JPS6068731A - Switch device - Google Patents

Abstract

PURPOSE:To attain quick and sure changeover and also to decrease the attenuation of a signal atended with changeover by constituting a switch device with an electronic switch means in the switch device to which a preamplifier is connected only at the reception. CONSTITUTION:The switch device 100 is a switch inputting a reception signal through the preamplifier at the reception and outputting a signal directly to an antenna not through the preamplifier at the transmission, and has a transceiver input terminal 15, an antenna terminal 16, a preamplifier input terminal 20, an output terminal 18 and a power terminal 25. A switch control section 23 detects the absence of a transmission carrier at the reception to turn on switching diodes D1-D8 and allows the preamplifier to be connected between the antenna terminal 16 and the transceiver input terminal 15. On the other hand, the carrier is detected at the transmission to invert the diodes D1-D8 to be OFF thereby releasing the connection of the preamplifier and leading directly a transmission signal appearing at the terminal 15 to the antenna terminal 16.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a switching device, and more particularly to a switching 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 SZN ratio of a received signal and improve reception sensitivity, a preamplifier or the like is connected to an antenna terminal of the transceiver.

In this case, when receiving, the received signal is input through the preamplifier, while when transmitting, it is output directly to the antenna feed line without going through the preamplifier.

Switch equipment is often required.

Conventionally, it is well known that this type of switch device is constructed using an electromagnetic type relay 1 having, for example, 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.
, connect the fixed contacts 6 and 7 of both switches 3 and 5, and connect the movable contact 8 of the other switch 5 to the second terminal 9 to which the antenna feed line is connected. The third and fourth terminals 12.13 are connected to the other fixed contacts 10.11 of the
(not shown) switches each movable contact 4.8.

When transmitting, the transceiver outputs a signal only through relay 1, and when receiving, it outputs a signal through the fourth and third terminals 13.
The signal is received via a preamplifier 14 inserted between the signals 12 and 12.

However, since the conventional switch device configured in this way is configured to switch using the mechanical displacement of the movable contacts 4 and 8, the switching response speed is slow, and there is a phenomenon called εW chattering. Small vibrations at contact points 4.8 tend 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.
If uncertainties such as chattering as described above occur in the contact operation of the switching device, the high-level high-frequency output signal from the transceiver is likely to be added to the preamplifier during transmission, which has the disadvantage of destroying the expensive gallium arsenide FET. .

[Purpose of the invention]

The present invention has been made to solve these conventional drawbacks, and aims to provide a switching 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. and a first non-contact switch element that performs 0N10FF between the terminal and the second terminal at high frequency.

a second transmission line connecting the first transmission line between the first terminal and the first non-contact switch element and a third terminal;
A second transmission line connected in series to the second transmission line and transmitting 0FF10N at high frequency between the first terminal and the third terminal.
a non-contact switch element, a signal detection circuit arranged between the first terminal and the first non-contact switch element and detecting a signal from the first terminal, and this signal detection circuit. The first non-contact switch element and the second non-contact switch element are switched in response to a detection signal from the first non-contact switch element to cut off the first and second terminals at high frequency, and the first and third terminals are cut off at high frequency. It is equipped with a control circuit that conducts high-frequency conduction between the two.

According to the configuration of the present invention, the first non-contact switch element and the second transmission line are connected to the first transmission line by detecting the signal from the signal source and based on this detection signal. The second non-contact switch element inserted in 0N10
FF, turn on these transmission lines (①), and turn on the second transmission line.
It is possible to turn off the first transmission line and turn on the second transmission line while turning off the first transmission line, and since a non-contact switch device is used, a fast switching response speed can be obtained, and it is reliable. In particular, even when switching and connecting a preamplifier, it is possible to prevent damage to semiconductor elements in the preamplifier, such as expensive gallium arsenide FETs.

[Embodiments of the invention]

The present invention will be explained in detail below.

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

In FIG. 2, a first terminal 15 connected to, for example, an antenna terminal of a transceiver as a signal source includes a capacitor C1 and an inductor Ll+L2.

Capacitor C! and a second terminal 16 are connected in series,
A first transmission path 17 is formed between the first terminal 15 and the second terminal 16.

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 the inductor L1 and the inductor L2, and a plurality of PIN diodes (hereinafter simply referred to as diodes) are connected between this connection point and the ground as a first non-contact switch element. ) D+ to D4 are connected in parallel and in the forward direction to ground.

At the connection point between capacitor C1 and inductor L1.

Diodes D, D6 are connected in series via an inductor L9, and an inductor L4 is connected to the diode D5.
and the third terminal 18 via the capacitor C4 in series.
are connected to form a second transmission path 19.

Note that the diodes D6 and D6 are connected in the forward direction to the first transmission line 17, and the symbol cs + C6 is a capacitor for impedance matching.

A diode D7. D is connected in series and in the forward direction to the first transmission line F, and the fourth terminal 20 is connected to this diode D8 through the inductor L and capacitor C7 in series, and the third A transmission path 21 is formed. Note that the symbols Ca and C9 are capacitors for impedance matching.

Inductor L1 is connected to inductor L1.
7 are arranged adjacent to each other and the first terminal 15 is connected to the base of the transistor TR of the gate 23.

Note that if the inductor L7 is arranged so as to be coupled to the inductor L2, detection will be more reliable.

Carrier control circuit 23, transistor TR,
, TR2, and a photocoupler 24 having one light emitting element and a light receiving element. The emitter of transistor TR is grounded, and the collector is connected to the next stage transistor TR2.
connected to the heath of the.

The collector of the transistor TR2 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 TR becomes a high potential and the transistor TR2 is turned ON, and the light emitting element of the photocoupler 24 is operated to detect light from the light receiving element. It is configured to output direct current.

On the other hand, when a signal is output from the signal detection circuit 22, the collector of the transistor TR becomes a low potential, turning off the transistor TR2, 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 DIo, and when power is supplied to the power terminal 25, the LED 26 lights up.

The output of the carrier control circuit 23 is transmitted to the second transmission line 19 via a resistor 171 and a choke coil RFC.
is connected to the diode D[i in
1 diode D8.

Since the diodes Ds-D are forward-connected to the output of the carrier control circuit 23, the output current from the carrier control circuit 23 is connected to the diodes D5 to D.
8 and diodes D1 to D4, and each diode D
1 to D8 are 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 the LED 27 indicates the state in which the carrier control circuit 23 is outputting current.

Next, the present invention configured as described above will be explained in detail.

For example, the antenna terminal of a transceiver is connected to the first terminal 15, the antenna feed line is connected to the second terminal 16, and the input/output terminal of the preamplifier is connected between the fourth and third terminals 20. When a predetermined power is supplied to the terminal 25,
LED26 lights up.

Power is supplied to the carrier control circuit 23.

Here, when the transceiver is in the reception state, the carrier control circuit 23 receives no detection signal from the signal detection circuit 22, so the collector potential of the transistor TR becomes high and the transistor TR2 turns on.
The photocoupler 24 operates, and a predetermined current is output from the photocoupler 24.

This output current is transmitted through choke coil RFC, diode Ds + Ds + inductor L3. L, and flows through the diode DI-D4, while the choke coil RFC
2, Diode Da, D? , inductor L6 +
L2 and diodes D, ~D4.

Then, diodes D1 to D4 are turned on.

While the inductor 1 and the inductor 2 in the first transmission line 17 are in a high-frequency cutoff state, the diodes D5 to D are turned on and ff52 and the third
The transmission lines 19 and 21 become conductive at high frequencies.

Therefore, high frequency conduction occurs between the first terminal 15 and the third terminal 18, and high frequency conduction occurs between the second terminal 16 and the fourth terminal 20, 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 detected by the signal detection circuit 22 and applied to the carrier control circuit 23.

Then, the base potential of the transistor TR increases and the collector potential decreases, turning the transistor TR2 into an OFF state and no current is output from the photocoupler 24. That is, the output of the carrier control circuit 23 becomes low level.

Therefore, no direct current flows through the second and third transmission paths 19 and 21, and the diode Dl#D is in the OFF state, so that the first terminal 15, the third terminal 18, and the second The terminal 16 and the fourth terminal 20 are disconnected.

Therefore, the high frequency signal applied to the first terminal 5 is directly outputted to the second terminal 16 through the first transmission line 17 without flowing to the second and third transmission lines 19.21. .

According to the applicant's experiments, for example, the first terminal 15
and conduction between 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.

~D8 becomes OFF, the first terminal 15 and the second terminal 16 become conductive, and the first terminal 15 and the third terminal 18 and 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 PI as a non-contact switch element of the first to third transmission lines 17, 19.21.
Using the N diodes D1 to DB, the signal detection circuit 22 detects a high frequency signal flowing through the first transmission line 17, and uses this detection signal to set the diode DH=D e to 0N10F.
Since F operation was performed, compared to a configuration using a conventional relay,
The switching response speed is fast, and uncertain operations such as chattering can be avoided, ensuring reliable operation.

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

Note that in implementing the present invention, other contactless switch elements other than the PIN diodes D1 to D8 can be used as the above-mentioned noncontact switches, but if PIN diodes are used, the configuration becomes simpler.

Further, although an example is shown in which the photocoupler 24 is used in the carrier control circuit 23, the present invention is not limited to the example using this, and the diodes D1 to D8 are
The object of the present invention can be achieved by constructing a control circuit that causes F.

However, the diodes D5 to D8 may have a slight signal detection function, and if the photocoupler 24 is not used, the second and third transmission lines 19, 21 .
Carrier control circuit 23 and signal detection circuit 22
A closed loop circuit is likely to be formed, and the detected signal is sent to the signal detection circuit 2 via the carrier control circuit
2 and lower the gain.

However, if the photocoupler 24 is used in the carrier control circuit 23, an electrical closed loop circuit will not be constructed.
Signal gain reduction can be effectively suppressed.

Furthermore, in the present invention, an example has been shown in which the second transmission line 19 and the third transmission line 21 are connected to the first transmission line 17; Transmission line 2
Even if 1 is omitted, the object of the present invention can be achieved.

In addition, according to the configuration shown in FIG. 2, the first and second terminals 15 and 16 can be used as input and output terminals without having to be used separately for input terminals and output terminals, and the directionality can be changed. This has the advantage that it does not need to be taken into account.

Further, in the present invention, the diodes D1 to D can be connected in a direction opposite to that shown in FIG. 2, and the control circuit may be configured accordingly.

As explained above, the switch device of the present invention is provided.

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 drawings]

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...Second transmission line 21...Third transmission line 22...Signal detection circuit 23... ...Control circuit (carrier control circuit VPI) 24...Photocouplers 01 to C9...Capacitors DI to D4...First non-contact switch element (PI)
N diode) Ds, D, ... second non-contact switch element (PIN
Diode) D? , Dll...Third non-contact switch element (P
IN diode) L5 to L7 ... Inductor agent Patent attorney Miharu Saifuji

Claims (1)

[Claims] A first terminal connecting a first terminal connected to a signal source and a second terminal
Φ transmission line and. a first non-contact switch element connected to the first transmission line and performing 0N10FF between the first terminal and the second terminal at high frequency; a second transmission path connecting the first transmission path between the first terminal and the first non-contact switch element and a third terminal; A second transmission line connected in series to the second transmission line and transmitting 0FF10N at high frequency between the first terminal and the third terminal.
with non-contact switch equipment. a signal detection circuit arranged between the first terminal and the first non-contact switch element and detecting a signal from the first terminal; A switch device comprising a control circuit that switches and operates the first non-contact switch element and the second non-contact switch element based on a detection signal from the signal detection circuit.