JPS6112129A - High frequency signal switching circuit - Google Patents

Abstract

PURPOSE:To keep the line even at a fault of a high frequency switch drive circuit and a current supply source for a high frequency switch by conducting a transmission signal of the high frequency switch when the drive circuit connected to the high frequency switch is opened. CONSTITUTION:A signal inputted from an active set switching information input terminal 1a and a spare set switching information input terminal 1b is inputted to a control circuit 2. The circuit 2 discriminates whether the active set or the spare set is to be selected and outputs drive signals 9a, 9b of active and spare high frequency switches SW4a, 4b to an exclusive OR circuit 11 and SW circuits 14a, 14b based on the discrimination. The circuit 11 opens the circuits 14a, 14b when the signals 9a, 9b are indentical and opens also them when the power supply supplying a current to the circuit 14a, 14b or the SW4a, 4b is interrupted. Since the SW4a, 4b are constituted to pass through the signal when no current flows, the signal from the terminal 18 passes through the SW4b and a circulator 8 and is outputted from a terminal 16. The most power of the signal from the terminal 17 is absorbed by a dummy in the isolator 10 and the rest is outputted while being attenuated by the reflection attenuation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an improvement in a high frequency signal switch circuit in a set reserve type transmitter used in microwave communication devices etc. that require high reliability.

[Traditional field]

In order to improve the reliability of communication lines, set backup type transmitters use some method to detect failures in the active unit and switch to the backup unit to prevent communication interruptions and increase reliability. In this case, switching must be performed in the radio frequency band after the transmitter output, so a high-frequency switch is attached to each transmitter output, and a high-frequency switch drive circuit is also provided to drive it. . Therefore, the high frequency switch drive i
Even if the circuit itself fails, it is necessary to maintain the line in some way, and it is desirable to further improve its reliability.

Conventionally, as a protection circuit when a high-frequency switch drive circuit fails, a circuit has been used that fixes the output to either the working machine or the standby machine, for example, to the working machine side. - As an example, FIG. 1 shows a configuration diagram of the above-mentioned conventional high frequency switch drive circuit. In FIG. 1, 1a is a switching information input terminal for the active machine, and 1b is a switching information input terminal for the standby machine. Respective switching information input terminals 1a, 1
The signal containing the switching information input from the control circuit 2
At this point, it is determined which signal to select, and the output No. 8 is applied to the base of transistor 5, thereby switching transistor 5 and driving relay 3. The relay 3 is connected to switch between two circuits as shown in FIG. Va, V
b is a terminal for connecting a power source for supplying current to the high frequency switches 4a+4b, and has terminals and voltages that are complementary to each other.

For example, the terminal Va has a value of +10V and the terminal Vb has a value of -10V. Terminals Va and Vb are fixed contacts 3a of relay 3
are respectively connected to the high frequency switch 4a.

4b is connected to the movable contact 3b. Furthermore, different terminals Vanvb are connected to the high frequency switches 4a and 4b.
Switching is performed so that the two are connected. and terminal Va
, Vb are used to drive the respective high frequency switches 4a, 4b'e.

However, with this circuit configuration, the final stage of the high frequency switch drive section is the relay 3, so the control circuit 2 and the transistor 5
Even in the event of a failure, the output is always fixed at either Va or Vb, so either the active or standby unit is selected to maintain the line. However, the above-mentioned emulsion retention method in which the tumor is fixed to either one cannot be said to be sufficiently safe because there is no evidence that one can be appropriately selected. For example, if the control circuit 2 fails and the selected transmitter also fails, the line will be disconnected. Further, in the above circuit, the high frequency switch 4aa4
When the power supply that supplies all the current to b is cut off,
Depending on the circuit configuration of the high-frequency switches 4 a r 4 b, both signals pass or are cut off, causing a line failure. As an example of a problem occurring when both pass through, a case where the high frequency signal circuit configuration of the set reserve system is as shown in FIG. 2 will be described. That is, in FIG.
The transmission signals input from the az6b pass through the high frequency switches 4a+4b', and are combined and output at the same level at the T-branch 7, but the frequencies of the output signals of the working machine and the standby machine,
The phases do not necessarily match, and the signals are not combined correctly at the T-branch 7, resulting in a line failure.

In this way, a high frequency signal switch circuit composed of a high frequency signal circuit including a conventional high frequency switch drive circuit and a high frequency switch has problems when the high frequency switch drive circuit and the selected transmitter fail, The drawback is that if the power supply that supplies current to the switch fails, it can cause damage to the line.

[Purpose of the invention]

An object of the present invention is to provide a high-frequency signal switch circuit that can maintain a line even if either the high-frequency switch drive circuit or the power supply that supplies current to the high-frequency switch fails, thereby achieving higher reliability. It is in.

[Structure of the invention]

The high frequency signal switch circuit according to the present invention includes a high frequency switch drive circuit that receives a control signal and generates output signals that are complementary to each other in accordance with the control signal during normal operation;
A high frequency signal switch circuit including a plurality of high frequency switches that switch transmission signals according to the output signal,
a detection circuit that detects a failure in the high-frequency switch drive circuit and a failure in a power source for supplying current to the high-frequency switch, and opens an output of the high-frequency switch drive circuit when the failure is detected; and the detection circuit. The high-frequency switch is connected to the output of the high-frequency switch, and the high-frequency switch is connected to the output terminal of the high-frequency switch, and the high-frequency switch is connected to the output terminal of
a circulator having one terminal and a plurality of other terminals as input terminals, each of which is connected to the output side of the plurality of high frequency switches; and an isolator connected to the input side of the high frequency switch. By including this, the circuit can be maintained even if either or both of the high frequency switch drive circuit and the power source that supplies current to the high frequency switch fail.

〔Example〕

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

FIG. 3 is a configuration diagram showing an embodiment of the present invention.

Signals containing switching information input from the active machine switching information input terminal 1 a and the standby machine switching information input terminal 1 b are input to the control circuit 2 . The control circuit 2 determines which transmitter to select, and based on the determination, outputs an output voltage 9 a for driving the high frequency switch for the active machine + an output voltage 9 b for driving the high frequency switch for the standby machine. These two output voltages 9
a + 9 b is input to an exclusive OR circuit 11 to detect a failure in the control circuit 2, and its output is connected to switch circuits 14a and 14b. Output voltage 9a, 9
When b is the same value, switch circuits 14a and 14b'fr
: Operates to open the switch circuits 14a and 14b, and closes the switch circuits 14a and 14b when the output voltages take mutually complementary values. That is, output voltage 9a+9b
When the same value of voltage is obtained, it is determined that there is a failure, the switch circuits 14a, 14b are opened, and the high frequency switches 4a, 4a, 4b are opened.
Current is prevented from flowing through 4b. Output voltage 9a
When e9b takes a complementary value, it is determined to be normal, the switch circuits 14a and 14b are closed, and the high frequency switch 4a
A4bK current is applied.

The switch circuits 14a and 14b also have a function of detecting a failure in the power supply that supplies current to the high frequency switches 4a and 4b, and even in the event of a failure, the switch circuit 14a
, 14b are open.

FIG. 4 shows an example of a circuit that realizes this. In FIG. 4, the output of exclusive OR circuit 11 is connected to the base of transistor 12 for driving relay 13. When the output voltages 9a+9b take the same value, the exclusive OR circuit 11
is output to turn off transistor 12. Furthermore, as is clear from FIG. 4, the high frequency switches 4a, 4
Even when the power supply 15 that supplies current to b is cut off, the relay 13
is off. Therefore, the switch circuits 3a and 3b detect both a failure in the control circuit 2 and a failure in the power supply 15,
Operates to open and close circuits.

The above is the control circuit 2. This is the operation of the high frequency switch drive circuit composed of the exclusive OR circuit 11° switch circuits 14a and 14b.

Next, the operation of the high frequency signal circuit will be explained. Current transmission signal input terminal 17. The transmission signal input from the backup transmission signal input terminal 18 is normally transmitted to the high frequency switch 4a*
4b, one of them is selected and output from the output terminal 16. When the working transmitting signal is selected, it passes through the isolator 10, the high frequency switch 4a, and is outputted from the output terminal 16 through the circulator 8' (I-).When the backup transmitting signal is selected, the high frequency switch J
According to bffi, the signal passes through the circulator 8, is reflected by the high frequency switch 4a, passes through the circulator 8 again, and is output from the output terminal 16.

Also, the high frequency switch 4 a + used here
4b has a circuit configuration that cuts off the signal when current is flowing, and allows the signal to pass when no current flows. As described above, when the switch circuits 14m and 14b are open, no current flows through the high frequency switches 4a*4b, so that both pass through. At this time, the active transmission signal is output as is to the output terminal 16, but the backup transmission signal passes through the high frequency switch 4a, most of the signal energy is absorbed by the dummy of the isolator 10, and the remaining energy is output from the high frequency switch 4a. The signal is attenuated by the amount of return loss seen from the terminal, and is output from the output terminal 16. Normally, the return loss is between about 20 dB and 30 dB, so the signals are simultaneously output from the output terminal 16 with a difference of 20 dB to 30 dB from the current transmission signal. At this time, there is a sufficiently large level difference of 20 dB to 30 dB, so the effect on the currently used transmission signal is very small (1 degree).Also, it is customary to provide a fading margin of 40 to 50 dB on the receiver side. Therefore, even signals with a low transmission output level of 20 dB to 30 dB can be received sufficiently, and even if the active transmitter is out of order, the backup transmitted signal will be received, so there will be no damage to the line. do not have.

〔effect〕

As can be seen from the above description, in the high-frequency signal switch circuit according to the present invention, even if the high-frequency switch drive circuit and the high-frequency switch drive power supply fail, the line can be maintained as long as either transmitter is operating normally. This has the effect of increasing the reliability of the line.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the configuration of a conventional high frequency switch switching circuit, Fig. 2 is a diagram showing a branching circuit using a T-branch, Fig. 3 is a diagram showing an embodiment of the present invention, and Fig. 4 is a diagram showing the configuration of a conventional high frequency switch switching circuit. FIG. 4 is a diagram representing an embodiment of the switch circuit in FIG. 3; 1a
is a switching information input terminal for the active machine, 2a is a switching information input terminal for the standby machine, 2 is a control circuit, 4a is a high frequency switch for the active machine, 4b is a high frequency switch for the standby machine, 8 is a circulator, and 9a is a high frequency switch for the active machine. Output voltage for switch drive, 9
b is the output voltage for driving the frequency switch for spare equipment, 10 is an isolator, 11 is an exclusive OR circuit, 12 is a relay driving transistor, 13 is a relay, 14a is a switch circuit for active equipment, and 14b is a switch for backup equipment. circuit, 1
5 is a power supply for driving the high frequency switch. Tokubo 1 application filed NEC Corporation Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Scope of Claims] A high-frequency switch drive circuit that receives a control signal and generates output signals that are complementary to each other according to the control signal during normal operation, and a plurality of high-frequency switch drive circuits that switch transmission signals according to the output signal. A high frequency signal switch circuit having a switch, detects a failure in the high frequency switch drive circuit and a failure in a power source for supplying current to the high frequency switch, and when the failure is detected, the output of the high frequency switch drive circuit a detection circuit that opens the circuit; the high-frequency switch connected to the output of the detection circuit, the high-frequency switch through which the transmission signal passes when the switch is opened; one terminal as an output terminal; and one terminal as an input terminal. and a circulator, each of which has a plurality of other terminals connected to the output side of the plurality of high-frequency switches, and an isolator connected to the input side of the high-frequency switch. High frequency signal switch circuit.