JP2003143033A - High-frequency switching module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-frequency module, including a switch circuit and a balun transformer circuit in a laminate structure, which realizes the miniaturization of a laminate and the space saving of a valid design space accompanied with the miniaturization. SOLUTION: The high-frequency switch module has a switching circuit for switching between a transmission path and a reception path in at least one transmission/reception system, and a balun transformer circuit for balance/ unbalance conversion, which is connected to at least one of the transmission and reception paths. In this module, one end of an unbalanced side circuit of the blun transformer connected to the switch circuit is brought into a opening state, thereby eliminating the necessity of a DC cut capacitor between the switch circuit and the balun transformer circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile terminal and a wireless L.
The present invention relates to a high-frequency switch module used in an AN device or the like, which is a combination of a high-frequency switch circuit used in a high-frequency band such as a microwave band and a balun transformer circuit that converts a signal to balanced / unbalanced.

[0002]

2. Description of the Related Art The spread of mobile phones in recent years has been remarkable, and mobile terminals are becoming smaller and more sophisticated. Under such circumstances, components mounted on a board in a mobile terminal are required to be smaller and have higher functionality.
Conventionally, as a means for responding to such a demand, each of the single-function components mounted on the board of the mobile terminal is
By making it smaller and more sophisticated, we have made efforts to make the mobile terminal smaller and more sophisticated by reducing the mounting area.

However, since there is a limit to the pursuit of miniaturization and high functionality of a single-function component alone, a laminated module component having a composite function from the conventional single-function component has attracted attention as a new means. By incorporating multiple functions in a single stack, the mounting area can be reduced compared to when mounting with single-function components.

To save the mounting area, it is effective to use a composite module of single-function components.
However, even in the case of a module part having a composite function, the demand for a small size and a low profile is the same as that of a single function part, and it is necessary to store the necessary electrode pattern in a limited space.

Examples of single-function parts include switches and balun transformers. The switch is for switching between a transmission path and a reception path, and the balun transformer is for performing balanced / unbalanced conversion of a signal to be handled.
Conventionally, when connecting this switch and balun transformer,
As shown in FIG. 10, the unbalanced side circuit of the balun transformer is connected to the subsequent stage of the switch circuit via DC cut capacitors, respectively. Such a combination of a switch circuit and a balun transformer circuit has been used to connect an unbalanced input / output circuit and a balanced input / output circuit. At this time, the balun transformer is used with one end of the unbalanced side circuit in the circuit being short-circuited, as shown in FIG.

Further, in a combination of the above switch circuit and balun transformer circuit, or in a high frequency switch module including the switch circuit, a DC cut capacitor necessary for the switch circuit to control transmission / reception switching is included in the circuit. It is installed in an appropriate place.
For example, the high-frequency switch module disclosed in Japanese Unexamined Patent Publication No. 11-225088 is provided before and after the transmission terminal Tx and the reception terminal Rx, and at the connecting portions of various circuits. These DC cut capacitors are formed by an electrode pattern in a laminated body formed of dielectric layers forming a high frequency switch module, or by an external chip capacitor.

[0007]

Usually, the DC cut capacitor has a relatively large capacitance value of several tens of pF, and if this value becomes small, the high frequency characteristics of the switch deteriorate.
Therefore, the capacitance value of the DC cut capacitor cannot be made smaller than necessary. In order to form the DC cut capacitor with the electrode pattern in the laminated body composed of the dielectric layer, it is necessary to arrange the electrode pattern forming the capacitor in a limited space on the dielectric layer. Also, when the DC cut capacitor is formed by the chip capacitor, a space for mounting the chip capacitor is required on the upper surface of the laminated body, for example.
In either case, it is necessary to secure a place for installing and forming the DC cut capacitor in the limited space.

Even in the case of forming a high frequency switch module including the switch circuit and the balun transformer circuit, DC cut capacitors are required at a necessary number of points including the connection point between the switch circuit and the balun transformer circuit. . However, as the miniaturization of the stack progresses,
The space for forming the electrode pattern on the dielectric layer or the space on the upper surface of the laminated body is becoming smaller, and in any of the cases described in the previous section, the formation of the capacitor is becoming difficult.

Therefore, according to the present invention, in a high-frequency module comprising a switch circuit and a balun transformer circuit for balanced / unbalanced conversion, which is connected to at least one of the transmission path and the reception path, a circuit configuration of the balun transformer circuit is provided. A high-frequency switch equipped with a balun transformer circuit, which focuses on its features, eliminates the need for a DC cut capacitor between the balun transformer circuit and the switch circuit, and easily copes with the miniaturization of parts within a limited space. The purpose is to provide a module.

[0010]

According to the present invention, when a switch circuit for switching a transmission path and a reception path and a balun transformer circuit for performing balanced / unbalanced conversion are connected to at least one of the transmission path and the reception system path, they are connected to each other. The present invention was conceived by finding that the DC cut capacitor normally required can be eliminated. That is, the present invention relates to a high frequency circuit including a switch circuit for switching between a transmission path and a reception path of at least one transmission / reception system, and a balun transformer circuit for balanced / unbalanced conversion connected to at least one of the transmission path and the reception path. In the switch module, by opening one end of the unbalanced side circuit of the balun transformer connected to the switch circuit, a high frequency without a DC cut capacitor between the switch circuit and the balun transformer circuit It is a switch module.

Further, according to the present invention, a filter circuit such as a bandpass filter may be provided in the preceding stage of the switch circuit to provide, for example, a high frequency switch module for Bluetooth.

The present invention is also directed to a multi-band high frequency switch module in which a demultiplexing circuit for demultiplexing a signal is connected to a front stage of the switch circuit and to a plurality of transmission / reception systems handled by the high frequency switch module and other high frequency switch modules. Also good.

Further, the present invention may be a high frequency switch module in which the antenna of the high frequency switch module including the balun transformer circuit and the antenna of the high frequency switch module for multi-band handling signals of the plurality of transmission / reception systems are shared. .

As described above, the present invention provides a switch circuit for switching between a transmission path and a reception path of at least one transmission / reception system, and a balanced / unbalanced conversion connected to at least one of the transmission path and the reception path. A high frequency switch module including a balun transformer circuit is characterized in that one end of an unbalanced side circuit of the balun transformer circuit connected to the switch circuit is opened. That is, by opening one end of the unbalanced-side circuit connected to the switch circuit of the balun transformer circuit, the path of the direct current flowing through the switch circuit is the point e-point c-in FIG. Since there is only a path that passes through the points a, b, and d, a DC cut capacitor is not required between the switch circuit and the balun transformer circuit. Therefore, even if the transmission / reception system to be handled is a dual band or a triple band, and even if the restrictions on the design space are severe, the number of DC cut capacitors does not need to be increased unnecessarily, and the pattern design can be facilitated accordingly. In addition, the loss between the switch circuit and the balun transformer circuit can be reduced because the DC cut capacitor is not provided, which leads to improvement of high frequency characteristics of the high frequency switch module. As described above, it is possible to contribute to miniaturization and high functionality of the laminated body of the high frequency switch module.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 shows an embodiment of the present invention, a block diagram of a high frequency switch module including a balun transformer circuit and a bandpass filter circuit in the switch circuit, and FIG. 2 shows a balun transformer circuit and a bandpass filter circuit in the switch circuit. It is what showed the equivalent circuit of the high frequency switch module containing. The present invention is connected to the switch circuit 1 of the balun transformer circuits 2 and 3 shown in FIG. 2 in the configuration of the high frequency module including the switch circuit 1, the balun transformer circuits 2 and 3 and the bandpass filter circuit 4 shown in FIG. By making one end j point and k point of the unbalanced side circuit open, the path of the direct current flowing through the switch circuit is set to point e-c point-a point-b point-d point in FIG. Therefore, the DC cut capacitor between the switch circuit 1 and the balun transformer circuits 2 and 3 can be omitted. Therefore, it is possible to reduce the capacitor electrode pattern or the chip capacitor mounting space required on the dielectric layer for forming this DC cut capacitor, and especially when the multi-band is used, it is effective in a limited space. The electrode pattern can be arranged on the substrate, and the size can be reduced.

Before going into the main theme of the present invention, a switch circuit according to the present invention will be described below with reference to the drawings. Figure 2
FIG. 4 is an example of an embodiment of the present invention and shows an equivalent circuit of a high frequency switch for single band including the balun transformer circuit and a bandpass filter circuit. This switch circuit includes two diodes D1 and D2 and two transmission lines Ls1 and Ls.
The diode D1 has an anode connected to the antenna terminal ANT side, a cathode connected to the transmission Tx terminal side, and a transmission line Ls1 connected to the ground via the capacitor Cs2 on the cathode side. A control circuit Vc1 is connected between the transmission line Ls1 and the capacitor Cs2. The transmission line Ls2 is connected between the branch point a on the antenna side of D1 and the reception Rx terminal, the diode D2 having the cathode side connected between the transmission line Ls2 and the reception Rx terminal is connected, and the anode of the diode D2 is connected. On the side, a capacitor Cs between the ground and
1 is connected, a resistor Rs is connected between D2 and Cs1, and further connected to the control circuit Vc2.
Here, the control circuit Vc2 is high, and Vc1 is low.
When the voltage is applied, the diodes D2 and D1 are turned on. At this time, the current flows through the route of the resistor Rs, the diode D2, the transmission line Ls2, the diode D1, and the transmission line Ls1, and the transmission signal passes through the diode D1 and reaches the antenna terminal ANT and the branch point a on the reception Rx side. Here, since the transmission line Ls2 is on the reception Rx side and is grounded through the diode D2 in the ON state and the capacitor Cs1, the impedance on the reception Rx side seen from the branch point a looks infinite, and the transmission signal is eventually The branch point a is advanced to the ANT side, and the transmission circuit Tx and the antenna terminal ANT
Are connected. On the other hand, the control circuits Vc1 and Vc2
Diodes D2 and D1 are turned off without applying voltage to
Then, the received signal input from the antenna terminal ANT reaches the branch point a, but the diode D on the Tx side
Since 1 is in the OFF state, it cannot pass and heads for the transmission line Ls2. Since the diode D2 is also in the OFF state, the reception signal eventually passes through the transmission line Ls2 and goes to the reception Rx terminal side, and the antenna terminal ANT and the reception circuit Rx are connected. Further, at this time, by applying a high voltage to the control circuit Vc1 and a low voltage to Vc2 and applying a reverse voltage to the diodes D1 and D2, the received signal is prevented from leaking to the Tx side. In this way
Both the transmitting and receiving systems can share one antenna.

On the other hand, the balun transformer 2 connected to the transmission circuit Tx side has transmission lines Lb1, Lb2, Lb3, Lb.
4 and capacitors Cb1 and Cb3, and is connected to a connection point b between the diode D1 of the switch circuit and the transmission line Ls1. Cb1 is used for adjusting the balun transformer characteristic, and Cb3 is used for adjusting the impedance matching between the transmitting circuit Tx side of the switch circuit and the balun transformer circuit. The balun transformer can convert the balanced signal transmitted from the balanced input terminals Tx1 and Tx2 into an unbalanced signal. Where Lb3 and L
Since one end on the b4 side is in an open state, the current on the switch circuit side does not flow to the balun transformer circuit side. The balun transformer 3 connected to the receiving circuit Rx side includes transmission lines Lb5, Lb6, Lb7, Lb8 and capacitors Cb2, Cb4, and is connected to a connection point c between the diode D2 of the switch circuit and the transmission line Ls2. ing. Cb2 is for adjusting the balun transformer characteristics, and C
b4 is used for adjusting impedance matching between the receiving circuit Rx side of the switch circuit and the balun transformer circuit. The balun transformer can convert the unbalanced signal transmitted from the antenna side circuit into a balanced signal. Here, since one ends on the Lb5 and Lb6 sides are in an open state, the current on the switch circuit side does not flow to the balun transformer circuit side. The DC cut capacitors Cs1, Cs2, Cs3 and the resistor Rs may be mounted on the laminated body or may be built in. In some cases, it may be arranged on a substrate on which the high frequency switch module is mounted. The bandpass filter is for attenuating the band such as DAMPS / GSM / DCS / PCS / W-CDMA on the low frequency side, and for attenuating the 2f, 3f signals on the high frequency side.

FIG. 8 is a development view of a high frequency switch module for a single band including the switch circuit 1, the balun transformer circuits 2 and 3 and the bandpass filter circuit 4 shown in FIG. 2 in which internal electrode patterns are formed on a dielectric green sheet. Shows a part of. In the figure, (1) is the upper part of the laminated body, which is formed into a one-chip laminated body module by sequentially laminating and sintering. First, the balun transformer circuit will be described using this. Lb in FIG.
The transmission lines forming 1 are L5 and L6 in FIG. Similarly, the transmission lines forming Lb2 are L1 and L2, the transmission lines forming Lb3 are L7 and L8, and the transmission lines forming Lb4 are L3 and L4. Then, by closing one end of the electrode pattern L4, one end j of the transmission line Lb4 is in an open state. Further, Cb3 is formed by the electrode pattern of C2, and Cb1 is mounted on the laminated body using a chip capacitor as shown in FIG. On the other hand, the transmission lines forming Lb7 in FIG. 2 are L13 and L in FIG.
It is 14. Similarly, the transmission lines forming Lb8 are L9 and L10, and the transmission lines forming Lb5 are L15 and L16.
The transmission lines forming Lb6 are L11 and L12. Then, by closing one end of the electrode pattern L12, one end k of the transmission line Lb6 is in an open state. Further, Cb4 is formed by the electrode pattern of C3,
2 is mounted on the laminated body by using a chip capacitor as shown in FIG. As described above, in forming the balun transformer circuit, by making the j point and the k point of one end of Lb4 and Lb6 shown in FIG. 2 open, current does not flow from the switch circuit to each balun transformer circuit side, so that the balun transformer circuit does not flow. DC cut capacitor between circuits is no longer needed. Therefore, it is possible to reduce the space of the electrode pattern for forming the DC cut capacitor in manufacturing or the space for mounting the DC cut capacitor on the outer surface of the laminate, and to sufficiently reduce the design space. Is.

Incidentally, in the switch circuit 1, the diodes D1 and D2, the resistor Rs and the capacitor Cs2 are mounted parts (see FIG. 9), Cs1 is C12, and the strip line Ls1 is L17, L18, L20 and L2.
2 and Ls2 are formed by the electrode patterns of L19, L21, and L23. For the bandpass filter 4,
It is formed from electrode patterns such as C1, C4, C5, C8, C9, C10, and C11.

FIG. 3 shows an equivalent circuit of a single band high frequency switch module including the balun transformer circuit and a bandpass filter circuit, and the balun transformer circuit is connected only to the receiving circuit Rx side of the switch circuit. In the high frequency switch module shown in FIG. 3, the received unbalanced signal can be converted into a balanced signal by the balun transformer and taken out from the balanced output terminals Rx1 and Rx2. Further, since the balun transformer is not connected to the transmission circuit Tx side, the unbalanced signal can be directly input.

Similar to FIG. 3, FIG. 4 shows an equivalent circuit of a high frequency switch module for a single band provided with the balun transformer circuit and the bandpass filter circuit.
This is a case where the balun transformer circuit is connected only to the transmission circuit Tx side of the switch circuit. In the high frequency switch module shown in FIG. 4, balanced input terminals Tx1 and Tx2 are provided.
More balanced signals can be input. Further, since the balun transformer is not connected to the receiving circuit Rx side, the unbalanced signal can be directly taken out from the Rx terminal.

FIG. 5 is an equivalent circuit of a high frequency switch module for a single band provided with the balun transformer circuit and the bandpass filter circuit.
A semiconductor switch formed by a thin film made of aAs or the like is used. By using such a semiconductor switch as the switch, it is possible to suppress power consumption as compared with a high frequency switch module formed by a diode and an electrode pattern in a laminate composed of an electrode pattern and a dielectric layer.

FIG. 6 shows GSM (Global System for Mobile).
communications Transmission frequency 880 to 915 MHz Reception frequency 925
~ 960MHz) system, and DCS1800 (Digital
Cellular System Transmission frequency 1710 to 1785MHz Reception frequency 18
05 ~ 1880MHz) Dual band high frequency switch module compatible with Bluetooth (transmission and reception frequency 2400
Is a block diagram of a high-frequency switch module that combines the functions of a single-band high-frequency switch module that includes the balun transformer circuit and a bandpass filter circuit corresponding to the (~ 2480 MHz) system. The high frequency switch module shown in FIG.
p, SW1, LPF1 and BPF1 and Dip, SW2, LPF2 and BPF2 constituting the DCS1800 system
And an antenna ANT1 for transmitting and receiving both systems,
Further, the switch circuit SW3 and the balun transformer circuit Ba
The high-frequency switch module for a single band includes a lun and a high-frequency switch module for a single band including a bandpass filter circuit BPF3.
Antenna ANT2 for transmitting and receiving as a Bluetooth system
Are provided independently.

Similar to FIG. 6, FIG. 7 shows a single-band high-frequency switch module equipped with the balun transformer circuit and band-pass filter circuit compatible with the Bluetooth system in the dual-band high-frequency switch module compatible with the GSM system and the DCS1800 system. It is a block diagram of the high frequency switch module which compounded the function. In the high frequency switch module shown in FIG. 7, one antenna ANT1 is used for the GSM system and the DCS180.
0 system transmission / reception and the single band high-frequency switch module part including the balun transformer circuit and the bandpass filter circuit handle both transmission and reception of the Bluetooth system. The first duplexer Dip1 is used for the GSM system. Signal and the signal of DCS system and Bluetooth system are demultiplexed, and then D is added by the second demultiplexer Dip2.
Split the CS system and the Bluetooth system.

FIG. 9 is a perspective view of a single band high frequency switch module including a balun transformer circuit. In the high frequency switch module of the present invention, as shown in FIG. 8, the electrode pattern of the circuit which constitutes the high frequency switch module is formed in the laminated body, and the chip parts such as the diodes which cannot be formed in the laminated body and the parts which are difficult to form are By arranging on the laminated body, it can be made into one chip and downsized. Further, it is possible to make a multi-band high-frequency switch module compatible with a plurality of different systems into a small single chip.

FIG. 10 is a comparative diagram showing the components and the number of components required when the function of the single band high frequency switch module including the balun transformer circuit shown in FIG. 2 is formed by using a single functional component. is there. In the case of the high frequency switch module for a single band which is an embodiment of the present invention, the switch in FIG. 10 and the stacked body in one chip in FIG. 9 can be formed in approximately the same volume, and the number of parts can be greatly reduced. It is possible to reduce the mounting area,
It is very effective for downsizing mobile terminals.

[0027]

According to the present invention, the switch circuit and the balance
It is possible to eliminate the need for a DC cut capacitor with the balun transformer circuit that performs unbalance conversion, and it is possible to improve the design space shortage that accompanies the downsizing of the high-frequency switch module and multi-band. Therefore, it is possible to easily cope with the miniaturization design in the limited space.

[Brief description of drawings]

FIG. 1 is a block diagram of a high frequency switch module for a single band including a switch and a balun transformer according to the present invention.

FIG. 2 is an equivalent circuit diagram of a single band high frequency switch module including a switch and a balun transformer according to the present invention.

FIG. 3 is an equivalent circuit diagram of a single-band high-frequency switch module that is an embodiment of the present invention.

FIG. 4 is an equivalent circuit diagram of a single-band high-frequency switch module that is an embodiment of the present invention.

FIG. 5 is an equivalent circuit diagram of a single-band high-frequency switch module that is an embodiment of the present invention.

FIG. 6 is a block diagram of a high frequency switch module for multi-band according to an embodiment of the present invention.

FIG. 7 is a block diagram of a high frequency switch module for multi-band according to an embodiment of the present invention.

FIG. 8 is an internal electrode pattern diagram of the high frequency switch module for single band according to the embodiment of the present invention.

FIG. 9 is a perspective view of a single band high frequency switch module according to an embodiment of the present invention.

FIG. 10 is a component configuration diagram necessary when the single-band high-frequency switch module according to the embodiment of the present invention is formed of single-functional components.

FIG. 11 is an equivalent circuit diagram of a conventional balun transformer.

[Explanation of symbols]

Lb1, Lb2, Lb3, Lb4, Lb5, Lb6, L
b7, Lb8: transmission lines Ls1, Ls2: transmission lines L1, L2, L3, L4, L5, L6, L7, L8, L
9, L10, L11, L12, L13, L14, L1
5, L16, L17, L18, L19, L20, L2
1, L22, L23 L23: Transmission lines Lo1, Lo2, Lo3, Lo4: Transmission lines e1, e2, e3, e4: Capacitors C1, C2, C3, C4, C5, C6, C7, C8, C
9, C10, C11, C12: Capacitors Cb1, Cb2, Cb3, Cb4: Capacitors Cs1, Cs2, Cs3: Capacitor Tx: Transmission terminal Rx: Reception terminal ANT: Antenna terminal

Continued front page    (72) Inventor Masayuki Uchida             Hitachi Metals, 70-2 Minamieicho, Tottori City, Tottori Prefecture             Tottori Factory Co., Ltd. F-term (reference) 5J012 BA03 BA04                 5K011 BA01 DA02 DA22 DA25 JA01

Claims (4)

[Claims] 1. A high frequency wave having a switch circuit for switching between a transmission path and a reception path of at least one transmission / reception system, and a balun transformer circuit for balanced / unbalanced conversion connected to at least one of the transmission path and the reception path. In the switch module, by making one end of the unbalanced side circuit of the balun transformer connected to the switch circuit in an open state, a DC cut capacitor between the switch circuit and the balun transformer circuit is unnecessary. High frequency switch module. 2. The high frequency switch module according to claim 1, wherein a filter circuit is included in a front stage part of the switch circuit. 3. The high frequency switch module according to claim 1, wherein a demultiplexing circuit for demultiplexing a signal is connected to a plurality of transmission / reception systems handled by the high frequency switch module in a front stage of the switch circuit. High frequency switch module for multi-band. 4. The high frequency switch module according to claim 1, further comprising an antenna for transmitting and receiving a signal to be handled.