JPH09321829A - Transmission line changeover switching circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the element separation characteristic between two transmission lines and to make a device using the circuit small. SOLUTION: Field effect transistors(FETs) 1, 4 are conductive and FETs 2, 4 are nonconductive in the case of reception, a reception signal S1 (frequency f1) reaches a reception terminal RX from an input output terminal (RC) to a transmission line 1 and the capacitance of capacitors C1, C3 is set so that a resonance frequency of a bypass circuit (resonance circuit consisting of the FET4, the C1, C3, and a bonding wire L4) to bypass a very small signal S1 given to a transmission line 2 to a ground terminal G is in matching with the frequency f1 of the signal S1 in the case of reception. The conduction of the FETs is inverted in the case of transmission to that of the reception, a transmission signal S2 (frequency f2) reaches the terminal RC from a transmission terminal (TX) via the transmission line 2, and the capacitance of the capacitors C1, C2 is set so that the resonance frequency of a bypass circuit (resonance circuit consisting of the FET3, the C1, C3, and the bonding wire L4) to bypass a very small signal S2 given to the transmission line 1 to the terminal G is in matching with the frequency f2 of a very small signal S2 given to the transmission line 1. As a result, the isolation characteristic between the transmission lines 1, 2 in the case of the transmission and reception is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission line switching switching circuit for switching transmission lines with respect to a plurality of transmission lines for transmitting signals.

[0002]

2. Description of the Related Art Conventionally, an antenna switch is used to switch between transmission and reception in mobile communication such as a mobile phone of an automobile. It is composed of a plurality of FETs as a transmission line switching switching circuit for switching between a transmission line of one system for transmitting a signal received by the antenna and a transmission line of another system for transmitting a signal for transmission to the antenna. FE
T-switching circuits have been commonly used in the past.

FIG. 6 is a circuit diagram showing the structure of a conventional transmission line switching switching circuit (an example using an n-type FET is shown).

A switching circuit having such a structure using a plurality of FETs is an SPDT (Single Pole Dual Throug).
h) Called a switch. In this switching circuit, when a reception signal is input from the antenna to the input / output terminal RC, 0V and 3V are respectively applied to the control voltage terminals V1 and V2.
Is applied. The FET1 and FET4 are turned on, the FET2 and FET3 are turned off, and the reception signal input to the input / output terminal RC is transmitted to the reception terminal RX.

On the other hand, when a transmission signal is input to the transmission terminal TX, 3V and 0V are respectively applied to the control voltage terminals V1 and V2.
Is applied. The FET1 and FET4 are turned off, the FET2 and FET3 are turned on, and the signal input to the transmission terminal TX is transmitted to the input / output terminal RC.

A transmission line (reception line) 1 between the input / output terminal RC (first terminal) and the reception terminal RX (second terminal).
The switching operation of the transmission line between the transmission line (transmission line) 2 between the transmission terminal TX (third terminal) and the input / output terminal RC (first terminal) will be described.

During reception, the received signal S1 (using frequency f
1) is an input / output terminal RC (first terminal) and a receiving terminal RX
The FET 1 provided on the transmission line 1 is made conductive and the FET 2 provided on the transmission line 2 is made cut-off so that only the reception transmission line 1 between the (second terminals) is passed.

However, in a semiconductor switching element such as an FET, a very small reception signal S1 is transmitted via the FET2 and the transmission line 2 because a complete cutoff state cannot be obtained particularly in a high frequency band such as a millimeter wave. Terminal TX
A phenomenon of sneaking into the (third terminal) (hereinafter referred to as sneaking phenomenon) occurs. In order to prevent the reception signal S1 from sneaking into the transmission line 2, the transmission line 2
FET2 and the transmission terminal TX (the third
A series resonance circuit (hereinafter, referred to as a reception signal bypass circuit) including an FET 4, a capacitor C1, and an inductor (composed of a bonding wire) L4 is provided between a connection point C of the terminal) and a ground terminal G. By connecting the resonance frequency of this resonance circuit with the use frequency f1 of the reception signal S1, the impedance of this resonance circuit becomes substantially zero, so that a small amount of the reception signal S1 due to the sneak phenomenon causes the FET 4 and the capacitance in the conductive state to be small. Since the current flows to the ground terminal G through the resonance circuit composed of C1 and the inductor (bonding wire) L4, the inflow to the transmission terminal TX (third terminal) is prevented.

During transmission, the transmission signal S2 (used frequency f2) is transmitted to the transmission terminal TX (second terminal) and the input / output terminal R.
The FET 2 provided in the transmission line 2 is made conductive and the FET 1 provided in the transmission line 1 is cut off so that only the transmission transmission line 2 for transmission between C (first terminal) is passed. However, for the same reason as above, a small amount of the transmission signal S
A sneak phenomenon occurs to the reception terminal RX (second terminal) via the FET 1 and the transmission line 1 of 2. In order to prevent the sneak into the transmission line 1, the FET 3 and the capacitance between the connection point C of the FET 1 and the receiving terminal RX (second terminal) and the ground terminal G for cutting off the transmission line 1 are connected. A series resonance circuit (hereinafter referred to as a transmission signal bypass circuit) composed of C1 and an inductor L4 is connected, and the resonance frequency of this resonance circuit is the use frequency f of the transmission signal S2.
By matching with 2, the impedance of this resonance circuit becomes substantially zero, so that a small amount of the transmission signal S2 due to the sneak phenomenon passes through the resonance circuit constituted by the FET 3 and the capacitance C1 and the inductor L4 in the conductive state, and the ground terminal G Flow into the transmission terminal TX (third terminal) is prevented.

[0010]

Generally, in a transmission line switching circuit, the isolation characteristic deteriorates as the frequency increases, and it is very difficult to obtain sufficient isolation characteristic especially in the millimeter wave band. difficult. Therefore, in order to obtain good isolation in a desired band of a signal to be used, the technique of utilizing the resonance effect as described above has been conventionally adopted. However, in the conventional transmission line switching switching circuit as described above, the capacitance C1 forming the resonance circuit (reception signal and transmission signal bypass circuit) for preventing the sneak phenomenon needs to have a large value. However, there is a problem that the IC chip inevitably becomes large.

Further, when the use frequency f1 of the reception signal S1 and the use frequency f2 of the transmission signal S2 are the same, a single capacitor C1 constituting the reception signal bypass circuit and the transmission signal bypass circuit should be shared. However, when the use frequency f1 of the reception signal S1 and the use frequency f2 of the transmission signal S2 are different, the capacitance C1 forming the transmission signal bypass circuit and the capacitance C1 forming the transmission signal bypass circuit are provided.
However, there is a problem that two capacitors having different capacitance values have to be switched and used because their capacitance values are different.

The present invention is to solve the above-mentioned problems, and as an inductance for forming a resonance circuit of the reception signal bypass circuit and the transmission signal bypass circuit,
Improving the circuit configuration of the resonance circuit of the reception signal bypass circuit and the transmission signal bypass circuit while using the bonding wire, that is, in addition to the capacitance forming the resonance circuit of the conventional reception signal bypass circuit and the transmission signal bypass circuit, A transmission line that can obtain high isolation characteristics with a small circuit scale by providing capacitors, which are components of a resonance circuit, between the two terminals (reception terminal) and the third terminal (transmission terminal) and the ground terminal of the chip, respectively. An object of the present invention is to provide a switching circuit and a semiconductor device mounted with the switching circuit.

[0013]

A transmission line switching circuit according to the present invention includes a first transmission line between a first terminal and a second terminal and a second transmission line between a third terminal and the first terminal. In the line switching switching circuit for switching between the transmission line and the transmission line, the bypass circuits provided between the second terminal and the third terminal and the ground terminal each constitute a resonance circuit.

In the transmission line switching switching circuit of the present invention, one of the two transmission lines is made conductive.
A transmission line switching circuit for disconnecting the other, wherein at least a first transmission line for transmitting a first signal from a first terminal to a second terminal and a third terminal for a first terminal A second transmission line for transmitting the second signal, a first bypass circuit for bypassing the first signal flowing into the second transmission line to the ground terminal when transmitting the first signal, and a second A second bypass circuit for bypassing a second signal flowing into the first transmission line to a ground terminal when transmitting a signal, at least one of the bypass circuits and a switching element for switching the bypass circuit and a second bypass circuit. A resonance circuit having a first capacitor and a second capacitor arranged in parallel with the first capacitor, and at the time of transmission of a first signal, the first bypass circuit is set to an operating state, and Of the third signal of the first signal by deactivating the second bypass circuit and deactivating the first bypass circuit during transmission of the second signal. Inflow to terminal and second
To prevent the signal of 1 from flowing into the second terminal.

In the transmission line switching switching circuit of the present invention, the other bypass circuit has a switching element for switching of the other bypass circuit, the first capacitor, and a third parallel arrangement arranged in parallel therewith. To form a resonance circuit having a capacitor.

In the transmission line switching switching circuit of the present invention, the resonance frequency of the first bypass circuit is set to the use frequency of the first signal, and the resonance frequency of the second bypass circuit is set to the use frequency of the second signal. To match.

In the transmission line switching switching circuit of the present invention, the resonance circuit has an inductor arranged in series with the switching element, the first capacitor, and the capacitor arranged in parallel.

The transmission line switching switching circuit of the present invention switches between the first transmission line between the first terminal and the second terminal and the second transmission line between the third terminal and the first terminal. In the switching circuit for line switching,
First for connecting or disconnecting between the first terminal and the second terminal
Of the switching element, a second switching element that cuts off or connects between the third terminal and the first terminal, and is connected between the second terminal and the ground terminal via the first capacitor and the inductor. A third switching element, a fourth switching element connected between the third terminal and the ground terminal via the first capacitor and the inductor, and the third switching element between the second terminal and the ground terminal. Second capacitor arranged in parallel with the switching element and the first capacitor, and arranged in parallel with the fourth switching element and the first capacitor between the third terminal and the ground terminal. The third capacitor and the inductor, and in the signal transmission of the first transmission line, the first
Controlling the switching element and the fourth switching element to be in the conductive state and the second switching element and the third switching element to be in the blocking state, and in the signal transmission of the second transmission line, the second switching element and The third switching element is controlled to be in the conductive state, the first switching element and the fourth switching element are controlled to be in the blocking state, and in the signal transmission of the first transmission line, a circuit between the third terminal and the ground terminal. In the signal transmission of the second transmission line, the second impedance is set so that the impedance becomes zero as much as possible.
The values of the first, second and third capacitors and the inductor are set so that the circuit impedance between the terminal and the ground terminal becomes as close to zero as possible.

A transmission line switching circuit according to the present invention comprises a first transmission line for transmitting a first signal from a first terminal to a second terminal, and a second signal from a third terminal to a third terminal. A second transmission line for transmitting to the first terminal;
A first bypass circuit that bypasses the first signal that flows into the second transmission line to the ground terminal when transmitting the second signal, and a second signal that flows into the first transmission line when transmitting the second signal. A first switching element for connecting or disconnecting the first transmission line, and a second switching element for disconnecting or connecting the second transmission line; A fourth switching element that connects or disconnects the first bypass circuit, a third switching element that disconnects or connects the second bypass circuit, and the first switching element when transmitting the first signal. And a second switching element that supplies a voltage that brings the first switching element and the fourth switching element into a connected state and cuts off the first switching element and the fourth switching element during transmission of the second signal. The control voltage terminal is connected to the second switching element and the third switching element at the time of transmitting the second signal, and the second switching element and the third switching element at the time of transmitting the first signal And a first control voltage terminal for supplying a voltage for turning off the switch, and the first switching element is present between the first terminal and the second terminal of the first transmission line. And is connected to the second control voltage terminal via the first resistor, and the third switching element is connected between the second terminal and the first capacitor connected to the ground terminal, Is connected to the first control voltage terminal via a third resistor, the second switching element is present between the third terminal and the first terminal of the second transmission line, and
Is connected to the first control voltage terminal via a resistor
The fourth switching element is connected between a third terminal and a first capacitor connected to a ground terminal, is connected to the second control voltage terminal via a fourth resistor, and A second capacitor and an inductor are arranged between the second terminal and the ground terminal, and a third capacitor and an inductor are arranged between the third terminal and the ground terminal.

A transmission line switching switching circuit of the present invention is a circuit comprising the third switching element, a first capacitor, a second capacitor and an inductor, and the fourth switching element, a first capacitor and a third capacitor. The circuit composed of the capacitor and the inductor is configured as a resonance circuit.

The transmission line switching switching circuit of the present invention uses a bonding wire as the inductor.

In the transmission line switching switching circuit of the present invention, the switching element is an FET.

[0023]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing the configuration of the transmission line switching switching circuit of this embodiment, and shows an example in which an n-type FET is used as a switching element.
The reception signal S1 (used frequency f1) input from the input / output terminal RC (first terminal) is received by the reception terminal RX (second terminal:
A transmission line 1 for transmitting a reception signal S1 to an amplifier (not shown) and a transmission signal S2 (use frequency f2) are transmitted to a transmission terminal TX (third terminal: transmission signal is inputted from the amplifier). .) To the input / output terminal RC (first terminal), and the transmission line 1 has an F line.
ET1 and FET3 are provided, and the transmission line 2 is FET
2 and FET 4 are provided.

The FET1 of the transmission line 1 exists between the input / output terminal RC and the receiving terminal RX, and the FET3 is connected to the capacitor C1 connected to the receiving terminal RX and the ground terminal G. FE
The gate of T1 is connected to the control voltage V2 via the resistor R1.
The gate of the FET3 is connected to the control voltage terminal V1 via the resistor R3. On the other hand, the FET 2 of the transmission line 2 exists between the input / output terminal RC and the transmission terminal TX, and the FET 4 is connected to the capacitance C1 connected to the transmission terminal TX and the ground terminal G. The gate of the FET2 is connected to the control voltage terminal V1 via the resistor R2, and the gate of the FET4 is connected to the resistor R2.
4 is connected to the control voltage terminal V2. Furthermore, a capacitance C2 and a capacitance C3 are provided between the transmission terminal TX and the reception terminal RX and the ground terminal (G), respectively, and the FE
The circuit composed of T4, the capacitor C1, the capacitor C2, and the inductor (composed of a bonding wire) L4 and the F
The capacitance values of the capacitance C1, the capacitance C2, and the capacitance C3 are set so that the circuit including the ET3, the capacitance C1, the capacitance C3, and the inductor L4 becomes a resonance circuit.

The capacitance C1, the capacitance C2 and the inductor L4
By using a circuit composed of the above and a circuit composed of the capacitor C1, the capacitor C3, and the inductor L4 as a resonance circuit, the transmission line 1 and the transmission terminal T between the input / output terminal RC and the reception terminal RX.
The isolation between the X and the input / output terminal RC and the transmission line 2 is improved.

Next, the operation will be described. Each of these FETs constituting the transmission line switching circuit is turned on or off by the gate voltage applied to the control voltage terminals V1 and V2. When 0V is applied to the control voltage terminal V1, 3V is applied to the control voltage terminal V2. On the contrary, when 3V is applied to the control voltage terminal V1,
0V is applied to the control voltage terminal V2. Then, the FET to which the voltage of 3V is applied is turned on, and the FET to which the voltage of 0V is applied is turned off.

At the time of reception, that is, when the reception signal S1 (use frequency f1) is input to the input / output terminal RC, if 3V is applied to the control voltage terminal V2 and 0V is applied to the control voltage terminal V1, FET1 and FET4 are turned on. And FET2 and FE
T3 turns off. Therefore, most of the reception signal S1 input to the input / output terminal RC passes through the transmission line 1 from the input / output terminal RC because the FET 3 is in the off state.
Reach X. On the other hand, a small amount of received signal S1 flows into the transmission line 2 from the incomplete off state of the FET2,
Since the FET 4 is turned on, the trace amount of the reception signal S1 is received by the reception signal bypass circuit, that is, the connection point C to the connection points E and F
The minute reception signal S1 is bypassed to the ground terminal G by the electric path from the connection point C to the ground terminal G and from the connection point C to the ground terminal G via the connection points D and F. It is possible to prevent the signal S1 from flowing into the transmission terminal TX.

The reception signal bypass circuit comprises FET4,
The resonance circuit is composed of the capacitance C1, the capacitance C3, and the inductor L4.
Set the capacity value of.

Further, at the time of transmission, that is, when the transmission signal S2 (use frequency f2) is input to the transmission terminal TX, if 3V is applied to the control voltage terminal V1 and 0V is applied to the control voltage terminal V2, FET2 and FET3 are turned on. ON, FET1 and F
ET4 will be off. Therefore, most of the transmission signal S2 input to the transmission terminal TX passes through the transmission line 2 from the transmission terminal TX and the input / output terminal R because the FET 4 is in the off state.
Reach C. On the other hand, a slight amount of the transmission signal S2 flows into the transmission line 1 due to the incomplete OFF state of the FET1, but since the FET3 is on, the slight amount of the transmission signal S2 is transmitted from the transmission signal bypass circuit, that is, the connection point A. This minute amount of the transmission signal S2 is bypassed to the ground terminal G by the electric path from the connection point E and F to the ground terminal G and from the connection point A through the connection points B and F to the ground terminal G. Therefore, it is possible to prevent a slight amount of the transmission signal S2 from flowing into the reception terminal RX.

The transmission signal bypass circuit comprises FET3,
The resonance circuit is composed of the capacitance C1, the capacitance C2, and the inductor L4.
Set the value of.

A feature of the transmission line switching circuit according to the present invention is that the resonance circuits constituting the reception signal bypass circuit and the transmission signal bypass circuit are connected to a capacitance C1, a capacitance C2,
That is, the capacitor C3 and the inductor L4 are used.

First, the inductor L4 of the resonance circuit which constitutes the reception signal bypass circuit and the transmission signal bypass circuit.
By using the bonding wire for the IC chip, the circuit scale of the IC chip can be reduced.

Next, (in contrast to the receiving signal bypass circuit and the transmitting signal bypass circuit of the conventional transmission line switching switching circuit, the capacitive component of the resonance circuit is composed of only a single capacitor C1) In the reception signal bypass circuit and the transmission signal bypass circuit of the transmission line switching switching circuit of the present invention, each capacitance has a small capacitance value because the capacitance component of the resonance circuit is composed of a plurality of capacitances C1, C2 and C3. The circuit scale of the chip can be further contributed to miniaturization.

Furthermore, the capacitance C1 which is a component of the resonance circuit of the bypass circuit, such as the reception signal bypass circuit and the transmission signal bypass circuit of the conventional transmission line switching switching circuit, has different capacitance values during reception and transmission. While the circuit configuration is complicated in that it is used by switching, the receiving signal bypass circuit and the transmitting signal bypass circuit according to the present invention have a use frequency f1 of the reception signal S1 and a use frequency f2 of the transmission signal S2. , The value of the capacitor C3 in the reception signal bypass circuit and the value of the capacitor C2 in the transmission signal bypass circuit may be set so that the resonance frequency of the circuit matches the operating frequency. The circuit configuration of the circuit can be simplified.

FIG. 2 is a circuit diagram showing the structure of an antenna switch for a mobile phone using the switching circuit of this embodiment, and shows an example in which an n-type FET is used as a switching element. In this switching circuit, a transmission line 1 for inputting an input signal from the antenna ANT1 from an input / output terminal RC and transmitting it from a receiving terminal RX to an amplifier (not shown), and a transmission signal from the amplifier are transmitted to the transmitting terminal. There is a transmission line 2 for transmitting from the TX to the input / output terminal RC and the antenna ANT1, and the transmission line 1 has an FE.
T1 and FET3 are provided, and FET2 is provided on the transmission line 2.
And FET 4 are provided.

The FET1 of the transmission line 1 exists between the input / output terminal RC and the receiving terminal RX, and the FET3 is connected to the receiving terminal RX and the capacitor C1 connected to the ground G. FE
The gate of T1 is connected to the control voltage V2 via the resistor R1.
The gate of the FET3 is connected to the control voltage terminal V1 via the resistor R3. On the other hand, the FET2 of the transmission line 2 exists between the input / output terminal RC and the transmission terminal TX, and the FET4 is connected to the transmission terminal TX and the capacitance C1 connected to the ground G. The gate of the FET2 is connected to the control voltage terminal V1 via the resistor R2, and the gate of the FET4 is connected to the resistor R2.
4 is connected to the control voltage terminal V2. In addition, capacitors C2 and C3, which are characteristic parts of the present invention, are provided between the transmission terminal TX and the reception terminal RX and the ground G, respectively. The input / output terminal RC and the receiving terminal R are formed by the circuit configuration of forming the resonance circuit by the capacitors C2 and C3 and the bonding wires L2, L3 and L4.
The isolation between the transmission line 1 between X and the transmission line 2 between the transmission terminal TX and the input / output terminal RC is improved.

Since the operation of FIG. 2 is substantially the same as that of the switching circuit of FIG. 1, the description of the operation will be omitted.

An equivalent circuit at the time of reception in the switching circuit of the present invention, that is, the transmission line 1 (reception transmission line)
FIG. 3A shows an equivalent circuit in the case where the reception signal S1 (used frequency f1) is transmitted only to the above.

In order for the received signal to be transmitted only to the transmission line 1, the FET 1 of the transmission line 1 is in the conductive state and the FET 3 of the same.
Is in a cutoff state, the FET2 of the transmission line 2 is in a cutoff state, and the same FE
It is necessary to make T4 conductive. At that time, FET1 is a resistor Ron1, FET3 is a capacitor Coff3, FET2 is a capacitor Coff2, and FET4 is a resistor R.
on4, respectively.

Since Ron1 is as small as several Ω, the input / output terminal RC and the receiving terminal RX have almost the same potential. Then, the capacitors Coff3, C1 in the transmission line 1,
The values of C and L are set so that the impedance of the circuit composed of C2 and L4 becomes infinite, and Ron4, which is a reception signal bypass circuit in the transmission line 2,
The capacitance values of the capacitors C1 and C3 are set so that the impedance of the resonance circuit composed of C1, C3 and L4 becomes zero, that is, the resonance frequency of this resonance circuit matches the operating frequency f1 of the reception signal S1. Set.

An equivalent circuit at the time of transmission in the switching circuit of the present invention, that is, the transmission line 2 (transmission transmission line)
FIG. 3B shows an equivalent circuit when the transmission signal S2 (used frequency f2) is transmitted only.

In order for the transmission signal to be transmitted only to the transmission line 2, the FET 2 of the transmission line 2 is in the conductive state and the FET 4 of the same is in the conductive state.
Is cut off, FET1 of transmission line 1 is cut off, same FE
It is necessary to make T3 conductive. At that time, FET2 is a resistor Ron2, FET4 is a capacitor Coff4, FET1 is a capacitor Coff1, and FET3 is a resistor R.
on3, respectively.

Since Ron2 is as small as several Ω, the input / output terminal RC and the transmission terminal TX have almost the same potential. Then, L3 in the transmission line 2, the capacitor Coff4,
The values of C and L are set so that the impedance of the circuit composed of C1, C3 and L4 becomes infinite.
Ro, which is a transmission signal bypass circuit in the transmission line 1.
The capacitances of the capacitors C1 and C2 are set so that the impedance of the resonance circuit composed of n3, C1, C2, and L4 becomes zero, that is, the resonance frequency of the resonance circuit matches the use frequency f2 of the transmission signal S2. Set the value.

As a result, the input / output terminal RC and the transmission terminal TX
And the isolation between the reception terminal RX and the transmission terminal TX is improved. In the transmission line switching switching circuit of this embodiment, the used frequency f1 of the reception signal S1 and the used frequency f2 of the transmission signal S2 are, for example, PH.
In the S method, both are 1.9 GHz, and L2, L3, L4
Values of 1.2nH, 1.2nH, 0.5nH
Therefore, the values of the capacitors C1, C2, and C3 are 2.5 pF, 1.0 pF, and 1.0 pF, respectively. The values of the capacitors C1, C2 and C3 are determined by the use frequency f1 of the reception signal S1 and the use frequency f2 of the transmission signal S2, and if the numerical value changes, the values naturally change.

The characteristics of the transmission line switching switching circuit of this embodiment are shown in FIG. 4, and the characteristics of the conventional switching circuit are shown in FIG.

First, regarding isolation, FIG.
In the conventional transmission line switching switching circuit, the value does not change over the entire frequency band, whereas in the transmission line switching switching circuit of the present embodiment of FIG. 4, the conventional switching is performed near the signal frequency of 2 GHz, which is the resonance frequency. More isolation than the circuit is obtained.

Next, in the conventional transmission line switching switching circuit of FIG. 5, the value of the insertion loss is almost unchanged over the entire frequency band, whereas in the transmission line switching switching circuit of the present embodiment of FIG. In that case, it is possible to obtain an excellent characteristic that the value extremely decreases near the signal frequency of 2 GHz which is the resonance frequency.

The transmission line switching circuit of the present embodiment includes a reception signal bypass circuit for bypassing a reception signal flowing into the transmission transmission line to the ground terminal during reception, and a transmission signal flowing into the reception transmission line during transmission to the ground terminal. The transmission signal bypass circuit for bypassing to the capacitor C1, C
By using a resonance circuit composed of 2, the capacitor C3 and the inductor L4, the isolation characteristic between the reception transmission line and the transmission transmission line can be improved.

Next, in the transmission line switching switching circuit of this embodiment, a bonding wire is used for the inductor L4 of the resonance circuit which constitutes the reception signal bypass circuit and the transmission signal bypass circuit, thereby reducing the circuit size of the IC chip. can do.

Further, in the transmission line switching switching circuit of this embodiment, since the capacitive components of the resonance circuit forming the reception signal bypass circuit and the transmission signal bypass circuit are composed of a plurality of capacitors C1, C2 and C3, Has a small capacitance value, which can further contribute to miniaturization of the circuit scale of the IC chip.

Further, in the transmission line switching circuit of this embodiment, the reception signal bypass circuit and the transmission signal bypass circuit receive when the use frequency f1 of the reception signal S1 and the use frequency f2 of the transmission signal S2 are different. Since the value of the capacitance C3 in the signal bypass circuit and the value of the capacitance C2 in the transmission signal bypass circuit may be set so that the resonance frequency of the circuit matches the operating frequency, the circuit configuration of the transmission line switching switching circuit is simple. Can be

Further, the transmission line switching switching circuit of this embodiment is for selecting a frequency signal from a plurality of different local oscillators in a local switching circuit composed of a plurality of stages of local switches, for example, a mixer of a receiving system or a transmitting system. It can be applied to a local switching circuit or the like composed of a plurality of stages of local switches.

[0054]

According to the present invention, the first bypass circuit bypasses the second signal flowing into the second transmission line to the ground terminal when transmitting the first signal, and the first bypass circuit when transmitting the second signal.
Isolation characteristics between the first transmission line and the second transmission line by configuring each of the second bypass circuits for bypassing the second signal flowing into the transmission line of the first transmission line to the ground terminal. Can be improved.

According to the present invention, the first bypass circuit, which bypasses the second signal flowing into the second transmission line to the ground terminal when transmitting the first signal, includes the fourth switching element and the first switching circuit.
A second bypass circuit for bypassing the second signal flowing into the first transmission line to the ground terminal when the second signal is transmitted, It is possible to improve the isolation characteristic between the first transmission line and the second transmission line by using the resonance circuit including the switching element of No. 3, the first capacitor, the second capacitor, and the inductor. .

Next, according to the present invention, the circuit scale of the IC chip can be reduced by using the bonding wire for the inductor of the resonance circuit which constitutes the first bypass circuit and the second bypass circuit.

Further, according to the present invention, since the capacitive component of the resonance circuit which constitutes the first bypass circuit and the second bypass circuit is composed of a plurality of capacitors, each capacitor has a small capacitance value and the circuit of the IC chip. The scale can be further contributed to miniaturization.

Further, according to the present invention, in the first bypass circuit and the second bypass circuit, when the use frequency of the first signal and the use frequency of the second signal are different, Since the capacitor value of 3 may be set so that the resonance frequency of the second capacitor in the second bypass circuit matches the used frequency, the circuit configuration of the transmission line switching switching circuit can be simplified. You can

[Brief description of drawings]

FIG. 1 is a configuration diagram of a transmission line switching switching circuit according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a mobile phone antenna switch using the transmission line switching switching circuit of the above embodiment.

FIG. 3A is an equivalent circuit diagram in the case where a reception signal is transmitted by the transmission line 1 in the transmission line switching switching circuit of the above embodiment. (B) It is an equivalent circuit diagram when a transmission signal is transmitted by the transmission line 2 in the transmission line switching switching circuit of the above embodiment.

FIG. 4 is a diagram showing characteristics (isolation, insertion loss) in the transmission line switching switching circuit of the above embodiment.

FIG. 5 is a diagram showing characteristics (isolation, insertion loss) in a conventional transmission line switching switching circuit.

FIG. 6 is a configuration diagram of a conventional transmission line switching switching circuit.

[Explanation of symbols]

RC input / output terminal (antenna terminal) RX receiving terminal TX transmitting terminal G ground terminal V1 control voltage terminal V2 control voltage terminal FET1 field effect transistor (transmission line 1) FET2 field effect transistor (transmission line 1) FET3 field effect transistor ( FET4 Field effect transistor (between transmission terminal TX and ground terminal G) C1 capacitance C2 capacitance (new insertion) C3 capacitance (new insertion) L1 bonding wire L2 bonding wire L3 bonding wire L4 bonding wire

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuro Sawai 2-5-5 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd. 5-5, Sanyo Electric Co., Ltd.

Claims (10)

[Claims] 1. A line switching switching circuit for switching between a first transmission line between a first terminal and a second terminal and a second transmission line between a third terminal and the first terminal, A transmission line switching switching circuit, characterized in that a bypass circuit provided between the second terminal and the third terminal and a ground terminal constitutes a resonance circuit. 2. A transmission line switching circuit for switching one of two transmission lines to a conductive state and the other to a cutoff state, wherein at least a first signal is applied from a first terminal to a second terminal. First to transmit
The transmission line, the second transmission line that transmits the second signal from the third terminal to the first terminal, and the first signal that flows into the second transmission line when transmitting the first signal to ground. A first bypass circuit for bypassing the terminal, and a second bypass circuit for bypassing the second signal flowing into the first transmission line to the ground terminal when transmitting the second signal, at least the bypass circuit One constitutes a resonance circuit having a switching element for switching the bypass circuit, a first capacitor, and a second capacitor arranged in parallel with the first capacitor, and at the time of transmitting the first signal. Setting the first bypass circuit in an operating state and the second bypass circuit in a non-operating state;
When the second signal is transmitted, the second bypass circuit is activated and the first bypass circuit is deactivated so that the first signal flows into the third terminal and the second signal A switching circuit for switching transmission lines, characterized in that each of the switching circuits prevents inflow to the terminals of 2. 3. A resonance circuit in which the other bypass circuit includes a switching element for switching the other bypass circuit, the first capacitor, and a parallel-arranged third capacitor arranged in parallel therewith. The transmission line switching switching circuit according to claim 2, wherein the switching circuit is configured. 4. The resonance frequency of the first bypass circuit and the resonance frequency of the second bypass circuit are substantially matched with the use frequency of the first signal and the use frequency of the second signal, respectively. Item 3. A transmission line switching switching circuit according to item 3. 5. The transmission according to claim 2, 3 or 4, wherein the resonance circuit has an inductor arranged in series with the switching element, the first capacitor and the capacitor arranged in parallel. Line switching switching circuit. 6. A line switching switching circuit for switching between a first transmission line between a first terminal and a second terminal and a second transmission line between a third terminal and the first terminal, wherein: The line switching switching circuit includes a first switching element that connects or disconnects the first terminal and the second terminal, and a second switching element that disconnects or connects the third terminal and the first terminal. A switching element, a third switching element connected between the second terminal and the ground terminal via the first capacitor and the inductor, and a first capacitor and the inductor between the third terminal and the ground terminal. A fourth switching element connected through the second switching element, and a second capacitor arranged in parallel with the third switching element and the first capacitor between the second terminal and the ground terminal,
A signal of the first transmission line, which includes a third capacitor arranged in parallel with the fourth switching element and the first capacitor between a third terminal and a ground terminal, and the inductor. In the transmission, the first switching element and the fourth switching element are controlled to be in the conductive state, and the second switching element and the third switching element are controlled to be in the disconnected state, and in the signal transmission of the second transmission line, The second switching element and the third switching element are controlled to be in a conductive state, and the first switching element and the fourth switching element are controlled to be in a blocking state.
In the signal transmission of the transmission line of, so that the circuit impedance between the third terminal and the ground terminal becomes zero as much as possible,
In the signal transmission of the second transmission line, it is necessary to set the values of the first, second and third capacitors and the inductor so that the circuit impedance between the second terminal and the ground terminal becomes zero as much as possible. Characteristic transmission line switching switching circuit. 7. A first transmission line for transmitting a first signal from a first terminal to a second terminal, and a second signal for transmitting a second signal to a third terminal.
A second transmission line for transmitting from the terminal to the first terminal, and a first bypass circuit for bypassing the first signal flowing into the second transmission line to the ground terminal when transmitting the first signal; A second bypass circuit for bypassing a second signal flowing into the first transmission line to a ground terminal when transmitting the second signal, the first bypass circuit connecting or disconnecting the first transmission line. A switching element, a second switching element that blocks or connects the second transmission line, a fourth switching element that connects or blocks the first bypass circuit, and a block or connects the second bypass circuit. And a third switching element for connecting the first switching element and the fourth switching element during the transmission of the first signal, and the first switching element and the fourth switching element during the transmission of the second signal. A second control voltage terminal that supplies a voltage for turning off the fourth switching element, and the second switching element and the third switching element are connected when transmitting the second signal, A first control voltage terminal that supplies a voltage for turning off the second switching element and the third switching element during transmission of the first signal;
And the first switching element exists between the first terminal and the second terminal of the first transmission line, and is connected to the second control voltage terminal via the first resistor. Connected, the third switching element is connected between a second terminal and a first capacitor connected to a ground terminal, and is connected to the first control voltage terminal via a third resistor. The second switching element is present between the third terminal and the first terminal of the second transmission line, and is connected to the first control voltage terminal via a second resistor, The fourth switching element is connected between the third terminal and the first capacitor connected to the ground terminal, is connected to the second control voltage terminal via the fourth resistor, and A second capacitor and inductor are connected between the second terminal and the ground terminal. Transmission line switching switching circuit, characterized in that the third capacitor and an inductor between the ground terminal and the third terminal, respectively arranged. 8. A circuit composed of the third switching element, a first capacitor, a second capacitor and an inductor, and a circuit composed of the fourth switching element, a first capacitor, a third capacitor and an inductor. 8. The transmission line switching switching circuit according to claim 6 or 7, wherein each of them is a resonance circuit. 9. The transmission line switching circuit according to claim 5, 6, 7 or 8, wherein a bonding wire is used as the inductor. 10. The transmission line switching circuit according to claim 2, wherein the switching element is a FET.