JP3295333B2 - Dielectric filter - Google Patents

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, it is necessary to use external components or to use a dielectric substrate on which electrodes are formed to constitute a capacitor.

[0005]

In order to obtain the capacitance between the resonators, a dielectric substrate is bonded, and a conductive film is formed on the bonding surface of the dielectric substrate. Attempts have been made to form one. However, the dielectric material used for the dielectric filter has a dielectric constant.
35 to 90 are used, and a stray capacitance is generated between the conductor film and another conductor film, which 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 an adhesive surface of a dielectric substrate to obtain a dielectric filter having a small number of parts, and the conductor film and another conductor such as an inner conductor are provided. It is to reduce the stray capacitance between the film.

[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, a first dielectric substrate having a plurality of parallel grooves, a second dielectric substrate adhered to the surface of the first dielectric substrate on which the grooves are formed, A third dielectric substrate bonded to a surface of the dielectric substrate opposite to a surface bonded to the first dielectric substrate, wherein a surface of the groove of the first dielectric substrate and a second dielectric substrate are bonded. An inner conductor is provided on the surface facing the concave groove of the body substrate, and an outer conductor is provided on the surface of the first dielectric substrate and the third dielectric substrate that are not bonded and the end surface of each dielectric substrate where the groove does not open. In a dielectric filter having a short-circuit conductor at one end surface where the concave groove opens, at least one of the bonding surfaces of the second dielectric substrate and the third dielectric substrate has two or more conductor films facing the inner conductor. glass comprising, those conductive film formed in the third dielectric substrate-side surface of the second dielectric substrate Those having features that are connected by a conductor film located above.

A first dielectric substrate having a plurality of parallel grooves; a second dielectric substrate adhered to the surface of the first dielectric substrate having the grooves formed therein; A third dielectric substrate bonded to a surface of the dielectric substrate opposite to a surface bonded to the first dielectric substrate, wherein a surface of the groove of the first dielectric substrate and a second dielectric substrate are bonded. An inner conductor is provided on the surface facing the concave groove of the body substrate, and an outer conductor is provided on the surface of the first dielectric substrate and the third dielectric substrate that are not bonded and the end surface of each dielectric substrate where the groove does not open. In a dielectric filter having a short-circuit conductor on one end surface where the concave groove opens, a conductor film facing the inner conductor is provided on at least one of the bonding surfaces of the second dielectric substrate and the third dielectric substrate, these conductive films are located in the second dielectric third dielectric substrate side of the glass layer formed on the surface of the substrate Drawn to the end face by that conductor film
And is connected to the terminal electrode.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A conductor film for forming a capacitor is formed at a position facing an inner conductor on an adhesive surface of a dielectric substrate. A conductor pattern for connecting a conductor film to the surface of the glass layer after forming a glass layer on the bonding surface of the dielectric substrate on the side where the inner conductor is formed between the conductor film and another conductor film to be connected To form

[0011]

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

1 and 2 are perspective views showing an embodiment of the present invention. FIG. 1 shows a state before assembling, and FIG. 2 shows a state after assembling. A dielectric block 10 for integrating three dielectric substrates is formed of a ceramic material having a relatively high dielectric constant of about 90. This dielectric block is formed by bonding a dielectric substrate 11 having a groove and flat dielectric substrates 12 and 13. An inner conductor 14 is formed in a through hole of the dielectric block 10, and an outer conductor 15 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 conductive film is formed on the surface of the dielectric substrate 12 which is bonded to the dielectric substrate 13.
16 is formed at a position facing the inner conductor 14. The conductor film 16 faces the inner conductor 14 and forms a capacitance therebetween. In this example, a conductor film 16 facing the inner conductor 14 of the resonator at both ends is formed.

A glass layer 17 is formed on the surface of the dielectric substrate 12 between the conductor films 16. On the surface of the glass layer 17, a conductor pattern 18 for connecting the conductor films 16 to each other is formed. Note that the conductor film 19 of the terminal electrode is formed at the same time when the outer conductor 15 is formed.
Is also formed.

[0015] By adopting the above structure, as shown in FIG. 3, 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, the stray capacitance between the conductor pattern 18 and the inner conductor can be significantly reduced.

FIG. 4 is a perspective view showing another embodiment of the present invention. A dielectric block having two through holes is formed by bonding three dielectric substrates in the same manner as described above using a ceramic material having a relatively high dielectric constant of about 90. Although the assembled state is not shown, an inner conductor is formed in the through hole of the dielectric block, and an outer conductor is formed on a surface parallel to a direction in which the through hole extends. A conductor film is also formed on one of the end faces where the through holes are opened, and becomes a short-circuit conductor.

In this dielectric filter, a conductor film 36 is formed on the surface of the second dielectric substrate 42 facing the third dielectric substrate 43 at a position facing the inner conductor. This conductor film 46 faces the inner conductor and forms a capacitor therebetween. In this example, a conductor film 46 facing the inner conductor of the resonator at the output end is formed.

A glass layer 47 is formed on the surface of the dielectric substrate 41 between the conductor film 46 and the end face on which the input electrodes are formed. On the surface of the glass layer 47, a conductor pattern 48 for connecting the conductor film 46 and the input electrode is formed.

By employing the structure shown in FIG.
To be the circuit shown is realized 5, 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 dielectric filter of a type in which a dielectric filter having a through hole is bonded to a dielectric substrate, 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. did it.

[0021]

According to the present invention, a circuit element can be formed by the conductive film on the bonding surface of the dielectric substrate, 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, 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 a perspective view showing an embodiment of the present invention.

FIG. 3 is an equivalent circuit diagram of the dielectric filter of FIG. 1;

FIG. 4 is a perspective view showing another embodiment of the present invention.

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

[Explanation of symbols]

 10: Dielectric block 11, 12, 13, 41, 42, 43: Dielectric substrate 16, 46: Conductive film 17, 47: Glass layer 18, 48: Conductive pattern

Claims (2)

(57) [Claims] 1. A first dielectric substrate having a plurality of three or more parallel grooves, and a second dielectric substrate adhered to the surface of the first dielectric substrate on which the grooves are formed. And a third dielectric substrate adhered to the surface of the second dielectric substrate opposite to the surface adhered to the first dielectric substrate, and the surface of the concave groove of the first dielectric substrate An inner conductor is provided on a surface of the second dielectric substrate facing the concave groove, and a second dielectric of the first dielectric substrate is provided.
A surface opposite the surface to which the substrate is bonded and a third dielectric
Of the body substrate opposite the surface to be bonded to the second dielectric substrate
In a dielectric filter having an outer conductor on the front surface and an end face of each of the dielectric substrates where the concave groove is not opened, and a short-circuit conductor on one end surface where the concave groove is opened, a second dielectric substrate and a third dielectric substrate are provided. Less bonding surface of body substrate
Inner conductor formed in two concave grooves that are not adjacent to each other
The two conductor films are provided at positions facing each other, and the third
In the surface of the second dielectric substrate on the bonding side with the dielectric substrate
A glass layer at a position facing the inner conductor formed in the concave groove between
Is formed, and the conductive film over the glass layer
A dielectric filter, wherein two conductive films are connected . 2. A first dielectric substrate having two or more parallel grooves, and a second dielectric substrate adhered to the surface of the first dielectric substrate on which the grooves are formed. And a third dielectric substrate adhered to a surface of the second dielectric substrate opposite to a surface adhered to the first dielectric substrate, and a surface of the groove of the first dielectric substrate. An inner conductor is provided on a surface of the second dielectric substrate opposed to the concave groove, and a second dielectric of the first dielectric substrate is provided.
A surface opposite the surface to which the substrate is bonded and a third dielectric
Of the body substrate opposite the surface to be bonded to the second dielectric substrate
In a dielectric filter having an outer conductor on the front surface and an end surface of each dielectric substrate where the concave groove does not open, and a short-circuit conductor on one end surface where the concave groove opens, a second dielectric substrate and a third dielectric substrate are provided. Less bonding surface of body substrate
Neither is it adjacent to one of the input or output terminals.
A conductor film at a position facing the inner conductor formed in the concave groove.
The second dielectric substrate on the side of the bonding surface with the third dielectric substrate
Input or output terminals on the surface of the
At the position facing the inner conductor formed in the concave groove in the middle of the groove,
A glass layer is formed, and a conductor film straddling this glass layer
A dielectric filter , wherein an input terminal or an output terminal is connected to the conductor film .