JPH05110316A - Resonator - Google Patents

Abstract

PURPOSE:To solve a problem that the length of the resonator is long because the characteristic impedance of a single line for a conventional ring resonator comprising a lumped constant capacitor and the single line is uniform with respect to the resonator made of a strip line or a microstrip line used for a filter or an oscillator or the like at a high frequency band used for various electric equipments. CONSTITUTION:A characteristic impedance of a 2nd single line 11 connecting to a 1st single line 10 is decreased more than the 1st single line 10, and its open ends are connected by a lumped constant capacitor 12, resulting that the capacitor is added equivalently with respect to ground, and the total length of the 1st and 2nd single lines formed in a loop is reduced more than that of a conventional ring resonator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a high frequency band filter,
The present invention relates to a resonator using a strip or microstrip line used for an oscillator or the like.

[0002]

2. Description of the Related Art In recent years, resonators used in the high frequency band are
A strip or a microstrip line structure having a quarter wavelength is often used, but it has a drawback that characteristics such as resonance frequency and no-load Q vary depending on the method of grounding at high frequency. As a resonator for improving this, there is known a ring resonator which has no high frequency grounding and can be miniaturized. The structure of this ring resonator is known, for example, from Japanese Patent Laid-Open No. 54-42674.

A conventional ring resonator will be described below. FIG. 3 shows a conventional ring resonator. In FIG. 3, 1 is a microstrip line, a single line formed in a loop shape, and 2 is a lumped constant capacitance. In this figure, although the shape is rectangular, the electrical characteristics are the same as the ring shape, so a rectangular shape will be described here. Further, the line can be applied to both a strip and a microstrip line, but here, a microstrip line will be described as a representative.

The operation of the ring resonator having the above structure will be described below. This resonator can realize a much smaller resonator than the ordinary one-wavelength ring resonator by using the above-described structure, that is, the loop-formed single line 1 and the lumped constant capacitance 2. ..
In addition, this resonator is a compact one without compromising the features of the one-wavelength ring resonator, such as no high-frequency grounding and a small radiation loss due to the loop-shaped structure. is there.

[0005]

However, with the above configuration, it is possible to achieve miniaturization without deteriorating the features of the one-wavelength ring resonator, but the characteristic impedance of a single line is reduced. Therefore, there is a problem that the resonator length is long.

The present invention solves the above-mentioned problems of the prior art, and an object of the present invention is to provide a compact resonator by reducing the resonator length.

[0007]

In order to achieve this object, the present invention has a characteristic impedance of a second single line connected to the first single line which is smaller than that of the first single line. In addition, the open end is connected by a lumped constant capacitance. In addition, the open end of the second single line can be made close to each other, and the distributed capacitance between the open ends of the second single line can be used together.

[0008]

According to the present invention, by adding the second single line having the characteristic impedance lower than that of the first single line by the above structure, the capacitance is equivalently added to the ground. Therefore, in order to obtain the same resonance frequency, compared to the conventional ring resonator in which a lumped constant capacitance is loaded at both ends of a single line with a uniform characteristic impedance, it is formed in a loop shape. Further, it is possible to shorten the total length of the first and second single lines, that is, the resonator length. Further, by making the open ends of the second single lines close to each other, the distributed capacitance between the open ends of the second single line can be used together, and further downsizing can be achieved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram of a resonator in a first embodiment of the present invention. In FIG. 1, 10 is a first single line formed in a loop shape, 11 is a second single line having a characteristic impedance lower than that of the first single line, and 12 is a lumped constant capacitance. Is.

Regarding the resonator configured as described above,
The operation will be described. By changing the characteristic impedance of a single line stepwise and lowering the characteristic impedance on the open end side, equivalently, it means that a capacitance is added between the ground and the same. To obtain the resonance frequency, the first single line 10 and the second single line 10 formed in a loop shape are used.
The total length of the single line 11 is shorter than the resonator length of the conventional ring resonator, and the resonator can be further downsized.

Further, even if the resonance frequency deviates from the desired frequency, the frequency can be easily adjusted by slightly trimming the second single line portion.

As described above, according to the present embodiment, the characteristic impedance of the single line is changed stepwise and the characteristic impedance at the open end side is lowered, so that it is equivalent to the ground. Since capacity has been added in between,
To obtain the same resonance frequency, the total length of the loop-shaped first single line and the second single line is shorter than the resonator length of the conventional ring resonator. Therefore, the size of the resonator can be further reduced.

Another embodiment of the present invention will be described below with reference to the drawings. 2 shows a resonator according to another embodiment of the present invention, FIG. 2 (a) is a diagram of the resonator according to the second embodiment of the present invention, and FIG. 2 (b) is a resonator according to the third embodiment. FIG.

In FIGS. 2A and 2B, 20 is a loop-shaped first single line, 21 is a second single line having a characteristic impedance lower than that of the first single line, Reference numeral 22 denotes a lumped constant capacity, which has the same configuration as that of FIG. The difference from the configuration of FIG. 1 is that the open ends of the second single line are arranged close to each other and the distributed capacitances 23 and 24 between them are used together. In FIG. 2A, the distributed capacitance 23 by parallel coupling between the open ends of the second single line is used, and in FIG. 2B, the distributed capacitance 24 by comb-shaped coupling is used.

Regarding the resonator constructed as described above,
The operation will be described below. By making the open ends of the second single line close to each other, the distributed capacitance between the open ends of the second single line can be used together, and further downsizing can be achieved.

As described above, by bringing the open ends of the second single line close to each other, the distributed capacitance between the open ends of the second single line can be utilized, and further downsizing can be achieved.

In the second and third embodiments, the second
Although the example of utilizing the distributed capacitance between the open ends of the single line has been presented, it goes without saying that the distributed capacitance may be increased by making the shape into a wave shape.

[0019]

As described above, according to the present invention, the characteristic impedance of the second single line connected to the first single line is firstly measured.
By making it smaller than the single line, the equivalent capacitance is added between the ground and the open end is connected by the lumped constant capacitance, so the same resonance frequency is obtained. In comparison with a conventional ring resonator in which a lumped constant capacitance is loaded at both ends of a single line with a uniform characteristic impedance, the total of the first and second single lines formed in a loop shape is Can be shortened, that is, the resonator length can be shortened. Further, by making the open ends of the second single line close to each other and utilizing the distributed capacitance therebetween, it is possible to use the distributed capacitance between the open ends of the second single line in addition to the lumped constant capacitance. Further downsizing can be achieved.

Even if the resonance frequency deviates from the desired frequency, the frequency can be easily adjusted by trimming the second single line portion.

[Brief description of drawings]

FIG. 1 is a plan view of a resonator according to a first embodiment of the present invention.

FIG. 2A is a plan view of a resonator according to a second embodiment of the present invention. FIG. 2B is a plan view of a resonator according to a third embodiment of the present invention.

FIG. 3 is a plan view of a conventional resonator.

[Explanation of symbols]

 10, 20 First single line 11, 21 Second single line 12, 22 Lumped constant capacitance 23, 24 Distributed capacitance between open ends of second single line

Claims (3)

[Claims] 1. A first single line composed of a strip or a microstrip line, and a characteristic impedance connected to the first single line is a characteristic impedance of the first single line. A resonator having a second single line that is smaller than the above, and a lumped constant capacitance loaded at the open end of the second single line. 2. The resonator according to claim 1, wherein the open ends of the second single line are brought close to each other, and the distributed capacitance between the open ends of the second single line is used together. 3. The resonator according to claim 2, wherein the open ends of the second single lines are close to each other, and the open ends of the second single line are formed in a comb tooth shape or a wave shape. ..