JPS63284915A - Lc resonator - Google Patents

Abstract

PURPOSE:To constitute an LC resonator without forming a through hole, by connecting capacitor electrodes on one sides not being confronted with each other in two pairs of capacitor electrodes to a common potential terminal, and setting the capacitor electrodes on the other sides as electrodes for input- ting/outputting a signal. CONSTITUTION:A dielectric substrate 1 is constituted of a ceramic with a high permittivity, and the electrodes 2 and 3 are formed on the surfaces of the electrodes. The electrode 2 is constituted of the capacitor electrodes C1a-C3a, and the electrode 3 is constituted of the capacitor electrode C4a. Meanwhile, the electrodes 4 and 5 are formed on the rear plane of the substrate 1. The electrode 4 is constituted of the capacitor electrode C1b, and the electrode 5 is constituted of the capacitor electrodes C2b-C4b. And, inductor electrodes L1 and L2 connect between the electrodes C2a and C3a, and between the electrodes C2b and C3b, respectively. Also, inputting/outputting leads 6 and 9 are connected to the electrodes 4 and 3, respectively, and ground leads 7 and 8 are connected to the electrodes 5 and 2, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to an LC resonator in which capacitor electrodes and inductor electrodes are formed on the front and back surfaces of a dielectric substrate.

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

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

In FIG. 7(A), 1 is a dielectric substrate made of dielectric ceramics, etc., and an inductor electrode (Ll
), (L2) and one side capacitor electrode (C1a
), and another set of electrodes 11 symmetrical to this electrode 10 are formed. Two electrodes 12 and 13 are formed on the back surface of the dielectric substrate 1 as shown in FIG.
a), a region (C1b) opposite to (C2a),
(C2b) acts as the other capacitor electrode. In the same figures (A) and (B), a through hole is formed at the location shown at 14.15, the inside of the hole is filled with conductive paste, and an electrode 10.11 is formed on the surface of the substrate.
and electrodes 12 and 13 formed on the back surface of the substrate are electrically connected to each other. Furthermore, 16.19 represents a lead for inputting and outputting signals, and 17.18 represents a lead connected to ground. In this manner, capacitor electrodes and inductor electrodes are formed on the front and back surfaces 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 Joule loss occurs in this part. There was a problem in that this caused the Q of the resonator to decrease. For example, in the 400 MHz 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 there was.

The object of the present invention is to provide an LC resonator that solves the various problems mentioned above.

Means for Solving the fd1 Problem The LC resonator of the present invention has a dielectric substrate with a first major surface including:
2! A capacitor electrode on one side of each of the capacitors of lJl and a first inductor electrode connecting these two one-sided capacitor electrodes are formed, and a second inductor electrode of the dielectric substrate is formed.
on the main surface thereof, another one-sided capacitor electrode facing each of the two one-sided capacitor electrodes, and a first inductor electrode located at a specific distance from the first inductor electrode and connecting between the two other one-sided capacitor electrodes. 2 inductor electrodes are formed, one of the capacitor electrodes of the two sets of capacitor electrodes that do not face each other is connected to a common potential terminal, and the remaining capacitor electrode of one side is used as a signal input/output electrode. It is a feature.

(81 action) In the LC resonator of the present invention, two one-sided capacitor electrodes formed on the first main surface (surface) of the dielectric substrate,
Two sets of capacitors are formed by the other one-sided capacitor electrode formed on the second main surface (back surface) of the dielectric substrate and the dielectric substrate sandwiched between these opposing capacitor electrodes, each with two one-sided capacitor electrodes. The first and second inductor electrodes connected therebetween 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 FIGS. 1(A) and 1(B) are L which is an embodiment of this invention.
FIG. 2 is a diagram showing the structure of a filter using a C resonator, in which (A) shows the shape of a dielectric substrate and various electrodes formed on the surface of this dielectric substrate, and (B) This figure shows the shapes of the body substrate and, in particular, the various electrodes formed on the back surface of this dielectric substrate.

In FIG. 1(A), 1 has a high dielectric constant (for example, εr=3
It is a dielectric substrate made of ceramics such as 8.90),
Electrodes 2 and 3 are formed on its surface, and among them (C
1a), (C2a), (C3a), (C4
a) each represents one side of the electrodes forming the capacitor. On the other hand, as shown in FIG.
b) to (C4b) represent capacitor electrodes on the other side opposite to the capacitor electrodes on each side. Same figure (
In A), (LL) is one side capacitor electrode (C2a
) and (C3a), and in the figure (B), (L2) represents the second inductor electrode that connects between the capacitor electrodes (C2b) and (C3b) on the other side. represents an inductor electrode, and is provided at a distance l from the first inductor electrode.

In FIG. 1(B), 6 represents a signal input/output lead, which is connected to the electrode 4. 7 represents the lead connected to the ground which is a common potential, and is the capacitor electrode (C2b)
are joined to the parts. 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. FIG. 1A shows a capacitor and an inductor formed on a dielectric substrate as circuit symbols, and FIG. 1B shows a modified version of the circuit symbol as a general circuit diagram. As is clear from the figure, CI and 04 act as signal coupling capacitors, and the degree of C inductive coupling is as shown in Figures 1 (A) and (B
) can be set by the distance i shown in ).

As described above, an LC resonator is constructed without providing through holes in the dielectric substrate, and 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. Third
Figures (A) and (B) are diagrams showing the shape of the electrodes formed on the dielectric substrate in that case. ) represents the shape of the electrode on the second main surface as viewed from the first main surface side. In this example, the second and third stage ports are coupled by the capacitance of electrodes C4a and 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. Figure 4 is Figure 3 (A),
An equivalent circuit of the filter shown in FIG. 5B is shown, 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. Figure 3 (A), (B)
The difference from the electrode shape shown in Figure 1 is that a special electrode is not formed as a capacitor for coupling the front stage and the rear stage (it is constructed by the capacitance between the electrodes formed on the same surface of the dielectric substrate).

That is, in the same figure (B), capacitor electrodes C3b and C
5b, the coupling capacitor C
4.

(g) Effects of the Invention As described above, according to the present invention, an LC resonator can be constructed without forming through holes in a dielectric substrate, so there is no problem of Joule loss in 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 the drawing]

FIGS. 1(A) and 1(B) show an embodiment of the present invention.
A plan view showing the structure of a filter using a C resonator, Figures 2 (A) and (B) are diagrams showing the equivalent circuit of the same filter,
Figures 3 (A>, (B) are plan views showing the structure of filters according to other embodiments, Figures 4 and 5 are diagrams showing their equivalent circuits, and Figures 6 (A) and (B) FIGS. 7(A) and 7(B) are plan views showing the structure of a filter according to still another embodiment.
8 is a plan view showing the structure of a filter using a conventional LC resonator, and FIG. 8 is a diagram showing an equivalent circuit of the filter shown in FIGS. 7(A) and 7(B). l - dielectric substrate, 2 to 5 - electrodes, C2a, C3a - capacitor electrode on one side constituting two sets of capacitors, C2b, C3b - capacitor electrode on the other side, Ll - first inductor electrode, L2 - first inductor electrode. 2 inductor electrode, 6.9-signal input/output lead, 7.8-ground 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, and the dielectric On the second main surface of the substrate, another one-sided capacitor electrode facing each of the two one-sided capacitor electrodes, and at a position a specific distance away from the first inductor electrode and between the two other one-sided capacitor electrodes. One of the capacitor electrodes of the two sets of capacitor electrodes that do not face each other is connected to a common potential terminal, and the remaining capacitor electrode on one side is used as a signal input/output electrode. An LC resonator characterized by: