JP2002305423A - Low-pass filter and high-frequency switch module using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-pass filter in a laminated structure, capable of realizing the miniaturization of a laminate and the space reduction of a valid design space accompanied with this and a high-frequency switching module using this low-pass filter. SOLUTION: In this low-pass filter formed by forming a first capacitor C1, a second capacitor C2, a third capacitor C3, and a transmission line L1 on a plurality of dielectric layers by electrode patterns, respective first, second, and third capacitor patterns P4, P2, and P5 are formed on those different dielectric layers, and a ground pattern e is arranged between the P2 and P5. The P4 and the P5 are connected through a conductor. In this case, the P4 is formed to face the P2 so that the first capacitor C1 can be formed, the P2 is formed, so as to be faced to the ground pattern e and the second capacitor C2 can be formed, and the ground pattern e is formed to face the P5 so that the third capacitor C3 can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-pass filter circuit used in a portable terminal or the like for removing a high-frequency signal component when transmitting a signal, and a high-frequency switch module using the same.

[0002]

2. Description of the Related Art In recent years, the spread of mobile phones has been remarkable, and the functions and services of mobile phones have been improved. As this new mobile phone, a dual-band or triple-band mobile phone has been developed.
These mobile phones handle two or three transmission / reception systems, and are each configured using a demultiplexing circuit and a switch circuit as a signal path corresponding to a frequency and a high-frequency switch for switching a plurality of frequencies. A high-frequency switch module is used.

For example, in a high-frequency switch module disclosed in Japanese Patent Application Laid-Open No. 11-225088, a transmission line of a branching circuit, a low-pass filter circuit, and a switch circuit is formed in a plurality of dielectric layers in order to reduce the size. Then, a laminated high-frequency switch module in which a chip element such as a diode or a chip capacitor is mounted on the laminated body to form a one-chip laminated high frequency switch module (hereinafter, simply referred to as a laminated body).

[0004]

In the high-frequency switch module, a low-pass filter for removing high-frequency signal components is provided in a transmission path of the switch circuit. This low-pass filter is constituted by an LC circuit, and is formed by an electrode pattern in a laminate composed of an electrode pattern and a dielectric layer. Further, a capacitor constituting the LC circuit is obtained by a capacitor pattern formed on the dielectric layer.

FIG. 1A shows an example of an equivalent circuit of a low-pass filter with an attenuation pole. For the sake of explanation, the capacitor C1,
The respective electrodes forming C2 and C3 will be referred to as P1 to P6. FIG. 7 is a part of an internal electrode pattern diagram of a dual-band high-frequency switch module that handles a GSM system and a DCS system.
Electrode patterns of capacitors constituting each low-pass filter of the SM system and the DCS system are arranged.
Conventionally, when a low-pass filter is formed by an electrode pattern in a laminate composed of a dielectric layer, the electrode patterns corresponding to the electrode patterns P2 and P5 on the circuit main line side forming the capacitors C2 and C3 in FIG. As seen in the eight layers, they have been formed adjacently on the same dielectric layer. That is, the electrode patterns C9 and C10 corresponding to the electrode patterns P2 and P5 are formed on the eighth layer, and the capacitances of the capacitors C2 and C3 are formed between the ground (ground) pattern e3 formed on the ninth layer. Was. Further, the electrode pattern C4 is formed on the seventh layer, and the capacitance formed between the electrode pattern C4 and the electrode patterns C9 and C10 is combined to form the capacitance of the capacitor C1. . Further, a resonance circuit is formed by the capacitance of the capacitor C1 and the transmission line, and a low-pass filter installed in the transmission circuit on the GSM side has been formed. The other DCS low-pass filter is also C11, C12,
It was formed by the same electrode arrangement of e3 and C5.

As described above, the electrode patterns P2 and P5 are formed on the same dielectric layer only when they form the same low-pass filter, and both the capacitors C2 and C3 are connected to the common ground. (Ground) and for vague reasons such as being able to form. However, as the miniaturization of the laminate progresses, the space for forming the electrode pattern on the dielectric layer becomes smaller, but the electrode patterns of the capacitors C2 and C3 forming the low-pass filter are formed on the same layer as described above. In this case, it is difficult to form a capacitor pattern having a size required for design. Especially in the case of high frequency switch module with dual band or more,
As shown in the eighth layer of FIG. 7, a total of four electrode patterns C9, C10, C11, and C12 forming the low-pass filters on the GSM side and the DCS side are formed on the same layer. There is not enough space to change the size and shape, and in some cases, the shape and size of the surrounding electrodes are affected. In such an electrode pattern arrangement, if the design space becomes smaller due to the miniaturization of the laminate, it may be impossible to arrange electrodes of a required size and shape.

Therefore, the present invention changes and improves the arrangement of the capacitor patterns constituting the low-pass filter on the dielectric layer, so that it is possible to easily cope with miniaturization of components and multiband in a limited space. And a high-frequency switch module including the low-pass filter.

[0008]

SUMMARY OF THE INVENTION The present invention comprises a first capacitor, a second capacitor, a third capacitor, and a transmission line, wherein each of the capacitors and the transmission line is formed on a plurality of dielectric layers. The first, second and third capacitor patterns are formed on different dielectric layers, respectively, and a ground pattern is provided between the second and third capacitor patterns. And a first capacitor pattern and a third capacitor pattern are connected by a conductor, and the first capacitor pattern and the second capacitor pattern are opposed to each other so that the first capacitor is connected to the second capacitor pattern. The second capacitor is connected to the ground pattern by facing the ground pattern to the second capacitor. A low-pass filter in which third capacitors are respectively formed by facing three capacitor patterns.

Further, the present invention provides a first capacitor and a second capacitor.
, A third capacitor, and a transmission line, wherein each of the capacitors and the transmission line is formed by an electrode pattern formed on a plurality of dielectric layers. Each capacitor pattern is formed on a different dielectric layer, an earth pattern is provided between the second capacitor pattern and the third capacitor pattern, and the first capacitor pattern and the third capacitor pattern are connected by a conductor. ,
The first capacitor is opposed to the second capacitor pattern, and the first capacitor is opposed to the second capacitor pattern and the ground pattern. The second capacitor is connected to the ground pattern and the third capacitor pattern. A low-pass filter wherein a third capacitor is formed by facing capacitor patterns, and a resonance circuit is formed by a capacitance obtained by the first capacitor and a transmission line.

Further, the present invention provides a demultiplexing circuit for distributing received signals of a plurality of transmission / reception systems having different pass bands, and a switch circuit for switching between a transmission path and a reception path at a stage subsequent to at least one path of the demultiplexing circuit. And a low-pass filter circuit including a low-pass filter circuit configured by an LC circuit. The low-pass filter includes a first capacitor, a second capacitor, a third capacitor, and a transmission line. The line is formed by an electrode pattern formed on a plurality of dielectric layers, and the first, second, and third capacitor patterns are formed on different dielectric layers, respectively. An earth pattern is provided between the third capacitor pattern and the first capacitor pattern and the third capacitor pattern. Are connected by a conductor, and the first capacitor pattern and the second capacitor pattern are opposed to each other, and the first capacitor is opposed to the second capacitor pattern and the ground pattern. Earth pattern and 3rd
A high-frequency switch module characterized by being a low-pass filter in which a third capacitor is formed by opposing the above capacitor patterns.

Further, the present invention provides a demultiplexing circuit for distributing received signals of a plurality of transmission / reception systems having different pass bands, and a switch circuit for switching between a transmission path and a reception path at a stage subsequent to at least one path of the demultiplexing circuit. And a low-pass filter circuit including a low-pass filter circuit configured by an LC circuit. The low-pass filter includes a first capacitor, a second capacitor, a third capacitor, and a transmission line. The line is formed by an electrode pattern formed on a plurality of dielectric layers, and the first, second, and third capacitor patterns are formed on different dielectric layers, respectively. An earth pattern is provided between the third capacitor patterns, and the first and third capacitor patterns are The first capacitor pattern is connected by a conductor, and the first capacitor pattern is opposed to the second capacitor pattern, and the second capacitor is connected to the ground pattern by the second capacitor pattern. Pattern and third
A high-frequency switch module, wherein a low-pass filter is formed by forming a third capacitor by opposing the capacitor patterns described above, and forming a resonance circuit with the capacitance obtained by the first capacitor and the transmission line. is there.

One feature of the present invention is that, of the first to third capacitor patterns constituting the low-pass filter, an earth pattern is provided between the second capacitor pattern and the third capacitor pattern. That is, the second capacitor pattern and the third capacitor pattern are formed separately on different dielectric layers with the ground pattern interposed therebetween, thereby forming the second capacitor pattern and the third capacitor pattern. The required area and space are half that of the conventional case, and the space that can be used for changing the size and shape of each of the second and third capacitor patterns increases. Therefore,
Even if a dual band or triple band is used and space restrictions become severe, pattern design becomes easy.
Further, by distributing and forming the electrode patterns which have been formed on the same layer until now on different layers, interference between the patterns on the same layer can be suppressed, which leads to improvement of the high frequency characteristics of the high frequency switch module. As described above, it is possible to contribute to the miniaturization and high performance of the laminated body of the high-frequency switch module. The low-pass filter according to claim 2 is a low-pass filter in which a resonance circuit is added to claim 1 and an attenuation pole is provided. A high-frequency switch module according to a fourth aspect is characterized in that a resonance circuit is added to the low-pass filter according to the third aspect to provide an attenuation pole.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. According to the present invention, when forming the low-pass filter of the equivalent circuit shown in FIG. 1A with the electrode pattern on the dielectric layer, as shown in FIG. 1B, the second capacitor pattern P2 with the ground pattern e interposed therebetween. And the third capacitor pattern P5 are formed. The first capacitor pattern P4 and the third capacitor pattern P5 are connected by a conductor, and the ground pattern e faces the second capacitor pattern P2 and the third capacitor pattern P5. To form a second capacitor C2 and a third capacitor C3. On the other hand, the first capacitor C1 is formed with the first capacitor pattern P4 and the second capacitor pattern P2 facing each other. Therefore, the area of the electrode pattern occupied on the same dielectric layer can be reduced as compared with the conventional arrangement shown in FIG. 1 (c). They can be arranged, and miniaturization can be achieved.

Before entering the main body of the present invention, a low-pass filter formed by an electrode pattern according to the present invention and an electrode pattern in a laminate composed of a dielectric layer will be described with reference to the drawings. FIG. 2 shows a circuit of a single-band high-frequency switch including the low-pass filter according to an embodiment of the present invention. This switch circuit comprises two diodes DP1, DP2 and two transmission lines LP1,
LP2, and the diode DP1 is connected to the antenna terminal AN.
The anode is connected to the T side, the cathode is connected to the transmission TX side, and the transmission line LP1 connected to the ground is connected to the cathode side. A transmission line LP2 is connected between the antenna side of DP1 and the reception RX, and the reception R
A diode DP2 having a cathode connected to the X side is connected to the anode of the diode DP2, a capacitor CP6 is connected to the ground, a resistor RP is connected between DP2 and CP6, and connected to the control circuit VC2. Is done. A voltage (for example, +3) is applied to the control circuit VC2.
When V) is applied, the diodes DP2 and DP1 are turned on, and the transmission circuit TX and the antenna terminal ANT are connected. When no voltage is applied to the control circuit, the antenna terminal ANT and the receiving circuit RX are connected. In this way, one antenna can be shared by both the transmitting and receiving systems. The low-pass filter connected to the transmission circuit TX includes a transmission line LP3 and capacitors CP3, CP4,
CP7, which is a diode DP1 of a switch circuit
And the transmission line LP1. Harmonics can be suppressed by this low-pass filter. still,
DC cut capacitors CP1, CP2, CP5, CP6
Further, the resistor RP may be mounted on the laminated body or may be built therein. In some cases, it is also possible to dispose it on a substrate on which the high-frequency switch module is mounted.

Next, FIG. 3 shows an embodiment of a dual band. In this embodiment, GSM (Global System for Mobile communication) is used as a first transmitting / receiving system having a different pass band.
s, transmission frequency 880-915MHz, reception frequency 925-960MHz)
DCS (Digital Cell)
ular System, transmission frequency 1710-1785MHz, reception frequency 1
805-1880 MHz) A high-frequency switch module for handling a system, a first switch circuit SW1 for switching a transmission signal and a reception signal of a first transmission / reception system (GSM), and a first switch circuit connected to a transmission path of the first switch circuit. , A second switch circuit SW2 for switching between a transmission signal and a reception signal of a second transmission / reception system (DCS), a second low-pass filter circuit 2 connected to a transmission path of the second switch circuit, It is composed of demultiplexing circuits 11 and 21 for demultiplexing the first transmission / reception system and the second transmission / reception system.

First, the notch circuit 11 on the GSM side constituting the demultiplexing circuit includes an inductor LF1, capacitors CF1 and CF3. The capacitor CF3 is connected for the purpose of improving the low-pass filter characteristic of the demultiplexing characteristic. On the other hand, the notch circuit 21 on the DCS side has inductors LF2 and LF3 and capacitors CF2 and CF
4 This transmission line LF3 and the capacitor C
F4 is connected for the purpose of improving the high-pass filter characteristic of the demultiplexing characteristic. In addition, for example, a band-pass circuit, a low-pass circuit, a high-pass circuit, or the like, other than the notch circuit, may be used as the branching circuit, and these may be appropriately combined.

Next, the first switch circuit will be described. The first switch circuit is a switch circuit S on the upper side of FIG.
W1 is for switching between GSM transmission TX and reception RX. This switch circuit SW1 includes two diodes DG1, DG2 and two transmission lines LG1, LG2.
The transmission line LG has a diode DG1, an anode connected to the antenna terminal ANT side, a cathode connected to the transmission TX side, and a ground connected to the cathode side.
1 is connected. A transmission line LG2 is connected between the antenna side and the reception RX, a diode DG2 having a cathode connected to the reception RX side is connected, and a capacitor CG6 is connected between the anode of the diode DG2 and the ground. , A resistor RG is connected therebetween, and is connected to the control circuit VC1. And TX TX
The low-pass filter circuit inserted on the circuit side includes a transmission line LG3 and capacitors CG3, CG4, and CG7, and is inserted between the diode DG1 of the switch circuit SW1 and the transmission line LG1.

Next, the second switch circuit is a switch circuit SW2 on the lower side of FIG. 3, which switches between the transmission TX and the reception RX of the DCS system. This switch circuit SW2
Consists of two diodes DP1 and DP2 and two transmission lines LP1 and LP2. The diode DP1 has an anode connected to the antenna terminal ANT side, a cathode connected to the transmission TX side, and a cathode connected to the ground. Transmission line LP1 is connected. A transmission line LP2 is connected between the antenna and the reception RX, a diode DP2 having a cathode connected to the reception RX is connected, and a capacitor CP6 is connected between the anode of the diode DP2 and the ground. , DP2 and CP6, a resistor RP is connected to the control circuit VC2. The low-pass filter circuit inserted on the transmission TX circuit side includes a transmission line LP3 and a capacitor CP.
3, CP4 and CP7, and a switch circuit SW2
Between the transmission line LP1 and the diode DP1. The DC cut capacitors CG2, CG5, CP
2, CP5 and the resistors RG and RP may be mounted on the laminate or may be built in. In some cases, it is also possible to dispose it on a substrate on which the high-frequency switch module is mounted.

The control operation of these two transmission / reception circuits is basically the same as in the case of the single band described above. That is, when the GSM transmission is enabled, a predetermined voltage is applied to the voltage terminal VC1. GS
When M-system reception is enabled, no voltage is applied to VC1. Similarly, when a predetermined voltage is applied to the voltage terminal VC2, DCS transmission is enabled, and when no voltage is applied to VC2, DCS reception is enabled. During reception, no voltage is applied to either of the voltage terminals VC1, VC2.

FIG. 4 shows a part of the internal electrode pattern diagram of the dual band high frequency switch module shown in FIG. FIG. 5 shows only the electrode patterns constituting the low-pass filter installed in the circuit on the GSM side among the internal electrode patterns shown in FIG. To explain this, among the capacitors constituting the low-pass filter 1 installed in the GSM-side circuit shown in FIG.
G7 is formed from the capacitor patterns Co1 and Co2 shown in FIG. 5, and the capacitors CG3 and CG4 are formed from the capacitor pattern Co2 and the ground pattern e and Co3 and the ground pattern e, respectively. The low-pass filter 2 on the DCS side is also formed by the same electrode pattern arrangement. The aim of this patent is to form an electrode pattern Co with a ninth layer on which an earth pattern e is formed, as in the seventh to tenth layers shown in FIG.
2 is distributed on the eighth layer and the electrode pattern Co3 is distributed on the tenth layer, so that the space per layer required for arranging the electrode patterns forming the capacitor can be reduced to half of the conventional one, and the size of the laminated body can be reduced. Is that it can sufficiently cope with the reduction of the design space accompanying the development.

Returning to FIG. 4, the electrode pattern forming the low-pass filter provided over the seventh to tenth layers will be described. On the GSM side, the ground pattern e3 of the ninth layer is described.
By arranging the capacitor pattern C9 on the eighth layer and the capacitor pattern C10 on the tenth layer with the
Are formed, and the capacitor pattern CG7 shown in FIG. 3 is formed by the capacitor pattern C4 of the seventh layer and the capacitor pattern C9 of the eighth layer. DCS side low-pass filter is also c11, C12, e
3, the same electrode pattern arrangement by C5. As a result of a trial production based on the arrangement of the electrode patterns described above, as can be seen by comparing the sizes of the dielectric layers of FIGS. 4 and 7, the embodiment of FIG.
3% miniaturization was achieved.

FIG. 6 is a perspective view of a dual band high frequency switch module. The high-frequency switch module of the present invention forms electrode patterns of circuits constituting the high-frequency switch module in a laminate as shown in FIGS. 4 and 6, and arranges chip components such as diodes on the laminate. It can be miniaturized by one chip.

[0023]

According to the present invention, the shortage of the effective design space due to the miniaturization and multi-banding of the high-frequency switch module can be improved. Therefore, it is possible to easily cope with miniaturization and design easiness in a limited space.

[Brief description of the drawings]

1A is an equivalent circuit diagram of a low-pass filter according to the present invention, FIG. 1B is a schematic sectional view of an electrode pattern, and FIG. 1C is a schematic sectional view of a conventional electrode pattern.

FIG. 2 is an equivalent circuit diagram of a single-band high-frequency switch.

FIG. 3 is an equivalent circuit diagram of a dual-band high-frequency switch.

FIG. 4 is an internal electrode pattern diagram of a dual-band high-frequency switch module according to an embodiment of the present invention.

FIG. 5 is an internal electrode pattern diagram showing only a low-pass filter portion according to the embodiment of the present invention.

FIG. 6 is a perspective view of a laminated body of the dual-band high-frequency switch module according to the embodiment of the present invention.

FIG. 7 is an internal electrode pattern diagram of a conventional dual-band high-frequency switch module including a low-pass filter.

[Explanation of symbols]

P1, P2, P3, P4, P5, P6: electrodes forming a capacitor LF1, LF2, LF3, LP1, LP3: transmission line LG1, LG2, LG3, LP2: transmission line CG1, CG2, CG3, CG4, CG5, CG6 , C
G7: Capacitors CP2, CP3, CP4, CP5, CP6, CP7: Capacitors CF1, CF2, CF3, CF4: Capacitors TX: Transmission terminal RX: Reception terminal ANT: Antenna terminal SW: Switch circuit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroyuki Tatai 70-2, Minamisakae-cho, Tottori-shi, Tottori Prefecture F-term in Hitachi Metals Co., Ltd. Tottori Plant 5J006 HB05 HB21 HB22 JA03 KA01 KA24 LA23 NA07 NB09 5J012 BA03 5J024 AA01 BA01 DA04 DA29 EA01 5K011 DA02 DA27 JA01 KA04

Claims (4)

[Claims] A first capacitor, a second capacitor,
A low-pass filter comprising a third capacitor and a transmission line, wherein each of the capacitors and the transmission line is formed by an electrode pattern formed on a plurality of dielectric layers;
The first, second, and third capacitor patterns are respectively formed on different dielectric layers, and an earth pattern is provided between the second capacitor pattern and the third capacitor pattern. The third capacitor pattern is connected by a conductor, the first capacitor pattern is opposed to the second capacitor pattern, and the second capacitor pattern is opposed to the second capacitor pattern by the second capacitor pattern. Wherein the third capacitor is formed by making the ground pattern and the third capacitor pattern face each other. 2. A first capacitor, a second capacitor,
A low-pass filter comprising a third capacitor and a transmission line, wherein each of the capacitors and the transmission line is formed by an electrode pattern formed on a plurality of dielectric layers;
The first, second, and third capacitor patterns are respectively formed on different dielectric layers, and an earth pattern is provided between the second capacitor pattern and the third capacitor pattern. The third capacitor pattern is connected by a conductor, the first capacitor pattern is opposed to the second capacitor pattern, and the second capacitor is opposed to the second capacitor pattern and the ground pattern. The third capacitor is formed by making the ground pattern and the third capacitor pattern face each other, and a resonance circuit is formed by the capacitance obtained by the first capacitor and the transmission line. And a low-pass filter. 3. A demultiplexing circuit for distributing received signals of a plurality of transmission / reception systems having different passbands, and at least one of the demultiplexing circuits.
A high-frequency switch module having a low-pass filter circuit including a switch circuit for switching between a transmission path and a reception path and an LC circuit at a stage subsequent to the two paths, wherein the low-pass filter includes a first capacitor and a second capacitor. , A third capacitor, and a transmission line, wherein each of the capacitors and the transmission line is formed by an electrode pattern formed on a plurality of dielectric layers, and the first, second, and third capacitor patterns are formed. Are respectively formed on different dielectric layers, an earth pattern is provided between the second capacitor pattern and the third capacitor pattern, and the first capacitor pattern and the third capacitor pattern are connected by a conductor. The first capacitor pattern is opposed to the second capacitor pattern so that the first capacitor Is a low-pass filter in which the second capacitor is formed by opposing the ground pattern and the second capacitor pattern, and the third capacitor is formed by opposing the ground pattern and the third capacitor pattern. High-frequency switch module characterized. 4. A demultiplexing circuit for distributing received signals of a plurality of transmission / reception systems having different pass bands, and at least one of the demultiplexing circuits.
A high-frequency switch module having a low-pass filter circuit including a switch circuit for switching between a transmission path and a reception path and an LC circuit at a stage subsequent to the two paths, wherein the low-pass filter includes a first capacitor and a second capacitor. , A third capacitor, and a transmission line, wherein each of the capacitors and the transmission line is formed by an electrode pattern formed on a plurality of dielectric layers, and the first, second, and third capacitor patterns are formed. Are respectively formed on different dielectric layers, an earth pattern is provided between the second capacitor pattern and the third capacitor pattern, and the first capacitor pattern and the third capacitor pattern are connected by a conductor. The first capacitor pattern is opposed to the second capacitor pattern so that the first capacitor pattern is formed. Forming a second capacitor by facing the second capacitor pattern and a ground pattern, and forming a third capacitor by facing the ground pattern and a third capacitor pattern. A high-frequency switch module comprising a low-pass filter in which a resonance circuit is formed by the capacitance obtained by the above and a transmission line.