JPH0326002A - Dielectric filter - Google Patents

Abstract

PURPOSE:To obtain a small sized and inexpensive dielectric filter by constituting a series resonance capacitor with opposite electrodes formed on a 2nd substrate. CONSTITUTION:Five electrodes 2a-2e are formed on the surface 1a of a 1st substrate 1 made of a dielectric substance or the like and coupling capacitors C1-C4 are formed between the electrodes. A plate shaped capacitor chip 3 is mounted on the electrode 2c in the middle. The tip 3 is formed between opposed electrodes 3b, 3b formed on both faces of the 2nd substrate 3a of a small size made of a dielectric substance or the like, one of the opposed electrodes 3b is connected to the electrode 2c to form a series resonance capacitor C5 in terms of the circuit. Since a small sized substrate is used for the 1st substrate, miniaturization is attained and the cost is reduced.

Description

[Detailed Description of the Invention] The present invention relates to an FFL electric field system in which a plurality of dielectric resonators are capacitor-coupled to obtain band bus characteristics. In a bandpass filter, for example, a three-stage circuit is constructed with a circuit as shown in FIG. A total of four coupling capacitors 01 to C4 are connected to the other two dielectric resonator devices 1 so that two coupling capacitors are connected to each other.

FIG. 6 shows an assembled structure of the filter in FIG. 5.

This filter has a coupling capacitor CI-C between each of the five electrodes 15a to 15e formed on the upper surface of the substrate 14.
4, connect the terminal pin 16 which also serves as a series resonance capacitor attached to the inner conductor 1lb of the dielectric resonator 11 to the center electrode 15C, and connect the terminal pin 16 which also serves as a series resonance capacitor attached to the inner conductor 1lb of the dielectric resonator 11, and the adjacent electrodes 15b and 15d.
Terminal 1 attached to inner conductor i 1 b of dielectric resonator 1l
7 is connected. As shown in FIG. 7, this terminal 17 has a substantially cylindrical base end attached to the inner conductor 1lb.
The tip side has a tongue piece. Note that the electrodes 15a at both ends,
A terminal (not shown) for input/output is connected to 15e.

The terminal bin 16 is a metal bin 16 as shown in FIG.
One end of a is inserted into the resin mounting jig 16b, and this state is used as the inner conductor 1 of the dielectric resonator 11.
A series resonance capacitor is inserted between the metal pin 16a and the inner conductor lb by inserting it into the metal pin 16a from one end side. As shown in FIG. 10, this capacitor is designed to sharpen the characteristics at the end of the passband by forming a pole A as shown in the solid line from the broken line, or in other words, to make it polarized. However, if the capacitance of the series resonance capacitor is secured by the terminal pin 16 mentioned above, the metal pin 16a
Since the space between the inner conductor and the inner conductor 1lb is made of resin, there is a problem in that the capacitance changes greatly depending on the temperature and the frequency characteristics vary. In order to solve this problem, as shown in FIG.
An electrode 15f is formed adjacent to electrode 5c, and both electrodes 15
It is conceivable to create a series resonance capacitor C5 for polarization between C and 15f, and connect the terminal 17 attached to the inner conductor 1lb of the dielectric resonator 1l to the electrode 15f. In this case, the area of the electrode 15f is small, so a large capacity cannot be obtained, and if an attempt is made to increase the electrode area to obtain a large capacity, the substrate must be made larger.
There was a problem with increasing the size.

The present invention has been made to solve such problems,
The purpose of the present invention is to provide a small, inexpensive dielectric filter with stable frequency characteristics.

In the present invention, a plurality of coupling capacitors are connected in series,
At least one location between adjacent coupling capacitors is
In a dielectric filter that is grounded via a series circuit of a series resonant capacitor and a dielectric resonator, and other parts are grounded via the dielectric resonator, the coupling capacitor is connected between the electrodes formed on the first substrate. and a series resonant capacitor is configured with opposing electrodes formed on both sides of a second substrate, the second substrate having one side electrode formed on the first substrate. It is characterized in that it is mounted on the first substrate in a state connected to one of the coupling capacitor electrodes.

In the present invention, a series resonance capacitor is constructed by the opposing electrode formed on the second substrate, so the capacitance of the capacitor does not depend on the temperature, unlike in the case of the conventional terminal connector 6. In addition, since the series resonance capacitor is formed with electrodes that are opposed to each other on the substrate surface rather than adjacent to each other, the capacitance can be increased while being compact. Moreover, for this purpose, a small one can be used as the first substrate.

Figure 1 is a perspective view showing an example of a dielectric filter according to the present invention, and Figure 2 is a front view showing the main parts thereof. 1 in the figure is
For example, it is a first substrate made of a dielectric material or the like, and five electrodes 2a to 2e are formed on the upper surface 1a of the substrate l, and coupling capacitors 01 to C4 are arranged between these electrodes. .

Note that although the electrodes 2a to 2e have an uneven shape at both ends (left and right ends in the figure) in order to increase the capacitance, they may be straight.

A plate-shaped capacitor chip 3 is mounted on the central electrode 2c. In this capacitor chip 3, a capacitor is constructed between opposing electrodes 3b formed on both sides of a small-sized second substrate 3a made of a dielectric material, etc., and one of the opposing electrodes 3b is connected to an electrode 2c. A series resonance capacitor C5 is connected to the circuit. The connection between one of the opposing electrodes 3b and the electrode 2c is performed by soldering such as reflow, silver baking, conductive adhesive, or the like.

The inner conductor 4b of the dielectric resonator 4 has an outer conductor 4a grounded to the opposing electrode 3b on the upper side of the capacitor chip 3, the electrode 2c connected to the capacitor chip 3, and the electrodes 2b and 2d adjacent on both sides. The terminal 5 attached to the terminal 5 is connected. This terminal 5 is the same as the terminal 17 shown in FIG.

Since the dielectric filter according to the present invention is designed in this way, its equivalent circuit is the same as that shown in FIG.

Note that the capacitor chip 3 does not necessarily need to be provided on the central electrode 2C, and may be provided on the electrodes 2b and 2d that connect the dielectric resonator 4. Polarization is also possible in this case.

Further, the present invention is not limited to a dielectric filter consisting of three stages,
Of course, the present invention can also be applied to a dielectric filter consisting of two stages or four stages or more.

Furthermore, although the above embodiment has a configuration in which a series resonance capacitor is provided at only one location in series with the dielectric resonator, the present invention is not limited to this, and as shown in FIG. 3, a series resonance capacitor is provided at two locations. Dielectric filter and 3 with C6 and C7
It can also be applied to those provided in more than one place. The structure in this case will be explained using a dielectric filter in which series resonance capacitors are installed at two locations as an example. As shown in FIG. Six electrodes 2 are formed, and capacitor chips 3 are placed on the two corresponding electrodes 2 and connected. As a result, the series resonance capacitor C6C7 is connected between the electrodes 2 forming the coupling capacitor.

In addition, although the above explanation uses dielectric resonators that are separated one by one, the dielectric resonator is not limited to this, and a structure in which one block has multiple inner conductors can be used. You can.

As described in detail above, in the case of the present invention, a series resonance capacitor is constructed by the opposing electrodes formed on the second substrate, so that the dependence of this capacitor capacitance on temperature can be suppressed and the frequency It is possible to stabilize the characteristics, and since the series resonance capacitor is composed of electrodes that are opposed to each other on the substrate surface instead of being adjacent to each other as in the conventional case, the capacitance is large. In addition, since a small substrate can be used for the first substrate, the size can be reduced, and the cost can be reduced.

4. In addition to this, the combination circuit can be treated as one block, which has the effect of improving workability.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a dielectric filter according to the present invention, FIG. 2 is a front view showing essential parts of the present invention, FIG. 3 is an equivalent circuit diagram showing another embodiment of the present invention, and FIG. is a front view showing its structure, Fig. 5 is an equivalent circuit diagram of a polarized three-stage dielectric filter, Fig. 6 is a perspective view of a conventional dielectric filter, and Fig. 7 is the terminal used for it. 8 is a sectional view showing the terminal pin used therein, FIG. 9 is a diagram for explaining the details of polarization, and FIG. 10 is a perspective view showing another conventional example. Fig. 1 Fig. 2 1...First substrate, 2.2a to 2e... Electrode, 3.
...Capacitor chip, 3a...Second board, 3b.
... Electrode, 4... Dielectric resonator. Za osozc Z (1 doe

Claims (1)

[Claims] (1) Multiple coupling capacitors are connected in series, and at least one point between adjacent coupling capacitors is grounded via a series circuit of a series resonant capacitor and a dielectric resonator, and the other points are connected to a dielectric In the dielectric filter grounded via the resonator, the coupling capacitor is the first
The series resonant capacitor is composed of opposing electrodes formed on both sides of a second substrate, and the second substrate has one side electrode connected to the first substrate. A dielectric filter, characterized in that it is mounted on a first substrate in a state connected to one of the coupling capacitor electrodes formed on the substrate.