JPH10190311A - Dielectric filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the occurrence of unnecessary stray capacitance and to provide a satisfactory characteristic by providing plural conductor films which are insulated from an outer conductor and face an inner conductor and forming a conductor pattern connecting a conductor film on the face of a dielectric block through a glass layer. SOLUTION: The conductor film 15 insulated from the outer conductor 12 are foamed on positions facing the inner conductor 11 at a part of the surface where the outer conductor 12 is formed. The glass layer 16 is formed on the surface of the dielectric block 10 between the conductor films 15. the conductor pattern 17 connecting the conductor films 15 is formed on the surface of the glass layer 16. Capacity is added between the resonators of input/output terminals with such constitution. When capacity is added, an attenuation pole is formed on the low pass side of pass band and the dielectric rate of glass is about 10. Thus, stray capacitance between the conductor pattern 17 and the inner conductor 11 can considerably be reduced.

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 dielectric filter, and more particularly, to a dielectric filter suitable for use as a filter for adding a capacitance for forming an attenuation pole.

[0002]

2. Description of the Related Art Dielectric resonators (filters) and multilayer LC filters have come to be used as filters available in the hundreds of MHz band for mobile communication equipment and the like. Coaxial T
EM resonance type dielectric filters are widely used as filters and duplexers because high Q is obtained.

There are two types of dielectric filters: one that connects a plurality of dielectric resonators alone, and one that forms a plurality of resonators integrally by forming a plurality of through holes in a dielectric block. Further, a structure in which a dielectric substrate having a groove formed thereon is bonded is also employed.

In a dielectric filter, techniques for adjusting inductive coupling and capacitive coupling between resonators and connecting capacitance and inductance between resonators are used to adjust the pass band characteristics. In order to add capacitance or the like between the resonators, external components are required, or a dielectric substrate needs to be used.

[0005]

In order to obtain a capacitance between resonators, an attempt has been made to form a conductor film on the surface of a dielectric block, and to form a capacitor or an inductor with the conductor film. However, the dielectric material used for the dielectric filter has a dielectric constant of 35 to 90, and a stray capacitance occurs between the conductor film and another conductor film,
This is a major factor that causes deterioration of characteristics.

According to the present invention, a conductor film for obtaining capacitance and inductance is formed on the surface of a dielectric block to obtain a dielectric filter having a small number of components, and the conductor film and another conductor film such as an inner conductor. To reduce the stray capacitance between them.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems by forming a low dielectric constant layer between a conductor pattern connecting a conductor film and a dielectric block.

That is, an inner conductor is provided in a through-hole of a dielectric block having a plurality of parallel through-holes, an outer conductor is provided on a surface parallel to a direction in which the through-hole extends, and a short-circuit conductor is provided on one end face where the through-hole is opened. In the dielectric filter, a plurality of conductor films are provided on the surface on which the outer conductor is formed, the plurality of conductor films being insulated from the outer conductor and facing the inner conductor, and the conductor pattern connecting the conductor films is insulated through the glass layer. It is characterized by being formed on the surface of the body block.

In addition, an inner conductor is provided in a through-hole of a dielectric block having a plurality of parallel through-holes, an outer conductor is provided on a surface parallel to a direction in which the through-hole extends, and a short-circuit conductor is provided at one end face of the through-hole. In the dielectric filter, on the surface on which the outer conductor is formed, a conductor film that is insulated from the outer conductor and faces a predetermined inner conductor is provided, and a conductor pattern that connects the conductor film and one of the input / output electrodes is formed. It is characterized by being formed on the surface of the dielectric block via the glass layer.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A conductor film insulated from an outer conductor is formed at a position facing an inner conductor on a side surface of a dielectric block. This conductor film can be formed simultaneously with the formation of the outer conductor. After a glass layer is formed on the surface of the dielectric block between the conductor film and another conductor film to be connected, a conductor pattern for connecting the conductor film is formed on the surface of the glass layer.

[0011]

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

FIG. 1 is a perspective view showing an embodiment of the present invention. The dielectric block 10 having three through holes is formed of a ceramic material having a relatively high dielectric constant of about 90.
An inner conductor 11 is formed in a through hole of the dielectric block 10, and an outer conductor 12 is formed on a surface parallel to a direction in which the through hole extends. Although not shown, a conductor film is also formed on one of the end faces where the through-holes are opened, and serves as a short-circuit conductor.

In the dielectric filter according to the present invention,
A conductor film 15 insulated from the outer conductor is formed at a position facing the inner conductor 11 without forming the outer conductor on a part of the surface on which the outer conductor 12 is formed. The conductor film 15 faces the inner conductor 11 and forms a capacitor therebetween. In this example, a conductor film 15 facing the inner conductor 11 of the resonator at both ends is formed.

The dielectric block 10 between these conductor films 15
A glass layer 16 is formed on the surface. This glass layer 16
A conductor pattern 17 for connecting the conductor films 15 to each other is formed on the surface of the substrate. Note that the conductor film 18 of the terminal electrode is formed at the same time as the formation of the outer conductor 12 and the conductor film 15.

[0015] By adopting the above structure, as shown in FIG. 2, so that the capacitance C ₅ is added between the resonator input and output ends. When this capacitance is added, an attenuation pole can be formed on the lower side of the pass band. Since the dielectric constant of glass is about 10, stray capacitance between the conductor pattern 17 and the inner conductor can be significantly reduced.

FIG. 3 is a perspective view showing another embodiment of the present invention. A dielectric block 30 having two through holes is formed of a ceramic material having a relatively high dielectric constant of about 90. An inner conductor 31 is formed in the through hole of the dielectric block 30, and an outer conductor 32 is formed on a surface parallel to a direction in which the through hole extends.
To form Although not shown, a conductor film is also formed on one of the end faces where the through-holes are opened, and serves as a short-circuit conductor.

In this dielectric filter, the outer conductor 32
The outer conductor is not formed on a part of the surface on which is formed, but a conductor film 35 insulated from the outer conductor is formed at a position facing the inner conductor 31. This conductor film 35 faces the inner conductor 31 and forms a capacitance therebetween. In this example, a conductor film 35 facing the inner conductor 31 of the resonator at the output end is formed.

The conductor film 35 and the conductor film 38a of the input electrode
A glass layer 36 is formed on the surface of the dielectric block 30 in between. A conductor pattern 37 connecting the conductor film 35 and the conductor film 38a of the input electrode is formed on the surface of the glass layer 36.
The conductor film 38 of the terminal electrode is formed at the same time as the formation of the outer conductor 32 and the conductor film 35.

By adopting the structure shown in FIG.
Realized the circuit shown in FIG. 4, capacitor C ₈ is added between the input terminal and the output side of the resonator. When the resonators are inductively coupled, an attenuation pole is obtained on the higher side of the pass band, and can be used as a trap or the like.

The present invention can be applied to a laminated dielectric filter or a dielectric filter having four or more elements. It is also possible to realize an inductance by a conductor pattern or to form a plurality of connection conductor patterns.

[0021]

According to the present invention, a circuit element can be formed by a conductor film on the surface of a dielectric block, and a small-sized dielectric filter with a small number of components can be realized.

Further, since the conductor film is formed through the glass having a low dielectric constant, the generation of unnecessary stray capacitance can be minimized, and a dielectric filter having good characteristics can be obtained.

[Brief description of the drawings]

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

FIG. 2 is an equivalent circuit diagram of the dielectric filter of FIG. 1;

FIG. 3 is a perspective view showing another embodiment of the present invention.

FIG. 4 is an equivalent circuit diagram of the dielectric filter of FIG.

[Explanation of symbols]

 10, 30: Dielectric block 11, 31: Inner conductor 12, 32: Outer conductor 15, 35: Conductor film 16, 36: Glass layer 17, 37: Conductor pattern

Claims (4)

[Claims] An inner conductor is provided in a through hole of a dielectric block having a plurality of parallel through holes, an outer conductor is provided on a surface parallel to a direction in which the through hole extends, and a short-circuit conductor is provided at one end surface of the through hole. In the dielectric filter, a plurality of conductor films are provided on the surface on which the outer conductor is formed, the plurality of conductor films being insulated from the outer conductor and facing the inner conductor, and the conductor pattern connecting the conductor films is insulated through the glass layer. A dielectric filter formed on a surface of a body block. 2. A dielectric block having a plurality of parallel through holes, an inner conductor in a through hole of the dielectric block, an outer conductor on a surface parallel to a direction in which the through hole extends, and a short-circuit conductor on one end surface of the through hole opening. In the dielectric filter, on the surface on which the outer conductor is formed, a conductor film that is insulated from the outer conductor and faces a predetermined inner conductor is provided, and a conductor pattern that connects the conductor film and one of the input / output electrodes is formed. A dielectric filter formed on a surface of a dielectric block via a glass layer. 3. A dielectric block having a plurality of parallel through holes, an inner conductor in the through hole, an outer conductor on a surface parallel to a direction in which the through hole extends, and a short-circuit conductor on one end surface of the through hole opening. A dielectric filter having a plurality of conductor films on the surface on which the outer conductor is formed, the plurality of conductor films being insulated from the outer conductor and facing the inner conductor to form a capacitor, and the conductor pattern connecting the conductor films is made of glass. A dielectric filter formed on a surface of a dielectric block via a layer. 4. A dielectric block having a plurality of parallel through holes, an inner conductor in the through hole, an outer conductor on a surface parallel to a direction in which the through hole extends, and a short-circuit conductor on one end surface of the through hole opening. The dielectric filter includes a conductor film on the surface on which the outer conductor is formed, the conductor film being insulated from the outer conductor and facing a predetermined inner conductor to form a capacitor, and the conductor film and one of the input / output electrodes are connected to each other. A dielectric filter, wherein a conductive pattern to be connected is formed on a surface of a dielectric block via a glass layer.