JPH0252459B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a switch device, and particularly to a switch device suitable for use between an antenna terminal of a transceiver, such as a personal radio, and an antenna feed line.

[Prior art and its problems]

2. Description of the Related Art In transceivers and the like, in order to increase the S/N ratio of a received signal and improve reception sensitivity, a preamplifier or the like is connected to an antenna terminal of the transceiver.

In such cases, the received signal is input through a preamplifier during reception, but is output directly to the antenna feed line without going through the preamplifier during transmission, so a switch device is often required.

Conventionally, it is well known that this type of switch device is constructed using, for example, an electromagnetic type relay 1 having two circuits and two contacts, as shown in FIG.

That is, the first terminal 2 connected to the antenna terminal of the transceiver is connected to the movable contact 4 of one switch 3 of the relay 1, the fixed contacts 6 and 7 of both switches 3 and 5 are connected, and the other switch is connected to the movable contact 4 of one switch 3 of the relay 1. The movable contact 8 of switch 3 and 5 is connected to the second terminal 9 to which the antenna feed line is connected.
The third and fourth fixed contacts 10 and 11 are connected to the other fixed contacts 10 and 11 of
Terminals 12 and 13 of the transceiver are connected to each other, and each movable contact 4 and 8 is switched by a drive mechanism (not shown), and a signal is output only through relay 1 when the transceiver is transmitting, and a signal is output when receiving. The signal is received via a preamplifier 14 inserted between the fourth and third terminals 13 and 12.

However, since the conventional switch device configured in this way is configured to switch using mechanical displacement of the movable contacts 4 and 8, the switching response speed is slow, and the movable contacts suffer from so-called chatter. 4 and 8 thin vibrations are likely to occur,
Unreliable operation or contact failure is likely to occur during switching.

Therefore, switching between the antenna feed line and the preamplifier tends to be uncertain, and signal attenuation tends to occur.

Particularly in recent years, gallium arsenide FETs, which have good frequency characteristics for high-frequency signals, are often used in preamplifiers, and when uncertainties such as chatter as mentioned above occur in switching devices, high-level noise from the transceiver during transmission can occur. The problem is that the high-frequency output signal is easily added to a preamplifier, which can destroy the expensive gallium arsenide FET.

[Purpose of the invention]

The present invention has been made to solve these conventional drawbacks, and its object is to provide a switch device that has extremely fast switching response speed, reliable switching operation, and minimal signal attenuation.

[Structure and effects of the invention]

In order to achieve such an object, the present invention provides a first transmission line connecting a first terminal connected to a signal source and a second terminal, and a first transmission line connected to the first transmission line and connected to the first transmission line. a first non-contact switch element that turns ON/OFF between the terminal and the second terminal at high frequency;
a second transmission line connecting the first transmission path between the first terminal and the first non-contact switch element and the third terminal;
a second non-contact switch element that is connected in series to the second transmission line and turns OFF/ON between the first terminal and the third terminal at high frequency; a signal detection circuit arranged between a terminal and the first non-contact switch element and detecting a signal from the first terminal; and a signal detection circuit that detects a signal from the first terminal; and a control circuit that switches the element and the second non-contact switch element to cut off the first and second terminals at high frequency and conduct the first and third terminals at high frequency. This is what happens.

According to the configuration of the present invention, the first non-contact switch element connected to the first transmission line and the second transmission line detect the signal from the signal source and based on this detection signal, The second non-contact switch element inserted into the
Turn on the first transmission line and turn off the second transmission line
On the other hand, it is possible to turn off the first transmission line and turn on the second transmission line, and since a non-contact switch element is used, a fast switching response speed is obtained and reliable switching is ensured. It is possible to do so.

In particular, even when switching and connecting preamplifiers, etc., it is possible to suppress damage to semiconductor elements in the preamplifier, such as expensive gallium arsenide FETs.

[Embodiments of the invention]

The details of the present invention will be explained below.

FIG. 2 is a circuit diagram showing an embodiment of the switch device of the present invention.

In FIG. 2, a first terminal 1 is connected to an antenna terminal of a transceiver, for example, as a signal source.
5, a capacitor C ₁ , inductors L ₁ , L ₂ , capacitor C ₂ and a second terminal 16 are connected in series, and a first transmission path 17 is formed between the first terminal 15 and the second terminal 16. has been done.

Note that, for example, an antenna feed line is connected to the second terminal 16.

A semi-fixed capacitor _C3 for impedance matching is connected to the connection point between inductor _L1 and inductor _L2 , and a plurality of two PIN diodes (2 PIN diodes) are connected between this connection point and ground as the first non-contact switch element. (hereinafter simply referred to as diodes) D ₁ to _{D 4}
are connected in parallel and forward to ground.

At the connection point of capacitor C ₁ and inductor L ₁ ,
Diodes D ₅ and D ₆ are connected in series via an inductor L ₃ , and a third terminal 18 is connected to the diode D ₆ via an inductor L ₄ and a capacitor C ₄ in series. A passage 19 is formed.

Note that the diodes D ₅ and D ₆ are forward-connected to the first transmission line 17, and symbols C ₅ and C ₆ are capacitors for impedance matching.

Diodes D ₇ and D ₈ are connected in series and in the forward direction to the first transmission path 17 via an inductor L ₅ at the connection point between the capacitor C ₂ and the inductor L ₂ , and the inductor L is connected to the diode D ₈ in series. ₆ and the fourth terminal 20 through the capacitor C ₇ in series.
are connected to form a third transmission path 21. Note that symbols C ₈ and C ₉ are capacitors for impedance matching.

An inductor L ₇ is arranged close to the inductor L ₁ so as to be coupled thereto, and a signal detection circuit 22 for detecting a high frequency signal from the first terminal ₁₅ is configured _. It is connected to the base of the transistor _TR1 of the carrier control circuit 23 as a control circuit.

Note that if the inductor _L7 is arranged so as to be coupled to the inductor _L2 , detection becomes more reliable.

The carrier control circuit 23 includes transistors TR ₁ and TR ₂ and a photocoupler 24 having a light emitting element and a light receiving element. The emitter of the transistor TR ₁ is grounded, the collector is connected to the base of the next stage transistor TR ₂ , the collector of the transistor TR ₂ is connected to the power supply, and the emitter is connected to the photocoupler 24.

In the carrier control circuit 23, when there is no input signal from the signal detection circuit 22, the collector of the transistor _TR1 becomes high potential and the transistor
The configuration is such that when TR ₂ is turned ON, the light emitting element of the photocoupler 24 is activated and a direct current is output from the light receiving element.

On the other hand, when a signal is output from the signal detection circuit 22, the collector of the transistor _TR1 becomes a low potential and the transistor _TR2 is turned off, the light emitting element of the photocoupler 24 does not operate, and the output becomes L level. has been done.

Note that power to the carrier control circuit 23 is applied via a power terminal 25 and a protection diode _D10 , and when power is supplied to the power terminal 25, the LED 26 lights up.

The output of the carrier control circuit 23 is a resistor
It is connected to the diode D ₆ in the second transmission path 19 via R ₁ and the current coil RFC ₁ , and is also connected to the diode D ₈ in the third transmission path 21 via the resistor R ₂ and the current coil RFC ₂ . .

Since the diodes D ₅ to _{D 8} are forward-connected to the output of the carrier control circuit 23,
Output current from the carrier control circuit 23 flows through the diodes _D5 to _D8 and the diodes _D1 to _D4 , and each of the diodes _D1 to _D8 is turned on.

On the other hand, when the current output of the carrier control circuit 23 disappears, the diodes _D1 to _D8 are turned off.

Note that LED27 is carrier control circuit 2.
3 indicates a state in which current is being output.

Next, the operation of the present invention configured as described above will be explained.

For example, an antenna terminal of a transceiver is connected to the first terminal 15, an antenna feed line is connected to the second terminal 16, a preamplifier input/output end is connected between the fourth and third terminals 20 and 18, and the power supply terminal is connected. When the specified power is supplied to 25, the LED 26 lights up.
Power is supplied to the carrier control circuit 23.

Here, when the transceiver is in the receiving state, the carrier control circuit 23 controls the signal detection circuit 2.
Since no detection signal is input from transistor TR 2, the collector potential of transistor TR ₁ becomes high and the transistor
TR ₂ becomes ON, the photocoupler 24 operates, and a predetermined current is output from the photocoupler 24.

This output current flows through the chiyoke coil RFC ₁ , diodes D ₆ , D ₅ , inductors L ₃ , L ₁ and diodes D ₁ to _{D 4} , while the chiyoke coil
RFC ₂ flows through diodes D ₈ , D ₇ , inductors L ₅ , L ₂ and diodes D ₁ to _{D 4} .

Then, diodes D ₁ to D ₄ turn on, and the first
The inductor L ₁ and the inductor L ₂ in the transmission line 17 are in a high frequency cut off state, while the diodes D ₅ to D ₈ are turned on and the second and third transmission lines 19 and 21 are in a high frequency cut off state. becomes conductive.

Therefore, the first terminal 15 and the third terminal 18 are electrically connected at high frequency, and the second terminal 16 and the fourth terminal 20 are electrically electrically connected at high frequency, so that the received signal from the second terminal 16 is outputted to the preamplifier via the fourth terminal 20, and the output of the preamplifier is outputted from the third terminal 18 via the first terminal 15.

Next, a case will be described in which the transceiver enters the transmitting state and outputs a high frequency signal.

In this case, the high frequency signal is transmitted to the signal detection circuit 22.
carrier control circuit 2
Added to 3.

Then, the base potential of transistor TR ₁ increases, the collector potential decreases, and transistor TR ₂
is turned off, and the current output from the photocoupler 24 disappears. That is, the output of the carrier control circuit 23 becomes low level.

Therefore, no direct current flows through the second and third transmission lines 19 and 21, and the diodes _D1 to _D8 are turned OFF.
state, the first terminal 15 and the third terminal 1
8 and between the second terminal 16 and the fourth terminal 20.

Therefore, the high frequency signal applied to the first terminal 15 does not flow to the second and third transmission paths 19 and 21, but directly passes through the first transmission path 17 to the second transmission path.
It is output to terminal 16 of.

According to the applicant's experiments, for example, continuity between the first terminal 15 and the third terminal 18,
The signal separation degree at the time of interruption was 30 dB or more.

If the power is in the OFF state, each diode D ₁ ~
D ₈ becomes OFF, the first terminal 15 and the second terminal 16 become conductive, and the first terminal 15 and the third terminal 18 and between the second terminal 16 and the fourth terminal 20 respectively. is cut off in terms of high frequency, so the high frequency signal applied to the first terminal 15 and the received signal input to the second terminal 16 flow directly through the first transmission path 17.

Such a switch device of the present invention uses PIN diodes D ₁ to D ₈ as non-contact switch elements of the first to third transmission lines 17 , 19 , and 21 to switch the high-frequency signal flowing through the first transmission line 17 . Signal detection circuit 2
2 and use this detection signal to connect the diode.
Since D ₁ to D ₈ are operated ON/OFF, the switching response speed is faster than in a configuration using a conventional relay, and there is no uncertain operation such as chattering, and reliable operation can be ensured.

Therefore, even if a preamplifier using gallium arsenide FETs or the like is used, the expensive gallium arsenide FETs will not be destroyed.

In carrying out the present invention, it is possible to use other non-contact switch elements in addition to the PIN diodes D ₁ to _{D 8} as the non-contact switches described above, but if the PIN diodes are used, the configuration becomes easy.

Further, although an example in which the photocoupler 24 is used in the carrier control circuit 23 has been shown, the present invention is _not limited to the example in which this is used;
The object of the present invention can be achieved by constructing a control circuit that turns _D8 ON/OFF.

However, the diodes D ₅ to _{D 8} may have a slight signal detection function, and if the photocoupler 24 is not used, the second and third transmission lines 19 and 21 and the carrier control circuit 23
A closed loop circuit is likely to be formed by the signal detection circuit 22 and the detected signal flows to the signal detection circuit 22 via the carrier control circuit 23, reducing the gain.

However, if the photocoupler 24 is used in the carrier control circuit 23, an electrical closed loop circuit is not constructed, and a decrease in signal gain can be suppressed.

Furthermore, in the present invention, the first transmission line 17
The second transmission line 19 and the third transmission line 2
1 is shown, however, the object of the present invention can be achieved even if the second transmission line 19 or the third transmission line 21 is omitted.

In addition, according to the configuration shown in FIG. 2, the first and second terminals 15 and 16 are not used separately for input ends and output ends, and either one can be used as an input/output end. This has the advantage that there is no need to take this into account.

Further, in the present invention, diodes D ₁ to _{D 8}
It is also possible to connect in the opposite direction to that shown in FIG. 2 above, and the control circuit may be configured accordingly.

As explained above, the switch device of the present invention has
It is possible to obtain reliable switching operation with fast response speed.

This effect is particularly significant when switching circuits such as preamplifiers that use semiconductor elements that are sensitive to large inputs.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a conventional switch device, and FIG. 2 is a circuit diagram showing an embodiment of the switch device of the present invention. 1... Relay, 2, 15... First terminal, 9, 16
...Second terminal, 12, 18...Third terminal, 13,
20... Fourth terminal, 17... First transmission line, 19...
2nd transmission line, 21...Third transmission line, 22...Signal detection circuit, 23...Control circuit (carrier control circuit), 24...Photocoupler, _C1 to _C9 ...Capacitor, _D1 to _D4 ...First non-contact switch element (PIN diode), D ₅ , D ₆ ... second non-contact switch element (PIN diode), D ₇ , D ₈ ... third non-contact switch element (PIN diode), L ₁ to L ₇ ...
inductor.

Claims (1)

[Claims] 1. A first transmission line connecting a first terminal and a second terminal connected to a signal source; and a first transmission line connecting the first terminal and the second terminal connected to the first transmission line. a first non-contact switch element that turns ON/OFF between terminals at high frequency; and a third terminal is connected to the first transmission line between the first terminal and the first non-contact switch element. a second transmission line; and a second transmission line connected in series to the second transmission line and connected at high frequency between the first terminal and the third terminal.
a second non-contact switch element that turns OFF/ON; a signal detection circuit that is arranged between the first terminal and the first non-contact switch element and detects a signal from the first terminal; 1. A switch device comprising: a control circuit that switches the first non-contact switch element and the second non-contact switch element based on a detection signal from a signal detection circuit.