JP2000286601A - High-frequency switch device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a high-frequency switch device to select and connect one high-frequency signal out of a plurality of high-frequency signals without connecting a diode which causes attenuation or distortion of the signals to a transmission line. SOLUTION: In a high-frequency switch device 1/4-wavelength phase circuits 12 and 13 are respectively connected between high-frequency signal input-output terminals 2 and 4 and a high-frequency signal input-output terminal 3 for transmitting high-frequency signal and diodes 14 and 15 are forward connected to grounding positions. The switch device switches the high-frequency signals by turning off the diodes by setting the selected one 9 or 11 of connecting points 9 and 11 connected to the input-output terminals 2 and 4 at a low level and by turning on the diodes by setting the other connecting point at a high level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency switching device used for switching high-frequency signals, and more particularly to a high-frequency switching device for selecting and connecting an antenna or a transmitting / receiving device between an antenna and a transmitting / receiving device.

[0002]

2. Description of the Related Art In a time-division two-way communication system (TDD system), since a transmission frequency and a reception frequency are the same,
It is considered that one antenna is used for transmission and reception, and is used for a PHS (Personal Handy Phone System), for example.

In this case, a high-frequency switching device used for an antenna switching device (antenna sharing device) that switches and connects one antenna to a transmitting device or a receiving device includes:
There is one described in JP-A-8-237166.

FIG. 4 shows a circuit diagram of a conventional antenna switching device.

[0005] In FIG. 4, an antenna 29, a transmitting device 30, and a receiving device 31 are connected to an antenna switching circuit 28, and the antenna 29 is connected to the transmitting device 30 or the receiving device according to a control signal input terminal 32. The connection is switched to 31.

Here, the antenna 29 is connected to a connection point 34 through a capacitor 33, the transmission device 30 is connected to a connection point 37 through a transmission filter 35 and a capacitor 36, and the reception device 31 is connected to a reception filter 38. It is connected to a connection point 40 through a capacitor 39.

The connection points 34, 37, 40
Is a connection point inside the antenna switching circuit 28, and the capacitors 33, 36, and 39 are capacitors that block DC components of input / output signals.

[0008] Between the connection point 37 and the connection point 34,
A diode 41 having a forward direction from the connection point 37 to the connection point 34 is provided, and a quarter-wave phase circuit 42 is provided between the connection point 34 and the connection point 40.

A diode 43 is provided between the connection point 40 and the ground position so that the ground direction is forward from the connection point 40. A capacitor 44 and a coil 45 are connected between the connection point 37 and the control signal input terminal 32. Are connected in parallel, and a resistor 46 is provided in series with a parallel resonance circuit.

Here, when a high-level signal is input to the control signal input terminal 32, the diode 41 and the diode 43
, A current flows in the forward direction, so that both the diode 41 and the diode 43 are turned on.

Then, the connection point 37 and the connection point 34 are connected in a circuit (high-frequency signal passes), and the transmission signal output from the transmission device 30 is transmitted by the transmission filter 35 and the capacitor 3.
6, the connection point 37, the diode 41, the connection point 34, and the capacitor 33 are sequentially transmitted from the antenna 29.

The transmission signal is a quarter-wave phase circuit 4
2 does not flow to the connection point 40 because of the large impedance, and the transmission signal does not flow to the control signal input terminal due to the parallel resonance circuit composed of the capacitor 44 and the coil 45.

When a low level signal is input to the control signal input terminal 32, the diode 41 and the diode 43
, The diode 41 and the diode 43 are both turned off.

Then, the connection points 37 and 34 are cut off in circuit (the high-frequency signal does not pass), and the transmission signal output from the transmission device 30 does not reach the connection point 34.

The received signal received by the antenna 29 is
Capacitor 33, connection point 34, quarter wavelength phase circuit 4
2, connection point 40, capacitor 39, reception filter 38
And can be input to the receiving device 31 in order.

Here, since both the diode 41 and the diode 43 are in the off state, the received signal does not flow to the connection point 37 nor to the ground position through the diode 43.

[0017]

However, in the high-frequency switching device represented by the above-mentioned conventional antenna switching device,
Since the diode 41 is connected in series to the path of the transmission signal, there is a problem that the high-frequency signal is attenuated by the on-resistance of the diode 41.

Further, since the forward characteristics (specification of the current value versus the resistance value) of the diode are non-linear, there is a problem that a signal passing therethrough has a waveform distortion.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide an excellent high-frequency switching device that reduces attenuation and waveform distortion generated in a high-frequency signal passing through the high-frequency switching device.

[0020]

For this purpose, a high-frequency switching device according to the present invention comprises at least two high-frequency input / output terminals for inputting or outputting a high-frequency signal, and a high-frequency signal input or output to the at least two high-frequency input / output terminals. A high-frequency connection terminal for selectively connecting the at least two high-frequency input / output terminals in accordance with a control signal, a quarter-wave phase circuit between the high-frequency connection terminal, and a ground point. Between the high-frequency input / output terminal, a diode whose forward direction is the ground direction, and the high-frequency input / output terminal, which is selected from the high-frequency input / output terminals, input a high-level signal with respect to the ground position. The high-frequency input / output terminal includes the control signal for inputting a low-level signal with respect to a ground position, and the high-frequency input / output terminal that receives the high-level signal. It continued the diode is turned on, the diode connected to the high-frequency output terminal receives the signal of the low level is all turned off.

Further, in the high frequency switching device of the present invention, a transmitting device for outputting a transmission signal is connected to one of the at least two high frequency input / output terminals, and a reception signal is connected to the other of the at least two high frequency input / output terminals. And an antenna used for both transmission and reception is connected to the high-frequency connection terminal.

In the high-frequency switching device according to the present invention, a different antenna is connected to each of the at least two high-frequency input / output terminals, and a transmission device for outputting a transmission signal or a reception signal is input to the high-frequency connection terminal. , Or a transmitting / receiving device that performs both transmission signal output and reception signal input.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, there are provided at least two high frequency input / output terminals for inputting / outputting a high frequency signal, and a high frequency signal input / output to / from the at least two high frequency input / output terminals. And a high-frequency connection terminal for selectively connecting the at least two high-frequency input / output terminals according to a control signal.
A quarter-wave phase circuit between the high-frequency connection terminal, a diode having a forward direction from the high-frequency input / output terminal to the ground between the high-frequency input / output terminal, and a high-frequency terminal selected from the high-frequency input / output terminals; A high-frequency switching device comprising: a control signal for inputting a high-level signal to a ground position to an input / output terminal and a low-level signal to a high-frequency input / output terminal to a high-frequency input / output terminal; The diode connected to the high-frequency input / output terminal to which the high-level signal is input is turned on, and the diodes connected to the high-frequency input / output terminal to which the low-level signal is input are all off, and the diode is set to the on state. Only the high-frequency signal input / output to the high-frequency input / output terminal connected to the It can be.

According to a second aspect of the present invention, a transmitter for outputting a transmission signal is connected to one of the at least two high-frequency input / output terminals, and the other of the at least two high-frequency input / output terminals is connected to the other. 2. The high-frequency switching device according to claim 1, wherein a receiving device for inputting a reception signal is connected, and an antenna used for both transmission and reception is connected to the high-frequency connection terminal. Only the transmitted signal or the received signal can be electrically connected to the antenna and the transmission path of the high-frequency signal without inserting a diode.

According to a third aspect of the present invention, there is provided a transmitting device or a receiving device for connecting a different antenna to each of the at least two high frequency input / output terminals and outputting a transmission signal to the high frequency connection terminal. 2. The high-frequency switching device according to claim 1, wherein a receiving device for inputting a signal or a transmitting / receiving device for performing both output of a transmission signal and input of a reception signal is connected, and an antenna connected to the diode in the on state. Only the transmitter, the receiver, or the transmitter / receiver in which only the high-frequency connection terminal is connected to the high-frequency connection terminal can be electrically connected to the transmission path of the high-frequency signal without inserting a diode.

An embodiment of the present invention will be described below with reference to FIGS.

(Embodiment 1) First, Embodiment 1 of the present invention will be described.

FIG. 1 is a circuit diagram of a high-frequency switching device according to Embodiment 1 of the present invention.

The high-frequency switching device of the first embodiment includes a high-frequency switching circuit 1 for switching connection of a high-frequency signal, a high-frequency connection terminal 2 for inputting and outputting a high-frequency signal to and from the high-frequency switching circuit 1,
Three terminals, a high-frequency connection terminal 3 and a high-frequency connection terminal 4,
A control signal input terminal 5 for switching connection of a high-frequency signal.

Here, the selected one of the high-frequency connection terminals 2 and 4 is connected to the high-frequency connection terminal 3.

The high-frequency connection terminal 2 and the high-frequency switching circuit 1
Between the high-frequency connection terminal 3 and the high-frequency switching circuit 1, and between the high-frequency connection terminal 4 and the high-frequency switching circuit 1, respectively. , A capacitor 8.

The high frequency switching circuit 1 has a connection point 9 connected to the capacitor 6, a connection point 10 connected to the capacitor 7, and a connection point 11 connected to the capacitor 8 in the same manner.
A quarter-wave phase circuit 12 is provided between the connection point 9 and the connection point 10, and the fourth wavelength phase circuit 12 is provided between the connection point 10 and the connection point 11.
A one-wavelength phase circuit 13 is provided.

A diode 14 having a forward direction from the connection point 9 to the ground is provided between the connection point 9 and the ground position.
A diode 15 is provided between the connection point 11 and the ground position so that the ground direction from the connection point 11 is forward.

A control signal inverting circuit 1 for inverting the polarity of the control signal is provided between the control signal input terminal 5 and the connection point 9.
6 and a coil 17 are provided in series, and a coil 18 is provided between the control signal input terminal 5 and the connection point 11.

Here, the coil 17 and the coil 18 prevent a high-frequency signal input to the high-frequency connection terminal 3 or the high-frequency connection terminal 5 from flowing into the control signal input terminal 8.

Next, the operation of the high-frequency switching device according to the first embodiment of the present invention will be described.

When a high-level signal is input to the control signal input terminal 5, the connection point 9 goes low through the control signal inverting circuit 16 and the coil 17, and the diode 14 becomes reverse-biased to turn off the current. Does not flow.

On the other hand, the connection point 11 becomes high level through the coil 18, the diode 15 is turned on, and a forward current flows.

When the diode 14 is turned off, the high-frequency connection terminal 2 and the high-frequency connection terminal 3 are connected in a circuit and a signal flows. When the diode 15 is turned on, the high-frequency connection terminal 4 is grounded through the diode 15. The circuit between the high frequency connection terminal 3 and the high frequency connection terminal 4 is cut off.

When the diode 15 is on, the quarter-wave phase circuit 13 has a large impedance as viewed from the high-frequency connection terminal 4 side. The input high-frequency signal is prevented from flowing through the quarter-wave phase circuit 13.

Similarly, when a low level signal is input to the control signal input terminal 5, the connection point 9 is connected to the control signal inversion circuit 16
High level through the coil 17 and the diode 1
4 is turned on, a forward current flows, the connection point 11 becomes high level through the coil 18 and the diode 15
Is turned off because of reverse bias, and no current flows.

Therefore, the circuit between the high-frequency connection terminal 2 and the high-frequency connection terminal 3 is cut off in a circuit, and the high-frequency connection terminal 3 and the high-frequency connection terminal 4 are connected in a circuit, so that a signal flows.

Here, the quarter-wave phase circuit 12 is connected to the high-frequency connection terminal 2 when the diode 14 is on.
Since the impedance viewed from the side is large, the high-frequency signal input to the high-frequency connection terminal 3 or the high-frequency connection terminal 4 is prevented from flowing through the quarter-wave phase circuit 12.

Accordingly, the high-frequency connection terminal 2 and the high-frequency connection terminal 4 are controlled according to the signal input to the control signal input terminal 5.
Can be selected to be connected to the high-frequency connection terminal 3, and there is no need to insert a diode in the transmission path of the high-frequency signal.

(Embodiment 2) Next, Embodiment 2 of the present invention will be described.

FIG. 2 is a circuit diagram of an antenna switching apparatus according to a second embodiment of the present invention, which is a TDD system such as a PHS and uses one antenna by dividing time for both transmission and reception. It is.

The antenna switching device of the present invention is the same as the high-frequency signal switching device shown in FIG. 1, in which a high-frequency connection terminal 2 is connected to a transmission device 20 through a transmission filter 19,
An antenna 21 is connected to the high-frequency connection terminal 3, and a reception device 23 is connected to the high-frequency connection terminal 4 through a reception filter 22.
Connect.

At this time, the input signal of the control signal input terminal 5 is switched between a high level and a low level according to the transmission / reception timing.

At the time of transmission, when a high level is input to the control signal input terminal 5 to turn off the diode 14 and turn on the diode 15 and perform transmission from the transmission device 20, the transmission signal is transmitted. Arrives at the connection point 9 through the transmission filter 19 and the capacitor 6,
Quarter-wave phase circuit 12, connection point 10, capacitor 7
, A transmission signal is output from the antenna 21.

Here, the transmission signal does not flow through the diode 14 because the diode 14 is in the OFF state, and does not flow through the quarter-wave phase circuit 14 because of the large impedance.

At the time of reception, a low level is input to the control signal input terminal 5 to turn on the diode 14 and turn off the diode 15, and the reception signal received by the antenna 21 is transmitted to the connection point 10 through the capacitor 7. Arriving, a reception signal is input to the reception device 23 through the quarter-wave phase circuit 13, the connection point 11, the capacitor 8, and the reception filter 22.

Here, the received signal does not flow through the diode 15 because the diode 14 is in the OFF state, and does not flow through the quarter-wave phase circuit 13 because of the large impedance.

Therefore, it is possible to select which of the transmitting device 19 and the receiving device 22 is connected to the antenna 21 in accordance with the signal input to the control signal input terminal 5, and to connect a diode to the transmission path of the high-frequency signal. No need to insert.

Embodiment 3 Next, Embodiment 3 of the present invention will be described.

FIG. 3 shows a reception diversity system such as a cellular phone, and an antenna switching apparatus according to a third embodiment of the present invention which selects and uses two antennas having a high reception strength of a reception signal. FIG.

The antenna switching device of the present invention is the same as the high-frequency signal switching device shown in FIG. 1. The antenna 24 is connected to the high-frequency connection terminal 2, and the reception device 26 is connected to the high-frequency connection terminal 3 through the reception filter 25. And the antenna 27 is connected to the high-frequency connection terminal 4.

At this time, the input signal of the control signal input terminal 5 is switched between a high level and a low level in accordance with the difference in the reception strength between the antenna 24 and the antenna 27.

When the reception strength of the antenna 24 is high, a high level is input to the control signal input terminal 5 to turn off the diode 14 and turn on the diode 15.
To the connection point 9 through the
2. A reception signal is input to the reception device 26 through the connection point 10, the capacitor 7, and the reception filter 25.

Here, the received signal does not flow through the diode 14 because the diode 14 is in the off state, and does not flow through the quarter-wave phase circuit 14 because of the large impedance.

When the reception intensity of the antenna 27 is high, a low level is input to the control signal input terminal 5 to turn on the diode 14 and turn off the diode 15 so that the reception signal received by the antenna 26 To the connection point 11 through the
3. A reception signal is input to the reception device 26 through the connection point 10, the capacitor 7, and the reception filter 25.

Here, the received signal does not flow through the diode 15 because the diode 14 is in the OFF state, and does not flow through the quarter-wave phase circuit 13 because the impedance is large.

Therefore, it is possible to select which of the antenna 24 and the antenna 27 is connected to the receiving device 26 in accordance with the signal input to the control signal input terminal 5, and to insert a diode into the transmission line of the high-frequency signal. No need to do.

Although FIG. 3 shows the case of the reception diversity system, the control signal input terminals 5 of the antennas 24 and 27 are provided by using a transmission filter and a transmission device instead of the reception filter 25 and the reception device 26. May be transmitted from the antenna selected by the signal input to the.

The number of high-frequency connection terminals connected to the selected high-frequency signal may be one, and the number of input / output terminals of the selected high-frequency signal may be more than two as described above. A quarter-wave phase circuit is independently provided between each of the signal input / output terminals and the high-frequency connection terminal connected to the selected high-frequency signal, and a plurality of selected high-frequency signals are input. Each of the output terminals is independently provided with a diode having the installation point direction as a forward direction between the installation point and each terminal, and furthermore, only a terminal selected from among a plurality of terminals for inputting and outputting a high frequency signal is set to a high level by a control signal, A diode connected to the input / output terminal of the selected high-frequency signal by setting all the terminals for inputting / outputting the other high-frequency signals to the low level by the control signal Only the OFF state, it is possible to construct a high-frequency switching device by a diode connected to a terminal for inputting and outputting the other high-frequency signal is turned on.

[0065]

As described above, according to the present invention, it is possible to construct a high-frequency switching device without providing a diode in the transmission path of a high-frequency signal, so that high-frequency signal attenuation and waveform distortion due to the diode can be reduced. be able to.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a high-frequency switching device according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram of an antenna switching device according to a second embodiment of the present invention.

FIG. 3 is a circuit diagram of an antenna switching device according to a third embodiment of the present invention.

FIG. 4 is a circuit diagram of a conventional antenna switching device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 high-frequency switching circuit 2 high-frequency signal connection terminal 3 high-frequency signal connection terminal 4 high-frequency signal connection terminal 5 control signal input terminal 12 quarter-wave phase circuit 13 quarter-wave phase circuit 14 diode 15 diode 16 control signal inversion circuit 20 Transmitting device 21 Antenna 23 Receiving device 24 Antenna 26 Receiving device 27 Antenna

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5J006 KA03 KA24 LA02 5J012 BA04 5K011 BA01 DA01 DA22 GA04 JA01 KA04

Claims (3)

[Claims] At least two high-frequency input / output terminals for inputting or outputting a high-frequency signal, and a high-frequency connection for selectively connecting high-frequency signals input or output to the at least two high-frequency input / output terminals in accordance with a control signal A quarter-wave phase circuit between the terminal and the at least two high-frequency input / output terminals, and a quarter-wave phase circuit between the terminal and the high-frequency connection terminal; A high-level signal is input to the grounding position to the high-frequency input / output terminal that selects one of the high-frequency input / output terminals from the high-frequency input / output terminal. And the control signal for inputting the signal of the high level, the diode connected to the high frequency input / output terminal to which the signal of the high level is input is turned on, and the low level A high-frequency switching device that turns off the diode connected to a high-frequency input / output terminal to which a signal is input. 2. A transmission device for outputting a transmission signal is connected to one of the at least two high frequency input / output terminals, and a reception device for inputting a reception signal is connected to the other of the at least two high frequency input / output terminals. The high-frequency switching device according to claim 1, wherein an antenna used for both transmission and reception is connected to the high-frequency connection terminal. 3. A transmission device for outputting a transmission signal, a reception device for inputting a reception signal, or a transmission signal, wherein a different antenna is connected to each of the at least two high-frequency input / output terminals and the high-frequency connection terminal is connected. 2. The high-frequency switching device according to claim 1, further comprising a transmission / reception device that performs both output of the signal and input of a reception signal.