JPH0542168B2 - - Google Patents

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention relates to an LC resonator in which a capacitor electrode and an inductor electrode are formed on the front and back sides of a dielectric substrate.

(b) Prior Art Lumped constant type LC resonators, in which capacitor electrodes and inductor electrodes are formed on the front and back sides of a dielectric substrate, are used in filters and the like.

Figures 7A and 7B are diagrams showing the structure of a filter using this type of conventional LC resonator, and Figure 7A shows the shape of a dielectric substrate and the electrodes formed on its surface. omits the electrode formed on the surface,
It shows the shape of a dielectric substrate and an electrode formed on its back surface. Furthermore, FIG. 8 shows an equivalent circuit to the LC resonator shown in FIGS. 7A and 7B.

In FIG. 7A, 1 is a dielectric substrate made of dielectric ceramics, etc., and on its surface are inductor electrodes L1, L2 and a capacitor electrode C1 on one side.
An electrode 10 consisting of a and another one symmetrical to this
A set of electrodes 11 is formed. On the back surface of the dielectric substrate 1, there are two electrodes 12,
3 is formed, and a region C1 facing the capacitor electrodes C1a and C2a on one side shown in FIG.
b, C2b acts as a capacitor electrode on the other side. Through holes are formed at locations 14 and 15 in A and B of the same figure, and conductive paste is filled inside the holes, and electrodes 10 and 11 formed on the front surface of the substrate and electrodes 11 formed on the back surface of the substrate are formed. Electrode 1
2 and 13 are electrically connected to each other. Furthermore, 16 and 19 represent leads for inputting and outputting signals, and 17 and 18 represent leads connected to ground, respectively. In this way, a capacitor electrode and an inductor electrode are formed on the front and back sides of the dielectric substrate, thereby constructing a filter consisting of two sets of LC resonators as shown in FIG.

(c) Problems to be solved by the invention However, in such a conventional LC resonator, the electrical resistance of the through hole connecting the inductor electrode and the capacitor electrode on one side is high, so the Joule loss occurs in this part. occurs, and the Q of the resonator
There was a problem with the decrease in For example 400M
In the Hz band, the no-load Q was only about 70.
In addition, extra space is required to form the through holes, which makes it impossible to downsize the entire resonator, and furthermore, many processes are required to form the through holes, which is a cause of high costs. But it was hot.

An object of the present invention is to provide an LC resonator which solves the above-mentioned problems by devising the shapes of electrodes formed on the front and back sides of a dielectric substrate, eliminating the need for through holes.

(d) Means for Solving the Problems The LC resonator of the present invention has a capacitor electrode on one side of each of two sets of capacitors on the first main surface of the dielectric substrate, and a capacitor electrode on one side of each of the two sets of capacitors, and a gap between the two capacitor electrodes on one side. forming a first inductor electrode connecting the two one-sided capacitor electrodes to the second main surface of the dielectric substrate; A second inductor electrode is formed at a distance apart and connects the two other capacitor electrodes on one side, and one capacitor electrode of the two sets of capacitor electrodes that does not face each other is connected to a common potential terminal. However, the remaining capacitor electrode on one side is used as a signal input/output electrode.

(e) Effect In the LC resonator of the present invention, two one-sided capacitor electrodes are formed on the first main surface (front surface) of the dielectric substrate, and two capacitor electrodes are formed on the second main surface (back surface) of the dielectric substrate. Two sets of capacitors are formed by the other one-sided capacitor electrode and the dielectric substrate sandwiched between these opposing capacitor electrodes, and the first, second, and second capacitor electrodes connect the two one-sided capacitor electrodes.
The second inductor electrodes are inductively coupled to each other.
Two sets of parallel circuits of a capacitor and an inductor are constructed by connecting one side of the capacitor electrodes that do not face each other among the two sets of capacitor electrodes to a common potential terminal. By inputting and outputting signals from the other capacitor electrode of the two sets of capacitor electrodes that is not connected to the common potential terminal, an LC resonator in which two sets of LC parallel circuits are inductively coupled is constructed. Ru.

(f) Embodiment Figures 1A and 1B are diagrams showing the structure of a filter using an LC resonator, which is an embodiment of the present invention. The shapes of the various electrodes formed are shown, and FIG. In FIG. 1A, 1 is a dielectric substrate made of ceramics with a high dielectric constant (for example, εr=38.90), and electrodes 2 and 3 are formed on its surface, among which C1a and C2
a, C3a, and C4a each represent an electrode portion on one side of the electrodes constituting the capacitor. On the other hand, as shown in Figure B, electrodes 4 and 5 are formed on the back surface of the dielectric substrate 1, and C1b to C4b represent capacitor electrodes on the other side opposite to the capacitor electrodes on each side. In the same figure A, L1 represents the first inductor electrode connecting between the capacitor electrodes C2a and C3a on one side, and in the same figure B, L2 represents the first inductor electrode connecting between the capacitor electrodes C2a and C3a on the other side.
It represents a second inductor electrode connecting between C3b and C3b, and is provided at a distance l from the first inductor electrode.

In FIG. 1B, 6 represents a signal input/output lead, which is connected to the electrode 4. Reference numeral 7 represents a lead connected to the ground, which is a common potential, and is connected to the capacitor electrode C2b portion. In the same figure A, 8 represents a lead connected to the ground, and is joined to the capacitor electrode C3a portion. Reference numeral 9 represents a signal input/output lead, which is connected to the electrode 3.

FIGS. 2A and 2B show equivalent circuits of the filter constructed as described above. Figure A shows a capacitor and inductor formed on a dielectric substrate as circuit symbols, and Figure B shows a modified version of this as a general circuit diagram. As is clear from the figure, C1 and C4 act as signal coupling capacitors, and C2, L1 and C3, L2 each constitute a parallel LC resonant circuit. Note that the degree of inductive coupling between the inductors L1 and L2 can be set by the distance l shown in FIGS. 1A and 1B. As described above, an LC resonator is constructed without providing through holes in the dielectric substrate, and the Joule loss due to through holes is eliminated. According to the above embodiment, the no-load Q is about 120 to 140 in the 400 MHz band.

Although the above embodiment is a filter using two LC resonators, it is also possible to provide more stages. Figures 3A and 3B are diagrams showing the shape of the electrodes formed on the dielectric substrate in that case;
B represents the electrode shape on the first main surface of the dielectric substrate, and B represents the electrode shape on the second main surface as viewed from the first main surface side. In this example, the second and third stages are electrode C4a.
and are coupled by the capacitance of C4b. In this way, a multi-stage filter is constructed by forming a large number of electrodes having the shapes shown in the above embodiments and capacitively coupling the coupling at each stage. FIG. 4 shows an equivalent circuit of the filter shown in FIGS. 3A and 3B, and FIG. 5 is a circuit diagram showing a further modification of this.

FIGS. 6A and 6B show other embodiments in which a multi-stage filter is constructed. The difference from the electrode shape shown in Figures 3A and B is that the capacitor that connects the front and rear stages is constructed by the capacitance between the electrodes formed on the same surface of the dielectric substrate without forming a special electrode. The point is that That is, in FIG. B, a coupled capacitor C4 is constructed by bringing capacitor electrodes C3b and C5b close to each other.

(g) Effects of the Invention As described above, according to the present invention, an LC resonator can be constructed without forming through holes in the dielectric substrate, so there is no problem of Joule loss in the through holes, and Q. It is possible to obtain a high-quality resonator, and furthermore, it is possible to reduce the manufacturing cost and downsize the entire resonator.

[Brief explanation of drawings]

1A and 1B are plan views showing the structure of a filter using an LC resonator, which is an embodiment of the present invention;
Figures A and B are diagrams representing the equivalent circuit of the same filter.
Figures A and B are plan views showing the structure of a filter according to another embodiment, Figures 4 and 5 are diagrams showing their equivalent circuits, and Figures 6A and B are diagrams showing the structure of a filter according to another embodiment. The plan view showing the structure, Figure 7 A and B is the conventional
A plan view showing the structure of a filter using an LC resonator,
FIG. 8 is a diagram showing an equivalent circuit of the filter shown in FIGS. 7A and 7B. 1... Dielectric substrate, 2-5... Electrode, C2a, C3
a... Capacitor electrode on one side constituting two sets of capacitors, C2b, C3b... Capacitor electrode on the other side, L1... First inductor electrode, L2... Second
Inductor electrode, 6, 9... Signal input/output lead, 7, 8... Earth lead.

Claims (1)

[Claims] 1. A capacitor electrode on one side of each of two sets of capacitors and a first inductor electrode connecting between the two capacitor electrodes on one side are formed on the first main surface of the dielectric substrate. , on the second main surface of the dielectric substrate, another one-sided capacitor electrode facing each of the two one-sided capacitor electrodes, and the other one-sided capacitor electrode at a position a specific distance away from the first inductor electrode, and the two other one-sided capacitor electrodes. A second inductor electrode is formed to connect between the capacitor electrodes on one side, and the capacitor electrodes on one side that do not face each other among the two sets of capacitor electrodes are connected to the common potential terminal, and the remaining capacitor electrode on the other side is connected to the signal. An LC resonator characterized by having input/output electrodes.