JPH03272213A - High frequency branching filter - Google Patents

Abstract

PURPOSE:To make the size of the filter small without deteriorating the performance when the filter is mounted on a printed circuit board by arranging each capacitor electrode pattern of an adjacent pattern between coil patterns of the said circuit so as to apply magnetic shield among the coil patterns. CONSTITUTION:A dielectric printed circuit board such as a ceramic printed circuit board is employed for a printed circuit board 1. Plural circuits including thick film coils L1-L3 and capacitors C1-C3 are provided to the printed circuit board 1, and capacitor electrode patterns 2-7, 14-16 of an adjacent circuit are arranged among the coil patterns 8-13 of the adjacent circuit to be branched in plural circuits therefore. The magnetic coupling among the coil patterns 8-13 is formed. Thus, the magnetic coupling among the coils is reduced and the interference between the circuits is reduced, then the deterioration in the characteristic is avoided when the high frequency branching filter is employed.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a high frequency demultiplexing filter, and more specifically to a diplexer used when transmitting and receiving with one antenna, and a diplexer used when transmitting and receiving one input radio wave by frequency ( VHF and UHF
The present invention relates to a high-frequency demultiplexing filter that is used in a diplexer and the like that demultiplexes signals into (), and is particularly miniaturized without deteriorating performance when mounted on two circuit boards.

[Conventional technology]

FIG. 3 is a diagram showing an example of a circuit of a conventional duplexer. In FIG. 1, L1 to L3 are coils, C1 to C3 are capacitors, Rx is a receiving section, Tx is a transmitting section, and ANT is an antenna.

Conventionally, a diplexer as shown in FIG. 3, for example, has been known as an example of a high frequency demultiplexing filter.

This duplexer connects one antenna ANT to the transmitter T
It is used when shared by the receiving section RX and the receiving section RX, and is composed of a plurality of coils L1 to L3 and a plurality of capacitors C1 to C5. The coil L1 and capacitor C1, and the coil L2 and capacitor C3 constitute parallel resonant circuits each having a different resonance frequency.

In the above circuit, between the transmitter Tx and the antenna ANT, a certain frequency f^ is passed while another frequency fs (/s"rfA) is blocked, and vice versa between the antenna ANT and the receiver Rx. fB is passed through and /A is blocked. Therefore, the transmitter Tx and the antenna AN
The circuit between T (coil Ll.

capacitors C1, C2), antenna ANT and receiver R
Mutual interference between the circuits between x (coils L2, L3, and capacitor C3) is fatal to the function of the entire circuit.

By the way, when the above-mentioned diplexer is mounted on a circuit board, conventionally, a coil or a capacitor made of discrete components has been used.

Also, when downsizing, between coils (especially coil L).

Since magnetic coupling (between L2 and L2) becomes a problem, a simple countermeasure is to increase the distance between the two parts.

[Problem to be solved by the invention]

The above-mentioned conventional devices had the following drawbacks.

(1) When mounting with discrete components, there is a limit to high density due to the size of one component, and it cannot sufficiently meet the demand for miniaturization.

Furthermore, since a mounting process for the above-mentioned components is required, the manufacturing process is time-consuming.

(2) In order to achieve miniaturization, it is possible to form coils and capacitors with thick films on the printed circuit board, but if this simply increases the density, the magnetic waves will be split into two between the coils of adjacent circuits. A bond occurs.

Therefore, the characteristics of the high frequency demultiplexing filter are deteriorated.The present invention eliminates such conventional drawbacks and reduces interference caused by magnetic coupling, etc. that occurs between each circuit for dividing into two waves, without deteriorating the characteristics. The purpose is to reduce the size (secondarily, to reduce the cost of high-frequency demultiplexing filters).

[Means to solve the problem]

In order to achieve the above object, the present invention is constructed as follows.

(1) In a high frequency demultiplexing filter that demultiplexes a high frequency signal by providing a plurality of circuits including at least thick film coils and capacitors on a circuit board using a dielectric material.

By arranging each capacitor electrode pattern of the adjacent circuit between each coil pattern of the adjacent circuit that splits the wave into two among the plurality of sets of circuits, magnetic shielding is provided between the respective coil patterns.

(2) In the high frequency demultiplexing filter described in (1) above.

Each capacitor electrode pattern is arranged so as to surround each of the coil patterns.

(3) The high frequency demultiplexing filter described in (1) above.

A multilayer circuit board is used as the circuit board, and each of the capacitor electrode patterns of the adjacent circuits is separated into separate electrode patterns, and the separated electrode patterns are sandwiched between the dielectric layers of the two circuit boards from both sides. It consists of two integrated electrode patterns arranged and electrically connected.

[Effect]

Since the present invention is configured as described above, it has the following secondary effects.

When configured as in (1) above, two coils of adjacent circuits are magnetically shielded by the capacitor electrode pattern.

Therefore, the magnetic coupling between the two coils is reduced.

Since interference between circuits is reduced, when this high frequency demultiplexing filter is used, its characteristics will not deteriorate.

Moreover, when configured as in (2) above, the capacitor electrode pattern surrounds the coil, thereby further improving the magnetic shielding effect. Therefore, magnetic coupling between the coils becomes extremely small.

Furthermore, the configuration as described in (3) above reduces not only the magnetic coupling between the coils but also the coupling due to the electric field between the capacitors. Thereby, magnetic coupling and electric field coupling can be reduced at the same time.

〔Example〕

The following two embodiments of the present invention will be explained based on the drawings. FIG. 1 is an implementation diagram of a first embodiment of the present invention.

Figure A is an exploded plan view, and Figure B is a sectional view. In the figure.

The same reference numerals as in FIG. 3 indicate the same parts, and 1 is a circuit board (each circuit board constituting a multilayer circuit board), 2 to 7, and 14.
~16 is a capacitor electrode pattern.

8 to 13 are coil patterns, and 17 is an interrupted area.

This embodiment is an example in which the diplexer shown in FIG. 3 above is mounted on a multilayer circuit board (three layers).

Each circuit board 1 constituting the multilayer circuit board 2 uses a dielectric substrate such as a ceramic circuit board.

On the top layer circuit board 1 of this multilayer circuit board.

Capacitor electrode patterns 2 and 3, which are the electrodes on the antenna ANT side of capacitors C3 and 01, are integrally patterned by printing to form an integrated electrode, and on both sides thereof, coil patterns 10 forming coils Ll and L2 are formed. and 8 are patterned by printing integrally with the capacitor electrode pattern 2.3. In other words, the coil pattern 10 that constitutes the coil Ll and the coil pattern 8 that constitutes the coil L2 are combined with the capacitor electrodes that constitute the capacitors C1 and C3. Pattern 2, 3
(the capacitors are placed between the coil patterns 10 and 8 to form pole patterns 2 and 3).

Further, on the top layer circuit board 1, there is a coil pattern 12 that is separate from the above pattern and constitutes the coil L3,
Capacitor electrode pattern 14 constituting capacitor C2
On the internal circuit board 1, there is a counter electrode (
The capacitor electrode pattern (separated electrode) 7 constituting the transmitting part Tx side electrode) is patterned by mark -11, and the coil pattern 11 which integrally constitutes the coil Ll with this capacitor electrode pattern 7 and the capacitor C2 are patterned.
A capacitor electrode pattern 15 constituting a counter electrode is patterned by printing.

Furthermore, on the internal circuit board 1, a capacitor electrode pattern (separated electrode) 6, which constitutes the counter electrode (electrode on the receiving section Rx side) of the capacitor C3, is patterned by printing, separate from each of the above patterns. At the same time, coil patterns 9 and 13 that constitute coils L2 and L3 are patterned by printing integrally with this capacitor electrode pattern 6. ○On the circuit board 1 in the lowest layer, electrodes on the antenna ANT side of capacitors C3 and C1 are printed. The constituting capacitor electrode patterns 4 and 5 are integrally patterned by printing to form an integrated electrode, and separated from this to form a capacitor C2.
The capacitor electrode pattern 16 constituting the capacitor electrode pattern 16 is patterned by printing.

The capacitor electrode pattern and the coil pattern described above are formed at the same position on each circuit board 1, and predetermined connections are made using blind through holes (through holes whose insides are filled with conductors).

In this case, a capacitor electrode pattern (integrated electrode pattern) 2.3 formed on the top layer circuit board 1 and a capacitor electrode pattern (integrated electrode pattern) 4.5 formed on the bottom layer circuit board 1 are used. , capacitor electrode patterns (separated electrode patterns) 6 and 7 formed on the internal circuit board 1.

Each pattern is formed so as to be sandwiched between the dielectric layers constituting the substrate, and the capacitor electrode patterns 2 and 3 and the capacitor electrode patterns 4 and 5 are connected by a blind through hole to electrically connect the two electrode patterns. (short circuit).

By connecting the coil patterns (the two are connected using blind through holes between the top layer and the internal circuit board 1 (connecting between each coil pattern Ll, L2, Ls), it is possible to create a coil with almost two turns. Furthermore, when connecting the capacitor electrode patterns 2 and 3 to the capacitor electrode patterns 4 and 5, the connection is made by blind through holes that penetrate the relay regions 17 (three locations) on the internal circuit board 1.

As mentioned above, since the coils L and L2 are patterned on both sides of the capacitors C1 and C3 and separated from each other, there is almost no magnetic coupling between them.
It has a substantially (=magnetic) shield structure. Therefore, the magnetic coupling between the coils Ll and L2 is a fatal drawback, but as in the above embodiment, the magnetic coupling is almost no problem. This is because any design is possible.

Further, since capacitor electrode patterns 6.7 are sandwiched between capacitor electrode patterns 2, 3 and 4, 5, respectively, between capacitors C1 and 03.

Electric field coupling is almost eliminated. Therefore, the coil L
, and 42 and the electric field coupling between capacitors C1 and 03 are reduced or almost eliminated.

FIG. 2 is a diagram showing a second embodiment of the present invention, where FIG. A is an exploded plan view and FIG. B is a modified example. In the figure, the same reference numerals as in FIGS. 1 and 3 indicate the same parts.

In this embodiment, by changing the patterns of the coils Ll and L2 and the capacitors C1 and C3 shown in FIG.
This is an example in which the magnetic coupling between the coils L1 and 42 is further reduced.

The coil pattern 8 is enclosed in a U-shape by the capacitor electrode pattern 2, and the coil pattern 8 is enclosed by the capacitor electrode pattern 7 on the internal circuit board 1. The coil pattern 11 is enclosed in a U-shape, and the capacitor electrode pattern 6 encloses the coil pattern 9 in a U-shape. The shape of is also changed to match the upper layer electrode pattern.

As described above, by surrounding each coil pattern in a U-shape with a capacitor electrode pattern, the magnetic shielding effect can be enhanced and the magnetic coupling between the coils L1 and 42 can be further reduced. , As shown in Figure B (=, it is also possible to completely surround the coil pattern 10 with the capacitor electrode pattern 3. In addition, in the example of Figure B, not only the coil pattern 10 but also the coil patterns 8, 9° and The same applies to 11 (= applicable. In this case.

It is possible to further enhance the magnetic shielding effect.

Although the embodiments have been described above, the present invention can also be implemented in the following manner.

(1,) The circuit board is not limited to a multilayer circuit board, and a single-layer double-sided circuit board (dielectric board) may be used.

(2) The material of the circuit board may be not only ceramic but also other dielectric materials.

(3) In the above embodiment, it is also possible to form the coils L2 and L3 as one recal coil, and take out the center tap and connect it to the capacitor C8.

(4) In the above embodiment, the capacitor is constructed with two layers and the coil is constructed with two turns. However, the present invention is not limited to this example, and may be arbitrarily modified. However, the interference caused by the electric field can be reduced by setting the antenna-side electrode of the capacitor on the outside.

(5) Applications include not only the diplexer of the above embodiment but also other diplexers and various high frequency demultiplexing filters.

(6) In order to increase the capacitance of the capacitor, it is also possible to configure only the dielectric material between the electrodes of the capacitor portion as a high dielectric constant material.

3 4 [Effects of the Invention] As explained above, the present invention has the following effects.

(1) Magnetic coupling can be reduced between coils in each demultiplexing circuit. Therefore, even if the pattern density is increased, there is little deterioration of the characteristics, so it is possible to downsize the high frequency demultiplexing filter (corresponding to claim (1)).

(2) When the coil pattern is arranged to surround the capacitor electrode, the magnetic shielding effect between the coils is further improved, and interference between the coils is extremely reduced.

For this reason, there is almost no characteristic deterioration even when downsized (
(corresponding to claim (2)).

(3) Not only the magnetic coupling between the coils but also the coupling due to the electric field between the capacitors can be reduced, so interference between the circuits that separate the waves into two is extremely reduced.

Therefore, it is possible to perform high-density mounting on the negative layer, and the size can be reduced (corresponding to claim (3)).

(4) Since interference between circuits can be reduced, miniaturization is possible without deteriorating characteristics.

Therefore, when manufacturing a high frequency demultiplexing filter, the number of filters that can be taken out from the binary substrate increases, making it possible to reduce costs accordingly.

(5) When a multilayer circuit board is used as a circuit board, the necessary capacitors and coils can be easily obtained, and at the same time, the mounting area is extremely small.

In addition, a helical type coil can be obtained (L.

This is advantageous for miniaturization because it allows a large Q value) and a large capacity capacitor.

Particularly, the use of a ceramic multilayer circuit board is advantageous because a high dielectric material can be used (corresponding to claim (3)).

[Brief explanation of drawings]

FIG. 1 is an implementation diagram of a first embodiment of the present invention. FIG. 2 is an implementation diagram of the second embodiment. FIG. 3 is a diagram showing an example of a diplexer circuit. 1...Circuit board. 2 to 7... Capacitor electrode pattern. 8-13...Coil pattern. 14-16...Capacitor electrode pattern/. 17... Relay area. ANT...Antenna. TX...transmission section. RX...receiving section. L　l-L　s...Coil. C1NC5...Capacitor.

Claims (3)

[Claims] (1) In a high-frequency demultiplexing filter that demultiplexes a high-frequency signal by installing multiple sets of circuits including at least thick-film coils and capacitors on a circuit board using a dielectric material, one of the multiple sets of circuits described above is 1. A high-frequency branching filter characterized in that each of the capacitor electrode patterns of the adjacent circuit is arranged between each of the coil patterns of the adjacent circuit that causes waves, thereby magnetically shielding the coil patterns. (2) The high frequency branching filter according to claim 1, wherein each of the capacitor electrode patterns is arranged so as to surround each of the coil patterns. (3) A multilayer circuit board is used as the circuit board, and each capacitor electrode pattern of the adjacent circuit is separated into electrode patterns (6, 7), and the separated electrode patterns (6, 7) are connected to the circuit board. Claim (2) characterized in that it is composed of two integrated electrode patterns (2, 3 and 4, 5) that are arranged so as to sandwich them from both sides through a dielectric layer and are electrically connected. The high frequency demultiplexing filter described in 1) or (2).