JPH08237164A - Antenna multicoupler - Google Patents

Abstract

PURPOSE: To reduce a control current for changeover control of an antenna. CONSTITUTION: A diode D1 is interposed between an antenna ANT1 and a transmission filter 2 and a diode D2 is interposed between an antenna ANT2 and a reception filter 3. An anode of the diode D1 connects to a control terminal CONT1 and a cathode connects to ground via a λ/4 phase shift circuit 41 and a diode D3 used to block a transmission signal. Furthermore, an anode of the diode D2 connects to a control terminal C0NT2 and a cathode connects to ground via a λ/4 phase shift circuit 42 and the diode D3 used to block a reception signal. The antenna switching control current is reduced by using an independent control signal to connect the antenna ANT1 and the transmission filter 2 or to connect the antenna ANT2 and the reception filter 3 alternately.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention utilizes two antennas as antennas for diversity reception, and
The present invention relates to an antenna duplexer capable of sharing one antenna as a transmitting antenna and a receiving antenna.

[0002]

2. Description of the Related Art Heretofore, an antenna duplexer has been proposed in which two antennas are used as diversity receiving antennas and one antenna can be shared as a transmitting antenna.

FIG. 2 is a diagram showing a circuit configuration of a conventional antenna duplexer. The antenna duplexer 100 is composed of a transmission filter 101, a reception filter 102, and an antenna switching circuit 103 using a pin diode. A transmission circuit (not shown) is provided at the terminal Tx of the antenna duplexer 100.
And a receiving circuit (not shown) is connected to the terminal Rx. The antennas ANT1 and ANT2 are connected to the terminals ant1 and ant2, respectively. The antennas ANT1 and ANT2 are antennas for diversity reception, and the antenna ANT1 is also used as a transmission antenna.

The antenna switching circuit 103 includes diodes D1 to D3 composed of three pin diodes and two λ / 4.
It is composed of phase circuits 103A and 103B. λ /
The 4-phase circuit 103A prevents the transmission signal output from the transmission filter 101 from flowing into the diode D3, and the λ / 4 phase circuit 103B prevents the reception signal received by the antenna ANT2 from flowing into the diode D3. It is to prevent. The diodes D1 to D3 are control terminals CO
ON / by the antenna switching control signal input from NT
It is designed to be turned off.

The capacitors C1 and C2 are coupling capacitors, and the high frequency choke coils RFC1 and RFC2 prevent the transmission signal from flowing into the antenna ANT2 side and the control terminal CONT side.

The antenna switching control signal is a high level or low level state signal, and the antenna ANT1 is switched between the transmitting antenna antenna and the receiving antenna depending on the level state of the antenna switching control signal.

The antenna switching control signal is at a high level (ON
(State), a forward current flows through the diodes D1 to D3, and these diodes D1 to D3 are in a short-circuited state (ON state). When the diodes D1 to D3 are turned on, the transmission filter 101 and the terminal ant1 are circuit-connected, and the transmission signal output from the transmission circuit via the transmission filter 101 is transmitted via the diode D1 and the capacitor C1 to the antenna ANT1. And is radiated into the air. Further, the reception signal received by the antenna ANT2 is guided to the reception filter 102 via the diode D2.

The received signal received by the antenna ANT1 flows out to the ground through the λ / 4 phase circuit 103A and the diode D3 and is not guided to the receiving filter 102 side. In addition, the antenna ANT is connected via the diode D1.
The transmission signal guided to the 1st side is prevented from flowing into the diode D3 side by the λ / 4 phase circuit 103A, and does not flow out to the ground via the diode D3. Further, the reception signal received by the antenna ANT2 is prevented from flowing into the diode D3 side by the λ / 4 phase circuit 103B and does not flow out to the ground via the diode D3.

Therefore, when the antenna switching control signal is ON, the antenna ANT1 serves as a transmitting antenna and the antenna ANT2 serves as a receiving antenna.

On the other hand, when the antenna switching control signal is at a low level (OFF state), a reverse bias is applied to the diodes D1 to D3, and these diodes D1 to D3 are in an open state (OFF state). Diodes D1 to D3 are off
Then, the circuit between the transmission filter 101 and the terminal ant1 is opened, and the transmission signal is not guided to the antenna ANT1. The λ / 4 phase circuit 103A and the ground are opened in a circuit manner, and the reception signal received by the antenna ANT1 is guided to the reception filter 102 via the λ / 4 phase circuits 103A and 103B. Further, the circuit between the terminal ant2 and the receiving filter 102 is opened, and the received signal is not guided to the receiving filter 102. Therefore, when the antenna switching control signal is OFF, only the antenna ANT1 becomes the receiving antenna.

[0011]

In the above-described conventional antenna duplexer 100, since the parallel circuit of the diode D1 and the diode D2 is configured between the control terminal CONT and the diode D3, the antenna switching control signal is transmitted. ON
In this state, there is a problem in that a conducting current flows through both the diodes D1 and D2, and the control current for switching the antenna becomes large.

The present invention has been made in view of the above problems, and an object thereof is to provide an antenna duplexer having a small antenna switching control current.

[0013]

According to the present invention, there is provided a transmitting terminal to which a transmitting circuit is connected, a first antenna terminal to which a first antenna is connected, a receiving terminal to which a receiving circuit is connected, and a second antenna. A second antenna terminal to which is connected, an input end connected to the transmission terminal, and a transmission filter for limiting and outputting a transmission signal input from the transmission circuit to a predetermined transmission band, and an output end A reception filter connected to a reception terminal and configured to limit a reception signal received by the second antenna to a predetermined reception band and output the reception signal to the reception circuit; and a first filter including the first antenna and the transmission filter. Second connection and connection between the first and second antennas and the reception filter
Connection control means for controlling the connection, a first control terminal to which a control signal for controlling the first connection is input, and a control signal for controlling the second connection. An antenna duplexer comprising a second control terminal, wherein the antenna connection control means connects the cathode of the first diode switch to the input terminal of the first λ / 4 phase circuit that blocks the transmission signal. A first series circuit consisting of
A second series circuit in which the cathode of the second diode switch is connected to the input terminal of the second λ / 4 phase circuit for blocking the received signal, and the third diode switch whose cathode is grounded, It is composed of a T-type circuit in which the output terminals of the first and second series circuits are connected to the anode of the third diode switch, and the anode and cathode of the first diode switch are respectively connected to the transmission filter. The output terminal and the first control terminal and the first antenna terminal are connected, and the anode and the cathode of the second diode switch are respectively the second antenna terminal, the second control terminal and the reception terminal. The filter is connected to the input end of the filter.

[0014]

According to the present invention, the connection between the first antenna and the transmission filter is controlled by the control signal S1 input from the first control terminal, and the control signal S2 input from the second control terminal is controlled. The connection between the first antenna and the reception filter is controlled.

A high level control signal S is applied to the first control terminal.
1 is input and a low-level control signal S2 is input to the second control terminal (hereinafter, referred to as control mode 1), the first diode switch, the first λ / 4 phase circuit, and the third diode An energizing current flows only in the switch, the first and third diode switches are in an ON state (short circuit state), and the second diode switch is in an OFF state (open state). As a result, the transmission signal from the transmission circuit, which is input from the transmission terminal, is input to the transmission filter, limited to a predetermined transmission band by the transmission filter, and then transmitted through the first diode switch to the first antenna. Led to
The first antenna radiates into the air. On the other hand, the reception signal received by the second antenna is blocked by the second diode switch and is not guided to the reception filter side,
The reception signal received by the first antenna is guided to the ground side through the third diode switch and is not guided to the reception filter side.

When a high level control signal S1 is input to the second control terminal and a low level control signal S2 is input to the first control terminal (hereinafter referred to as control mode 2), An energizing current flows only through the diode switch, the second λ / 4 phase circuit, and the third diode switch, the second and third diode switches are turned on (short-circuited), and the first diode switch is turned off ( Open state). As a result, the reception signal received by the second antenna is guided to the reception filter through the second diode switch, limited to a predetermined reception band by the reception filter, and then received through the reception terminal. It is output to the circuit. On the other hand, the transmission signal output from the transmission filter is blocked by the first diode switch and is not guided to the first antenna.

When low level control signals S1 and S2 are input to the first and second control terminals (hereinafter referred to as control mode 3), the first to third diode switches are turned on.
The state becomes the FF state. As a result, the transmission signal output from the transmission filter is blocked by the first diode switch and is not guided to the first antenna. Further, the reception signal received by the second antenna is blocked by the second diode switch and is not guided to the reception filter side. However, the received signal received by the first antenna is
It is guided to the reception filter via the first and second λ / 4 phase circuits.

Therefore, in control mode 1 only the first antenna is used as a transmitting antenna, in control mode 2 the second antenna is used as a receiving antenna, and in control mode 3 the first antenna is used as a receiving antenna. Used.

[0019]

1 is a circuit diagram of an antenna duplexer according to the present invention. The antenna duplexer 1 is used, for example, in a wireless communication device such as a car phone, and is particularly applicable to a wireless device in which space diversity reception is performed using two antennas.

The antenna duplexer 1 includes a transmission filter 2,
It is composed of a receiving filter 3 and an antenna connection control circuit 4 (antenna connection control means) using a diode switch.

The antenna duplexer 1 includes an antenna ANT1.
The antenna terminal ant1 to which the (first antenna) is connected
(First antenna terminal), antenna terminal ant2 (second antenna terminal) to which the antenna ANT2 (second antenna) is connected, transmission terminal Tx to which a transmission circuit (not shown) is connected, and reception circuit (not shown) Is connected to the receiving terminal Rx,
A first control terminal CONT1 to which a control signal for controlling the connection between the antenna ANT1 and the transmission filter 2 is input, and a control signal for controlling the connection between the antenna ANT2 and the reception filter 3 are supplied. A second control terminal CONT2 for input is provided.

Antenna ANT1 and antenna ANT2
Is an antenna provided for diversity reception, and the antenna ANT1 is also used as a transmission antenna.

The transmission filter 2 is a filter such as an LPF (Low Pass Filter) which limits a transmission signal from the transmission circuit input from the transmission terminal Tx to a signal in a predetermined transmission band. It is composed of a dielectric filter in which coaxial resonators are cascaded in multiple stages.

The reception filter 3 is a filter such as a BPF (Band Pass Filter) for limiting the reception signal received by the antenna ANT1 or the antenna ANT2 to a signal in a predetermined reception band, for example, an integrally molded dielectric filter. Composed.

The antenna connection control circuit 4 is composed of diodes D1 to D3 (diode switches) consisting of three pin diodes, two λ / 4 phase circuits 41 and 42, and two high frequency choke coils RFC1 and RFC2. ,
It is connected as follows.

That is, the input terminal a of the λ / 4 phase circuit 41
Is connected to the cathode of the diode D1 to form a first series circuit, and the cathode of the diode D2 is connected to the input end b of the λ / 4 phase circuit 42 to form a second series circuit. The output terminal (the output terminals of the λ / 4 phase circuits 41 and 42) c of the serial circuit 2 of the second circuit has a third electrode whose cathode is grounded.
The anode of the diode D3 is connected to form a T-type circuit including the first series circuit, the second series circuit, and the diode D3.

The anode of the diode D1 is connected to the output end of the transmission filter 2 and is also connected to the first control terminal CONT1 via the high frequency choke coil RFC1, and the cathode of the diode D1 is the antenna terminal a.
It is connected to nt1. The cathode of the diode D2 is connected to the input end of the receiving filter 3, the anode of the diode D2 is connected to the antenna terminal ant2, and is also connected to the second control terminal CONT2 via the high frequency choke coil RFC2. There is.

The λ / 4 phase circuit 41 (first λ / 4 phase circuit) prevents the transmission signal output from the transmission filter 2 from flowing into the diode D3 side. Also, λ
The / 4 phase circuit 42 (second λ / 4 phase circuit) blocks the inflow of the reception signal received by the antenna ANT2 into the diode D3. λ / 4 phase circuit 41, 42
Is composed of, for example, a quarter-wave transmission line. λ /
The line constants of the four-phase circuits 41 and 42 are set so that, when the diode D3 is in the ON state (short-circuit state), the impedance seen from the input end to the diode D3 side becomes extremely large in the frequency band to be blocked.

The diode D1 is a switch circuit that controls the connection between the antenna ANT1 and the transmission filter 2, and ON / OFF (opening / closing) is controlled by a control signal S1 input from the control terminal CONT1. The diode D2 is a switch circuit that controls the connection between the antenna ANT2 and the reception filter 3, and the control terminal CONT.
ON / OFF (opening / closing) is controlled by a control signal S2 input from 2. The diode D3 constitutes an energization path for passing a control current (DC current) to turn on the diodes D1 and D2.

The capacitors C1 and C2 are coupling capacitors that cut the inflow of the control current to the antenna side and couple only high frequencies. Further, the high frequency choke coil RFC1 prevents the transmission signal from flowing into the control terminal CONT1, and the high frequency choke coil RFC1 controls the reception signal received by the antenna ANT2.
It prevents the inflow to the NT2 side.

The control signals S1 and S2 are high-level or low-level state signals, which are control signals S1 and S2.
The connection state of the antenna ANT1 and the antenna ANT2 is controlled as shown in the following Table 1 by the combination of the level states of.

[0032]

[Table 1]

Next, each control mode shown in Table 1 will be described. (1) Control Mode 1 The control mode 1 is a mode in which the antenna ANT1 is used as a transmitting antenna, and a high-level (H) control signal S1 is input to the control terminal CONT1 to control the control terminal CONT2.
The mode setting is performed by inputting the low-level (L) control signal S2 to.

When a high level control signal S1 is input to the control terminal CONT1, the diodes D1, D3 and λ /
A forward current flows through the 4-phase circuit 41, and the diode D1,
D3 is turned on (closed). In addition, the control terminal CO
When the low-level control signal S2 is input to NT2, the diode D2 is reverse-biased and the diode D2 is OF
The F state (open state) is set.

When the diode D1 is turned on, the transmission filter 2 and the antenna terminal ant1 are connected in a circuit manner, and the transmission signal output from the transmission circuit via the transmission filter 2 passes through the diode D1 and the capacitor C1. Is guided to the antenna ANT1 and radiated in the air. The transmission signal is blocked by the λ / 4 phase circuit 41 and does not flow to the ground via the diode D3.

On the other hand, the reception signal received by the antenna ANT1 is guided to the ground via the λ / 4 phase circuit 41 and the diode D3, and is not guided to the reception filter 3 side.
When the diode D2 is turned off, the antenna terminal ant1 and the receiving filter 3 are cut off in a circuit manner, and the reception signal received by the antenna ANT2 is not guided to the receiving filter 3 side.

Therefore, in the control mode 1, the antenna AN is
Only T1 operates as a transmitting antenna.

(2) Control Mode 2 The control mode 2 is a mode in which the antenna ANT2 is used as a receiving antenna, and the control signal S1 of low level (L) is input to the control terminal CONT1 to control the control terminal CONT2.
Mode setting is performed by inputting a high-level (H) control signal S2 to.

When a low level control signal S1 is input to the control terminal CONT1, the diode D1 is reverse biased and the diode D1 is turned off (opened).

When a high level control signal S2 is input to the control terminal CONT2, a forward current flows through the diodes D2 and D3 and the λ / 4 phase circuit 42, and the diodes D2 and D3 are turned on (closed state). Becomes

When the diode D1 is turned off, the transmission filter 2 and the antenna terminal ant1 are electrically cut off, and the transmission signal output from the transmission circuit via the transmission filter 2 is not guided to the antenna ANT1. . Further, the reception signal received by the antenna ANT1 is guided to the ground via the λ / 4 phase circuit 41 and the diode D3, and is not guided to the reception filter 3 side.

On the other hand, when the diode D2 is turned on, the antenna terminal ant2 and the reception filter 3 are circuit-connected, and the reception signal received by the antenna ANT2 is guided to the reception filter 3 side. The received signal is blocked by the λ / 4 phase circuit 42 and the diode D
It does not flow out to the earth via 3.

Therefore, in the control mode 2, the antenna AN
Only T2 operates as a receiving antenna.

(3) Control Mode 3 Control mode 3 is a mode in which the antenna ANT1 is used as a receiving antenna, and the control terminals CONT1 and CONT are used.
Mode setting is performed by inputting low-level (L) control signals S1 and S2 to 2.

When the low level control signals S1 and S2 are input to the control terminals CONT1 and CONT2, the diodes D1 to D3 are reverse biased and all are in the OFF state (open state).

When the diodes D1 and D2 are turned off, the transmitting filter 2 and the antenna terminal a as described above.
Between nt1 and receiving filter 3 and antenna terminal ant2
The transmission signal output from the transmission filter 2 is not guided to the antenna ANT1, and the reception signal received by the antenna ANT2 is not guided to the reception filter 3 during the circuit interruption.

On the other hand, when the diode D3 is turned off, the reception signal received by the antenna ANT2 is not leaked to the ground through the diode D3 and is transmitted to the reception filter 3 through the λ / 4 phase circuits 41 and 42. Be guided.

Therefore, in the control mode 3, the antenna AN is
Only T1 operates as a receiving antenna.

By the way, as the control mode, the control terminal C
High level control signals S1 and S to ONT1 and CONT2
A mode of inputting 2 (hereinafter, referred to as control mode 4) can be considered. The control mode 4 is a combination of the control mode 1 and the control mode 2 independently of each other.
NT1 serves as a transmitting antenna, and antenna ANT2 serves as a receiving antenna.

Aside from the case where simultaneous transmission and reception are required due to the configuration of the communication device, the antennas ANT1, A are time-divided.
In the case where transmission and reception are performed substantially at the same time by switching NT2 for transmission and reception, the control modes 1 to
If the switching control of 3 is performed, the same function as that of the control mode 4 can be achieved, and the control current flowing for the switching control of the diodes D1 to D3 is approximately half that of the control mode 4, so that the control is preferable. It is desirable to adopt modes 1 to 3.

As described above, the control terminals CONT1, CO
When a high-level control signal is input to at least one of NT2, the antennas ANT1 and ANT2 are switched and set to the transmitting antenna or the receiving antenna. It can be reduced. Thereby, a low power type antenna duplexer can be provided.

[0052]

As described above, according to the present invention,
Connection between first antenna and transmission filter and first and second
The antenna connection control means switches and controls the connection between the antenna and the receiving filter to use the first antenna and the second antenna as diversity receiving antennas, and also uses the first antenna as a transmitting antenna. A first control terminal to which a first control signal for controlling the connection between the first antenna and the transmission filter is input, and the connection between the second antenna and the reception filter. A second control terminal to which a second control signal for inputting is input, and of the first and second control signals independent of each other, the first control signal causes the first antenna to function as a transmission antenna and a reception antenna. While switching control is performed, it is controlled by the second control signal whether or not the second antenna is used as a receiving antenna. And it is possible to reduce the control current for the antenna control by performing switching setting of the second antenna alternately at each independent control signals. This makes it possible to reduce the power consumption of the antenna duplexer.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of an antenna duplexer according to the present invention.

FIG. 2 is a circuit configuration diagram of a conventional antenna duplexer.

[Explanation of symbols]

 1 antenna duplexer 2 transmission filter 3 reception filter 4 antenna connection control circuit 41, 42 λ / 4 phase circuit ANT1, ANT2 antenna ant1, ant2 antenna terminal CONT1, CONT2 control terminal Rx reception terminal Tx transmission terminal

Claims (1)

[Claims] 1. A transmission terminal to which a transmission circuit is connected, and a first terminal.
A first antenna terminal to which an antenna is connected, a receiving terminal to which a receiving circuit is connected, a second antenna terminal to which a second antenna is connected, and an input end are connected to the transmitting terminal, A transmission filter for limiting an input transmission signal to a predetermined transmission band and outputting the same, and an output end connected to the reception terminal for limiting a reception signal received by the second antenna to a predetermined reception band. Antenna connection for controlling the reception filter output to the reception circuit, the first connection between the first antenna and the transmission filter, and the second connection between the first and second antennas and the reception filter. From the control means, a first control terminal to which a control signal for controlling the first connection is input, and a second control terminal to which a control signal for controlling the second connection is input. Become antenna The antenna connection control means is a first series circuit in which the cathode of the first diode switch is connected to the input terminal of the first λ / 4 phase circuit that blocks the transmission signal, The second series circuit in which the cathode of the second diode switch is connected to the input terminal of the second λ / 4 phase circuit for blocking the reception signal, and the third diode switch whose cathode is grounded, And a T-type circuit in which an output terminal of the second series circuit is connected to an anode of the third diode switch, and an anode and a cathode of the first diode switch are outputs of the transmission filter, respectively. An end and the first control terminal and the first antenna terminal, and the anode and cathode of the second diode switch are respectively connected to the second antenna terminal and the second antenna terminal. Antenna duplexer, characterized in that connected to the second control terminal and input terminal of the reception filter.