JP2001211006A - Dielectric filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stabilized input-output coupling for dielectric filter. SOLUTION: A dielectric filter provided by joining plural rectangular solid dielectrics 11, 12, is provided with parts 13, 14 on one surface of each dielectric to expose dielectric material, and an earthing electrode made of conductor film formed on the surroundings of the part from which dielectric material is exposed and over other entire surface. The dielectric is mounted on the wiring substrate so as to have the exposed part close to an island-like conductor film 22 formed on the wiring substrate 20. The conductor film is used as the input-output electrode. The input-output electrode is not formed on the dielectric 11, 12, the conductor film 22 of the wiring substrate 20 is brought close to the dielectric, and an 20 input-output coupling capacitance is provided between the conductor film 22 and the earth conductor on the opposite side.

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 dielectric filter suitable for use in a high frequency band of 3 GHz or more, and more particularly to an input / output coupling structure suitable for surface mounting.

[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 more than 10 mm,
This goes against the demand for miniaturization of electronic components and cannot be put to practical use. The use of the TE mode resonator increases the size of the structure and also complicates the input / output coupling structure.

The inventor of the present invention has disclosed in Japanese Patent Application Nos. 9-368254 and 9-369215 that an input / output electrode is provided on one surface of a rectangular parallelepiped dielectric, and the entire surface of the other surface is surrounded while surrounding them. A dielectric filter with a covering earth electrode was proposed.

[0005]

In such a dielectric filter, the input / output electrode and the ground electrode are on the same surface, and the input / output electrode is surrounded by the ground electrode. Therefore, it is difficult to perform surface mounting when mounting on a printed circuit board and connecting to an external circuit. The present invention provides a small-sized dielectric filter which can be surface-mounted and has sufficient filter characteristics even in a high frequency band.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems by using a conductive film on a mounting wiring board as an input / output electrode.

That is, in a dielectric filter in which a plurality of rectangular parallelepiped dielectrics are joined, one surface of each dielectric has an exposed portion of the dielectric material, and the periphery of the exposed portion of the dielectric material is provided. It has a ground electrode made of a conductive film formed on the entire surface of the other surface except for the bonding surface, and the dielectric material is so arranged that the exposed portion of the dielectric material is close to the island-shaped conductive film formed on the wiring board. Are mounted on a wiring board, and the island-shaped conductor film is used as an input / output electrode.

In a dielectric filter integrally formed with a rectangular parallelepiped dielectric block, the dielectric filter includes an exposed portion of the dielectric material spaced on one surface of the dielectric, and the exposed portion of the dielectric material is provided. And a ground electrode made of a conductive film formed on the entire surface of the substrate and other surfaces, and the dielectric is wired so that an exposed portion of the dielectric material is close to the island-shaped conductive film formed on the wiring board. It is mounted on a substrate and is characterized in that its island-shaped conductor film is used as an input / output electrode.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Although the resonance mode of a dielectric filter to which the present invention is applied has not been completely analyzed yet, it is considered that the dielectric filter has a function close to that of a waveguide. It is considered that a resonator is constituted by the input / output electrode and the ground electrode formed on the surface of the dielectric, and the resonator is coupled to obtain a filter.

The dielectric filter is mounted on a wiring board by bonding a ground electrode and a wiring pattern with solder or the like.
If the input / output electrodes are formed on a dielectric, the earth electrode has a larger area, so that a large amount of solder adheres to the ground electrode to lift the dielectric. As a result, the input / output electrode part may not be able to be connected stably, but if the conductor film of the wiring board is used without forming a conductor film, the distance between the exposed part of the dielectric material and the distance can be kept constant. it can.

[0011]

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

FIG. 3 is a perspective view of an example of a dielectric filter to which the present invention is applied. Exposed portions 33, 34 of a square or rectangular island-shaped dielectric material are formed at the center of one surface of the rectangular parallelepiped dielectrics 31, 32. Conventionally, input / output electrodes are formed here, but are not formed in the present invention. Conductor films 35 and 36 are formed around the exposed portions 33 and 34 of the island-shaped dielectric material to serve as ground conductors.

A conductor film is formed on the entire surface of the dielectrics 31 and 32 other than the joint surface 37, and is connected to the conductor films 35 and 36 to form an earth conductor. Although not shown, a conductor film connected to the ground conductor is formed on a part of the joint surface.
Thereby, the coupling between the resonators can be adjusted.

FIG. 4 is a perspective view of another example of the dielectric filter to which the present invention is applied. Exposed portions 43 and 44 of a square or rectangular island-shaped dielectric material are formed on one surface of a rectangular parallelepiped dielectric 40 at intervals. Exposed part of island-shaped dielectric material
A conductor film 45 is formed around 43 and 44 to serve as a ground conductor.

A conductor film is also formed on the entire other surface, and is connected to the conductor film 45 to serve as a ground conductor. A through hole 48 is formed in the middle between the conductor films 43 and 44, so that the coupling between the resonators can be adjusted.

FIG. 1 is a front sectional view showing an embodiment of the present invention. Exposed portions 13 and 14 of a square or rectangular dielectric material are formed in the center of one surface of the rectangular parallelepiped dielectrics 11 and 12, and conductor films 15 and 16 are formed around them to form an earth conductor. Become. This dielectric is mounted on a wiring board 20, and a grounding conductor pattern 21 and an input / output conductor pattern 22 connected to the ground conductors 15 and 16 are formed on the wiring board 20. The input / output conductor pattern 22 is formed at a position facing the exposed portions 13 and 14 of the dielectric material of the dielectric. Of course, the conductor pattern 22 is made smaller than the area of the exposed portion, and has a size that does not contact the ground conductors 15 and 16.

FIG. 2 is a front sectional view showing the embodiment after soldering. Ground conductors 15 and 16 are conductor patterns for grounding
Soldered to 21, the dielectric filter is mounted and fixed on the wiring board 20. The input / output conductor pattern 22 connected to the conductor pattern 23 on the back surface faces the dielectric material at a small interval. The conductor pattern 22 is opposed to the ground conductors 15 and 16 on the back surface at the portions 13 and 14 where the dielectric material is exposed, so that input / output coupling capacitance can be obtained. FIG.
The connection of the dielectric filter integrally formed with the rectangular parallelepiped dielectric block shown in FIG. 4 to the wiring board is the same as that in FIG.

The dielectric filter according to the present invention is mounted and fixed on a printed circuit board by solder reflow or the like. At this time, the ground electrode is securely connected and fixed, and the input / output coupling capacitance can be obtained as designed.

[0019]

According to the present invention, since the input / output electrode portion is not soldered, the input / output coupling capacitance at the input / output electrode can be stabilized. Therefore, the yield is improved and the mechanical reliability is also improved. It is also advantageous for stabilizing characteristics.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing an embodiment of the present invention.

FIG. 2 is a front sectional view showing an embodiment of the present invention.

FIG. 3 is a perspective view of a dielectric filter to which the present invention is applied.

FIG. 4 is a perspective view of another dielectric filter to which the present invention is applied.

[Explanation of symbols]

 13, 14: Exposed portion of dielectric material 15, 16: Ground electrode 20: Wiring board 22: Input / output conductor pattern

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5E336 AA04 BB02 BC34 CC32 CC36 CC51 DD16 EE01 GG11 5J006 HC03 HC24 JA01 LA12 LA28 NA04 NC03 ND03 NE14

Claims (4)

[Claims] 1. A dielectric filter in which a plurality of rectangular parallelepiped dielectrics are joined to each other, each of the dielectrics having a surface on which one surface of the dielectric material is exposed. It has a ground electrode made of a conductive film formed on the entire surface of the other surface except for the bonding surface, and the dielectric material is so arranged that the exposed portion of the dielectric material is close to the island-shaped conductive film formed on the wiring board. Is mounted on the wiring board,
A dielectric filter, wherein the island-shaped conductor film is used as an input / output electrode. 2. A dielectric filter in which a plurality of rectangular parallelepiped dielectrics are joined to each other, each of the dielectrics having one surface on which a dielectric material is exposed, and a periphery of the dielectric material being exposed. It has a ground electrode made of a conductive film formed on the entire surface of the other surface except for the bonding surface, and the dielectric material is so arranged that the exposed portion of the dielectric material is close to the island-shaped conductive film formed on the wiring board. Is mounted on the wiring board,
A dielectric filter, wherein a ground electrode around a portion where a dielectric material is exposed is connected to another conductive film on a wiring board, and the island-shaped conductive film is used as an input / output electrode. 3. A dielectric filter integrally formed with a rectangular parallelepiped dielectric block, comprising an exposed portion of a dielectric material spaced on one surface of the dielectric, wherein the exposed portion of the dielectric material is provided. And a ground electrode made of a conductive film formed on the entire surface of the substrate and other surfaces, and the dielectric is wired so that an exposed portion of the dielectric material is close to the island-shaped conductive film formed on the wiring board. A dielectric filter mounted on a substrate, wherein the island-shaped conductive film is used as an input / output electrode. 4. A dielectric filter integrally formed with a rectangular parallelepiped dielectric block, comprising a portion of one surface of the dielectric where the dielectric material is exposed, and a portion where the dielectric material is exposed. And a ground electrode made of a conductive film formed on the entire surface of the substrate and other surfaces, and the dielectric is wired so that an exposed portion of the dielectric material is close to the island-shaped conductive film formed on the wiring board. A dielectric filter mounted on a substrate, wherein a ground electrode around a portion where the dielectric material is exposed is connected to another conductive film on the wiring substrate, and the island-shaped conductive film is used as an input / output electrode.