JPS5828934B2 - switch circuit - Google Patents

Description

[Detailed description of the invention] The present invention relates to a switch circuit.

The switch circuit according to the present invention can be used as a normal switching means in a wide range of fields, and will be described below by taking as an example a case where it is applied to a switching means of a working system and a standby system used in a carrier frequency system.

Generally, the carrier frequency system has both a working system and a backup system.
Alternative AC signals from both systems are supplied to the load.

Which system to select is determined based on a control signal, and this control signal operates a switch circuit to switch the connection of both the working system and the standby system to the load.

Conventionally, the switch circuit that performs the above-mentioned operations has been realized using relay contacts or diode switches, and the switch circuit has been placed in a position independent of the active and standby circuits. .

Here, since either the working system or the standby system is on the output side and the other is on the cutoff side, these systems will be referred to as the output system and the cutoff thread.The switch circuit will be connected to the output of the cutoff thread amplifier. The end impedance must be such that it does not affect the output system amplifier, that is, it must be able to ensure a sufficiently high impedance.

In this sense, the relay contacts and diode switches are suitable as switch circuits.

However, if we look at the former relay contact, (1)
Since it involves mechanical operation, reliability is low; (2) there is a limit to speeding up the switching time; (3) a large current is required for relay operation; and (4) heat generation occurs due to the electric current. (5) The heat generated requires a large mounting space, and (6) the relay itself is large and requires a large mounting space, making high-density mounting impossible.

Also, looking at the latter diode switch, (1
) In order to make the switch circuit conductive, it is necessary to flow a bias current commensurate with the peak value of the AC signal current that must be passed through it, so the power supply capacity is reduced, (2) the bias current causes heat generation, and (3) the Due to heat generation, the packaging density cannot be improved, and (4) on the other hand, a special reverse bias voltage is required to cut off the switch circuit, resulting in a complicated circuit configuration.

Furthermore, in the case of both relays and diode switches, as mentioned above, they occupy positions that are circuit-wise independent of both the output system and the cutoff thread, so the overall carrier frequency system becomes large. With its drawbacks.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to propose a switch circuit with a novel configuration which makes it possible to eliminate the above-mentioned disadvantages.

In accordance with the above object, the present invention has two switch parts, one of which is selectively conductive or cut-off, and the two switch parts are divided into an output system and a cutoff thread, and are built in, and are roughly connected to a platform system. The present invention is characterized in that it is configured to operate integrally with the output amplifier of the system.

Specifically, the primary winding of the output transformer disposed in the output stage of the output amplifier is grounded or floated in an alternating current manner, and when the output transformer is grounded, the primary winding of the output transformer and the transmission line are grounded. The secondary winding connected to the diodes and the transistors are coupled together, and the coupling between the primary and secondary windings is released when the windings float to provide a switching function. The float utilizes the reverse high impedance of the diode and the high collector impedance when the transistor is turned off, and the forward micro impedance shunts the DC current necessary to drive the output amplifier to connect the diode. The high impedance in the reverse direction is obtained by branching off the DC voltage necessary for driving the output amplifier and applying it to the diode as a reverse bias voltage. It is.

The present invention will be explained below with reference to the drawings.

As already mentioned, the present invention is explained by taking as an example a switch circuit that switches between a working system and a standby system used in a carrier frequency system, and FIG. 1 shows an outline of its configuration.

In the figure, 11 is a working system in the carrier frequency system, 12 is a standby system, and 13 is a transmission line for conveying AC signals from these amplifiers to the opposing station.

In this case, when one of the amplifiers operates as an output system, the other becomes a cutoff line, and the AC signal is sent from only one of the amplifiers to the transmission line 13, and this switching operation is performed. This is the switch circuit 14.

This switching operation is instructed by a control signal from the control line 15.

The switch circuit 14 shown in FIG. 1 was conventionally constructed with a relay or diode switch, and was associated with the disadvantages already mentioned.

Furthermore, it has already been mentioned that the conventional switch circuit 14 is arranged independently from both the active and standby systems as in the configuration shown in FIG.

Therefore, the present invention proposes a switch circuit having a configuration as shown in FIG. 2 in principle.

However, the switch circuit according to the present invention cannot operate independently, but operates in organic combination with the amplifiers of each system, so the amplifiers and their associated parts are also drawn at the same time.

In FIG. 2, 21 is a working system incorporating the switch circuit of the present invention, 22 is a standby system incorporating the switch circuit of the present invention, and 13 is a transmission line as in FIG.

Now, it is assumed that the active system 21 sends out an AC signal as an output system, while the standby system 22 is inactive as a breaking line.

In this case, the active switch SW1 is open and the switch SW2 is open.
and SW3 are closed, while the standby switch swi' is closed and the switches SW2' and SW3' are open.

Opening/closing control of these switch groups is performed by an opening/closing control signal (not shown).

In the active system 21, switch SW1 is open and switch S
Since W2 and SW3 are closed, the direct current (Dc) obtained by dividing the direct current for driving the amplifier AMP flows into the negative power supply -VEE following the loop 1oop1 in the figure.

At this time, ■ at the primary winding of the output transformer Tr -■
The terminal is AC grounded through capacitor C1.

As a result, the primary windings of the output transformer Tr and 2
The secondary windings ■-■ can be coupled, and the AC signal supplied from the input terminal IN passes through the primary winding, appears at the secondary winding, and is sent to the transmission line 13.

On the other hand, in the standby system 22, since the switch SW1' is closed and the switches SW2' and SW3' are open, the direct current IDC', which is the branched direct current for driving the amplifier AMP', is as shown in the figure. It follows the loop Ioop2' and flows into the negative power supply -vEE'.

At this time, the terminal (2) in the primary winding (-) of the output transformer Tr' becomes a float, and no current flows through the primary winding.

As a result, the primary winding ■'-■' and the secondary winding ■'-■' of the output transformer Tr' cannot be coupled, and the input terminal I
The AC signal supplied from N' does not appear in the secondary windings (1)-(1) and is not sent out to the transmission line 13.

Conversely, when the active system 21 is suspended and the backup system 22 becomes the output system, the active system 21 operates in exactly the same way as the backup system 22 described above, and the backup system 22 becomes the active system 22 as described above. It operates in exactly the same way as system 21.

As mentioned above, the most basic features of the present invention are:
The primary side of the existing output transformer is grounded or floated, thereby realizing the switching function.

In order to obtain this earth and float, the shunt DC current I
DOI I D'0 is made to flow through one of two loops, and the selection of that loop is performed by a group of switches.

However, the switch group (relay contact group) shown in Fig. 2 is described to explain the principle, and in reality,
It cannot be used due to problems in terms of mounting space, power consumption, operating speed, etc.

For this reason, the invention further proposes a preferred embodiment of the switch group.

FIG. 3 is a diagram showing the most preferred embodiment of the switch group.

However, since both the active and standby systems have exactly the same configuration, only the active side will be described.

As is clear from a comparison of FIGS. 2 and 3, switch SW1 is replaced by a series circuit of diodes D2 and D3, switch SW2 is replaced by diode D1, and switch SW3 is replaced by transistor TSI.

In this way, it can be integrated into an IC, the mounting space is small, the power consumption is reduced, and the operating speed is extremely high.

Next, the operation of the circuit shown in FIG. 3 will be explained.

First, a case will be described in which the switch circuit of the present invention is made conductive and an AC signal is sent to the transmission line 13.

The instruction to make the switch circuit conductive is given by a control signal (High 1evel) from the control line 15, causing the transistor Tsl to become saturated.

When the collector-emitter voltage of the transistor Tsl at the time of saturation is VOE, and the potential drop across the diode D1 is vDl, if a transistor Tsl with VOE<VDI is used, the DC current IDC will be point ■+0 point-○ point. Follow loop 1 oapl to negative power supply -V
Leading to EB.

This is because, if vcE x vDl, the voltage drop VD2+VD3 of diodes D2 and D3 in the loop 100p2 from point ■ to point 0 is vD2+vD3>VOE+vD
1, and almost no direct current flows through these diodes D2 and D3, which automatically approximates a cut-off state.

In other words, a state equivalent to the state in which switch SW1 is opened and switches SW2 and SW3 are closed in FIG. 2 occurs.

As a result, the AC signal from the input terminal IN flows to the ground through the primary winding ■-■ of the output transformer Tr, the transistor Tsl, and the capacitor C1, and the AC signal appears in the secondary winding ■-■, and the transmission line 13 It will be sent to

This is the conduction of the switch circuit.

On the other hand, the switch circuit is disconnected and the AC signal is transmitted to the transmission line 13'.
We will discuss the case where the supply is not carried out.

An instruction to turn off the switch circuit is given by a control signal (Low 1 level) from the control line 15, and the transistor Ts1 is cut off.

When the transistor Tsl is cut off, the potential at point 0 in the figure rises to the ground potential via the resistor R1.

Therefore, a reverse bias voltage is applied to the diode D1, and the diode D1 is cut off.

And diodes D2 and D3 between point ■ and point ■
A forward bias voltage will be applied to
flows into.

In this way, transistor Ts1 and diode D1
Since both of them are cut-off, the output
The ■ terminal in the primary winding ■-■ of r becomes a float,
The coupling between the primary winding and the secondary winding is released.

Therefore, no AC signal is sent to the transmission line 13.

This is a break in the switch circuit.

When using the above-mentioned switch circuit of the present invention, when looking at the output of the cutoff yarn from the output system output quadrangle, the primary side of the cutoff yarn output quadrance is open, resulting in high impedance, and the output system has a high impedance. It has no impact.

Further, the direct current flowing through the transistor Ts1 has a margin with respect to the alternating current signal current, and the influence of distortion caused by the transistor does not pose much of a problem.

Furthermore, regarding the zero point output of the amplifier AMP, it is convenient to configure the amplifier AMP close to a voltage source because the AC amplitude remains constant regardless of whether the switch circuit is on or off.

Furthermore, when looking at the insertion loss when the switch circuit of the present invention is inserted into an amplifier, it is at most the loss of two diodes, which is not a problem.

As explained above, according to the present invention, the DC current is only shunted from the DC power supply necessary to drive the amplifier, and the circuit configuration is simple, resulting in higher density, smaller size, and lower power consumption.
A switch circuit suitable for high-speed operation is realized.

[Brief explanation of drawings]

Fig. 1 is a block diagram schematically showing a state in which a general switch circuit is inserted into a carrier frequency system having both active and backup systems, and Fig. 2 is a basic switch circuit based on the configuration of Fig. 1 according to the present invention. Block diagram showing the state in which the configuration is incorporated, 3rd
This figure is a circuit diagram showing a preferred embodiment embodying the basic configuration shown in FIG. 2. In the figure, IL21 is the active system, 12.22 is the backup system,
13 is a transmission line, AMP, AMP' is an amplifier circuit, Tr,
Tr' is an output transformer, Di, D2 and D3 are diodes, and Tsl is a switching transistor.

Claims (1)

[Scope of Claims] 1. A switch that includes an amplifier and an output transformer connected to the output stage of the amplifier, and is turned on or off in order to transmit or stop output from the output winding of the output transformer. A switch circuit for driving the amplifier, in which the input winding connected to the output winding of the output transformer is grounded or floated in an alternating current manner to obtain the conduction or cutoff. A series circuit that shunts direct current from a direct current power source in the same direction, the first series circuit consisting of at least two diodes, and at least one diode and a switching transistor connected in parallel to the first series circuit. of the direct current in the series circuit, further comprising a second series circuit in which one end of the input winding is connected to a connection point between the diode and the switching transistor in the second series circuit and connected in parallel. A switch circuit characterized in that the outflow point is grounded by an AC passing capacitor, and the conduction or interruption is obtained by turning on and off the switching transistor.