JPH07115303A - High frequency filter - Google Patents

Abstract

PURPOSE:To reduce the size and to improve the reliability of a high frequency filter by providing a surface acoustic wave SAW filter on a sheet of coupling substrate that forms a coupling circuit part which couples a dielectric resonator and therefore by reducing the number of component parts and the manufacturing manhour. CONSTITUTION:The capacitor substrates 7 are put on the coupling electrodes 4 set on a coupling substrate 3, the coils 8 are placed between the electrodes 4 and an input-output electrode 5, and an SAW filter 2 is put on a wiring pattern 22. The filter 2 is connected to a coupling circuit part via the pattern 22. One of both ends of a connector terminal 10 pressed into an inner conductor forming hole 11 of a dielectric resonator 1 has a tongue shape and is connected to an electrode formed on the surface of each substrate 7. Then the stray capacity Cs is acquired by the inter-electrode capacity produced by the electrodes 4 provided on the substrate 3 and a ground electrode 6 formed on the other side of the substrate 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to, for example, a car telephone,
The present invention relates to a high frequency filter used for mobile communication equipment such as a mobile phone, which is configured by combining a surface acoustic wave filter and a dielectric resonator.

[0002]

2. Description of the Related Art In order to obtain a high-frequency filter having a small size and a large amount of attenuation, for example, as shown in an equivalent circuit diagram of FIG. A filter may be formed by combining the body resonators R1 and R2 with a trap circuit in which a coupling capacitance Ce, an inductance L, and a stray capacitance Cs are added. When configuring such a high-frequency filter,
Conventionally, a structure as shown in FIG. 3 has been adopted.

This high frequency filter includes a SAW mounting substrate 21 having a SAW filter 2 surface-mounted in a metal case (not shown), two dielectric resonators 1, and a coupling substrate for LC-coupling each dielectric resonator 1. 3 and 3 are stored and fixed.

A wiring pattern 22 such as an input / output electrode and a ground electrode is formed on the SAW mounting substrate 21, and the surface mounting SAW filter 2 is soldered and mounted.

A coupling electrode 4, an input / output electrode 5 and a ground electrode 6 are formed on the upper surface of the coupling substrate 3, a capacitor substrate 7 is connected on the coupling electrode 4, and the coupling electrodes 4 and 4 are coupled together. Coil 8 between the electrode 4 and the input / output electrode 5
And a chip capacitor 9 is connected between the coupling electrode 4 and the ground electrode 6.

A coupling terminal 10 press-fitted into the inner conductor forming hole of the dielectric resonator 1 is connected to the capacitor substrate 7, and each dielectric resonator 1 and the coupling circuit portion are electrically connected. . The SAW filter 2 and the coupling circuit section are connected by a jumper wire 23 between the wiring pattern 22 on the SAW mounting substrate 21 and the coupling electrode 4 on the coupling substrate 3.

Here, the coupling capacitance Ce shown in FIG. 4 is provided by the capacitor substrate 7, and the inductance L is provided by the coil 8.
Of the stray capacitance (capacity that drops to the ground) Cs by the chip capacitor 9. The outer conductor of each dielectric resonator 1, the ground electrode 6 of the coupling substrate 3, and the ground electrode of the SAW mounting substrate 21 are electrically connected to a metal case (not shown).

[0008]

However, in the high-frequency filter constructed by combining the above-mentioned conventional SAW filter and the dielectric resonator, the SAW mounted with the SAW filter is used.
A mounting board, a jumper wire that connects the SAW filter and the coupling circuit section of the dielectric resonator are required, and a chip capacitor is also used as a stray capacitance, so the number of parts is large and each part is assembled and soldered. Work is needed. Therefore, it is difficult to miniaturize, the cost of parts is high, and the productivity is low.

Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional high frequency filter, reduce the number of parts, reduce the manufacturing man-hours, achieve further downsizing, and be inexpensive and reliable. It is to provide a high-frequency filter having high performance.

[0010]

In order to achieve the above object, the present invention is a high frequency filter in which a SAW filter and a dielectric resonator are combined to form a filter, and a coupling for coupling the dielectric resonators. The SAW filter is mounted on one combined substrate that forms a circuit section.

Further, the stray capacitance constituting the coupling circuit portion is formed by the interelectrode capacitance formed between the electrodes formed on the upper and lower surfaces of the coupling substrate.

[0012]

According to the above construction, since the surface acoustic wave filter is mounted on the single coupling substrate forming the coupling circuit portion for coupling the dielectric resonator, the SAW mounting substrate on which the surface acoustic wave filter is mounted. Is unnecessary, and since the SAW filter and the coupling circuit unit can be connected by a wiring pattern, a jumper wire or the like for connecting the SAW filter and the coupling circuit unit is also unnecessary.

Further, the inter-electrode capacitance between the electrodes formed on the upper and lower surfaces of the combined substrate is defined as a stray capacitance,
Capacitor elements such as chip capacitors for stray capacitance can be eliminated.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments. In the figure, the same parts as those in the conventional example are designated by the same reference numerals.

FIG. 1 shows the structure of a high frequency filter according to the first embodiment of the present invention. FIG. 1A is an exploded perspective view of a dielectric resonator and a coupling substrate, FIG. 1B is a plan view of the coupling substrate shown in FIG. 1A, and FIG. 1C is a sectional view taken along line XX of FIG. It is a figure.

As shown in FIG. 1 (a), the high frequency filter of this embodiment comprises two dielectric resonators 1, a SAW filter 2, a capacitor substrate 7 and a coupling substrate 3 on which a coil 8 is mounted. Usually, an input / output terminal (not shown) is attached and housed and fixed in a metal case (not shown).

Each dielectric resonator 1 is composed of an inner conductor formed on the inner peripheral surface of the inner conductor forming hole 11 of the rectangular parallelepiped dielectric block and an outer conductor formed on the surface of the dielectric block. The inner conductor and the outer conductor are short-circuited at one opening surface of the inner conductor forming hole 11 and resonate at a predetermined frequency.

Inner conductor forming hole 1 of this dielectric coaxial resonator 1
The metal connection terminals 10 each having one end formed in a substantially cylindrical shape are press-fitted into each of the terminals 1, and are brought into contact with the inner conductors in the inner conductor forming holes 11 to be electrically connected.

The coupling substrate 3 is made of a dielectric material, and the coupling electrode 4, the input / output electrode 5 and the wiring pattern 22 for connecting the SAW filter 2 are formed on the upper surface thereof, and the lower surface of FIG.
As shown in (c), the ground electrode 6 is formed, and the SAW
The ground electrode portion of the wiring pattern 22 for connecting the filter 2 and the ground electrode 6 are connected by a through hole (not shown) or the like.

Then, the capacitor substrate 7 is provided on the coupling electrode 4 of the coupling substrate 3, the coil 8 is provided between the coupling electrodes 4 and between the coupling electrode 4 and the input / output electrode 5, and S is provided on the wiring pattern 22.
The AW filter 2 is mounted and mounted by soldering. Here, as shown in FIG. 1B, the coupling circuit unit and the SAW filter 2 are connected by a wiring pattern 22.

Then, the inner conductor forming hole 1 of the dielectric resonator 1 is formed.
The other end of the connection terminal 10 press-fitted into 1 is formed in a tongue shape and connected to the electrodes formed on the upper surface of each capacitor substrate 7 by soldering or the like.

With the above structure, as shown in FIG. 1C, an electrode formed by the coupling electrode 4 formed on the upper surface of the combined substrate 3 and the ground electrode 6 formed on the lower surface of the combined substrate 3. The stray capacity Cs is obtained by the inter capacity. In this way, a high frequency filter having an equivalent circuit similar to that of the conventional filter shown in FIG. 4 is realized.

As described above, the high frequency filter of this embodiment is characterized in that the SAW filter is mounted on one combined substrate and the stray capacitance Cs is obtained by the interelectrode capacitance of the combined substrate. Compared with conventional filters,
This eliminates the need for a SAW mounting board, jumper wires, and stray capacitance capacitor elements. By reducing the number of parts, etc., the size can be made smaller than the conventional one.

Next, FIG. 2 shows a plan view of a high frequency filter according to a second embodiment of the present invention. As shown in FIG. 2, the high-frequency filter according to this embodiment includes a dielectric substrate 1, a SAW filter 2, and a dielectric resonator 1 on a coupling substrate 3 made of a single dielectric.
The capacitor substrate 7 and the coil 8 are mounted. That is, not only the SAW filter 2 but also the dielectric resonator 1 is mounted on the coupling substrate 3. Although not shown, a ground electrode is formed on the lower surface of the combined substrate 3 as in the first embodiment, and is connected to a ground electrode (not shown) formed on the upper surface of the combined substrate 3 through a through hole or the like.

The stray capacitance Cs is also obtained by the inter-electrode capacitance formed between the upper and lower surfaces of the coupling substrate 3 as in the first embodiment, and realizes the high frequency filter of the equivalent circuit shown in FIG. In this case, not only the SAW filter 2 but also the dielectric resonator 1 and the like can be arranged at appropriate positions on the coupling substrate 3 and can be connected by the wiring pattern formed on the coupling substrate 3.
Since the unnecessary space can be reduced, the size can be further reduced.

Further, in this embodiment, since all the components can be attached and integrated on one combined substrate, the case such as a metal case can be reduced. In this case, the input / output portion of the filter can also be formed on the lower surface of the combined substrate by forming the input / output electrode on the lower surface of the combined substrate and connecting the input / output electrode on the upper surface of the combined substrate with a through hole or the like. Therefore, the number of input / output terminals and the like can be reduced, and a high frequency filter for surface mounting can be obtained.

In the above embodiment, the dielectric resonator is 2
Although the case where one dielectric resonator is used has been described, the present invention is not limited to this, and one or three or more dielectric resonators may be used. Further, a dielectric resonator having a plurality of inner conductor forming holes formed in one dielectric block may be used. The configuration of the coupling circuit unit is not limited to the above embodiment.

That is, according to the present invention, the SAW filter is mounted on one coupling substrate for coupling the dielectric resonators to form the filter.
The dielectric resonator, the coupling circuit section and the like may have any structure and configuration.

[0029]

As described above, according to the high frequency filter of the present invention, the coupling circuit portion for coupling the dielectric resonator is formed on one substrate, and the SAW filter is mounted on the substrate. , A SAW mounting substrate, a jumper wire connecting the SAW filter and the coupling circuit section, etc. can be eliminated. Further, the stray capacitance constituting the coupling circuit portion can be obtained by the interelectrode capacitance between the upper and lower surfaces of the coupling substrate, and the stray capacitance capacitor element can be eliminated. Further, by mounting the dielectric resonator also on one substrate, it is possible to reduce the housing such as a metal case and the input / output terminals of the filter, and realize the surface mounting filter.

As described above, according to the present invention, the number of parts can be greatly reduced, and therefore, the cost of parts and the number of manufacturing steps can be greatly reduced, and the inexpensive, compact, and high-reliability high frequency filter is provided. Can be obtained.

[Brief description of drawings]

1A is an exploded perspective view of a high-frequency filter according to a first embodiment of the present invention, FIG. 1B is a plan view of a combined substrate shown in FIG. 1A, and FIG. It is a XX sectional view.

FIG. 2 is a plan view of a high frequency filter according to a second embodiment of the present invention.

FIG. 3 is a perspective view showing an example of a conventional high frequency filter.

FIG. 4 is an equivalent circuit diagram of a high frequency filter using a general SAW filter and a dielectric resonator.

[Explanation of symbols]

 1 Dielectric Resonator 2 Surface Acoustic Wave (SAW) Filter 3 Coupling Substrate 4 Coupling Electrode 5 Input / Output Electrode 6 Earth Electrode 7 Capacitor Substrate 8 Coil 10 Connection Terminal 11 Inner Conductor Forming Hole 22 Wiring Pattern

Claims (2)

[Claims] 1. A high frequency filter in which a surface acoustic wave filter and a dielectric resonator are combined to form a filter, wherein the one coupling substrate that forms a coupling circuit portion coupling the dielectric resonator is formed on the one coupling substrate. A high frequency filter characterized by mounting a surface acoustic wave filter. 2. The high frequency filter according to claim 1, wherein the stray capacitance forming the coupling circuit portion is formed by an inter-electrode capacitance formed between electrodes formed on the upper and lower surfaces of the coupling substrate. .