JPH06169202A - Lamination type dielectric band elimination filter - Google Patents

Abstract

PURPOSE:To reduce the assembling man-hours such as troublesome soldering to the utmost and to attain the ease of miniaturization by integrally assembling a coupling capacitor to a resonator base so as to reduce the number of components to be added. CONSTITUTION:Resonator bases 10a,..., 10d of 1/4 wavelength resonance strip line type and shield bases 12a,..., 12c are alternately laminated and integrated in the broadwise direction. Each of the resonator bases 10a,..., 10d has an internal electrode 22 in the lengthwise direction in the middle of the inside of the paper-tablet shaped dielectric base and has an external electrode 24 and island electrodes 16a,..., 16d at an outer circumferential part. Each of the shield bases 12a,..., 12c integrates a shield electrode and has an electrode at its outer circumferential part. Outer bases 14a, 14b are provided to the outside of the resonator bases. The island electrodes are connected by a coil. The island electrode at both ends acts like an input/output coupling electrode. Furthermore, it is preferred that input/output terminal electrodes 38 are provided to the outer base.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resonator in which a plurality of resonator substrates each having a quarter-wavelength resonance type strip line are laminated in the thickness direction so as to sandwich a shield substrate therebetween, and the resonator substrates are integrated. The present invention relates to a laminated dielectric band elimination filter (BEF) in which independent island electrodes provided on the outer periphery of a substrate are connected by a coil. This dielectric filter is suitable for various types of radio equipment for microwaves, for example.

[0002]

2. Description of the Related Art As a microwave band elimination filter, a filter using a dielectric coaxial resonator is known. This is a structure in which coupling capacitors are connected to a plurality of dielectric coaxial resonators, and the capacitors are connected by coils.

In a dielectric coaxial resonator, a resonator hole is provided in a rectangular parallelepiped dielectric, and a metallized layer is formed on the entire outer surface except one surface where the resonator hole is open and the inner surface of the resonator hole. It is a structure. Of the surfaces where the resonator holes are open, the one without the metallization layer is the open surface and the one with the metallization layer is the short-circuit surface. This is a 1/4 wavelength resonance type. A plurality of these dielectric coaxial resonators are arranged in parallel. Separately, a wiring board is prepared, and as many coupling capacitors as the number of resonators are mounted on the wiring board, and the capacitors are connected by coils. Then, the internal electrode (inner surface metallization layer of the resonator hole) of each dielectric coaxial resonator and each capacitor are connected by a lead terminal.

[0004]

In the case of the dielectric coaxial resonator structure as described above, a wiring board and a coupling capacitor are required in addition to the resonator. In addition to assembling the capacitor, each capacitor and the resonator are required. Since it is necessary to connect the inner surface metallization layer of the hole with the lead terminal, the number of parts is large, the mounting man-hour is increased, and the assembly is complicated. In the dielectric coaxial resonator structure, since holes are formed in the dielectric block, there is a limit to miniaturization.

By the way, as a microwave filter,
There is also a type in which the resonator is composed of a strip line. For example, in the case of a quarter-wave resonator, a linear stripline resonator conductor is provided on a dielectric substrate, one end of which is open and the other end is short-circuited to an external electrode. When configuring a bandpass filter, it can be configured by arranging a plurality of the above-mentioned resonator conductors on a dielectric substrate and commonly connecting the short-circuit sides. However, band elimination filters cannot be realized.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to integrally incorporate a coupling capacitor into a resonator substrate, thereby reducing the number of parts to be added and causing troublesome soldering. It is an object of the present invention to provide a laminated dielectric band elimination filter having a structure in which the number of assembly steps is minimized and the size can be easily reduced.

[0007]

The present invention basically comprises
A quarter wavelength resonance strip line type resonator substrate and a shielding substrate are alternately laminated in the thickness direction to be integrated, and the resonator substrate has a structure in which a coupling capacitor is integrally incorporated, and a coil is provided therein. It is a laminated dielectric band elimination filter that is connected and coupled. Here, in each resonator substrate, typically, an internal electrode is formed in the central longitudinal direction of the inside of a strip-shaped dielectric substrate, and independent island electrodes and external electrodes are formed on the outer peripheral portion excluding one end face. It is a structure. Further, the shield substrate has a built-in shield electrode that spreads in a plane substantially perpendicular to the thickness direction and has an electrode on the outer peripheral portion. A plurality of the resonator substrates are stacked, and a shielding substrate is sandwiched between them. Further, outer substrates are provided further outside the resonator substrates located on both sides in the thickness direction. The outer substrate has electrodes on the outer main surface and the outer peripheral portion. Then, the island-shaped electrodes formed on the outer peripheral portion of each resonator substrate are connected by a coil. Here, the island-shaped electrodes of the resonator substrate located at both ends serve as input / output coupling electrodes. Further, it is preferable that the outer substrate is provided with input / output terminal electrodes that are electrically connected to the island electrodes of the resonator substrates located at both ends.

In addition to the above-mentioned structure, the resonator substrate is formed by combining, for example, an external dielectric having a notch in a part thereof and having a substantially U-shaped shape, and an internal dielectric fitted in the notch of the external dielectric, and joining them. 1 /
A three-dimensional structure in which the four-wavelength resonant strip line is folded back may be used. The shield substrate preferably has a structure in which a shield electrode is formed at the interface where two dielectrics are laminated. Usually, at least the open surface side of such a dielectric filter is covered with a shield such as a metal case or a metal plate.

[0009]

The resonator substrate is composed of the inner and outer electrodes
It becomes a strip line type resonator of / 4 wavelength resonance type.
An electrode-free portion (one without an electrode) at one end of the outer peripheral surface is an open surface, and one with an electrode at the other end is a short-circuit surface. However, in the case of the folded type, the open surface and the short circuit surface appear at the same end. The shield substrate located between the resonator substrates blocks direct coupling between the adjacent resonators and functions as independent resonators.

In each of the above-mentioned resonator substrates, an electrostatic capacitance is generated between the island-shaped electrode formed on the outer peripheral portion of the resonator substrate and the internal electrode of the resonator substrate, which acts as a coupling capacitor. Therefore, the band elimination filter characteristics are exhibited by connecting the respective island electrodes with a coil.

[0011]

FIG. 1 is a perspective view showing an embodiment of the laminated dielectric band elimination filter according to the present invention.
This is the case of a four-stage configuration. FIG. 5 shows an assembled perspective view of the main body portion (state before connecting the coil). This dielectric filter is composed of four quarter-wave resonator strip line type resonator substrates 10a, ..., 10d and three shield substrates 1.
2a, ..., 12c are alternately laminated in the thickness direction. Further, the outer substrates 14a and 14b are arranged outside the resonator substrates 10a and 10d located on both sides, and the respective dielectric substrates are positioned and bonded by an adhesive or the like to be integrated. Here, the resonator substrates 10a, ..., 10d are arranged in the same direction (positions of the open surface and the short circuit surface).

All the resonator substrates 10a, ..., 10d have the same shape. That is, the internal electrodes 22 are formed in the inner central longitudinal direction of the strip-shaped dielectric substrate 20 (the entire bonding surface of the two dielectric pieces), and the island-shaped electrodes 16a are formed on the outer peripheral portion excluding one end surface. , 16d and the external electrode 24 are formed. In this resonator substrate, the end surface on the electrodeless side is an open surface, and the end surface on the electrode formation side is a short circuit surface. The island-shaped electrodes 16a, ..., 16d are provided on the outer peripheral portion in the vicinity of the electrode-free end surface and are independent (formed so as to be separated from other electrodes) electrode patterns. These resonator substrates 10
, 10d, the resonance frequency or the capacitance of the capacitor can be finely adjusted by trimming the external electrode 24 or the island electrodes 16a, ..., 16d.

The dielectric substrate constituting the above-mentioned resonator substrate is a sintered body of a high dielectric constant material for microwave, which is usually used for a microwave filter, such as barium titanate. Here, the resonator substrates 10a, ..., 10d are
This is a combination of two dielectric pieces 26a and 26b as shown in FIG. One of the dielectric pieces 26a has a structure having electrodes on the outer peripheral surface except one end, and the other dielectric piece 26b.
Has a structure in which electrodes are provided on the outer peripheral surface excluding one end and the vicinity thereof and island-shaped electrodes 16a, ..., 16d are provided near the end surface on the electrodeless side. The resonator substrates 10a, ..., 10d can be configured by joining the two dielectric pieces 26a, 26b (FIG. 3).
B). .., 16d and the inner electrode 2
A coupling capacitor (equivalently indicated by symbol C) is formed between the two.

The resonator substrate having such a structure can actually be mass-produced by the following manufacturing method. Two sintered compact substrates of a high dielectric constant material for microwaves having a predetermined thickness and width are prepared. Silver paste is applied to the entire upper and lower surfaces and one end surface of one sintered body substrate and baked, and silver paste is applied to the entire lower surface, one end surface and most of the upper surface continuous to the other sintered body substrate. At the same time, it is separated toward the opposite end surface of the upper surface, coated with a silver paste in a strip shape, and baked. Next, the entire upper surface of one sintered substrate and the entire lower surface of the other sintered substrate are coated and bonded with an adhesive silver paste, and baked and integrated. After that, by cutting into a predetermined width, many resonator substrates as described above can be manufactured.

The shield substrates 12a, ..., 12c have a structure in which a shield electrode 28 that spreads in a plane perpendicular to the thickness direction is built in, and an electrode 32 is formed on the outer peripheral portion (excluding a part). Specifically, it is a plate-shaped body having the same outer shape (thickness may be different) as that of the resonator substrate, and as shown in FIG. 4, the main surfaces (but one surface) of the two dielectric bodies 30a and 30b.
In this structure, a shield electrode 28 is formed on the substrate, an electrode 32 is provided on the outer periphery thereof, and both dielectrics 30a and 30b are attached so that the shield electrodes 28 are back to back. Further, the outer substrates 14a and 14b have electrodes 36 formed on the outer main surface and the outer peripheral portion (excluding a part thereof) of the dielectric substrate 34, and the input / output terminal electrodes 38 which are electrically connected to the island electrodes 16a and 16d at both ends. Is formed. , 12c and one end surface of the outer substrates 14a, 14b are electrodeless portions, and the electrodes 32, 36 are not connected to the island electrodes 16a, ..., 16d and the input / output terminal electrodes 38. Similarly, the vicinity thereof is also an electrodeless portion. , 12c and the outer substrate 14
The materials a and 14b do not necessarily have to be made of the same material as the resonator substrate.

These dielectric substrates are arranged so that the resonator substrates 10a, ..., 10d are oriented in the same direction as described above (see FIGS. 1 and 5), and are bonded and integrated using an adhesive or the like. To do. In addition, in order to make the drawings easy to understand, a shadow line is drawn in each drawing, and a non-electrode portion (a portion where the base material of the dielectric is exposed) is shown with fine dots.

Returning to FIG. 1, each resonator substrate 10a,
..., four island-shaped electrodes 16a formed on 10d, ..., 16
, d are connected by three coils 18a, ..., 18c. FIG. 2A is a side view of the state after the coil connection. Each coil may be provided on the open surface side of the dielectric substrate, as shown in FIG. 2B. This makes it possible to reduce the height of the filter.

Usually, such a dielectric filter is mounted on a circuit board by covering it with a metal case and shielding it. The input / output terminal electrodes located at both ends are connected to the input / output pattern of the circuit board, and the earth tab provided on the metal case is also soldered to the earth pattern of the circuit board for electrical connection and mechanical fixing.

The stripline resonator substrate as described above has a quarter of the internal electrodes formed in the dielectric substrate.
A wavelength resonator is formed, which is short-circuited at the external electrode. Therefore, the resonance wavelength (in other words, the resonance frequency) is basically determined by the length dimension of the resonator substrate (length of the internal electrode). Further, the larger the thickness (dimension in the stacking direction) of the resonator substrate, the lower the resonance frequency, and the smaller the width (distance between the inner electrode and the outer electrode), the lower the resonance frequency. The resonator substrates are shielded from each other by a shielding substrate located between them. On each resonator substrate, a coupling capacitor is formed between the island electrode and the internal electrode, and interstage coupling is performed by the capacitor and the coil. The input and output are coupled by the capacitance between the internal electrodes of the resonator substrate located at both ends and the island electrodes. As a result, band elimination filter characteristics are obtained.

FIG. 6 shows another embodiment of the laminated dielectric band elimination filter according to the present invention. This is also an example of a four-stage configuration. Basically, the structure is similar to that of the embodiment shown in FIG. 1, and four quarter-wave resonator stripline type resonator substrates 50a, ..., 50d and 3 are used.
This is a type in which the shield substrates 52a, ..., 52c are alternately laminated in the thickness direction. Further, the outer substrates 54a and 54b are arranged outside the resonator substrates 50a and 50d located on both sides, and the respective dielectric substrates are positioned and joined by an adhesive or the like to be integrated. Here, the shape of each substrate is not a simple rectangular plate shape as in the above embodiment, but a shape having a step (notched one corner).

Details of the resonator substrates 50a, ..., 50d are shown in FIG. These resonator substrates 50a, ..., 50
d is an external dielectric 6 in which a notch is provided in a part to make the whole substantially U-shaped and one leg thereof is formed longer than the other.
0 and an internal dielectric 70 fitted in the cut of the external dielectric 60. Where the external dielectric 60
The electrode 64 is formed on the outer peripheral portion excluding the end face 62 of the long leg. Further, the internal dielectric 70 joins the two long and short dielectric pieces 71, 72 through the electrode 74 except for the one end aligned and the vicinity thereof, and is independent near the joining surface of the longer dielectric piece 71. This is a structure in which an island-shaped electrode 75 is formed, and an electrode 78 is formed on the island-shaped electrode 75, the protruding end surface 76 of the long dielectric piece 71, and the outer peripheral portions of both dielectric pieces 71, 72. Then, the internal dielectric 70 is attached to the electrodeless end face 76.
Is located in the vicinity of the end surface 62 of the long leg portion of the outer dielectric 60, and the outer electrode 78 of the inner dielectric 70 is in contact with the cut surface of the outer dielectric 60.
Insert it into the notch of 0 and fix it by glass bonding. Here, the long leg end surface 62 of the outer dielectric body 60 is made to project beyond the tip of the long dielectric piece 71 of the inner dielectric body 70, and the resulting electrode portion that extends and is exposed inside the long leg portion. 64a is used as a frequency trimming electrode.

The shield substrates 52a, ..., 52c also have two plate-shaped dielectrics 80a, 80b with one corner cut out.
In this structure, the shield electrode 82 is formed on one surface and the electrode 84 is provided on the outer peripheral surface (excluding the step portion and the tip surface thereof), and the shield electrodes 82 are joined back to back (see FIG. 7B). The outer substrates 54a and 54b also have the same stepped shape, and electrodes are formed on the outer main surface and the outer peripheral portion (but part thereof is excluded), and the resonator substrates 5 at both ends are formed.
An input / output terminal electrode 88 that is electrically connected to the island-shaped electrodes 56a and 56d of 0a and 50d is formed on the step portion and the outer surface thereof.

The resonator substrates 50a, ..., 50d are arranged between the respective resonator substrates 50a ,.
Thereby act as independent resonators, and electrostatic capacitance is formed between the island-shaped electrode 75 and the internal electrode (the electrode on the joint surface between the external dielectric 60 and the internal dielectric 70).
It acts as a coupling capacitor. Therefore, the coils 58a, ..., 58 are provided between the island electrodes 56a ,.
By connecting with c, a band elimination filter characteristic occurs. In this configuration, each coil 58a,
, 58c are accommodated in the stepped portion of the dielectric, so that it is easy to cover with a metal case or the like, and it is easy to downsize the whole.

In each of the above embodiments, the input / output terminal electrode is formed to extend to the outer main surface of the outer substrate. This is preferable because the soldering portion (fillet) can be visually confirmed at the time of surface mounting, the mounting reliability can be increased, and the work can be facilitated.
Although each of the above-described embodiments is an example of a four-stage configuration using four resonator substrates, the present invention can be applied to a plurality of other stages of filters.

[0025]

As described above, according to the present invention, the coupling capacitor is integrated by providing the quarter-wavelength resonant strip line having the electrodes formed inside the dielectric substrate and forming the island electrodes on the outer circumference. A resonator substrate can be constructed by incorporating the resonator substrate into a single layer, and the resonator substrate can be laminated and integrated with a shield substrate interposed therebetween, and the island electrodes can be connected with a coil to form a band elimination filter. Further, since the resonator substrate has built-in capacitors for input / output coupling and inter-stage coupling, a wiring substrate and the like, which have been conventionally required, are not required, and the number of components and the number of mounting steps are reduced. This allows the filter to be made even smaller,
Since the occupied area can be reduced when mounting, it is advantageous for downsizing of equipment.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a filter according to the present invention.

FIG. 2 is a side view thereof.

FIG. 3 is an explanatory diagram of a resonator substrate.

FIG. 4 is an explanatory diagram of a shield substrate.

FIG. 5 is an assembled perspective view of the filter before coil mounting.

FIG. 6 is a perspective view showing another embodiment of the filter according to the present invention.

FIG. 7 is an explanatory diagram of the resonator substrate and the shield substrate.

[Explanation of symbols]

 , 10d Resonator substrate 12a, ..., 12c Shielding substrate 14a, 14b Outer substrate 16a, ..., 16d Island electrodes 18a, ..., 18c Coil 20 Dielectric substrate 22 Internal electrode 24 External electrode

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication H01P 1/212

Claims (6)

[Claims] 1. A plurality of resonator substrates, each having a quarter-wave resonant strip line formed by forming electrodes inside and outside a dielectric substrate, are laminated so that a shielding substrate is sandwiched between them. An outer substrate is arranged further outside the resonator substrates located on both sides in the thickness direction to form an integrated structure,
The shield substrate has a built-in shield electrode that spreads in a plane substantially perpendicular to the thickness direction and has electrodes on the outer peripheral portion, and the outer substrate has electrodes on the outer main surface and the outer peripheral portion. Independent island-shaped electrodes are formed on the outer periphery of the resonator substrate, the island-shaped electrodes are connected by coils, and the island-shaped electrodes on the resonator substrate located at both ends serve as input / output coupling electrodes. Elimination filter. 2. The resonator substrate has a 1/4 wavelength resonance structure in which an internal electrode is formed in the inner central longitudinal direction of a dielectric substrate and independent island electrodes and external electrodes are formed in the outer peripheral portion except one end face. The filter according to claim 1, which is a strip line. 3. The resonator substrate is a combination of an external dielectric body having a U-shaped portion with a notch partly formed therein, and an internal dielectric body fitted into the notch of the outer dielectric body, and an electrode formed on the joint surface thereof. The filter according to claim 1, wherein the filter has a three-dimensional structure in which a quarter-wavelength resonant strip line is folded back. 4. The resonator substrate has an outer dielectric body in which a notch is provided in a part so that the whole is substantially U-shaped, and one leg portion thereof is longer than the other, and an inner portion which is fitted into the notch of the outer dielectric body. A structure in which dielectrics are combined, wherein the outer dielectric has electrodes on the outer peripheral portion excluding the end faces of the long legs, and the inner dielectric has two long and short dielectric pieces aligned at one end and excluding the vicinity thereof. And form an island-shaped electrode that is exposed independently in the vicinity of the bonding surface of the longer dielectric piece,
The structure is such that electrodes are formed on the outer peripheral portion excluding the projecting end faces of the island-shaped electrode and the long dielectric piece, and the inner dielectric is positioned such that its electrode-free end face is in the vicinity of the long leg end face of the outer dielectric and 2. The structure in which the outer peripheral electrode of the inner dielectric is fitted into and fixed to the notch of the outer dielectric in a direction in which the outer peripheral electrode is in contact with the notch surface of the outer dielectric, and the quarter-wave resonant strip line is three-dimensionally formed to be folded back. Filters. 5. The filter according to claim 1, wherein input / output terminal electrodes that are electrically connected to the island-shaped electrodes of the resonator substrate located at both ends are formed on the outer substrate. 6. The filter according to claim 1, wherein the shield substrate has a structure in which a shield electrode is formed at an interface where two dielectrics are laminated.