JPH11112253A - Switch circuit, transmitter, receiver and transmitter-receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a switch circuit whose circuit scale is not increased. SOLUTION: A switch circuit consists of a reception antenna 1, a 1st amplifier circuit 2, and a 2nd amplifier circuit 3 a 1st signal path where a high frequency signal received from the reception antenna 1 is branched at a branch point P1 and supplied to a 1st terminal P3 via the 1st amplifier circuit 2, a 2nd signal path where the high frequency signal is branched at the branch point P1 and fed to a 2nd terminal P5 via the 2nd amplifier circuit 3, the 1st amplifier circuit 2 consists of a series connection between a 1st transmission line 4 and a 1st amplifier 5 from the branch point P1 toward the 1st terminal P3, and the 2nd amplifier circuit 3 consists of a series connection between a 2nd transmission line 6 and a 2nd amplifier 7 from the branch point P1 toward the 2nd terminal P5. The electric length of the transmission lines is selected so that the impedance of the amplifiers when viewed through the transmission lines of the amplifier circuits 2, 3 in their non-operating state is higher than the impedance when the amplifier circuits are in operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switch circuit used for a high-frequency circuit or the like, and to a transmitting device, a receiving device, and a transmitting / receiving device using the switch circuit.

[0002]

2. Description of the Related Art In a conventional communication apparatus, as shown in the circuit diagram of FIG.
Between the first signal path output from the output terminal P3 through the amplifier 5 and the second signal path output from the output terminal P5 through the second amplifier 7, This is performed by turning on / off the provided switch means 26a and 26b.

However, such a conventional configuration requires switch means 26a and 26b for switching the signal path in addition to the first and second amplifiers 5 and 7, and has a problem that the circuit scale becomes large. .

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to provide a switch circuit which suppresses an increase in circuit scale.

Another object of the present invention is to provide a transmitting device, a receiving device, and a transmitting / receiving device using the above switch circuit.

[0006]

A first switch circuit according to the present invention switches between a conducting state and a non-conducting state of the signal path by switching between an operating state and a non-operating state of an amplifier provided in the signal path. It is characterized by the following.

[0007] This makes it possible to switch between the conducting state and the non-conducting state of the signal path without providing a switching means separately from the amplifier.

In particular, it is preferable that the amplifier is set so that the reflection coefficient at the time of non-operation is closer to 1 than the reflection coefficient at the time of operation at at least one of the input and output terminals.

In this case, the amount of signal reflection at the terminal of the amplifier increases and the amount of signal flowing through the amplifier decreases when the amplifier is not operating as compared with when the amplifier is not operating.
The signal path becomes non-conductive.

In addition, a transmission line is connected to at least one of the input side and the output side of the amplifier so that, when the amplifier is not operating, the impedance of the amplifier seen through the transmission line is higher than when the amplifier is operating. It is preferable to set the electrical length of the transmission line.

In this case, when the amplifier is not operating, the amount of signal flowing to the amplifier is smaller than when the amplifier is operating, and the signal path is non-conductive.

In a second switch circuit according to the present invention, a first signal path including a first amplifier and a second signal path including a second amplifier are connected separately at a branch point.
In a switch circuit in which one of the second signal paths is selected to be conductive, the selection of the conductive state is switched between an operating state and a non-operating state of the first and second amplifiers.

Thus, the switching of the conduction / non-conduction of the signal path can be performed without providing a switching means separately from the first and second amplifiers.

In particular, the signal path of the first and second signal paths, in which the amplifier provided in the signal path is in the operating state, is configured to be conductive, and in this case, the signal path to be conductive. Are amplified.

It is preferable that the impedance of the non-operating amplifier from the branch point is set to be higher than the impedance of the amplifier during operation.

In this case, the amount of signal flowing through the signal path decreases when the amplifier is not operating compared to when it is operating, and
The signal path becomes non-conductive.

Further, the first signal path is constituted by a first amplifier circuit having a transmission line connected to the first amplifier, and the second signal path is connected to a transmission line to the second amplifier. And a second amplifier circuit,
The electrical length of the transmission line is set such that the impedance of the amplifier when viewed through the transmission line of the second amplification circuit is higher than the impedance of the second amplification circuit during operation when the second amplification circuit is not operating. preferable.

In this case, when the amplifier circuit is not operating, the amount of signal flowing to the amplifier circuit is smaller than when the amplifier circuit is not operating, and the signal path becomes non-conductive.

A third switch circuit according to the present invention comprises first and second amplifiers, and a first directional coupler for coupling the first and second amplifiers on the input side. In a switch circuit in which one of a signal path passing through the second amplifier and a signal path not passing through the first and second amplifiers is selected to be in a conductive state, the selection of the conductive state is made by the operation state of the first and second amplifiers. And a non-operating state.

Thus, the switching of the conduction state between the signal path passing through the first and second amplifiers and the signal path not passing through the first and second amplifiers can be switched separately from the first and second amplifiers. This can be performed without providing any means.

A fourth switch circuit according to the present invention comprises first and second amplifiers, and a second directional coupler for coupling the first and second amplifiers on the output side. In a switch circuit in which one of a signal path passing through the second amplifier and a signal path not passing through the first and second amplifiers is selected to be in a conductive state, the selection of the conductive state is made by the operation state of the first and second amplifiers. And a non-operating state.

Thus, the switching of the conduction state between the signal path passing through the first and second amplifiers and the signal path not passing through the first and second amplifiers is switched separately from the first and second amplifiers. This can be performed without providing any means.

A fifth switch circuit according to the present invention includes a first and a second amplifier connected in parallel with each other, a first directional coupler for coupling the first and the second amplifier on an input side, First,
A second directional coupler for coupling the second amplifier at the output, comprising a signal path through the first and second amplifiers and a first,
In a switch circuit in which one of the signal paths not passing through the second amplifier is selected to be in a conductive state, selection of a conductive state is performed by switching between an operating state and a non-operating state of the first and second amplifiers. Features.

Thus, the switching of the conduction state between the signal path passing through the first and second amplifiers and the signal path not passing through the first and second amplifiers is switched separately from the first and second amplifiers. This can be performed without providing any means.

Further, in the third and fifth switch circuits of the present invention, the first directional coupler has the first and second terminals connected to the first and second terminals having an isolation terminal relationship with each other. The input side of the amplifier is connected, a signal input portion is connected to a third terminal of the third and fourth terminals having an isolation terminal relationship with each other, and a signal output portion is connected to the fourth terminal. It is characterized by having.

In the fourth and fifth switch circuits of the present invention, the second directional coupler has first and second terminals connected to the first and second terminals having an isolation terminal relationship with each other. An output side of the amplifier is connected, a signal input portion is connected to a third terminal of the third and fourth terminals having an isolation terminal relationship with each other, and a signal output portion is connected to the fourth terminal. It is characterized by being.

In the third, fourth, and fifth switch circuits of the present invention, the signal paths passing through the first and second amplifiers are made conductive by bringing the first and second amplifiers into the operating state. In this case, a signal passing through a signal path that becomes conductive is amplified.

In particular, in each of the first and second amplifiers, it is preferable that at least one of the input and output terminals has a non-operating reflection coefficient closer to 1 than an operating reflection coefficient. preferable.

In this case, the amount of signal reflection at the terminal of the amplifier increases and the amount of signal flowing through the amplifier decreases when the first and second amplifiers are not operating as compared to when the first and second amplifiers are operating. , The signal path becomes non-conductive.

The amplifier or one of the first and second amplifiers includes a transistor, an input matching circuit connected to a gate terminal of the transistor, and an output matching circuit connected to a drain terminal of the transistor. Preferably, at least one of the input matching circuit and the output matching circuit is a reflection type matching circuit.

In this case, at least one of the input and output terminals of the amplifier can make the reflection coefficient during non-operation closer to 1 than the reflection coefficient during operation.

Preferably, the reflection type matching circuit comprises a reactance element or a transmission line which can be equivalently expressed as a reactance element.

In this case, in at least one of the input and output terminals of the amplifier, the reflection coefficient during non-operation can be made closer to 1 than the reflection coefficient during operation.

It is preferable that the reflection type matching circuit has no resistance element.

In this case, in at least one of the input and output terminals of the amplifier, the reflection coefficient during non-operation can be made closer to 1 than the reflection coefficient during operation.

In particular, the transistor or the first and second amplifiers are operated by applying a voltage larger than the pinch-off voltage of the transistor between the gate terminal and the source terminal, and the pinch-off voltage is applied to the transistor. It is preferable that the non-operating state be set by applying a smaller voltage.

In this case, the input and output terminals of the amplifier during operation are matched and the reflection coefficient is small. However, in the amplifier during non-operation, the intrinsic portion of the transistor has no resistance component and has a high impedance. Because it is a pi-shaped circuit consisting of capacitive reactance, the gate input and drain output are separated, the gate input and drain output and the source are both substantially open, and the input side of the amplifier,
The reflection coefficient at the output side terminal can be made close to 1.

The transmitting apparatus according to the present invention comprises a first and a second amplifier, and a first directional coupler for coupling the first and the second amplifier on the input side, wherein the first directional coupler is provided. Is connected to the input sides of the first and second amplifiers with the first and second terminals having an isolation terminal relationship with each other, and is provided with a third terminal among the third and fourth terminals having the isolation terminal relationship with each other.
A terminal is connected to a transmission antenna, and a fourth terminal is connected to a transmission circuit. One of a transmission path that passes through the first and second amplifiers and a transmission path that does not pass through the first and second amplifiers is connected. In the transmission device that is selected to be in the conductive state, the selection of the conductive state is performed by switching between the operating state and the non-operating state of the first and second amplifiers.

Thus, the switching between the case where the signal input from the transmission circuit is output through the transmission path passing through the first and second amplifiers and the case where the signal is output from the transmission antenna is performed by the first and second switching units. This can be performed without providing a switch means separately from the amplifier of the above.

The receiving apparatus according to the present invention comprises first and second amplifiers, and a second directional coupler that couples the first and second amplifiers on the output side. The output terminals of the first and second amplifiers are connected to the first and second terminals having an isolation terminal relationship with each other, and the third terminal of the third and fourth terminals having the isolation terminal relationship with each other.
A terminal is connected to a receiving antenna, and a fourth terminal is connected to a receiving circuit. One of a receiving path passing through the first and second amplifiers and a receiving path not passing through the first and second amplifiers are connected. In the receiving device that is selected to be in the conductive state, the selection of the conductive state is performed by switching between the operating state and the non-operating state of the first and second amplifiers.

Thus, the switching between the case where the signal is output to the receiving circuit through the receiving path passing through the first and second amplifiers and the case where the signal input from the receiving antenna is output to the receiving circuit is performed by the first method. This can be performed without providing a switch means separately from the second amplifier.

The transmitting and receiving apparatus according to the present invention comprises: a first and a second amplifier connected in parallel to each other; a first directional coupler for coupling the first and the second amplifier on an input side; , Second
And a second directional coupler that couples the amplifiers on the output side. The first directional coupler has first and second terminals connected to the first and second terminals having an isolation terminal relationship with each other. An input side of the amplifier is connected, a first antenna for transmission and reception is connected to a third terminal of the third and fourth terminals having a relation of an isolation terminal, and a transmission circuit is connected to a fourth terminal. And the second directional coupler is connected to the first and second terminals having an isolation terminal relationship with each other.
The output side of the second amplifier is connected, a second terminal for transmission and reception is connected to the third terminal among the third and fourth terminals having a relation of an isolation terminal, and the fourth terminal is connected to the fourth terminal. In a transmitting / receiving device to which a receiving circuit is connected and one of a signal path passing through the first and second amplifiers and a signal path not passing through the first and second amplifiers is selected to be in a conductive state, selection of a conductive state is performed. The switching is performed by switching between an operating state and a non-operating state of the first and second amplifiers.

Accordingly, the signal input from the transmitting circuit is output from the second antenna through the first and second amplifiers, and the signal input from the first antenna is output from the first and second amplifiers.
A case where the signal is output to the receiving circuit through the second amplifier and a case where the signal input from the transmitting circuit is output from the first antenna without passing through the first and second amplifiers and is input from the second antenna The switching between the case where the signal is output to the receiving circuit without passing through the first and second amplifiers can be performed without providing switching means separately from the first and second amplifiers.

[0044]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A switch circuit according to a first embodiment of the present invention will be described below.

The switch circuit according to the first embodiment includes:
As shown in FIG. 1, a high-frequency signal input from the receiving antenna 1 is branched at a branch point P1 through the first amplifying circuit 2 and includes a receiving antenna 1, a first amplifying circuit 2, and a second amplifying circuit 3. A first signal path flowing to the first output terminal P3; and a second output terminal branched at the branch point P1 and passing through the second amplifier circuit 3.
And a second signal path flowing to P5.

The first amplifier circuit 2 has a first transmission line 4 and a first amplifier 5 connected in series from the branch point P1 toward the first output terminal P3, and a second amplifier circuit 2 is provided. Circuit 3
The circuit configuration is such that the second transmission line 6 and the second amplifier 7 are connected in series from the branch point P1 toward the second output terminal P5.

As shown in FIG. 2, the first and second amplifiers 5 and 7 according to the present embodiment
Is a one-stage amplifier circuit using one. Transistor 8
The source terminal S is grounded via the stabilizing transmission line Ls. The transmission line L is connected to the gate terminal G of the transistor 8.
1, an input matching circuit 9 also serving as a gate / bias circuit comprising a bypass capacitor Cb having a capacitance value of 10 pF and a drain terminal D is connected to transmission lines L3 and L4.
And an output matching circuit 10 also serving as a drain bias circuit comprising a bypass capacitor Cb having a capacitance value of 10 pF. As described above, the input matching circuit 9 and the output matching circuit 10 do not use a resistance element, and are reflection type matching circuits.

The characteristics of the transmission lines L1 to L4 and Ls are as shown in Table 1. As shown in FIG. 3, the frequency characteristics of the amplifiers 5 and 7 during the amplification operation are 38 GHz
It is matched so that input and output reflections are minimized at z and 41 GHz, and both have a gain of about 10 dB.

[0049]

[Table 1]

The equivalent circuit of the transistor 8 used in the amplifiers 5 and 7 applies a positive voltage Vds between the drain terminal D and the source terminal S, and is larger than the pinch-off voltage Vp between the gate terminal G and the source terminal S. When the voltage Vgs is applied and a current flows between the drain terminal D and the source terminal S to perform an amplification operation, as shown in FIG.
m, an intrinsic portion 11 composed of a drain-source resistance Rds, a channel resistance Ri, a gate-source capacitance Cgs, a gate-drain capacitance Cdg, and a drain-source capacitance Cds; an intrinsic portion 11 and terminals G, D, A parasitic resistance (Rg, Rd, Rs) of each terminal and a parasitic part 12, 13, 14 composed of a parasitic inductor (Lg, Ld, Ls) can be expressed between S and S.

On the other hand, by applying the positive voltage Vds and applying the Vgs smaller than the pinch-off voltage Vp, the drain terminal D ·
The equivalent circuit of the transistor 8 when no current flows between the source terminals S in the non-operating state, as shown in FIG.
1 can be expressed only by the inter-terminal capacitances Cgs, Cdg, and Cds.

Table 2 shows the circuit constant values of the transistor 8 during the amplification operation and the non-operation time. As can be seen from this table, in the case of non-operation, the resistance component of the intrinsic portion 11 disappears, and in particular, Cgs and Cdg take very small values as compared with those during operation. Therefore, since a pi-shaped circuit consisting of a high-impedance capacitive reactance due to the inter-terminal capacitances Cgs, Cdg, and Cds is provided, the gate terminal G and the drain terminal D are separated, and the input impedance of each of the gate terminal G and the drain terminal D is changed. Is almost open.

[0053]

[Table 2]

Further, as described above, the input matching circuit 9 employs a reflection type matching circuit. Therefore, the reflection coefficients Γ1 and に お け る at the input terminals P2 (P4) of the amplifiers 5 and 7 during non-operation.
As shown in the frequency characteristic diagram (Smith chart) of FIG. 5, 2 is close to 1 and is almost totally reflected, and is expressed by "Equation 1" and "Equation 2". Here, θa is the center frequency 41G of the amplifier 7.
The phase amount when the amplifier 5 is not operating in Hz, and θb indicates the phase amount when the amplifier 7 is not operating at the center frequency 38 GHz of the amplifier 5.

[0055]

(Equation 1)

Further, the transmission line 4 has a characteristic impedance 50 having an electrical length of half of θa at a frequency of 41 GHz.
By using an ohmic line, as shown by the arrow in FIG.
The impedance (reflection coefficient Γ1 ′) of the first amplifier circuit 2 side from the P1 side becomes higher than that at the time of operation at the center frequency of 41 GHz of the amplifier 7 and becomes substantially open.
It is represented by

[0057]

(Equation 2)

The transmission line 6 has a characteristic impedance 50 having an electrical length of half of θb at a frequency of 38 GHz.
By using an ohmic line, as shown by the arrow in FIG.
The impedance (reflection coefficient Γ2 ′) seen from the P1 side to the second amplifier circuit 3 side is higher than that at the time of operation at the center frequency of 38 GHz of the amplifier 5 and becomes substantially open.
It is represented by

[0059]

(Equation 3)

That is, in the switch circuit according to the present embodiment, the first amplifier 5 is connected to the gate terminal G of the transistor 8.
-The voltage Vgs between the source terminals S is made larger than the pinch-off voltage Vp to make the operation state, and the voltage Vgs between the gate terminal G and the source terminal S of the transistor 8 is made smaller than the pinch-off voltage Vp, and By putting it into operation,
The high-frequency signal having a frequency of 38 GHz input from the receiving antenna 1 passes through the first signal path from the branch point P1 and is amplified by the first amplifier 5 because the second amplifier circuit 3 is open. Output to the output terminal P3.

Conversely, the second amplifier 7 is activated by setting the voltage Vgs between the gate terminal G and the source terminal S of the transistor 8 higher than the pinch-off voltage Vp, and the first amplifier 5 is turned on. By setting the voltage Vgs between the gate terminal G and the source terminal S to be smaller than the pinch-off voltage Vp to make it inactive, the high frequency signal of 41 GHz input from the receiving antenna 1 is in an open state on the first amplifier circuit 2 side. Therefore, the signal passes through the second signal path from the branch point P1, is amplified by the second amplifier 7, and is output to the second output terminal P5.

FIG. 6 shows a simulation result of a passing characteristic between the branch point P1, the first output terminal P3, and the second output terminal P5 in the switch circuit according to the present embodiment. In both cases, the signal is amplified by about 10 dB when conducting, and an attenuation of 20 dB or more is obtained when not conducting.

As described above, in the switch circuit of the present embodiment, by switching the operation / non-operation state of the first and second amplifiers 5 and 7, the high-frequency signal input from the receiving antenna 1 is converted to the first signal. Switching between the case of flowing through the signal path and the case of flowing through the second signal path can be performed. That is, a circuit having both an amplification function and a switching function can be realized without requiring a special circuit for performing a switching operation. Further, since the amplifier in the non-conduction path is in a non-operating state, no power is consumed and power can be saved.

In the switch circuit according to the first embodiment, a circuit for receiving two types of high-frequency signals having different frequencies with one receiving antenna and switching a path through which the signal flows according to the frequency of the high-frequency signal is used. Although configured, the frequencies of the two types of high-frequency signals may be equal.

As shown in FIG. 7A, the first and second
For example, the input / output terminal of the second amplifier 7 is replaced with an amplifier 7 ', and when the amplifier 7' is not operated, the impedance when the second amplifier circuit 3 is viewed from the branch point P1 side. Is connected to a transmission line 6 ′ whose electric length is adjusted so as to be substantially open at the center frequency of the first amplifier 5, and by inverting the direction in which the high-frequency signal flows in the second amplifier circuit 3, transmitting and receiving A circuit may be configured. Further, as shown in FIG. 7B, a transmission-only circuit may be configured by similarly inverting the direction in which the high-frequency signal flows in the first amplifier circuit 2.

As shown in FIG. 8, a characteristic impedance 5 is connected to all input / output terminals of the first and second amplifiers 5 and 7 '.
The transmission lines 4, 4 ', 6, 6' of 0 ohms are connected in series, and when each of the amplifiers is inactive, the branch point of the transmission line
The electrical length of each transmission line is set so that the impedances viewed from P1 and P6 are all substantially open at the center frequency of the other amplifier, and the first and second amplifier circuits 2 'and 3' , Connected at branch points P1 and P6, the first and second
A circuit for switching the path through which the high-frequency signal flows may be configured by switching the operation / non-operation of the amplifiers 5 and 7 ′.

Further, in the switch circuit of the present embodiment, a changeover switch circuit in which one of two signal paths is selected to be conductive and the other is non-conductive is configured. A circuit that switches conduction / non-conduction of the amplifier circuit by switching operation / non-operation of the amplifier may be configured by one amplifier circuit. Furthermore, a circuit may be configured in which three or more amplifier circuits are connected in parallel to switch a path through which a high-frequency signal flows.

FIG. 9 shows a switch circuit according to a second embodiment of the present invention. This embodiment is a part of a transmitting and receiving apparatus, and includes first and second antennas 20 and 21 for transmitting and receiving.
A first and a second amplifier 18, connected in parallel with each other,
19, first and second 3 dB directional couplers 16 connected to the input and output sides of the first and second amplifiers, respectively.
17.

Both the first and second amplifiers 18 and 19 have the same configuration as the first amplifier 5 used in the switch circuit according to the first embodiment described above. That is, the first and second
The center operating frequency of the amplifiers 18 and 19 is 38 GHz,
The reflection at the input / output terminal becomes close to total reflection when the voltage Vgs between the gate terminal G and the source terminal S of the transistor 8 is made smaller than the pinch-off voltage Vp to be in a non-operation state.

The center operating frequencies of the first and second antennas 20 and 21 and the first and second 3 dB directional couplers 16 and 17 are all 38 GHz.

Hereinafter, a detailed connection of the present switch circuit will be described with reference to FIG. The first 3 dB directional coupler 16 includes:
The first antenna 20 is connected to the terminal 16a.
Input terminals of the first and second amplifiers 18 and 19 are connected to b and 16d, respectively, and a transmission circuit 22 is connected to the terminal 16c.

Further, the second 3 dB directional coupler 17
Has a second antenna 21 connected to a terminal 17a, and first and second amplifiers 18, 1 and 2 connected to terminals 17b and 17d, respectively.
9 is connected to the receiving terminal 23c.
Is connected.

In a transmitting / receiving device using the present switch circuit,
The transmission signal ftx is set to be a high-frequency signal having a center frequency of 38.0 GHz and a bandwidth of 50 MHz, and the reception signal frx is set to be a high-frequency signal having a center frequency of 38.1 GHz and a bandwidth of 50 MHz. The bands of the signals ftx and frx are close to each other but separated, and are substantially equal to the central operating frequency 38 GHz of all the components of the present switch circuit.

The operation of the above switch circuit will be described with reference to FIG. FIG. 10A shows the first and second amplifiers 18 and 19.
Indicate the case where both are in the operating state (ON). In this case, the transmission signal ftx input from the transmission circuit 22 to the terminal 16c of the first 3 dB directional coupler 16 is equally distributed with a phase delay of 90 degrees and 0 degrees, and is transmitted to the terminals 16b and 16d, respectively. Output (ftx1 (90), ftx2 (0)). Note that the transmission signal ftx
Is not output to the terminal 16a which is in the relation of the isolation terminal with the terminal 16c.

The transmission signals ftx1 (90) and ftx2 (0) output to the terminals 16b and 16d are input to the first and second amplifiers 18 and 19, respectively, and after being amplified, the second 3 dB
The signals are input to terminals 17b and 17d of the directional coupler 17, respectively.

The transmission signals ftx1 (90) and ftx2 (0) input to the terminals 17b and 17d respectively have a phase delay of 0 ° and 90 ° in the second 3 dB directional coupler 17 and are added to both terminals 17a and 17d. (Ftx1 (90), ftx2 (90)), and are superposed because the phase relationship is in phase, and the transmission signal ftx is radiated from the second antenna 21.

The transmission signal ftx input from the transmission circuit 22 passes through the first and second amplifiers 18 and 19, and
The signal path transmitted to and radiated from the antenna 21 is referred to as a first signal (transmission) path.

Although the transmission signals ftx1 (180) and ftx2 (0) (not shown) are also output from the terminal 17c of the second 3-dB directional coupler 17, the phase relations are reversed and cancel each other. Therefore, it is not output to the receiving circuit 23.

In FIG. 10A, the received signal frx incident on the first antenna 20 is transmitted to the first 3 dB directional coupler 1.
6, and are equally distributed with a phase delay of 0 degrees and 90 degrees and output to terminals 16b and 16d, respectively (frx1 (0), frx2 (90)). The reception signal frx is supplied to the terminal 16
No signal is output to the terminal 16c which is in the relation of an isolation terminal with a.

The received signals frx1 (0) and frx2 (90) output to the terminals 16b and 16d are input to first and second amplifiers 18 and 19, respectively, and after being amplified, a second 3 dB
The signals are input to terminals 17b and 17d of the directional coupler 17, respectively.

The received signals frx1 (0) and frx2 (90) input to the terminals 17b and 17d respectively have a phase delay of 90 degrees and 0 degrees respectively in the second 3 dB directional coupler 17, and both of the signals 17x and 90x have terminals 17c and 17d. (Frx1 (90), frx2 (90)). The received signals frx are output to the receiving circuit 23 because they are superimposed because they have the same phase relationship.

The above-described received signal frx incident on the first antenna 20 passes through the first and second amplifiers 18 and 19 and is output to the receiving circuit 23 through the second signal (reception).
Route.

Although the received signals frx1 (0) and frx2 (180) (not shown) are also output from the terminal 17a of the second 3 dB directional coupler 17, the phases are reversed and cancel each other. Therefore, it is not radiated from the second antenna 21.

Conversely, as shown in FIG.
When both of the amplifiers 18 and 19 are inactive (OFF), the reflections # 3, # 4, # 5 and # 6 at the input / output terminals of the first and second amplifiers 18 and 19 become close to total reflection, and the first , 4 of each of the second 3 dB directional couplers 16 and 17
Of the terminals, two terminals (16b and 16d, 17b and 17d), which are in the relation of an isolation terminal, respectively, are terminated by substantially total reflection. Therefore, between the remaining two terminals of the first and second 3 dB directional couplers 16 and 17 (16a-16
c, 17a-17c) operate as a filter (bandpass filter) having a center pass frequency of 38 GHz.

As described above, between the terminals 16a and 16c of the first 3 dB directional coupler 16 is conducted at the frequency of the transmission signal ftx. Therefore, the transmission signal ftx input from the transmission circuit 22 to the terminal 16c is First antenna 2 through terminal 16a
Emitted from 0.

The transmission signal ftx input from the transmission circuit 22 passes through the first 3 dB directional coupler 16 and
The signal path transmitted to and radiated from the antenna 20 is referred to as a third signal (transmission) path.

Similarly, the second 3 dB directional coupler 1
7 is conducted at the frequency of the reception signal frx between the terminals 17a and 17c, so that the light enters the second antenna 21 and the terminal 17a
Is output to the receiving circuit 23 through the terminal 17c.

The above-described received signal frx incident on the second antenna 21 passes through the second 3 dB directional coupler 17 and is output to the receiving circuit 23 through the fourth signal (reception).
Route.

As described above, in the switch circuit according to the second embodiment, when the first and second amplifiers 18 and 19 are both in the operating state (ON), the transmission signal inputted from the transmission circuit 22 is transmitted. The ftx is radiated from the second antenna 21 after being amplified through a first signal (transmission) path. On the other hand, the reception signal frx incident on the first antenna 20
Is output to the receiving circuit 23 after being amplified through a second signal (receiving) path.

Conversely, when both the first and second amplifiers 18 and 19 are in the non-operation state (OFF), the transmission signal ftx input from the transmission circuit 22 passes through the third signal (transmission) path. Radiated from the first antenna 20. On the other hand, the reception signal frx incident on the second antenna 21 is output to the reception circuit 23 through the fourth signal (reception) path.

That is, a circuit having both an amplifying function and a switching function can be realized without requiring a special circuit for performing a switching operation.

The first antenna 20 has first and second antennas.
When both of the amplifiers 18 and 19 are in the operating state (ON), they function as a receiving antenna as shown in FIG.
When both the second amplifiers 18 and 19 are in the non-operation state (OFF), they function as transmission antennas as shown in FIG. On the other hand, when the first and second amplifiers 18 and 19 are both in the operating state (ON), the second antenna 21 shown in FIG.
As shown in FIG. 11, when the first and second amplifiers 18 and 19 are both in the non-operation state (OFF), they function as reception antennas as shown in FIG.

Thus, the first and second antennas 20,
The switch 21 can switch the function for transmission / reception by switching the operation (ON) / non-operation (OFF) of the first and second amplifiers 18 and 19.

In the second embodiment, two antennas are used to form a circuit for alternately switching between antennas used for transmission and reception. However, two terminals 16a and 17a for connecting the antennas are used. Of these, the present invention can be applied to the case where the terminal 16a is grounded via the terminating resistor 24 instead of the first antenna 20 as shown in FIG. 12, for example. In this case, the function of the antenna 21 can be switched between transmission and reception by switching operation / non-operation of the first and second amplifiers 18 and 19.

In the second embodiment, the signal input to the first 3 dB directional coupler 16 is distributed by using the first and second 3 dB directional couplers 16 and 17.
A signal path for combining and outputting a signal in the second 3 dB directional coupler 17 via the first and second amplifiers 18 and 19 is configured. However, the first and second 3 dB directional couplers 16 and 17
The present invention can be applied even when only one of them is used.

[0096]

According to the present invention, it is possible to switch between a conducting state and a non-conducting state or to select a signal path to be in a conducting state without providing a switch means separately from the amplifier. A switch circuit in which an increase in circuit size is suppressed can be provided.

Further, according to the present invention, it is possible to provide a transmission device capable of switching a transmission path from a transmission circuit without providing a switching means separately from an amplifier.

Further, according to the present invention, it is possible to provide a receiving apparatus capable of switching a receiving path from a receiving antenna without providing switching means separately from an amplifier.

Further, according to the present invention, it is possible to provide a transmission / reception device capable of switching the operation of one antenna between transmission and reception.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a switch circuit according to a first embodiment of the present invention.

FIG. 2 is a circuit configuration diagram of the amplifier of FIG. 1;

FIG. 3 is a diagram illustrating a frequency characteristic when the amplifier of FIG. 2 operates.

FIG. 4 is a diagram showing an equivalent circuit of a transistor used in the amplifier of FIG. 1;

FIG. 5 is a diagram illustrating a frequency characteristic of an input side reflection coefficient of the amplifier of FIG. 2;

FIG. 6 is a diagram illustrating pass characteristics of the switch circuit according to the first embodiment of the present invention.

FIG. 7 is a configuration diagram showing another embodiment of the switch circuit according to the first embodiment of the present invention.

FIG. 8 is a configuration diagram showing another embodiment of the switch circuit according to the first embodiment of the present invention.

FIG. 9 is a configuration diagram of a transmission / reception device using a switch circuit according to a second embodiment of the present invention.

FIG. 10 is a diagram for explaining an operation of a transmission / reception device using a switch circuit according to a second embodiment of the present invention.

FIG. 11 is a diagram summarizing the operation of the transmission / reception apparatus using the switch circuit according to the second embodiment of the present invention.

FIG. 12 is a configuration diagram showing another embodiment of the transmission / reception device using the switch circuit according to the second embodiment of the present invention.

FIG. 13 is a configuration diagram of a conventional switch circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Receiving antenna 2 1st amplifier circuit 3 2nd amplifier circuit 4 1st transmission line 5 1st amplifier 6 2nd transmission line 7 2nd amplifier 8 Transistor 9 Input matching circuit 10 Output matching circuit 11 Transistor Intrinsic part 12 Transistor gate terminal side parasitic part 13 Transistor drain terminal side parasitic part 14 Transistor source terminal side parasitic part 16 First 3 dB directional coupler 17 Second 3 dB directional coupler 18 First amplifier 19 2nd amplifier 20 1st antenna 21 2nd antenna 22 transmission circuit 23 reception circuit 24 termination resistance

Claims (21)

[Claims] 1. A switch circuit that switches between a conductive state and a non-conductive state of the signal path by switching between an operating state and a non-operating state of an amplifier provided in the signal path. 2. The amplifier according to claim 1, wherein at least one of an input side terminal and an output side terminal is set such that a reflection coefficient in non-operation is closer to 1 than a reflection coefficient in operation. Item 2. The switch circuit according to Item 1. 3. A transmission line is connected to at least one of the input side and the output side of the amplifier, and when the amplifier is not operating, the impedance of the amplifier as viewed through the transmission line is higher than when the amplifier is operating. 3. The switch circuit according to claim 1, wherein an electrical length of the transmission line is set so as to be as follows. 4. A first signal path including a first amplifier and a second signal path including a second amplifier are separately connected at a branch point, and the first signal path includes a first amplifier and a second signal path. In a switch circuit in which one is selected and becomes conductive,
A switch circuit, wherein the selection of the conduction state is performed by switching between an operation state and a non-operation state of the first and second amplifiers. 5. The switch circuit according to claim 4, wherein, of the first and second signal paths, a signal path in which an amplifier provided in the signal path is in an operating state is turned on. 6. The switch circuit according to claim 4, wherein an impedance of the non-operating amplifier from the branch point is higher than an impedance of the amplifier during operation. 7. The first signal path includes a first amplifier circuit having a transmission line connected to the first amplifier, and the second signal path includes a transmission line connected to the second amplifier. When the first and second amplifier circuits are not operating, the impedance of the amplifier as viewed through the transmission line of the amplifier circuit is lower than the impedance of the amplifier during operation. 7. The switch circuit according to claim 4, wherein an electrical length of the transmission line is set to be higher. 8. The first and second amplifiers and the first and second amplifiers.
And a first directional coupler for coupling the amplifiers on the input side, and one of a signal path passing through the first and second amplifiers and a signal path not passing through the first and second amplifiers is selected. A switch circuit which is turned on and turned on, wherein the selection of the turned-on state is performed by switching between an operating state and a non-operating state of the first and second amplifiers. 9. The first and second amplifiers and the first and second amplifiers.
And a second directional coupler for coupling the amplifiers at the output side, and one of a signal path passing through the first and second amplifiers and a signal path not passing through the first and second amplifiers is selected. A switch circuit which is turned on and turned on, wherein the selection of the turned-on state is performed by switching between an operating state and a non-operating state of the first and second amplifiers. 10. A first and a second amplifier connected in parallel with each other, a first directional coupler for coupling the first and the second amplifier on an input side, and the first and the second amplifiers. And a second directional coupler for coupling the amplifiers at the output side, and one of a signal path passing through the first and second amplifiers and a signal path not passing through the first and second amplifiers is selected. A switch circuit which is turned on and turned on, wherein the selection of the turned-on state is performed by switching between an operating state and a non-operating state of the first and second amplifiers. 11. The first directional coupler has input terminals of the first and second amplifiers connected to first and second terminals which are in an isolation terminal relationship with each other. The signal input unit is connected to the third terminal of the third and fourth terminals, and the signal output unit is connected to the fourth terminal. The switch circuit as described. 12. The second directional coupler has output terminals of the first and second amplifiers connected to first and second terminals having an isolation terminal relationship with each other. The signal input unit is connected to the third terminal of the third and fourth terminals, and the signal output unit is connected to the fourth terminal. Or the switch circuit according to any one of 11. 13. A signal path passing through the first and second amplifiers is made conductive by putting the first and second amplifiers into an operating state.
13. The switch circuit according to any one of 0, 11, and 12. 14. The first and second amplifiers are both set so that at least one of input and output terminals has a non-operating reflection coefficient closer to 1 than an operating reflection coefficient. 10. The method according to claim 9, wherein
The switch circuit according to any one of 0, 11, 12, and 13. 15. The amplifier, or one of the first and second amplifiers, includes a transistor, an input matching circuit connected to a gate terminal of the transistor, and an output matching circuit connected to a drain terminal of the transistor. The switch circuit according to claim 1, wherein at least one of the input matching circuit and the output matching circuit is a reflection type matching circuit. 16. The switch circuit according to claim 15, wherein said reflection type matching circuit is constituted by a reactance element or a transmission line that can be equivalently expressed as a reactance element. 17. The switch circuit according to claim 15, wherein the reflection type matching circuit has no resistance element. 18. The transistor, wherein a voltage greater than a pinch-off voltage of the transistor is applied between a gate terminal and a source terminal, thereby activating the amplifier or the first and second amplifiers. 18. The switch circuit according to claim 14, wherein the switch circuit is brought into a non-operation state by applying a small voltage. 19. A first and a second amplifier, and a first directional coupler that couples the first and the second amplifier on an input side, wherein the first directional couplers are connected to each other. The first and second terminals having the relation of an isolation terminal are connected to the first and second terminals.
An input side of the second amplifier is connected, a transmission antenna is connected to a third terminal of the third and fourth terminals having an isolation terminal relationship, and a transmission circuit is connected to the fourth terminal. A transmission path that passes through the first and second amplifiers and a transmission path that does not pass through the first and second amplifiers is selected to be in a conductive state; 1. A transmitting device, which is performed by switching between an operation state and a non-operation state of a second amplifier. 20. A first and a second amplifier, and a second directional coupler that couples the first and the second amplifier on an output side, wherein the second directional couplers are connected to each other. The first and second terminals having the relation of an isolation terminal are connected to the first and second terminals.
The output side of the second amplifier is connected, the receiving terminal is connected to the third terminal of the third and fourth terminals having the relationship of the isolation terminal, and the receiving circuit is connected to the fourth terminal. In a receiving apparatus in which one of a reception path passing through the first and second amplifiers and a reception path not passing through the first and second amplifiers is selected to be in a conductive state, the selection of the conductive state may be 1. A receiving apparatus, which is performed by switching between an operating state and a non-operating state of a second amplifier. 21. First and second amplifiers connected in parallel with each other, a first directional coupler for coupling the first and second amplifiers on an input side, and the first and second amplifiers. And a second directional coupler that couples the amplifiers on the output side. The first directional coupler is connected to the first and second terminals having an isolation terminal relationship with each other. The input side of the second amplifier is connected, the first terminal for transmission and reception is connected to the third terminal among the third and fourth terminals having the relation of the isolation terminal, and the transmission terminal is connected to the fourth terminal. A circuit is connected, and the second directional coupler is connected to output terminals of the first and second amplifiers at first and second terminals having an isolation terminal relationship with each other. The third terminal among the third and fourth terminals in the relationship has a transmission / reception A second antenna is connected to the second terminal, a receiving circuit is connected to the fourth terminal, and a signal path passing through the first and second amplifiers and a signal path not passing through the first and second amplifiers are connected. In the transmission / reception device in which one is selected and brought into a conduction state, the selection of the conduction state is made by the first and second states.
A transmitting / receiving apparatus that switches between an operating state and a non-operating state of the amplifier.