-circuit region 201 and the short-circuit region 203 and acts as an inductance, and as a result, the ground electrode 70 is interposed between the resonance element 21 and the resonance element 23. And inductive coupling occurs. Here, the inductance 171
It is represented by.

FIG. 9 shows that the ground electrode 70 is also formed on the front side surface 501 of the laminated body 500 between the resonant elements 21 and 23 as described above.
3 shows an equivalent circuit of a laminated dielectric filter in the case of continuously providing. The inductance 171 generated via the ground electrode 70 is added to the inductance 131 existing between the resonance elements 21 and 23, the inductive coupling between the resonance elements 21 and 23 becomes large, and the attenuation pole becomes In some cases, the characteristics may not meet the standard because the attenuation characteristics may be deteriorated due to being too close to the center frequency of the pass band.

FIG. 10 shows the frequency characteristics of the laminated dielectric filter constructed as described above. The broken line is the front side surface 501 of the laminated body 500, which is the resonance element 21.
Short circuit area 201 and short circuit area 203 of the resonance element 23
The frequency of the laminated dielectric filter when the ground electrode 70 is not provided between the resonator elements 21 and 23 and the front side surface 501 of the dielectric 500 between the resonant elements 21 and 23 is the dielectric exposed portion 75 exposed from the ground electrode 70. The characteristics indicate that the solid line is provided with the ground electrode 70 on the entire front surface 501 of the laminated body 500,
The frequency characteristic of the laminated dielectric filter in the case where the dielectric exposed portion 75 is not provided is shown.

When the ground electrode 70 is provided on the entire front side surface 501 of the laminated body 500 and the dielectric exposed portion 75 is not provided (see the solid line), the attenuation pole B is too close to the center frequency of the pass band A of the filter. Although the attenuation characteristic is deteriorated, the ground electrode 70 is not provided on the front side surface 501 of the laminated body 500, which is between the resonance element 21 and the resonance element 23, and the resonance element 21 and the resonance element are not provided. In the case where the front side surface 501 of the laminate 500 between 23 is the dielectric exposed portion 75 exposed from the ground electrode 70 (see the broken line), the attenuation pole B occurs on the lower frequency side and the pass band of the filter is increased. The amount of attenuation increases in a region away from A and on the side opposite to the pass band with respect to the attenuation pole B (C region in FIG. 10), and the attenuation characteristic is improved.

In this embodiment, the resonance element 21
Of the frequency characteristics when the dielectric exposed portion 75 is provided in the case where the overlapping area of the coupling electrode 91 and the coupling electrode 91 and the distance therebetween and the overlapping area of the resonant element 23 and the coupling electrode 91 and the distance between them are constant. Since the change is shown in FIG. 10, the band width of the pass band A of the filter is wide, but the overlapping area of the resonance element 21 and the coupling electrode 91 and the distance between them, the resonance element 23 and the coupling electrode 9 are large.
If the capacitance values of the electrostatic capacitances 151 and 152 formed between the resonant elements 21 and 23 and the coupling electrode 91 are reduced by changing the overlapping area with 1 and the distance therebetween, from FIG. Obviously, the attenuation pole B can be separated from the passband A while keeping the bandwidth of the passband A of the filter constant. Moreover, the amount of attenuation in the region (C region) on the side opposite to the pass band A with respect to the attenuation pole B is increased, and the attenuation characteristic is improved. In FIG. 11, the solid line shows the frequency characteristic when the dielectric exposed portion 75 is not provided, and the broken line shows the frequency characteristic when the dielectric exposed portion 75 is provided.

Further, in this embodiment, the resonance element 2
Inner layer ground electrodes 81, 82 facing the open ends of 1, 23
Is provided, the capacitance 1 formed between the open end of the resonance element 21 and the inner-layer ground electrodes 81, 82, respectively.
41 and 142 are added to the capacitance 211 of the parallel resonance circuit when the resonance element 21 is equivalently converted, and the capacitance 145 formed between the open end of the resonance element 23 and the inner-layer ground electrodes 81 and 82, respectively. , 146 are added to the capacitance 231 of the parallel resonance circuit when the resonance element 23 is equivalently converted. Therefore, if the resonance frequencies are the same, the inductances 212 and 232 of the parallel resonance circuit can be small. As a result, the lengths of the resonant elements 21 and 23 are shortened, and the length of the entire laminated dielectric filter can be shortened.

In this case, in order to downsize the laminated dielectric filter, the inner layer ground electrodes 81 and 82 and the resonance element 2 are arranged.
When the facing area with 1 and 23 is increased, the resonance element 2
1 and the resonance element 23 are more strongly inductively coupled to each other and the characteristic of the filter is broadened over a wide band. However, in this embodiment, the resonance elements 21 and 23 are provided with the coupling electrodes 91 facing each other. Therefore, not only can the inductive coupling formed between the resonance elements 21 and 23 be suppressed by the capacitances 151 and 152 formed between the coupling electrode 91 and the resonance elements 21 and 23, respectively, Laminate 500 between the resonant element 21 and the resonant element 23
Since the dielectric exposed portion 75 is also provided on the front side surface 501 of the above, the strength of the inductive coupling itself between the resonant element 21 and the resonant element 23 can be reduced, and a filter having a desired bandwidth can be easily obtained. You can

Next, a method of manufacturing the laminated dielectric filter of the first embodiment will be described.

In the laminated dielectric filter of this embodiment, the resonant elements 21 and 23, the electrodes 31 and 33, the input electrode 41, the output electrode 42, the inner-layer ground electrodes 81 and 82, and the coupling electrode 91 are completely dielectric. Since it is built into the
1, 23, electrodes 31, 33, input electrode 41, output electrode 42, inner layer ground electrodes 81, 82 and coupling electrode 91.
It is desirable to use a conductor with a low loss and a low specific resistance, 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 which 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 -based composition (Re: rare earth component) with some glass-forming components or glass powder added, barium oxide-titanium oxide-neodymium oxide-based dielectric ceramic composition powder with some glass powder added There is something I did.

As an example, MgO: 18 wt% -Al _{2
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 sheet having a thickness of 0.2 mm to 0.5 mm was prepared by a doctor blade method.

Next, the conductor patterns shown in FIG. 1 are printed with the silver paste as the conductor paste, and then the green sheets necessary for adjusting the thickness of the green sheets on which these conductor patterns are printed are overlapped and drawn. After stacking and stacking so as to have the structure No. 1, the stack 500 was fired at 900 ° C. to form a stack 500.

The upper surface 503, the lower surface 505, the input terminal portion 61, and the output terminal portion 62 of the laminated body 500 configured as described above.
As shown in FIG. 2, a ground electrode 70 made of a silver electrode is printed on the side surface except the dielectric exposed portion 75, and further insulated from the ground electrode 70, and the input electrode 41 and the output electrode 42 are separately provided. The silver electrodes to be connected were printed as the input terminal 51 and the output terminal 52 in the input terminal portion 61 and the output terminal portion 62, and the printed electrodes were baked at 850 ° C.

FIG. 12 is a perspective view for explaining the laminated dielectric filter of the second embodiment of the present invention. In the first embodiment described above, the left end of the exposed dielectric portion 75 matches the right end of the resonant element 21, the right end of the exposed dielectric portion 75 matches the left end of the resonant element 23, and the dielectric The width of the exposed portion 75 is equal to the distance between the resonant element 21 and the resonant element 23, whereas in the present embodiment, the left end portion of the dielectric exposed portion 75 is located inside the right end portion of the resonant element 21. That is, the right end portion of the dielectric exposed portion 75 is located inside the left end portion of the resonant element 23, and the width of the dielectric exposed portion 75 is smaller than the distance between the resonant element 21 and the resonant element 23. First
Although it is different from the embodiment described above, the other configurations are the same and the manufacturing method is also the same. In the present embodiment, the dielectric exposed portion 75
Is smaller than that of the first embodiment, the inductive coupling is added between the resonant element 21 and the resonant element 23 through the ground electrode 70 by providing the dielectric exposed portion 75. The effect of suppressing is smaller than that of the first embodiment. Therefore, the amount by which the attenuation pole moves away from the pass band of the filter also becomes small.

FIG. 13 is a perspective view for explaining a laminated dielectric filter of the third embodiment of the present invention. In the first embodiment described above, the upper portion of the dielectric exposed portion 75 reaches the upper surface 503 of the laminated body 500, and the lower portion thereof reaches the laminated body 5.
In the present embodiment, the upper portion of the dielectric exposed portion 75 does not reach the upper surface 503 of the laminated body 500 and the lower portion of the dielectric exposed portion 75 does not reach the lower surface 505 of the laminated body 500. It differs from the first embodiment in that it does not reach the lower surface 505 and the dielectric exposed portion 75 is provided in the central portion of the front side surface 501 of the laminated body 500, but other configurations are the same and the manufacturing method is also the same. It is the same. Also in this embodiment, by providing the dielectric exposed portion 75, the resonant element 21 and the resonant element 2 are provided.
It is possible to prevent inductive coupling from being added to the filter 3 through the ground electrode 70, so that the attenuation pole is separated from the pass band of the filter, and the attenuation pole is in a region opposite to the pass band. The amount is increased and the damping characteristic is improved.

[0063]

According to the present invention, the one-side short-circuit type first resonance element and the second resonance element are provided adjacent to each other, and a part of the first resonance element and a part of the second resonance element are provided. Since the coupling electrodes facing each other are provided, the capacitance is connected in parallel with the inductive coupling formed between the first resonant element and the second resonant element, and this capacitance causes Inductive coupling formed between the first resonance element and the second resonance element can be suppressed, and a filter having a predetermined bandwidth can be obtained.

Further, by providing the coupling electrodes facing the first and second resonant elements adjacent to each other in this way, electrostatic capacitance and inductance are provided between the first and second resonant elements adjacent to each other. A parallel resonance circuit that consists of
As a result, the attenuation pole is formed on the high frequency side or the low frequency side of the pass band of the filter, and the attenuation characteristic of the filter is improved.

Furthermore, in the present invention, not only the coupling electrode facing the part of the first resonant element and the part of the second resonant element which are adjacent to each other is provided, but the first resonant element is The dielectric is exposed from the third ground electrode between the first short-circuited region short-circuited to the third ground electrode and the second short-circuited region where the second resonant element is short-circuited to the third ground electrode. Since the dielectric exposed portion is provided, a parallel resonant circuit including a capacitance and an inductance is inserted between the first and second resonant elements to induce induction between the first resonant element and the second resonant element. Not only can the strength of the coupling be adjusted by capacitance, but the first
It is also possible to adjust the strength of the inductive coupling itself between the second resonance element and the second resonance element, and as a result, the bandwidth of the filter and the position of the attenuation pole can be separately changed. The filter characteristic can be easily obtained.
By setting the position of the attenuation pole away from the pass band of the filter, the amount of attenuation on the side opposite to the pass band with respect to the attenuation pole can be increased, and the attenuation characteristic can be further improved.

[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 a plan view of a main part of the laminated dielectric filter according to the first embodiment of the present invention.

4 is a sectional view taken along line XX of FIG.

5 is a cross-sectional view taken along the line YY of FIG.

FIG. 6 is an equivalent circuit diagram of the laminated dielectric filter according to the first embodiment of the present invention.

FIG. 7 is a perspective view of a laminated dielectric filter having no exposed dielectric portion.

FIG. 8 is a plan view of a main part of a laminated dielectric filter having no exposed dielectric part.

FIG. 9 is an equivalent circuit diagram of a laminated dielectric filter having no exposed dielectric portion.

FIG. 10 is a diagram for explaining frequency characteristics of the laminated dielectric filter according to the first embodiment of the present invention.

FIG. 11 is a diagram for explaining another frequency characteristic of the laminated dielectric filter of the present invention.

FIG. 12 is a perspective view of a laminated dielectric filter according to a second embodiment of the present invention.

FIG. 13 is a perspective view of a laminated dielectric filter according to a third embodiment of the present invention.

FIG. 14 is a schematic development view of a conventional laminated dielectric filter devised by the present inventors.

FIG. 15 is a perspective view of a conventional laminated dielectric filter devised by the present inventors.

FIG. 16 is an equivalent circuit diagram of a conventional laminated dielectric filter devised by the present inventors.

[Explanation of symbols]

11-17 ... Dielectric layer, 21-23 ... Resonant element, 31-
33 ... Electrodes, 41 ... Input electrodes, 42 ... Output electrodes, 5
DESCRIPTION OF SYMBOLS 1 ... Input terminal, 52 ... Output terminal, 61 ... Input terminal part, 6
2 ... Output terminal part, 70 ... Ground electrode, 75 ... Dielectric exposed part, 81, 82 ... Inner layer ground electrode, 91 ... Coupling electrode, 1
11, 112 ... electrostatic capacitance, 121-123 ... electrostatic capacitance,
131 to 133 ... Inductance, 141 ... Capacitance,
142 ... Electrostatic capacity, 145 ... Electrostatic capacity, 146 ... Electrostatic capacity, 151 ... Electrostatic capacity, 152 ... Electrostatic capacity, 171 ... Inductance, 201 ... Short circuit area, 203 ... Short circuit area,
211 ... Capacitance, 212 ... Inductance, 221 ...
Capacitance, 222 ... inductance, 231, ... capacitance, 232 ... inductance, 500 ... laminated body, 501
... front side surface, 503 ... top surface, 505 ... bottom surface

Claims (1)

[Claims] 1. A dielectric having an upper surface, a lower surface and a side surface, a first ground electrode provided on the upper surface of the dielectric, and a second ground electrode provided on the lower surface of the dielectric. A third ground electrode provided on the side surface of the dielectric body, and a one-side short-circuit type provided in the dielectric body and having one end short-circuited to the third ground electrode in a first short-circuit region of the side surface A first resonance element, and a one-sided short-circuited type provided in the dielectric body adjacent to the first resonance element and having one end short-circuited to the third ground electrode in a second short-circuit region of the side surface. A second resonance element, and a coupling electrode facing a part of the first resonance element and a part of the second resonance element in the dielectric layer. , The first short circuit region of the side surface and the second short circuit region Between 絡領 region, the multilayer dielectric filter, wherein the dielectric is provided with a dielectric substrate exposed portion exposed from the third ground electrode.