JPH06283903A - Dielectric filter - Google Patents

Abstract

PURPOSE:To provide a dielectric filter which can easily adjust the degree of coupling between the strip lines set on the adjacent dielectric layers and also can be miniaturized. CONSTITUTION:A dielectric filter consists of a ground electrode 4, an input-side strip line 2, an output-side strip line 3, and a ground electrode 5 which are successively laminated on a dielectric laminated substrate 1 via a dielectric layer. Either one of both lines 2 and 3 is formed in an approximately L shape including the lst straight line parts 2x and 3x and the 2nd straight line parts 2y and 3y. Then both lines 2 and 3 are connected together in a state where the parts 2x and 3x are opposite to each other via the dielectric layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric filter whose coupling degree can be easily adjusted and whose mounting area can be reduced.

[0002]

2. Description of the Related Art Conventionally, a dielectric filter has a through-hole formed in a rectangular parallelepiped block made of a dielectric porcelain, and a conductor is provided on the inner surface of the through-hole and the outer peripheral surface except one end surface having the opening of the through-hole. A plurality of resonators formed by forming a film are coupled. Further, a plurality of through holes are formed in one dielectric porcelain block, and at the same time, a conductor film is formed on the outer peripheral surface excluding the inner surface of the plurality of through holes and one end surface having the openings of the through holes. It was

Furthermore, without using a dielectric ceramic block,
Based on the technique of a multilayer circuit board, a pair of capacitor electrode patterns is formed on both front and back surfaces of a dielectric ceramic substrate, and a coil pattern to be connected to the capacitor electrode pattern is formed on either surface to form an L- There is a resonator forming a C resonance circuit, and two or more such resonators are arranged in parallel to form a filter.

This is because when the resonance frequency is less than 1 GHz, the lumped-constant concept holds, and the filter operates, but when the resonance frequency exceeds 1 GHz, the lumped-constant concept shows that the capacitance value of the capacitor of the LC resonator and The inductance value of the coil becomes very small, and there is a limit to the formation of the capacitor electrode pattern and the coil pattern.

Therefore, as a dielectric filter based on the concept of distribution constant, there is a laminated dielectric filter in which a plurality of dielectric layers are laminated.

A plurality of strip lines are arranged in parallel between two dielectric layers, and the dielectric layer sandwiching the strip lines is sandwiched between two ground electrodes.

In this laminated dielectric filter, the strip lines arranged in parallel are formed in a straight line, and the degree of coupling between the strip lines is adjusted by setting the interval between the adjacent strip lines to a predetermined interval. This has been achieved by variously changing the material of the dielectric layer and using a material having a specific dielectric constant of a predetermined value.

[0008]

However, in the above-mentioned laminated dielectric filter, when the coupling degree is set at the intervals between the strip lines, the strip lines are formed by forming the conductor film by the screen printing method. For example, blurring occurs, and the interval is 8
If the thickness is 0 μm or less, there are problems such as unstable characteristics.

On the contrary, when the distance between the two strip lines is increased to weaken the degree of coupling, the length of the filter corresponding to the length of the strip line does not change accordingly, but the filter The width direction increases, and the area occupied by the mounting when mounted on the printed wiring board significantly increases.

The present invention has been devised in view of the above-mentioned problems, and an object thereof is to easily adjust the degree of coupling between strip lines that are coupled to each other and to easily reduce the mounting area. It is to provide a dielectric filter.

[0011]

According to the present invention, strip lines are respectively arranged between different dielectric layers, and at least one of the strip lines adjacent to each other with the dielectric layer sandwiched is a first straight line. And a second straight line portion, each of which has a substantially L-shape, and is electromagnetically coupled to an adjacent strip line at the first straight line portion.

[0012]

According to the present invention, the coupling between the resonance means forming the dielectric filter, that is, the coupling between the strip lines adjacent to each other via the dielectric layer is performed by at least one strip line having a substantially L-shaped first shape. In the straight part of. Therefore, since the adjustment of the coupling degree is determined by the length of the first straight line portion,
The adjustment becomes easy. Further, since the adjacent strip lines are coupled to each other via the dielectric layer, it is possible to ignore the blurring of the conductor film at the time of forming the conductor to be the strip line, which further reduces the mounting area.

Further, as described in claim 2,
By disposing the intermediate conductor connected to one end of the strip line between the dielectric layers different from the dielectric layer in which the strip line is arranged, the length of the strip line connected to the intermediate conductor can be reduced, The mounting area can be further reduced.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings.

FIG. 1 is an external perspective view of a dielectric filter of the present invention, FIG. 2 (a) is a structural view showing a cross section taken along line XX in the drawing, and FIG. 2 (b) is Y- in the drawing. FIG. 4 is a structural view showing a cross section taken along line Y, and FIG. 3 is an exploded perspective view of a dielectric laminated substrate.
In the figure, a filter using two strip lines on the input side and the output side is shown.

Reference numeral 10 is a dielectric filter, 1 is a dielectric laminated substrate, 2 is a strip line on the input side, 3 is a strip line on the output side, 4, 5 are ground electrodes, 7 is an input terminal, and 8 is The output terminal 9 is a ground terminal. 2
Reference numerals 1, 22, 31, and 32 are intermediate conductors (hereinafter referred to as auxiliary strip lines), respectively.

The dielectric filter 10 includes strip lines 2, 21, 22, 3, 31, 32 and ground electrodes 4,5.
2A and 2B, the dielectric laminated substrate 1 in which the input terminal 7, the output terminal 8 and the ground terminal 9 are formed on each end surface of the dielectric laminated substrate 1 on which FIG. As shown in FIG. 3, for example, six dielectric layers 1a to 1f are laminated.

In the figure, each of the dielectric layers 1a to 1f constituting the dielectric laminated substrate 1 is made of barium titanate or the like having a predetermined relative dielectric constant, and the first ground electrode 4 is arranged on the dielectric layer 1a. Has been done. In addition, the dielectric layer 1a and the dielectric layer 1
The first auxiliary strip lines 21 and 31 on the input / output side of a predetermined shape are provided in parallel with b. Further, between the dielectric layers 1b and 1c, a substantially L-shaped input-side strip line 2 is arranged. Also, the dielectric layer 1
A substantially L-shaped output-side stripline 3 is arranged between the c and the dielectric layer 1d. Also, the dielectric layer 1d
Between the dielectric layer 1e and the dielectric layer 1e, the second input / output side
The auxiliary strip lines 22 and 32 are arranged side by side. Further, the second ground electrode 5 is arranged between the dielectric layer 1e and the dielectric layer 1f.

Input side stripline 2, first and second
Auxiliary strip lines 21 and 22, output side strip line 3, first and second auxiliary strip lines 31 and 32
The ground electrodes 4 and 5 are made of Ag, Cu, and Pd, respectively.
It is formed by printing a conductive paste containing a metal such as a Pb-based or Pb-based metal as a main component.

As shown in FIG. 3, the strip line 2 on the input side has a substantially L-shape composed of a first straight line portion 2x and a second straight line portion 2y, and the tip of the first straight line portion 2x. Is exposed from one end surface (the left end surface in FIG. 3) of the dielectric layers 1b and 1c, and the tip of the second linear portion 2y is orthogonal to the exposed end surface of the first linear portion 2x. It is exposed from the end surface (the end surface in the back direction of the paper in FIG. 3).

The strip line 3 on the output side has a substantially L-shape composed of a first straight line portion 3x and a second straight line portion 3y, and the tip of the first straight line portion 3x is a dielectric layer 1c. It is exposed from one end face with 1d (right end face in FIG. 3), and
The end of the linear portion 3y is exposed from an end surface (an end surface on the front side of the paper surface of FIG. 3) orthogonal to the exposed end surface.

That is, the tip of the first straight line portion 2x of the input side strip line 2 and the tip of the first straight line portion 3x of the output side strip line 3 are respectively extended to the end faces facing each other, and the input side The second straight portion 2y of the side stripline 2
And the tip of the second straight line portion 3y of the output-side stripline 3 are extended to the end faces facing each other.

Further, these two strip lines 2, 3
Are arranged such that the first straight line portions 2x and 3x overlap each other with the dielectric layer 1c interposed therebetween, and the first straight line portions 2x and 3x are electromagnetically coupled to each other.

The first and second auxiliary strip lines 21 and 22 on the input side have the same end faces as the end faces of the substrate on which one ends of the first straight line portions 2x of the input side strip line 2 are exposed. Is exposed to. The other ends of the auxiliary strip lines 21 and 22 are connected between the dielectric layers 1a and 1b,
It is an open end midway between 1d and 1e.

The first and second auxiliary strip lines 31 and 32 on the output side have the same end faces as the end faces of the substrate at which one ends of the first straight line portions 3x of the output side strip line 3 are exposed. Is exposed to. The other ends of the auxiliary strip lines 31 and 32 are connected between the dielectric layers 1a and 1b,
It is an open end midway between 1d and 1e.

The ground electrode 4 is formed on the dielectric layer 1a by the first straight line portions 2x and 3x of the strip lines 2 and 3 on the input / output side.
So that a strip-shaped margin is formed on the exposed end surface,
It is formed over almost the entire surface.

The ground electrode 5 has the same shape as that of the ground electrode 4, and the first straight line portion 2x of the strip lines 2 and 3 on the input / output side is provided between the dielectric layer 1e and the dielectric layer 1f. Three
It is formed on the end surface where x is exposed over substantially the entire surface.

The input terminal 7 is a laminated laminated dielectric substrate 1
At the end face of the first straight line portion 2 of the strip line 2 on the input side.
The tip of x is formed on the exposed end surface (the end surface on the left side in FIG. 3). Due to the formation of the input terminal 7, the tip of the first straight portion 2x of the strip line 2 on the input side, the first and the second
One end of each of the auxiliary strip lines 21 and 22 is connected to each other.

The output terminal 8 is formed on the end face (the end face on the right side in FIG. 3) opposite to the end face on which the input terminal 7 is formed. Due to the formation of the output terminal 8, the tip of the first linear portion 3x of the strip line 3 on the output side and the ends of the first and second auxiliary strip lines 31 and 32 are connected to each other.

The ground terminals 9, 9 are formed on two end faces of the laminated dielectric substrates 1 that are laminated, that is, on the front and rear end faces of the paper surface of FIG. By the ground terminals 9 and 9, the second straight line portions 2y and 3 of the strip lines 2 and 3 on the input and output sides are formed.
The tip portion of y and the ground electrodes 4 and 5 are connected to each other.

As a result, in the above-described dielectric filter, the input side strip line 2, the input side resonance portion formed around the first and second auxiliary strip lines 21 and 22, and the output side strip line 3, The first and second auxiliary strip lines 31 and 32 are formed on the output side resonance portion, and both strip lines 2 and 3 are formed on the dielectric layer 1.
The first linear portions 2x and 3x are connected to each other via c and are coupled to each other to operate as a filter.

The method of manufacturing such a dielectric filter is as follows.
It is formed using a lamination technique of a ceramic multilayer substrate.

For example, six dielectric green sheets (to be the dielectric layers 1a to 1f) are prepared, and a predetermined conductive paste is used to print on each green sheet to form a conductor film having a predetermined shape. . That is, a conductor film to be the first auxiliary strip lines 21 and 31 on the input side and the output side is provided on the green sheet to be the dielectric layer 1b, and a substantially L-shaped input side is provided on the green sheet to be the dielectric layer 1c. Stripline 2
The conductor film to be the dielectric layer 1d is formed on the green sheet to be the dielectric layer 1d, and the conductor film to be the strip line 3 on the output side is formed on the green sheet to be the dielectric layer 1e. Conductor films that will become the second auxiliary strip lines 22 and 32 are formed by printing, respectively. In addition, a conductor film serving as the second ground electrode 5 is printed and formed on substantially the entire surface of the green sheet serving as the dielectric layer 1f except for one end of the end surface on the side where the input / output terminals 7 and 8 are formed. .

Next, the green sheets to be the dielectric layers 1a to 1f are arranged so that the first straight line portion 2x of the input side strip line 2 and the first straight line portion 3x of the output side strip line 3 face each other. Then, they are sequentially laminated and thermocompression bonded. After that, it is cut into a predetermined shape, and the dielectric green sheet and the conductor film arranged therein are collectively fired.

Next, a conductor film to be the first ground electrode 4 is printed on the upper surface of the fired dielectric laminated substrate 1, that is, on the dielectric layer 1a, by using a predetermined conductive paste. Similar to the second ground electrode 5, its shape is formed so as to exclude one end of the end surface on the side where the input / output terminals 7 and 8 are formed. Further, a conductor film serving as an input terminal 7 is provided on the end surface of the laminated dielectric substrate 1 on the input side where one end of the strip line 2 on the input side and the first and second auxiliary strip lines 21 and 22 is exposed. Side strip line 3 and the first and second auxiliary strip lines 31, 32, a conductor film to be the output terminal 8 is further provided on the end faces where one ends of the strip lines 2, 3 are further exposed.
The ground terminals 9, 9 are formed by printing on the end faces of the second linear portions 2y, 2x where the tips are exposed. After that, the conductor film to be the first ground electrode 4, the input terminal 7, the output terminal 8, and the ground terminals 9, 9 is baked.

As a result, in the resonance portion on the input / output side, a dielectric filter having a quarter wavelength type resonance portion in which one ends of the strip lines 2 and 3 are open and the other ends are short-circuited is achieved. Become.

In the above structure, no dielectric layer is present on the first ground electrode 4, but another dielectric layer is added on the dielectric layer 1a of the laminated dielectric substrate 1. Then, a conductor film serving as the first ground electrode 4 is formed on the green sheet serving as the dielectric layer 1a, and the ground electrode 4 is used as the other dielectric layers 1a to 1f and the strip lines 2, 21 and 2.
It is also possible to collectively stack and fire the conductor films to be the second, third, 31, 32, and second earth electrodes 5.

By adjusting the degree of coupling between these two resonance parts, it is possible to control the center frequency, band, etc. of the filter to a predetermined value. Conventionally, in adjusting the degree of coupling, a strip line is used. Has a linear shape, and the length of the strip line determines the resonance frequency, so that the coupling degree is adjusted only by the mutual distance without changing the length of the strip line.

However, in the dielectric filter of the present invention, the width and length of the first straight line portions 2x and 2y of the strip lines 2 and 3 on the input and output sides facing each other through the dielectric layer 1c are set to predetermined values. Then, the degree of coupling is adjusted by arbitrarily changing the facing state, and this allows easy adjustment. For example, in order to increase the degree of coupling, basically, the lengths of the strip lines 2 and 3 are not changed, and the facing areas of the first straight line portions 2x and 3x of the strip lines 2 and 3 are increased. That is, when increasing the length of the first straight line portions 2x and 3x, the length of the second straight line portions 2y and 3y is shortened in order to adjust the resonance frequency. Also, the first straight portion 2
It is achieved by increasing the width of x, 3x. In addition, weakening the degree of coupling can be easily achieved by vice versa.

Therefore, in contrast to the dielectric filter shown in the prior art, which is controlled by the distance between the linear strip lines, in the present invention, both strip lines 2, 3 are provided via the dielectric layer 1c. Control is performed by the facing area. Therefore, even if the conductor film bleeding occurs due to the printing of the conductor film of the strip lines 2 and 3, the variation in the coupling degree due to the bleeding can be almost ignored.

In this way, the small area of the laminated dielectric substrate 1 can be easily achieved, and when the dielectric filter is mounted on the printed wiring board, the mounting area can be made extremely small.

Further, as shown in the embodiment, by connecting the auxiliary strip lines 21, 22, 31, 32 to the strip lines 2 and 3 on the input and output sides, the lengths of the strip lines 2 and 3 can be further shortened. Is possible.

FIG. 4 is a schematic diagram for explaining that,
The relationship between the strip line 2 on the input side, one auxiliary strip line 21, and the ground electrode 4 is shown.

In the figure, the conductor indicated by XX'-X '' corresponds to the ground electrode 4 of the embodiment, and is YY'-Y ''.
The conductor indicated by is the strip line 2 on the input side of the embodiment.
, The conductor indicated by ZZ ′ corresponds to the auxiliary strip line 21 of the embodiment, the conductor indicated by X ″ −Y ″ corresponds to the ground terminal 9, and is indicated by Y−Z. The conductor provided corresponds to the input terminal 7. The distances from the side of the ground electrode 9 to the discontinuous points are L and X. Also, Y'-
A region surrounded by Y ″ and X′-X ″ is an I region, Y−
A region surrounded by Y ′ and ZZ ′ is a II region, and a region surrounded by XX ′ and ZZ ′ is a III region.

In the above structure, the length of the strip line 2 is the phase of the signal determined by the distance traveled by the signal wave input from the input terminal 7, and the discontinuity (X ', Y',
By combining the change with the phase of the reflected wave that occurs in Z ′), the length can be set short. Each area
Assuming the voltages and currents of I, II, and III and solving them in a distributed constant manner, the following equations and equations can be obtained.

[0046]

[Equation 1]

Here, 2 β ₃ (XL) represents the transmission phase rotation in the region III, 2 Φ represents the rotation of the reflection phase in X = L, and π represents the opposite phase.

[0048]

[Equation 2]

Here, if the dielectric constants of the dielectrics in each region are equal (using the same dielectric material), β ₁ = β
₂ = β ₃ = β, which gives

[0050]

[Equation 3]

It becomes In the above equations, β ₁ , β ₂ , β ₃ : phase constants in each region Z ₀₁ , Z ₀₂ , Z ₀₃ : characteristic impedance Φ in each region: phase difference.

In FIG. 4, the thickness of the dielectric layer 1b corresponding to the area II is increased and the thickness of the dielectric layer 1a in the area III is decreased, that is, the characteristic impedance Z ₀₂ is increased and the characteristic impedance Z ₀₃ is decreased. As a result, the left side of the above equation becomes smaller and the value of XL becomes smaller.

As a result, the portion X where the input terminal 7 is formed
From the ground electrode 9 to the ground terminal 9 of the ground electrode 4 can be shortened, and thus the length of the strip line 2 can be shortened. The same applies to the output side stripline 3.

Therefore, the miniaturization of the substrate due to the input side stripline 2 and the output side stripline 3 being coupled to each other in the stacking direction via the dielectric layer 1c can be further miniaturized. .

[Other Embodiments] (1) In the above-described filter embodiment, the input side strip line 2 and its auxiliary strip lines 21 and 22 are the input side terminal 7, the output side strip line 3 and its auxiliary strip. Although the lines 31 and 32 are connected via the output side terminal 8, as shown in FIG. 5, the dielectric layers 1b, 1c and 1d are connected.
In addition, the tip of the first straight portion 2x of the strip line 2 on the input side, the via hole conductor 23 connecting the tips of the auxiliary strip lines 21 and 22 to each other, and the strip line 3 on the output side
Of the first straight line portion 3x of the auxiliary strip line 3
It is also possible to form a via-hole conductor 33 that connects the tips of the first and the second ends 32, and to connect the via-hole conductors 23 and 33 to each other.

(2) In the above-described embodiment, both of the two strip lines 2 and 3 are formed in a substantially L shape and are connected to each other by the first straight line portions 2x and 3x.
If either one of the strip lines has a substantially L shape, the facing area for coupling the strip lines 2 and 3 can be controlled. That is, the other strip line may have a linear shape.

(3) In the above-mentioned embodiment, the dielectric filter having two resonance parts formed by the two strip lines 2 and 3 has been described, but three or more resonance parts may be formed. In this case, the input-side strip line 2, the strip line that serves as an intermediate resonance portion, and the output-side strip line 3 are formed between adjacent dielectric layers, and an L-shaped strip line formed between the adjacent dielectric layers. The extension direction of the second straight line portion may be arranged in different directions.

(4) Also, the auxiliary strip lines 21, 2
With respect to 2, 31, and 32, in the embodiment, two auxiliary strip lines are connected to the strip lines 2 and 3, respectively, but the auxiliary strips may be omitted.

Further, for example, only the auxiliary strip line 21 on the input side is formed on the dielectric layer 1b, the first auxiliary strip line 31 on the output side is omitted, and on the dielectric layer 1e. May form only the auxiliary strip line 32 on the output side and omit the second auxiliary strip line 22 on the input side.

(5) Further, when there is no restriction on the stacking direction of the dielectric filter, a dielectric layer may be added and the auxiliary strip lines may be separated sufficiently so as not to be coupled to each other.

(6) In the above embodiment, one end of the strip line (the end connected to the input / output terminals 7 and 8) is an open end, and the other end is a short-circuited end connected to the ground terminal 9. However, with this short-circuited end open, 1/2
A resonator having a wavelength may be configured.

[0062]

As described above, according to the present invention, the strip line constituting the resonance portion is formed in a substantially L shape, and the other straight line and the dielectric layer are formed in the L-shaped first straight line portion. They are connected to each other in the stacking direction. Therefore, the degree of coupling between the adjacent strip lines can be controlled by the portions facing each other, and therefore the degree of coupling can be adjusted extremely easily.

Therefore, the dielectric filter has a small mounting area for the printed wiring board to be mounted.

[Brief description of drawings]

FIG. 1 is an external perspective view of a dielectric filter of the present invention.

2A is a sectional view showing a structure of a section taken along line XX of FIG. 1, and FIG. 2B is a sectional view showing a structure of a section taken along line YY of FIG.

FIG. 3 is an exploded perspective view of a dielectric laminated substrate.

FIG. 4 is a schematic diagram for explaining an operation when an auxiliary strip line is connected.

FIG. 5 is an exploded perspective view showing another embodiment of the present invention.

[Explanation of symbols]

 10 ... Dielectric resonator 11 ... Dielectric laminated substrate 1a-1d ... Dielectric layer 2 ... Input strip line 21 ... Input side strip line 1 auxiliary strip line 22 ..... second auxiliary strip line on input side 3 ........ strip line on output side 31 ........ first on output side Auxiliary strip line 32 ..... Second auxiliary strip line on output side 4, 5 ..... Earth electrode 7 ........ Input terminal 8 .. Terminal 9 ... Ground terminal

Claims (1)

[Claims] 1. Strip lines are respectively arranged between different dielectric layers, and at least one of the strip lines adjacent to each other across the dielectric layer is
A dielectric filter having a substantially L shape having a first straight line portion and a second straight line portion, and electromagnetically coupled to a strip line adjacent to the first straight line portion.