JP2000077907A - Dielectric filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dielectric filter capable of being used in >=3 GHz high frequency and adjusting bandwidth. SOLUTION: This filter has a structure connecting plural rectangular parallelepiped dielectrics 11 and 12 and island-shaped input-output electrodes 13 and 14 surrounded by ground electrodes 15 and 16 are formed on one surface of the respective dielectrics. Ground conductors are also formed on the surfaces other than the connected faces of the dielectrics and resonators are connected at a connected plane 17 exposing the dielectrics to construct the filter. A conductor film 18 is formed at the ambient part of the connected plane 17 and the dielectrics are connected by utilizing the conductor film 18. It is possible to adjust the connection by a conductor film 19 crossing the center of the connected face.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a small-sized dielectric filter suitable for use in a high-frequency band of 3 GHz or more, and more particularly to a joint structure of a dielectric and coupling adjustment by the same.

[0002]

2. Description of the Related Art With the spread of mobile communication equipment, utilization of a frequency higher than a frequency band currently used is being studied. Until now, mobile communications have used frequencies up to about 2GHz, and filters used in mobile stations have been mainly used in combination with dielectric coaxial resonators or in blocks. .

However, when this dielectric coaxial resonator is used at a high frequency such as 5 GHz or more, the size defined by the frequency becomes small, making it difficult to obtain input / output coupling. Requires a larger outer diameter. For example, in order to secure the required Q at a frequency of 5 GHz, the outer diameter needs to be set to more than 10 mm.
This goes against the demand for miniaturization of electronic components and cannot be put to practical use. Alternatively, a TE mode resonator is used, but the structure is increased in size and the input / output coupling structure is complicated.

[0004]

SUMMARY OF THE INVENTION The present invention relates to
An object of the present invention is to provide a dielectric filter which has sufficient filter characteristics in a high frequency band such as GHz, has a high Q, and meets the requirements of miniaturization and thinning. In addition, the present invention provides a dielectric filter which has sufficient mechanical strength and can easily adjust the bandwidth.

[0005]

The present invention solves the above-mentioned problems by employing a structure completely different from the conventional structure and by using an electrode structure at a junction of a dielectric.

That is, in a dielectric filter in which a plurality of rectangular parallelepiped dielectrics are joined, an input / output electrode made of an island-shaped conductor film is provided on one surface of each dielectric, and is separated and insulated from the input / output electrode. An earth electrode made of a conductive film is formed on substantially the entire remaining surface of the surface and on the entire other surface except the bonding surface, and the conductive film is formed around the bonding surface.

Also, in a dielectric filter in which a plurality of rectangular parallelepiped dielectrics are joined, an input / output electrode of an island-shaped conductor film is provided on one surface of each dielectric, and is separated and insulated from the input / output electrode. It has a ground electrode made of a conductive film formed on almost the entire remaining surface of the surface and the entire surface other than the bonding surface, and extends from the surface where the input / output electrode is formed at the center of the bonding surface to the opposite surface It has an electrode for adjustment, and is characterized in that a conductor film is formed on a peripheral portion of a joining surface.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The resonance mode of a dielectric filter according to the present invention has not been completely analyzed yet, but it is considered that it has a function close to that of a waveguide. It is conceivable that an island-shaped electrode on one surface of the dielectric is used as the input / output coupling structure, and the resonator is coupled on the joint surface where a part of the dielectric is exposed to obtain filter characteristics.

The dielectric filter according to the present invention is composed of two or more rectangular parallelepiped ceramic dielectrics, and the following are formed on each dielectric. Dielectrics are joined to each other by using the input / output electrode, the ground electrode, and the conductor film around the joint surface.

[0010]

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

FIGS. 1A and 1B show an example of a dielectric filter according to the present invention. FIG. 1A is an exploded perspective view, and FIG. 1B is a side view of a joint surface. Square or rectangular island-shaped electrodes 13 and 14 are formed in the center of one surface of the rectangular parallelepiped dielectrics 11 and 12 and used as input / output electrodes. Conductive films 15 and 16 are formed around the island-shaped electrodes 13 and 14 to serve as ground conductors. The island-shaped electrodes 13, 14 and the electrodes surrounding them are separated and insulated.

A conductor film is also formed on the entire surface other than the joint surface 17 and is connected to the conductor films 15 and 16 to serve as an earth conductor. A conductor film 18 is formed around the joint surface 17 with a predetermined width. In addition, a conductor film 19 is formed at the center of the bonding surface so as to cross from the surface on which the input / output electrodes are formed to the opposing surface. Has been adjusted. It is desirable that the conductor film 18 on this joint surface be formed on both bonding surfaces, and only one conductor film 19 is required.

The surfaces on which the conductor films 18 and 19 are formed are joined by solder, a conductive adhesive or the like to assemble a dielectric filter according to the present invention. The island-shaped conductor films 13 and 14 are connected to the wiring pattern on the wiring board, and the conductor film surrounding the
15 and 16 are connected to the earth pattern.

A dielectric of 10.0 × 10.0 × 2.5 mm (dielectric constant 37)
In the center of the 10.0 × 10.0 mm surface of 2.0 × 2.0 mm input and output electrodes were formed, and a sample was prepared in which a ground conductor was formed around the periphery at 0.5 mm intervals, and the size of the conductor film on the joining surface was changed. Assembled. The width of the surrounding conductor film was 0.5 mm, and the width of the conductor film crossing the center was changed.

FIG. 2 shows that the width of the conductor film crossing the bonding surface is 3.2 mm.
The center frequency is 3.56GHz
As a result, a bandpass characteristic with a 3 dB bandwidth of 100 MHz was obtained.
In FIG. 3, the width of the conductor film is reduced to 2.8 mm, and the other components are the same as those described above. In this example, the center frequency is 3.55GH
The 3dB bandwidth was 125MHz at z. The coupling between the resonators changes depending on the width of the conductor film, and the stronger the coupling, the wider the bandwidth. The larger the exposed area of the dielectric, the stronger the coupling.

FIG. 4 shows that the size of the dielectric is reduced to 6.
1.2 × 1.2m on the surface of a 0 × 6.0 × 2.5mm dielectric (dielectric constant 37)
FIG. 6 is an explanatory diagram of characteristics of an assembly in which m input / output electrodes are formed, a conductor film having a width of 0.5 mm is formed around a joint surface, and the width of a central conductor film is set to 1.4 mm. Center frequency is 5.93
The 3dB bandwidth in GHz was 174MHz. As the size of the dielectric became smaller, the center frequency increased.

FIGS. 5A and 5B show another embodiment of the dielectric filter according to the present invention. FIG. 5A is an exploded perspective view, and FIG. 5B is a side view of a joint surface. Square or rectangular island-shaped electrodes 53, 54 are formed at the center of one surface of the rectangular parallelepiped dielectrics 51, 52, and are used as input / output electrodes. Island-shaped electrodes 53, 54
The conductor films 55 and 56 are formed around the periphery and serve as ground conductors. The island-shaped electrodes 53 and 54 and the electrodes surrounding them are separated and insulated. A conductor film is also formed on the entire surface other than the joining surface, and is connected to the conductor films 55 and 56 to serve as a ground conductor. A conductor film 58 is formed around the bonding surface 57 with a predetermined width.

Using a dielectric having the same size as the example shown in FIG. 1, an element having input / output electrodes of the same size is placed around the periphery such that the center of the bonding surface is an exposed portion of the dielectric of 3.4 × 0.5 mm. FIG. 6 shows the characteristics when the conductor film was formed. The center frequency was 3.55GHz and the 3dB bandwidth was 94MHz. With such a structure, the connection can be adjusted, but there is a drawback that positioning at the time of bonding becomes difficult.

[0019]

According to the present invention, it is easy to adjust the coupling between the resonators. Therefore, it is possible to adjust the coupling state by changing the area and position of the electrode to obtain an arbitrary bandwidth.

Further, since the periphery of the bonding surface is bonded to each other by the metal films, there is an advantage that the bonding strength is increased and the effect of being hardly affected by an external electromagnetic field.

[Brief description of the drawings]

FIG. 1A is an exploded perspective view showing an embodiment of the present invention.
(B) is a side view of the joint surface

FIG. 2 is an explanatory diagram of characteristics of an example of a dielectric filter according to the present invention.

FIG. 3 is an explanatory diagram of characteristics of an example of a dielectric filter according to the present invention.

FIG. 4 is an explanatory diagram of characteristics of another example of the dielectric filter according to the present invention.

5 (a) is an exploded perspective view showing another embodiment of the present invention, and FIG. 5 (b) is a side view of a joint surface.

FIG. 6 is an explanatory diagram of characteristics of the example shown in FIG.

[Explanation of symbols]

 11, 12, 51, 52: Dielectric 13, 14, 53, 54: Conductor film (input / output electrode) 15, 16, 55, 56: Conductor film (earth electrode) 17, 57: Bonding surface 18, 58: Conductor Membrane 19: Conductor film (for adjusting the coupling)

Claims (3)

[Claims] 1. A dielectric filter in which a plurality of rectangular parallelepiped dielectrics are joined to each other, each of which has an input / output electrode formed of an island-shaped conductor film on one surface thereof and is separated and insulated from the input / output electrode. A dielectric filter comprising a ground electrode made of a conductive film formed on substantially the entire remaining surface of the surface and the entire surface other than the bonding surface, and a conductive film formed on a peripheral portion of the bonding surface. 2. A dielectric filter in which a plurality of rectangular parallelepiped dielectrics are joined to each other, and each of the dielectrics has an input / output electrode formed of an island-shaped conductive film on one surface thereof and is separated and insulated from the input / output electrode. A ground electrode made of a conductive film formed on almost the entire remaining surface of the surface and the entire other surface except for the bonding surface is provided.A conductive film is formed around the bonding surface, and a dielectric is formed by the conductive film on the bonding surface. A dielectric filter characterized by being joined. 3. A dielectric filter in which a plurality of rectangular parallelepiped dielectrics are joined to each other, each of which has an input / output electrode formed of an island-shaped conductor film on one surface thereof and is separated and insulated from the input / output electrode. It has a ground electrode made of a conductive film formed on almost the entire remaining surface of the surface and the entire surface other than the bonding surface, and extends from the surface where the input / output electrode is formed at the center of the bonding surface to the opposite surface Equipped with electrodes for adjustment,
A dielectric filter, wherein a conductive film is formed on a peripheral portion of a bonding surface.