JP2002280926A - High-frequency switch module for multiband - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-frequency switch module, handling a plurality of transmission reception systems with different pass bands, that can reduce insertion loss and reflection loss. SOLUTION: A conventional high-frequency switch module, comprising a branching circuit that branches signals to a plurality of the transmission reception systems and a switch circuit that selects transmission and reception systems for each transmission reception system, has deteriorated impedance matching due to parasitic capacitance caused by a highly dense pattern accompanying a downsized module resulting in deteriorating the insertion loss and the reflection loss. The high-frequency switch inserts an impedance matching means between a switching circuit and a branching circuit at a higher frequency among a plurality of transmission reception systems, handled by the high frequency switch module or employs at least a capacitor electrode of the branching circuit as the impedance matching means, so as to reduce the circuit loss.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency composite component, and more particularly to a multi-band high-frequency switch module for handling a plurality of transmission / reception systems having different pass bands.

[0002]

2. Description of the Related Art In a digital cellular phone or the like, a high-frequency switch is used to switch a connection between an antenna and a transmission circuit or a connection between an antenna and a reception circuit.
A conventional high-frequency switch has a first diode in which an anode is connected to a transmission circuit side and a cathode is connected to an antenna side as described in JP-A-6-197040, and a first diode connected between the antenna and the reception circuit. A strip line to be connected, a second diode having an anode connected to the receiving circuit side, and a cathode connected to the ground side, wherein the strip line is built in the multilayer substrate,
And the second diode is mounted on the upper surface of the multilayer substrate. In this high frequency switch circuit, the transmission / reception system corresponds to a single band.

In recent years, the spread of mobile phones has been remarkable, and the functions and services of mobile phones have been improved in conjunction with the increase in the number of mobile phones. As one form of this new mobile phone, dual-band mobile phones have begun to appear on the market. Dual-band mobile phones can use two transmission / reception systems with different frequencies, so a transmission / reception system that is convenient for the user is selected, which is effective in eliminating waiting time, etc. It is expected that use will expand.

In a dual-band mobile phone, if a dedicated processing circuit is provided for each transmission / reception system, the size and cost of the device will increase. For this reason, a multi-band high-frequency switch that has a common antenna and can selectively switch between the transmission circuit and the reception circuit of the first transmission / reception system or the transmission circuit and the reception circuit of the second transmission / reception system is used. FIG. 6 shows an example of a block configuration of a high-frequency switch used in a dual band, which is described in Japanese Patent Application Laid-Open No. H11-225088.

[0006] In FIG. 6, the area surrounded by the broken line is modularized to form the high-frequency switch module 30. GSM (Global System for GSM)
Mobile communications A transmission frequency of 880 to 915 MHz, a reception frequency of 925 to 960 MHz, and a DCS1800 (Digital Cellular System transmission frequency of 1710 to 1785 MHz reception frequency of 1805 to 1880 MHz) as a second transmission / reception system. Alternatively, the receiving circuit is configured to be selectively connected to the antenna 32 by the switch circuits 13 and 23. The selection control is performed by controlling the DC voltages VC1 and VC2 applied to the control voltage terminals 18 and 28.
Done by On the other hand, the demultiplexing circuit 31 includes, for example, notch circuits 11 and 21 and has predetermined frequency pass characteristics. Further, low-pass filters 15, 25 between the switch circuits 13, 23 and the transmission circuit terminals 19, 29.
Functions to remove high-frequency noise transmitted from the transmission circuit side.

When the block diagram shown in FIG. 6 is specifically constituted by circuit elements, an equivalent circuit shown in FIG. 7 is obtained. First, the notch circuit 11 on the GSM side that constitutes the demultiplexing circuit includes an inductor LF1 and capacitors CF1 and CF3. The capacitor CF3 has the function of improving the low-pass filter characteristics of the demultiplexing characteristics. On the other hand, the notch circuit 21 on the DCS side includes inductors LF2 and LF3 and capacitors CF2 and CF4.
Consists of The capacitor CF4 and the inductor LF3 are
This has the effect of improving the high-pass filter characteristics of the demultiplexing characteristics.

Next, the switch circuit will be described. The switch circuit 13 transmits and receives RX and RX signals of the GSM system.
Is switched by the DC voltage VC1 applied to the control voltage terminal 18. In this switch circuit 13, two diodes DG1 and DG2 are connected in positions and directions as shown in FIG. The diode DG1 has an anode connected to the antenna 32 side and a cathode connected to the transmission TX terminal 19 side. Similarly, the cathode of the diode DG2 is connected to the transmission line LG.
2 and the receiving RX terminal 17 side, and the anode is grounded via the capacitor CG6. The low-pass filter 15 shown in FIG. 6 includes an inductor LG3 and a capacitor CG3,
It is composed of CG4 and CG7.

At the time of transmission, when a high level DC voltage is applied to the control voltage terminal 18, the diodes DG1 and DG2 conduct and become ON, and the input impedance of the transmission line LG2 is regarded as infinite. The transmission signal 19 reaches the antenna 32 through the diode DG1, the notch circuit 11, and the like. For a received signal, the control voltage terminal 18 is at zero potential, so that the diodes DG1 and DG2 are non-conductive and turned off, and the antenna 3
2 is transmitted to the reception RX terminal 17 through the notch circuit 11, the transmission line LG2, and the like. The system on the GSM side has been described above.
The S1800 system has a similar configuration and circuit operation.

In such a high-frequency switch module, upon reception of a GSM system or DCS1800 system, diodes DG1, DG2 or DP1, DP2 are used.
Is turned off, but at this time, the diodes DG1, DG2 or DP1, DP2 each have a capacitance component. Among such capacitance components, when receiving a GSM system, the diode DG
2 or DP2 when receiving DCS1800 system
Each have a capacitance component. At this time, the impedance seen from the antenna 32 changes, causing deterioration of reflection loss and insertion loss.

As means for solving the problem that the capacitance component of the diode deteriorates the impedance matching when the diode is in the OFF state, for example, JP-A-7-31568 and JP-A-8-148901 disclose the means. In a single-band high-frequency switch, it is disclosed as a solution to connect a capacitor between one end of the strip line on the antenna side and ground.

[0011]

As described above, low-frequency insertion loss and low-reflection characteristics are one of important index characteristics of a high-frequency switch module, and are carefully designed and manufactured to meet the requirements. Is managed. As portable terminals become more multi-band in addition to being smaller and lighter, high-frequency switch modules also need to be smaller, lighter and compatible with multi-bands. In a high-frequency switch module having a laminated structure, more electrodes and line patterns must be arranged in a smaller-sized laminated body, and as a result, the relative distance between the electrode patterns in the laminated body is reduced. Therefore, interference between electrode patterns and an increase in parasitic capacitance are caused. This parasitic capacitance also degrades impedance matching and is considered to be a cause of reflection loss and insertion loss. Further, the examples disclosed in JP-A-7-31568 and JP-A-8-148901 are high-frequency switches for a single band, so there is no viewpoint of miniaturization, and specific examples in a high-frequency switch module for a multi-band. No solution was disclosed. Therefore, in practical use, when a request exceeding the limit of miniaturization is issued, it has been difficult for the prior art to respond. SUMMARY OF THE INVENTION As described above, the present invention has been made to solve the problem of parasitic capacitance caused by the increase in the density of internal patterns, and has as its object to provide a small, high-performance high-frequency switch module. Hereinafter, the solution will be described in detail.

[0012]

SUMMARY OF THE INVENTION According to the present invention, an insertion loss of a high-frequency switch module is provided by disposing impedance matching means in a higher-frequency side transmission / reception system circuit in a high-frequency switch module that handles a plurality of transmission / reception systems. Reduction or low reflection characteristics can be obtained. The reason for disposing the impedance matching means in the transmission / reception system circuit on the higher frequency side is that in a high frequency switch module handling a plurality of transmission / reception systems, parasitic capacitance is likely to be generated in the circuit on the higher frequency side and is easily affected by the parasitic capacitance. is there. Further, the configuration method of the impedance matching means according to the present invention, the arrangement position in the module, the insertion position on the circuit, and the like are based on the results derived by trial production experiments. To
Hereinafter, the solution means will be described for each claim. According to the first aspect of the present invention, the impedance matching means is connected between the demultiplexing circuit of the transmitting and receiving system on the higher frequency side and the switch circuit of the transmitting and receiving system on the higher frequency side among the plurality of transmitting and receiving systems handled by the high frequency switch module. Is the way.
It has been found through trial experiments that the configuration in which the above means is inserted between the branching circuit and the switch circuit is more effective. It is desirable that the impedance matching means is formed by an electrode pattern between the stacks of modules, and since this method has a simple configuration, a plurality of transmission / receptions can be easily designed without requiring the addition of components that increase the manufacturing cost. It has the advantage of being able to clear the strict space constraints such as handling systems.

However, the effects of the present invention can be sufficiently obtained at positions other than the above connection positions. With the downsizing of the switch module, the thickness of some of the dielectric layers forming the laminate is reduced, and at the same time, the relative distance between the electrodes or conductors is shortened. Parasitic inductance increases. Also, the electromagnetic mutual induction effect increases. For this reason, impedance matching is broken, which causes deterioration of insertion loss and reflection loss. Since such parasitic capacitance and parasitic inductance are generated in various places in the switch module due to the layout of the electrodes and line patterns, the insertion position of the compensation circuit as a matching means is more than a measure at one place. It is more effective to split it into two or more places. That is, in the present invention, a plurality of impedance matching means may be provided, in which case better characteristics can be obtained. In this case, the impedance matching can be effectively improved by arranging the impedance matching means in the transmission / reception system circuit on the higher frequency side which is more susceptible to the parasitic capacitance and the parasitic inductance. .

An embodiment of the present invention is to connect the impedance matching means according to the present invention at or near a place where more parasitic capacitance or parasitic inductance is generated. In other words, the method of connecting the means according to the present invention near the cause of the deterioration of the impedance matching is the most reasonable method. For example, when a relatively long wiring conductor approaches the ground electrode in the switch module, the parasitic capacitance increases. If the means of the present invention is connected to this wiring conductor, a greater effect can be obtained.

According to a second aspect of the present invention, in the high-frequency switch module, the impedance matching means connected between the branching circuit and the switch circuit comprises:
This is a method of sharing at least the capacitor electrode of the branching circuit. With the miniaturization of the laminate, the density of the electrodes and line patterns inside the laminate increases, and as space becomes less available, it is difficult to add a new electrode pattern. Therefore, by sharing the existing electrode patterns, the number of additional electrode patterns can be minimized. In addition, when the impedance matching means to be connected is one capacitor, this method is very effective and simplest. Therefore, there is no problem such as an increase in manufacturing cost and an increase in man-hours.

According to a third aspect of the present invention, the size of the capacitor for compensating impedance matching is specified. By setting the value of the capacitance to be substantially equal to the parasitic capacitance at the receiving terminal, the insertion loss and the reflection loss can be reduced. Can be minimized. Therefore, the present invention provides a design guide for capacitors as impedance matching means.

As described above, the gist of the present invention is to provide a high-frequency switch module having a branching circuit for branching a signal to a plurality of transmitting and receiving systems and a switch circuit for switching between a transmitting system and a receiving system of the transmitting and receiving system. The switch circuit is configured such that a first diode is inserted between the circuit and the antenna, a transmission line is inserted between the antenna and the receiving circuit, and a second diode is inserted between the transmission line and the ground of the receiving circuit. A multi-band high-frequency switch module in which impedance matching means is connected between the branching circuit and the switch circuit to a circuit of a higher-frequency side transmission / reception system among a plurality of transmission / reception systems handled by the high-frequency switch module. As a result, it becomes easy to compensate for deterioration of impedance matching due to parasitic capacitance and parasitic inductance.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an equivalent circuit according to an embodiment of the present invention. This embodiment is similar to the DCS1800 of FIG.
And the connection position of the capacitor Cx as an impedance matching means for the GSM system. The capacitor Cx is inserted between a conductor connecting the branching circuit 21 and the switch circuit 23 and ground. Capacitors
Cx is disposed in the switch module and is provided at a location where a space required for formation is obtained. In particular, the transmission line LP
2, the impedance of the conductor and the like can be reduced, so that a high-frequency switch module with more stable characteristics can be obtained.

Next, a description will be given of a suitable capacitance value of a capacitor connected for impedance matching. FIG. 2 shows the relationship between the capacitances of the capacitors to be compensated obtained by a trial production experiment. The capacitor capacity Cx represents a capacitor capacity for impedance matching added to the circuit to reduce the influence of the parasitic capacity.

In FIG. 2, since the receiving frequency band is 1805 to 1880 MHz in the DCS1800 system, the case of 1805 MHz is indicated by a solid line and 1880 MHz.
The case of z is indicated by a broken line. Both are characteristic curves convex downward. From these results, the capacitance value of the capacitor that can minimize the insertion loss is 0.3 to 0.4 pF. Also, at 1880 MHz on the high frequency side, insertion loss is slightly reduced, and it is necessary to increase the capacitance to be compensated. Therefore, when operating in a wide band, care must be taken in setting the capacitor capacitance Cx.

FIG. 3 is an equivalent circuit when the present invention is applied to a triple band portable terminal. In this figure, the GSM system and the DCS1800 system (hereinafter simply DCS
PCS (Personal Cellular System)
Transmission frequency 1850-1910MHz Reception frequency 1930-1990
MHz) is a high-frequency switch module corresponding to the system. In the figure, a capacitor denoted by Cx is an impedance matching unit. Hereinafter, the operation of the high-frequency switch circuit and the operation of the Cx capacitor will be described.

(1) DCS / PCS transmission TX mode When the DCS / PCS transmission TX is connected to the filter circuit F2, a positive voltage is supplied from the voltage control circuit VC1, and the positive voltages are CP9, CP3 and CP2. , CP7, CF5, C
The DC component is cut by the capacitor of P5 and applied to the circuit including diodes DP1 and DP3.
Is turned on. When the diode DP1 is turned on, the impedance between the DCS / PCS transmission TX and the connection point IP2 decreases. In addition, the transmission line LP3 is resonated by being grounded at a high frequency by the diode DP3 and the capacitor CP7 which are turned on, and the impedance when the DCS reception RX and the PCS reception RX are viewed from the connection point IP2 becomes extremely large. Therefore, DCS / PCS
The transmission signal from the transmission TX is transmitted to the filter circuit F2 without leaking to the DCS reception RX and the PCS reception RX.

(2) DCS reception RX mode When the DCS reception RX is connected to the filter circuit F2, the diodes DP1, DP2, DP3, and DP4 are turned off by applying 0 voltage from the voltage control circuits VC1 and VC2. Become. When the diode DP1 is turned off, the impedance between the connection point IP2 and the DCS / PCS transmission TX increases. Also, diode DP3 is OFF
In this state, the impedance of the diode DP3 increases, and the connection point IP2 and the connection point IP3 are connected via the transmission line LP3. Further, when the diode DP2 is turned off, the impedance between the connection point IP3 and the PCS reception RX increases. Further, since the diode DP4 is in the OFF state, the impedance of the diode DP4 increases, and IP3 and the DCS reception RX are connected via LP4. For this reason, the received signal from the filter F2 is DCS /
It is transmitted to the DCS reception RX without leaking to the PCS transmission TX and the PCS reception RX.

(3) PCS RX Mode When connecting the PCS RX and the filter F2, a voltage of 0 is supplied from the voltage control circuit VC1, a positive voltage is supplied from the voltage control circuit VC2, and the positive voltage is , CP5, CP6, CP11 and CP8, the DC component is cut off and applied to a circuit including diodes DP4 and DP2, and the diodes DP4 and DP2 are turned on. On the other hand, the diodes DP1 and DP3 are turned off. Diode DP1
Is turned off, the connection point IP2 and DCS / P
The impedance during CS transmission TX increases. Further, when the diode DP3 is turned off, the impedance of the diode DP3 increases, and the connection point IP2 and the connection point IP3 are connected via the transmission line LP3. When the diode DP2 is turned on, the connection points IP3 and P
The impedance during CS reception RX decreases. Also,
Due to the diode DP4 and the capacitor CP6 in the ON state, the transmission line LP4 is resonated by being grounded at a high frequency, and the impedance when the DCS reception RX side is viewed from the connection point IP3 becomes very large. Therefore, the filter F
2 are DCS / PCS transmission TX and DCS
It is transmitted to the PCS reception RX without leaking to the reception RX. Here, Cx can compensate for deterioration of impedance matching due to parasitic capacitance generated near the connection point IP3. Therefore, in both the PCS and DCS reception modes, the reflection loss and the insertion loss can be improved.

(4) GSM transmission TX mode When the GSM transmission TX is connected to the filter F1, a positive voltage is supplied from the voltage control circuit VC3, and the positive voltage is CG4, CG5, CG2, CG3, CG11, CG9. The DC component is cut off by the capacitor, and is applied to a circuit including the diodes DG2 and DG1, and the diodes DG2 and DG1 are turned on. When the diode DG1 is turned ON, GS
The impedance between the M transmission TX and the connection point IP1 becomes low. The diode DG2 and the capacitor CG5 that are turned on resonate because the transmission line LG3 is grounded at a high frequency, and the impedance when the GSM reception RX side is viewed from the connection point IP1 becomes very large. Therefore, G
The transmission signal from the SM transmission TX is transmitted to the filter F1 without leaking to the GSM reception RX.

(5) GSM Reception RX Mode When the GSM reception RX is connected to the filter F1, a voltage of 0 is applied to the voltage control circuit VC3, so that the diodes DG1 and DG2 are turned off. When the diode DG1 is turned off, the connection point IP1 and GSM
The impedance between the transmission TX increases. Further, since the diode DG2 is in the OFF state and the impedance is large, the connection point IP1 and the GSM reception R are connected via the transmission line LG3.
X is connected. Therefore, the reception signal from the filter F1 does not leak to the GSM transmission TX and the GSM reception RX
Is transmitted to

FIG. 4 is an external view of a high-frequency switch module to which the present invention is applied. This high-frequency switch module is for a dual band, but can also be manufactured for a triple band. The structure of FIG.
5 is a case where a diode, a capacitor, a resistor, and the like are mounted on the upper surface of FIG. The effects of the present invention can be equally obtained by mounting or incorporating a DC cut capacitor on the laminate 55. Furthermore, a capacitor or the like mounted on the laminate 55 can be installed on a mounting board of the high-frequency switch module depending on the configuration of the peripheral circuit or the space. Next, a method for forming a laminate and a capacitor electrode according to the present invention will be described.

The internal structure of the laminate will be described.
In this laminate, a green sheet made of a ceramic dielectric material that can be fired at a low temperature is prepared, and a conductive paste mainly composed of Ag is printed on the green sheet to form a desired electrode pattern. It is configured by laminating and integrally firing.

FIG. 5 shows a print pattern of a laminate 55 composed of 15 layers. The first layer is the top surface, and the fifteenth layer is the bottom surface. Here, the method for forming the equivalent circuit shown in FIG. 1 will be described taking as an example a case where a capacitor Cx is provided only in the transmission / reception system circuit on the high frequency side. Among the electrode patterns constituting the capacitor CF4, the electrode patterns on the switch circuit 23 side opposite to the electrode patterns on the antenna side are c3 and c6 of the seventh and eighth layers in FIG. 5, respectively. On the other hand, of the electrode patterns constituting the capacitor Cx added to the high-frequency switch module circuit for impedance matching, the electrode pattern on the circuit main line side and the electrode pattern on the opposite ground side are c6 and e of the eighth and ninth layers.
6. As described above, by sharing part c6 of the electrode pattern forming the capacitor CF4 with the capacitor Cx, it is not necessary to newly provide an electrode pattern, and efficient impedance matching can be achieved.

[0030]

According to the present invention, it is possible to improve the insertion loss and the reflection loss deterioration due to the parasitic capacitance due to the miniaturization of the high-frequency switch module, which has been a problem in the past, and to provide a method which does not have a problem in manufacturing or cost.

[Brief description of the drawings]

FIG. 1 is an equivalent circuit diagram of a high-frequency switch according to an embodiment of the present invention.

FIG. 2 shows compensation capacitor capacitance and loss characteristics.

FIG. 3 is an equivalent circuit diagram of the portable terminal for triple band according to the present invention.

FIG. 4 is a schematic view of a high-frequency switch module of a dual-band mobile phone according to the present invention.

FIG. 5 is a printing pattern of the dual-band high-frequency switch module according to the present invention.

FIG. 6 is a block diagram of a high-frequency switch module according to the related art.

FIG. 7 is an equivalent circuit of a conventional high-frequency switch module.

[Explanation of symbols]

 11, 21: Notch circuit 13, 23: Switch circuit 15, 25: Low-pass filter 17, 27: Receive RX terminal 18, 28: Control voltage terminal 19, 29: Transmit TX terminal 30: High frequency switch module 31: Demultiplexer circuit 32 : Antenna 51: Land 55: Laminate

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hiroyuki Takai 70-2, Minamisakaemachi, Tottori City, Tottori Prefecture F-term in the Tottori Plant of Hitachi Metals, Ltd. (reference) 5J012 BA03 BA04 5J024 AA01 BA11 CA03 DA01 DA25 EA03 5K011 DA02 DA22 EA06 FA01 GA04 JA01 KA13 5K060 BB07 CC04 DD04 HH11 HH39 JJ02 JJ04 JJ06 JJ21 LL07 LL29

Claims (3)

[Claims] 1. A high-frequency switch module comprising: a demultiplexing circuit for demultiplexing a signal to a plurality of transmission / reception systems; and a switch circuit for switching a transmission system and a reception system of the transmission / reception system.
A switching circuit for inserting a first diode between the transmission circuit and the antenna, a transmission line between the antenna and the reception circuit, and a second diode between a connection point between the transmission line and the reception circuit and the ground; A multi-band transmission / reception system among the plurality of transmission / reception systems handled by the high-frequency switch module, wherein an impedance matching means is connected between the demultiplexing circuit and the switch circuit in a transmission / reception system circuit on a higher frequency side. For high frequency switch module. 2. A high-frequency switch module comprising: a demultiplexing circuit for demultiplexing a signal to a plurality of transmission / reception systems; and a switch circuit for switching a transmission system and a reception system of the transmission / reception system.
A switching circuit for inserting a first diode between the transmission circuit and the antenna, a transmission line between the antenna and the reception circuit, and a second diode between a connection point between the transmission line and the reception circuit and the ground; And an impedance matching means is connected between the demultiplexing circuit and the switch circuit, and the impedance matching means shares at least a capacitor electrode of the demultiplexing circuit. 3. The method according to claim 1, wherein
The high-frequency switch module for a multi-band, wherein a capacitance value of a capacitor of the impedance matching means is about a parasitic capacitance value at a receiving terminal of the switch circuit.