JPH0767059B2 - LC filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Field of Application> The present invention mainly relates to an LC used as a bandpass filter.
Regarding filters.

<Prior Art> Conventionally, as a single resonator, a structure as shown in FIG. 2 (a) is known, and the rectangular dielectric substrate 11 of the resonator 10 is known. For each front and back,
A pair of conductor patterns facing each other with this substrate 11 in between
12 and 13 are formed. Then, each conductor pattern 12 (1
3) is provided with a pair of capacitor electrodes 14 (15) arranged at both ends (upper and lower sides in the figure) of the substrate 11 and a coil electrode 16 (17) connecting these one ends to each other. The coil electrode 16 and the coil electrode 17 are arranged at the respective side positions of the substrate 11 which are separated from each other.
Further, the capacitor electrode 14 located under the surface of the substrate 11
Is connected to the input terminal 18, and the output terminal 19 is connected to the capacitor electrode 15 located on the lower side of the back surface thereof. Therefore, the resonator 10 is represented by an equivalent circuit as shown in FIG. The reference symbols C1 and C2 in FIG. 2 (b) are capacitor electrodes 14 and 15.
And a substrate 11 sandwiched between them, and L1 and L2 are inductances composed of coil electrodes 16 and 17.

On the other hand, as the LC filter 20, a combination of a plurality of the resonators 10 is known, and as an example thereof, as shown in FIG. 3 (a), three resonators 10 are arranged in parallel. There is one. The LC filter 20 includes a dielectric substrate 21 formed in a rectangular shape, and three conductor patterns 12 and 13 forming the above-described resonator 10 are provided on each of the front and back surfaces of the substrate 21. Are formed in parallel along the longitudinal direction. The coil electrode 16 of each conductor pattern 12 formed on the front surface of the substrate 21 and the coil electrode 17 of each conductor pattern 13 formed on the back surface of the substrate 21 are arranged close to each other via the substrate 21, and these When the coil electrodes 16 and 17 are magnetically coupled to each other, a filter structure as shown in the equivalent circuit diagram of FIG. 3B can be obtained. The reference numeral 22 in these figures
Is an input terminal, 23 is an output terminal, and 24 is a ground terminal.These terminals 22 to 24 are capacitor electrodes 14 and 1 corresponding to each other.
Connected to each of the 5.

<Problems to be Solved by the Invention> The LC filter 20 having the conventional configuration has the following disadvantages. That is, this LC filter
When forming 20, the three conductive patterns 12 (13) are simultaneously formed at once by screen-printing a conductive paste on each of the front and back surfaces of the dielectric substrate 21. , If the positioning accuracy at the time of printing on the front and back surfaces of the substrate 21 is low, the conductor pattern printed on each of the front and back surfaces of the substrate 21
12, 13 The mutual forming positions are displaced from each other. And
Due to this printing shift, the formation positions of the coil electrodes 16 and 17 that should be arranged close to each other via the substrate 21 are shifted, and as a result, the conductor patterns 12 and 13 formed on the front and back surfaces of the substrate 21 respectively.
The magnetic coupling between the coil electrodes 16 and 17, that is, between the resonators 10 is changed and becomes unstable.

Therefore, not only the filter characteristics of each LC filter 20 are deteriorated, but also the bandwidths of the manufactured LC filters 20 are varied, which makes it impossible to improve productivity. Also, if you try to avoid such inconvenience,
Conductor pattern 1 on each of the front and back surfaces of the dielectric substrate 21
Positioning of 2 and 13 must be performed with high accuracy, which increases the labor and time required to form the conductor pattern, resulting in an increase in cost.

The present invention has been made in view of the above conventional inconvenience, and was devised to solve the problem. Even if the positions of the conductor patterns formed on the front and back surfaces of the dielectric substrate are displaced from each other, the filter characteristics are deteriorated. It is an object of the present invention to provide an LC filter that can improve productivity and reduce cost without causing the above problem.

<Means for Solving the Problems> In order to achieve such an object, the present invention has three conductor patterns formed in parallel on each of the front and back surfaces of a dielectric substrate, and the dielectric substrate is interposed therebetween. Each of the conductor patterns formed at the positions facing each other includes a pair of capacitor electrodes spaced apart along a direction orthogonal to the parallel direction of these conductor patterns, and a coil electrode at which one end portions of both capacitor electrodes are connected to each other. In a LC filter having a U-shape when viewed from above, the coil electrodes of a pair of adjacent conductor patterns that are formed on either one of the front and back surfaces of the dielectric substrate are arranged in a proximity position where they are magnetically coupled to each other. On the other hand, a pair of conductors which are formed on the other surface of the dielectric substrate and are adjacent to each other and have a position combination different from that of the conductor patterns adjacent to each other on the one surface. Characterized in that it is arranged turn coil electrodes are in proximity position magnetically coupled to each other.

<Operation> According to the above configuration, the coil electrodes of a pair of conductor patterns adjacent to each other on one of the front and back surfaces of the dielectric substrate are closely arranged and magnetically coupled to each other, while being adjacent to each other on the other surface of the dielectric substrate. Further, the coil electrodes of a pair of conductor patterns different from the position combination on the one surface are closely arranged to be magnetically coupled.

Therefore, even if the conductor patterns formed on the front and back surfaces of the dielectric substrate are misaligned with each other, the magnetic coupling between the resonators forming the LC filter does not become unstable,
While effectively preventing the deterioration of the filter characteristics,
Bandwidth variation between the manufactured LC filters will be prevented.

<Example> Hereinafter, an example of the present invention is described based on a drawing.

FIG. 1 (a) is a plan view showing the configuration of an LC filter according to the present invention, and FIG. 1 (b) is an equivalent circuit diagram thereof. Reference numeral 1 in FIG. 1 (a) is an LC filter, and this LC filter 1 is the resonator 10 described in the conventional example (FIG. 3 (a),
(See (b)) are combined and arranged in parallel.

This LC filter 1 is provided with a dielectric substrate 2 formed in a rectangular shape, and the conductor patterns 12 and 13 constituting the above-described resonator 10 are provided on the substrate 2 on the front and back surfaces of the substrate 2, respectively.
3 are formed in parallel by screen-printing a conductive paste along the longitudinal direction of. Each of the conductor patterns 12 and 13 is formed at each position facing each other with the dielectric substrate 2 interposed therebetween.
Each of the conductor patterns 12 formed in parallel on the surface of the substrate 2 has both end portions along the short side direction of the substrate 2 (upper and lower sides in the figure).
Each of the positions, that is, a plan view including a pair of capacitor electrodes 14 spaced apart along a direction orthogonal to the parallel direction of these conductor patterns 12 and a coil electrode 16 connecting one end portions of both capacitor electrodes 14 to each other. It has a U-shape. In addition, each of the conductor patterns 13 formed in parallel on the back surface of the substrate 2 also has a pair of capacitor electrodes 15 spaced apart along the direction orthogonal to the parallel direction of the conductor patterns 13 and one end of both capacitor electrodes 15. It has a U-shape in a plan view and is composed of a coil electrode 17 that connects the parts to each other.

Furthermore, while the coil electrodes 16 of the pair of conductor patterns 12 formed adjacently on the left side surface of the dielectric substrate 2 are closely arranged so as to be magnetically coupled to each other, on the right side rear surface of the substrate 2. The coil electrodes 17 of the pair of conductor patterns 13 formed adjacent to each other are also arranged close to each other so as to be magnetically coupled to each other.

That is, here, a pair of adjacent conductor patterns formed on the front surface (one of the front and back surfaces) of the dielectric substrate 2
While the 12 coil electrodes 16 are arranged in the proximity position where they are magnetically coupled to each other, the conductor pattern 12 is formed on the back surface (other surface) of the substrate 2 so as to be adjacent to it and on the front surface (one surface) thereof. Arranges the coil electrodes 17 of the pair of conductor patterns 13 in different position combinations in the proximity positions where they are magnetically coupled to each other.

At this time, the coil electrodes 16 and 17 of the conductor patterns 12 and 13 facing each other via the dielectric substrate 2 are arranged so as to be largely separated from each other so as not to be magnetically coupled to each other.

Further, the input terminal 3 is formed on the capacitor electrode 14 formed on the front surface of the substrate 2 and located on the lowermost left side, and the capacitor electrode 14 formed on the back surface of the substrate 2 is located on the lowermost right side.
The output terminal 4 is connected to 15. A ground terminal 5 is connected to each of the capacitor electrode 14 formed on the front surface of the substrate 2 and located on the lower right side and the capacitor electrode 15 formed on the back surface of the substrate 2 and located on the lower left side. There is.

Therefore, in this LC filter 1, its substrate 2
Conductor pattern 1 formed on the front and back surfaces of
Coil electrodes 16 and 17 placed close to each other
The two are magnetically coupled to each other, and a filter configuration as shown in the equivalent circuit diagram of FIG. 1 (b) is obtained. In addition, reference numerals C1 and C2 in FIG. 1 (b)
Indicates a capacitor constituted by the capacitor electrodes 14 and 15 and the substrate 2 sandwiched therebetween, and L1 and L2 indicate inductances formed by the coil electrodes 16 and 17.

<Effects of the Invention> As described above, according to the present invention, while the coil electrodes of a pair of conductor patterns adjacent to each other on one of the front and back surfaces of the dielectric substrate are closely arranged to be magnetically coupled,
Since the coil electrodes of a pair of conductor patterns adjacent to each other on the other surface of the dielectric substrate and different from the position combination on the one surface are closely arranged and magnetically coupled, each of the front and back surfaces of the dielectric substrate is Even if the printed conductor patterns are displaced from each other, no inconvenience will occur, and the magnetic coupling between the resonators constituting the LC filter will not become unstable.

Therefore, the deterioration of the filter characteristics of the LC filter is effectively prevented, and the band widths of the manufactured LC filters do not vary, so that the productivity can be improved. In addition, this eliminates the need for highly accurate positioning of the conductor pattern on each of the front and back surfaces of the dielectric substrate, thus saving the labor and time required to form the conductor pattern, resulting in cost reduction. The effect of being able to achieve is obtained.

[Brief description of drawings]

1 (a) and 1 (b) relate to an embodiment of the present invention.
FIG. 1A is a plan view showing the structure of the LC filter, and FIG. 1B is its equivalent circuit diagram. Further, FIGS. 2 (a) and (b) and FIG. 3 (a),
FIG. 2 (b) is a conventional example, FIG. 2 (a) is a plan view showing a single resonator, and FIG. 2 (b) is an equivalent circuit diagram thereof.
FIG. 3 (a) is a plan view showing the structure of the LC filter, and FIG. 3 (b) is an equivalent circuit diagram thereof. In the figure, reference numeral 1 is an LC filter, 2 is a dielectric substrate, and 12, 1
3 is a conductor pattern, 14 and 15 are capacitor electrodes, and 16 and 17 are coil electrodes.

Claims (1)

[Claims] 1. A conductor pattern having three conductor patterns formed in parallel on each of the front and back surfaces of a dielectric substrate, and each conductor pattern formed at each of the positions facing each other through the dielectric substrate,
An LC filter having a U-shape in a plan view, which is composed of a pair of capacitor electrodes spaced apart along a direction orthogonal to the parallel direction of these conductor patterns and a coil electrode in which one end portions of both capacitor electrodes are connected to each other. In the above, while the coil electrodes of a pair of adjacent conductor patterns formed on one of the front and back surfaces of the dielectric substrate are arranged in a proximity position where they are magnetically coupled to each other, on the other surface of the dielectric substrate. An LC characterized in that the coil electrodes of a pair of conductor patterns that are formed and adjacent to each other and have a position combination different from that of the conductor patterns that are adjacent on the one surface are magnetically coupled to each other. filter.