JP2682161B2 - Dielectric resonator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a portable radio device and the like.
GHz dielectric resonator.

2. Description of the Related Art Resonators used in the frequency band of several 100 MHz to several GHz include the dielectric resonator shown in FIG. 6 previously proposed by the present applicant and the helical resonator shown in FIG. In FIG. 6, (a) is a front view, (b) is a side view,
(C) is a rear view.

The dielectric resonator shown in FIG. 6 has two capacitor electrode patterns 52a, 52b, 53a, 53b and a coil pattern 54 on the front surface 51a and the back surface 51b of a dielectric substrate 51 made of, for example, FRDR material or the like.
a and 55a are formed by screen printing silver paste, for example.

The electrode patterns 52a and 53a, and 52b and 53b are opposed on both front and back surfaces of the dielectric substrate, and have a dielectric constant of the substrate 51,
Capacitors C1 and C2 having a capacity determined by the thickness and the facing area of the capacitor electrodes are formed. On the other hand, the coil patterns 54a and 55a have two capacitor electrode patterns 52a and 52b, 53a and 53b on the front and back surfaces 51a and 51b of the dielectric substrate 51, respectively.
Are connected.

Since each of the coil patterns 54a and 55a forms a coil in terms of high frequency, assuming that the inductances are L1 and L2, as shown in FIG. 7, the resonator has coils L1 and L2 on both sides of the first capacitor C1. Are connected in series to an LC circuit in which a second capacitor C2 is connected in parallel.

The helical resonator shown in FIG. 8 is obtained by winding a helical coil 21 around an insulator column 24 with a metal cap.
The LC resonator is formed by the inductance of the helical coil 21 itself and the capacitance formed between the helical coil 21 and the metal cap 22.

Problems to be Solved by the Invention By the way, in the dielectric resonator shown in FIG.
If a shield is applied because it is affected by an external electromagnetic field, it is necessary to provide a shielding metal plate at a position separated by a desired distance from the capacitor electrode pattern 52a, the coil pattern 54a, etc. There was a problem.

On the other hand, in the helical resonator shown in FIG. 8, since the metal cap 22 has a shielding function, there is no need to separately provide a shield, but it is difficult to reduce the size and is not suitable for surface mounting.

Accordingly, the present invention provides a very useful dielectric resonator which is compact, is suitable for surface mounting, and does not require a separate shield.

Means for Solving the Problems In a dielectric resonator according to the present invention, a planar coil pattern and an earth pattern are opposed to each other with a dielectric layer sandwiched in a sintered body in which a dielectric sheet is fired and integrated. Formed,
One end of the coil pattern and the ground pattern are drawn out to the end surface of the sintered body, and both patterns are connected by a first external electrode provided on the end surface, while the other end of the coil pattern is open. The intermediate portion of the coil pattern is extended to the end surface of the sintered body and is connected to the second external electrode provided on the end surface.

Operation According to the above configuration, while the coil pattern functions as an inductor, on the open end side of the coil pattern,
A necessary capacitance component is secured between the ground pattern and the earth pattern.
Since one end of the coil pattern is connected to the ground pattern, a resonance circuit composed of an inductor and a distributed constant type capacitance component is formed as a whole. In this case, unlike the helical resonator, the resonator of the present invention has a planar structure, and the coil pattern and the ground pattern are drawn out to the end surface of the sintered body and are connected to the external electrodes provided on the end surface. , The parts structure is suitable for surface mounting.

In addition, if the dielectric layer between the coil pattern and the ground pattern is made thin, the distributed capacitance increases correspondingly, the resonance frequency can be lowered, and the size can be reduced.

EXAMPLE FIG. 1 is an exploded perspective view showing the structure of a dielectric resonator according to the present invention, and FIG. 2 is a front view thereof. This resonator comprises, for example, a protective layer 4 having a spiral coil pattern 2 formed on one side and a protective layer 4 formed on one side on both sides of a dielectric layer 1 having several tens of dielectric sheets 1a having a thickness of about 40 μm. The protective layer 5 on which the ground pattern 3 is formed is laminated with the coil pattern 2 and the ground pattern 3 facing the dielectric layer 1 and pressure-bonded,
This laminate is made by firing external electrodes 6 and 7 having a U-shaped cross section at two points on the side A, and the dielectric sheet is integrated by firing. (See Figure 2). The protective layers 4 and 5 are made of a dielectric sheet that forms the dielectric layer 1, and the coil pattern
2, the ground pattern 3 and the external electrodes 6 and 7 are conductive A
It consists of g, Cu, etc.

FIG. 3 is a diagram showing a coil pattern 2 (solid line) and an earth pattern 3 (broken line) formed with the dielectric layer 1 sandwiched therebetween. The coil pattern 2 is provided with an input terminal 2a and a ground terminal 2b so as to be exposed at the side surface A, while the ground pattern 3 is provided with a ground terminal 3a so as to be exposed at the side surface A. As shown in FIG. 2, the input terminal 2a is connected to the external electrode 6 and the two ground terminals 2b are connected.
And 3a are connected to the external electrode 7. That is, the coil pattern 2 has the same potential as the ground pattern 3.

Further, since the dielectric layer 1 is interposed between the coil pattern 2 and the ground pattern 3, stray capacitance is generated. Although the stray capacitance is generated not only between the coil pattern 2 and the ground pattern 3 but also at another place, for example, in a portion adjacent to the coil pattern 2 itself, it is mainly between the coil pattern 2 and the ground pattern 3. And the dielectric constant or thickness of the dielectric layer 1 or the coil pattern 2
It is determined by the area etc. In addition, the dielectric layer 1 includes an insulator having a dielectric constant.

Therefore, although the configuration is such that no capacitor pattern is formed, the product of the present invention is a dielectric resonator having an equivalent circuit as shown in FIG. Further, in this resonator, since the coil pattern 2 has the same potential as the ground pattern 3 as described above, the capacitance of the capacitor can be increased and the resonance frequency can be lowered by bringing them close to each other. According to the experiment, the applicable frequency of the resonator of the present invention can be set to several hundred MHz to several GHz by adjusting the dielectric constant and thickness of the dielectric layer 1 or the area of the coil pattern 2, etc. Shows an example thereof. However, this characteristic is that the dielectric layer 1 has a thickness of 300 μm and the entire vertical dimension a is 5 μm.
mm, lateral dimension b is 5.7 mm (see FIG. 1). From this, it is understood that in the case of the present invention, thinning is possible.

Since the resonator of the present invention is planar, the resonator of the present invention may be placed with the external electrodes 6, 7 aligned on the printed circuit board. At this time, since the outer sides are covered with the protective layers 4 and 5, it is possible to prevent the coil pattern 2 and the ground pattern 3 from being damaged.
The protective layers 4 and 5 may have any thickness.

Although the coil patterns 2 and the ground patterns 3 are formed on one side of the protective layers 4 and 5 in the above-mentioned embodiment, the present invention is not limited to this, and the coil patterns 2 are formed on one side of two dielectric sheets. It is also possible to dispose the ground pattern 3 and the ground pattern 3 on both sides of the dielectric layer 1 and to provide a dielectric sheet for a protective layer without a coil pattern or a ground pattern outside the dielectric layer 1.

Further, in the above embodiment, the coil pattern 2 is formed in a spiral shape, but the coil pattern is not limited to this, and may have another shape, for example, a meandering shape.

Further, in the above-described embodiment, the dielectric layer 1 is made by stacking a plurality of thin dielectric sheets, but the present invention is not limited to this, and a dielectric sheet having a predetermined thickness may be used. Can be implemented.

Further, it is not necessary to perform the production of the product of the present invention one by one, and a plurality of coil patterns 2 are formed on one wide dielectric sheet, and the same number of ground patterns 3 are formed on the same dielectric sheet. After stacking the sheets in this state, they may be cut into individual pieces and fired.
In this case, it is easier to expose the input terminal 2a and the ground terminals 2b and 3a to the side surface, as compared with the case of manufacturing one by one.

EFFECTS OF THE INVENTION As described above, according to the present invention, a resonance circuit composed of an inductance element and a distributed capacitance can be realized by opposing a coil pattern whose one end is open and a ground pattern, and the coil pattern has a planar structure. In addition, since it has a structure in which a coil pattern, an earth pattern, and a dielectric layer are laminated, and the coil pattern and the earth pattern are drawn out to the end surface of the sintered body and connected to external electrodes, resonance suitable for surface mounting is achieved. Can be provided.

Moreover, if the dielectric layer is made thin, the capacitance between the coil pattern and the ground pattern is increased, and the resonance frequency can be reduced, and at the same time, the size can be reduced.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a structure of a dielectric resonator according to the present invention, FIG. 2 is a front view thereof, FIG. 3 is a plan view showing an essential part of the present invention, and FIG. 4 is shown in FIG. Fig. 5 is an equivalent circuit diagram of the dielectric resonator shown in Fig. 5, Fig. 5 is a graph showing an example of frequency characteristics of the dielectric resonator, and Fig. 6 (a) is a front view showing the structure of a conventional dielectric resonator. 6B is a side view thereof, FIG. 6C is a rear view thereof, FIG. 7 is an equivalent circuit diagram thereof, and FIG. 8 is a sectional view showing another conventional example (helical resonator). 1 ... Dielectric layer, 1a ... Dielectric sheet, 2 ... Coil pattern, 3 ... Ground pattern, 6,7 ... External electrodes.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Ken Tonegawa Ken 26-2-10 Tenjin, Nagaokakyo City, Kyoto Prefecture Murata Manufacturing Co., Ltd. (56) References JP-A-64-30314 (JP, A) JP-A-SHO 59-51606 (JP, A) Actually opened 61-100006 (JP, U) Actually opened 51-90743 (JP, U)

Claims (1)

(57) [Claims] 1. A planar coil pattern and a ground pattern are formed to face each other with a dielectric layer sandwiched therebetween in a sintered body in which a dielectric sheet is fired and integrated. One end of the coil pattern and the ground pattern are formed. Is drawn to the end surface of the sintered body,
Both patterns are connected by a first external electrode provided on the end face, while the other end of the coil pattern is open, and an intermediate portion of the coil pattern is pulled out to the end face of the sintered body, A dielectric resonator characterized in that it is connected to a provided second external electrode.