JPH0983206A - High frequency switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the high frequency switch with a small insertion loss and in which a control voltage application wiring pattern can be simplified. SOLUTION: A high frequency switch 1 has 1st to 4th ports P1-P4, distributed constant lines 2a-2d connected among the ports, a capacitor 3a, 3c, 3e, 3g connected respectively between a connecting point A, C, E, G of the distributed constant line 2a-2d and each port, a diode 4a-4d connected respectively between the connecting point A, C, E, G and a reference potential point, and a capacitor 3b, 3d, 3f, 3h connected respectively between the diode 4a-4d and the reference potential point. A 1st to 4th control voltage terminal Vc1-Vc4 is connected to a connecting point B, D, F, H between the diode 4a-4d and the capacitor 3b, 3d, 3f, 3h.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency switch for switching a signal path in a high frequency circuit such as a mobile phone, and more particularly to a high frequency switch having four ports and utilizing a distributed constant line.

[0002]

2. Description of the Related Art In a mobile phone, two antennas,
Or one antenna and one external connection terminal,
It may be shared by the transmitter and receiver. In such a configuration, for example, the switch circuit shown in FIG. 7 has been conventionally used.

The switch circuit 51 has a configuration in which three-port switches 52 and 53 are connected. Switch 52
It has a first port P21, a second port P22, and a third port P23. Similarly, the switch 53 includes
It has third ports P31, P32 and P33. The antenna ANT is connected to the second port P22 of the switch 52, and the third port P23 is connected to the external connection terminal EXT.
It has been. An example of use as an external connection terminal is a case where a predetermined signal is input from the external connection terminal when measuring the electrical characteristics of the receiving unit of the mobile phone having the switch circuit 51 built therein. Also, the third
A second antenna may be connected to the port P23. That is, in an in-vehicle mobile phone or the like, it is possible to connect and use the antenna equipped in the vehicle as the second antenna.

In the switch 52, the first port P
21 is the second port P22 or the third port P
23 is configured to be switched. The first port P21 is the first port P3 of the switch 53.
1 connected.

The first port P31 of the switch 53 is constructed so that the connection can be switched between the second port P32 and the third port P33. The second port P32 is connected to the transmitter Tx, and is connected to the third port P33.
Is connected to the receiving unit Rx.

By using the switch circuit 51, it is possible to realize a state in which either the antenna ANT or the external connection terminal EXT is connected to the transmission unit Tx or the reception unit Rx.

By the way, the 3-port type switch 52,
As a component for forming 53, a high frequency switch 61 using a diode shown in FIG. 8 is known. The high frequency switch 61 has the first to third ports P21 to P21.
23, P31 to P33 corresponding to first to third ports P
61 to P63. The first port P61 is connected to the cathode of the diode 65a via the capacitor 64. The anode of the diode 65a is connected to the second port P62 via the capacitor 66a.
Also, the anode of the diode 65a and the capacitor 66a
One end of the distributed constant line 67a is electrically connected to the connection point of. The distributed constant line 67a has a wavelength of λ /, where λ is the wavelength of the high-frequency signal flowing through the high-frequency switch 61.
It is composed of a strip line having a length of 4 or less, a micro strip line, a coplanar guide line, a high impedance transmission line, or the like. The other end of the distributed constant line 67a is connected to the ground potential via the capacitor 68a. Further, one end of the resistor 69a is connected to the connection point between the distributed constant line 67a and the capacitor 68a, and the other end of the resistor 69a is connected to the control voltage terminal Vc1. Further, the first port P61 is connected via a capacitor 64 to one end of a distributed constant line 71 configured similarly to the distributed constant line 67a. The other end of the distributed constant line 71 is connected to the ground potential.

Further, the cathode of the diode 65b is connected to the first port P61 via the capacitor 64. The anode of the diode 65b is connected to the third port P63 via the capacitor 66b.
In addition, similarly to the diode 65a side, the diode 65b
The distributed constant line 67b and the capacitor 6 are also connected to the anode of
A series circuit composed of 8b is connected to the ground potential. Further, one end of the resistor 69b is connected to a connection point between the distributed constant line 67b and the capacitor 68b, and the other end of the resistor 69b is connected to the control voltage terminal Vc2.

In the high frequency switch 61, the control voltage terminal V
By applying different control voltages to c1 and the control voltage terminal Vc2, the first port P61 is connected to the second port P62, or the third port P63.
Can be connected to. For example, when a positive control voltage is applied to the control voltage terminal Vc1 and a negative control voltage is applied to the control voltage terminal Vc2, the diode 6
A forward bias voltage is applied to 5a, and a reverse bias voltage is applied to the diode 65b. That is, the capacitors 66a and 68
Since a, 64, 66b, and 68b limit the portion through which direct current flows, the control current supplied from the control voltage terminal Vc1 is cut and the distributed constant line 67a and the diode 65a are cut off.
And the diode 65a is turned on by flowing into the circuit portion including the distributed constant line 71. On the other hand, the diode 65b
On the side, the reverse bias voltage is applied to the diode 65b, and the diode 65b is turned off.

As for the high frequency signal supplied from the second port P62, one end of the distributed constant line 67a can be set to the ground potential in a high frequency because the distributed constant line 67a is configured as described above. Therefore, the impedance inversion of λ / 4 makes the impedance of the series circuit including the distributed constant line 67a and the capacitor 68a as viewed from the connection point between the anode of the diode 65a and the capacitor 66a infinite. Therefore, the high frequency signal supplied from the second port P62 flows to the first port P61.

On the other hand, when a negative control voltage is applied to the control voltage terminal Vc1 and a positive control voltage is applied to the control voltage terminal Vc2, a reverse bias voltage is applied to the diode 65a, contrary to the above. A forward bias voltage is applied to the diode 65b.
That is, the diode 65a is turned off and the diode 65b is turned on. Therefore, no signal flows between the second port P62 and the first port P61,
A signal will flow between the first port P61 and the third port P63. Also in this case, since the impedance of the series circuit including the distributed constant line 67b and the capacitor 68b as viewed from the connection point of the anode of the diode 65b and the capacitor 66b becomes infinite, the high frequency signal does not flow to the distributed constant line 67b side.

The distributed constant lines 67a and 67b form a current path for flowing a control current to the diodes 65a and 65b, and the diode 6 is used for a high frequency signal.
The impedance of the distributed constant lines 67a and 67b viewed from the connection point between the anode of 5a and the capacitor 66a and the connection point of the anode of the diode 65b and the capacitor 66b is increased, and the insertion loss and the reflection loss are reduced.

As described above, in the high frequency switch 61,
By applying positive and negative control voltages to the control voltage terminals Vc1 and Vc2, a state in which the first port P61 is switched to the second port P62 or the third port P63 can be realized.

The switch circuit 51 shown in FIG.
The high frequency switch 61 is used as the switches 52 and 53. That is, it is configured by using two 3-port high frequency switches and connecting the first ports of each other to each other.

[0015]

The switch circuit 51 is
As described above, since it is configured by connecting the two high frequency switches 52 and 53, the high frequency signal passes through the two switches. For example, the transmitter Tx
The transmission output given by the signal passes through the two switches 53 and 52 before being given to the antenna ANT. Similarly, the high frequency signal input from the antenna ANT passes through the switches 52 and 53 and is given to the receiving unit Rx. Therefore, the insertion loss is inevitably large, so that there is a problem that it is necessary to increase the transmission output at the time of transmission, and the gain is lowered at the time of reception.

Further, in the switch circuit 51, since the switches 52 and 53 are constructed by using the high frequency switch 61, it is necessary to apply the control voltage to the two control voltage terminals in each of the switches 52 and 53, Each of the switches 52 and 53 requires two control voltage supply power supplies. As a result, a complicated wiring pattern for the power supply has to be formed on the circuit board.

The object of the present invention is to solve the above problems, and the insertion loss is small, the number of constituent parts can be reduced, and the wiring pattern for supplying the control voltage is simplified. It is to provide a high frequency switch to obtain.

[0018]

In order to solve the above problems, the present invention has first to fourth ports, and
A high-frequency switch in which a second port is connected to a third or fourth port, the first port and the third port, the third port, the second port, the second port, and the fourth port. And fourth,
It is characterized in that distributed constant lines are connected between the first ports.

Further, it is characterized in that diodes are respectively connected between the first to fourth ports and the reference potential.

Further, the invention is characterized in that first to fourth control voltage terminals are connected between the diode and the reference potential, respectively.

A distributed constant line is connected in parallel to the diode, one end of each of the distributed constant lines is connected to a common connection point, and a fixed voltage terminal is connected to the common connection point.

Further, at least one of the connection point between the diode connected to the first to fourth ports and the reference potential and the common connection point is connected to the first to fourth control terminals via a resistor. It is characterized in that it is connected to a voltage terminal and a fixed voltage terminal.

Further, at least one of the first to fourth ports is connected to the reference potential via a capacitor.

Further, it is characterized in that a resistor connected in parallel to at least one of the diodes is provided.

Further, a series circuit of a distributed constant line and a capacitor is connected in parallel with at least one of the diodes.

Further, a series circuit of a distributed constant line and a capacitor is connected in parallel with at least one of the diodes, and a capacitor is connected in parallel with a series circuit of the distributed constant line and the capacitor.

According to the high frequency switch of the present invention, the first,
Distributed ports are connected between the third ports, between the third and second ports, between the second and fourth ports, and between the fourth and first ports. Further, since these distributed constant lines form the ring-shaped circuit portion connected as described above, and the first to fourth ports are connected as described above, the ring-shaped circuit portion The ports are connected in the order of the first port, the third port, the second port, and the fourth port along the circumferential direction.

Therefore, by turning on any of the distributed constant lines between the first to fourth ports, the first and third ports are connected (first connection state) and the first and third ports are connected. , A state in which the fourth port is connected (second connection state), a state in which the second and third ports are connected (third connection state), or a state in which the second and fourth ports are connected The state (fourth connection state) can be realized.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In each of the embodiments, the same or equivalent parts as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

FIG. 1 shows a first high-frequency switch according to the present invention.
3 is a schematic circuit diagram for explaining the embodiment of FIG. The high frequency switch 1 has first to fourth ports P1 to P4,
It is a 4-port high frequency switch. First and third port P
1 and P3, 1st and 4th ports P1 and P4, 2nd,
Between the third ports P2 and P3, the second and fourth ports P2,
Distributed constant lines 2a, 2b, 2c, and 2d are connected between P4 for switching. That is,
The distributed constant lines 2a to 2d are connected in a ring shape.

Then, the high frequency switch 1 realizes the following first to fourth connection states, and it is possible to switch between these connection states. First
In the connection state, the first and third ports P1 and P3 are connected, and in the second connection state, the first and fourth ports P1 and P3 are connected.
1 and P4 are connected, in the third connection state, the second and third ports P2 and P3 are connected, and in the fourth connection state, the second and fourth ports P2 and P4 are connected The realized state is realized.

Therefore, the high frequency switch 1 of this embodiment can be preferably used in the high frequency switch circuit 51 of FIG. That is, in the high frequency switch circuit 51 of FIG. 7, the transmitter Tx is connected to the antenna ANT (during transmission) and the transmitter Tx is connected to the external connection terminal EXT (the external connection terminal EXT is connected to the second antenna). When the receiver Rx is connected to the antenna ANT (during reception), the external connection terminal EX is connected to the receiver Rx.
It is only necessary to realize one of the states in which T is connected (e.g., when the performance of the receiving unit is evaluated or when an external antenna is connected to the external connection terminal EXT to receive). When the high frequency switch 1 of the present embodiment is used, for example, the first port P1 is used as the transmitter Tx, the second port P2 is used as the receiver Rx, and the third port P3 and the fourth port P4 are used, respectively. By connecting the antenna ANT and the external connection terminal EXT, it can be used similarly to the high frequency switch circuit 51.

FIG. 2 is a circuit diagram of a first embodiment of the high frequency switch according to the present invention. In this embodiment, the first and third
Between the ports P1 and P3, and the first and fourth ports P1 and P4
Distributed constant lines 2a to 2d are connected between the second and third ports P2 and P3, and between the second and fourth ports P2 and P4. That is, the distributed constant lines 2a to 2d are connected in a ring shape as illustrated.

The first port P1 is connected to the connection point A of the distributed constant lines 2a and 2b via the capacitor 3a,
The diode 4a and the capacitor 3b are connected in series between the connection point A and the reference potential, that is, the ground potential.
The connection point B between the diode 4a and the capacitor 3b
Is connected to one end of the resistor 5a, and the other end of the resistor 5a is connected to the first control voltage terminal Vc1.

Similarly, the second port P2 is connected to the connection point C between the distributed constant lines 2c and 2d via the capacitor 3c, and the diode 4 is connected between the connection point C and the ground potential.
b and the capacitor 3d are connected in series. And
One end of the resistor 5b is connected to the connection point D between the diode 4b and the capacitor 3d, and the other end is the second control voltage terminal V
It is connected to c2.

Similarly, the third port P3 is connected to the connection point E with the distributed constant lines 2a and 2c via the capacitor 3e, and the diode 4 is connected between the connection point E and the ground potential.
c and the capacitor 3f are connected in series. And
One end of the resistor 5c is connected to the connection point F between the diode 4c and the capacitor 3f, and the other end is the third control voltage terminal V
It is connected to c3.

Similarly, the fourth port P4 is connected to the connection point G with the distributed constant lines 2b and 2d via the capacitor 3g, and the diode 4 is connected between the connection point G and the ground potential.
d and the capacitor 5d are connected in series. And
One end of the resistor 5d is connected to the connection point H between the diode 4d and the capacitor 3h, and the other end is the fourth control voltage terminal V
It is connected to c4.

At this time, the distributed constant lines 2a to 2d are composed of strip lines, microstrip lines, coplanar guide lines, etc. having a length of λ / 4 or less, where λ is the wavelength of the high frequency signal flowing through the high frequency switch 1. Has been done. The distributed constant lines 2a to 2d are so-called λ / 4.
Although it is a line, it is actually configured to have a length of λ / 4 or less as described above because it is affected by the inductance and the stray capacitance.

Next, the operation of the high frequency switch 1 will be described. Table 1 shows the relationship between the directions of the diodes 4a to 4d, the control voltages of the first to fourth control voltage terminals Vc1 to Vc4, and the operations between the ports.

[0040]

[Table 1]

Here, a case where the first connection state is realized will be described. Second and third control voltage terminals Vc2, V
A positive control voltage + Vcc is applied to c3, and the first and fourth control voltage terminals Vc1 and Vc4 are connected to the ground potential, that is, 0.
Set to [V]. In this case, the control voltage applied from the second control voltage terminal Vc2 is dropped by the resistor 5b and applied as a forward bias voltage to the diode 4b. Further, a voltage obtained by subtracting the voltage drop due to the resistor 5b, the diode 4b and the distributed constant line 2d from the control voltage applied from the second control voltage terminal Vc2 is also applied to the diode 4d as the forward bias voltage. Therefore, the diodes 4b and 4d are turned on, and the series circuit of the diode 4b and the capacitor 3d and the diode 4d are formed.
The impedance of the series circuit of the capacitor 3h becomes zero at the operating frequency, and the connection points C and G are short-circuited to the ground potential.

On the other hand, the control voltage applied from the third control voltage terminal Vc3 is dropped by the resistor 5c, the diode 4c and the distributed constant line 2a and applied to the diode 4a as a reverse bias voltage. Further, a voltage obtained by subtracting the voltage drop in the resistor 5c from the control voltage applied from the third control voltage terminal Vc3 is also applied to the diode 4c as a reverse bias. Therefore, the diodes 4a and 4c are turned off, and the capacitance of the series circuit of the diode 4a and the capacitor 3b and the capacitance of the series circuit of the diode 4c and the capacitor 3f can be maintained.

Here, the distributed constant lines 2a to 2d are designed so as to operate as an impedance inverting circuit at the operating frequency. Further, since the connection points C and G are short-circuited to the ground potential, the connection point A, From E to distributed constant lines 2b, 2
When looking at the c side, the impedance becomes infinite.
Therefore, since the connection points A and E are connected and the connection points C and G are short-circuited to the ground potential, the first and third ports P1 and P3 are connected.
Only during the period is turned on.

To realize the second to fourth connection states, the control voltages as shown in Table 1 may be applied to the first to fourth control voltage terminals Vc1 to Vc4.

As described above, according to the high frequency switch 1 of the first embodiment, a 4-port high frequency switch can be constructed.

The high frequency signal flowing between the pair of ports flows only through one distributed constant line connected between the pair of ports. Therefore, the insertion loss can be halved as compared with the high frequency switch circuit configured by using the conventional 3-port high frequency switch in which the high frequency signal has passed through the two diodes, and the life of the elements constituting the high frequency switch is reduced. Can also be long. In addition, when used in mobile phones, for example, to reduce battery consumption,
It is possible to extend the call time and the standby time.

Furthermore, the first and second ports are symmetrical with respect to the connection to the third and fourth ports. Therefore, it can be suitably used as a changeover switch for a diversity antenna.

Further, among the control voltages applied to the first to fourth control voltage terminals, two terminals can be set to the ground potential, and in that case, one type of voltage, for example, positive or All that is required is to apply a negative control voltage. Therefore, the wiring pattern on the printed wiring board on which the high frequency switch is mounted can be simplified. In addition, it is possible to greatly contribute to miniaturization of electronic equipment in which the high frequency switch is incorporated.

Furthermore, since two diodes are inserted in one bias circuit, current consumption is reduced.

FIG. 3 is a circuit diagram of a second embodiment of the high frequency switch according to the present invention. The high frequency switch 10 differs from the high frequency switch 1 of the first embodiment in the following points.

The distributed constant line 6 is connected to the diodes 4a to 4d.
a to 6d are respectively connected in parallel, and the distributed constant line 6a
One end of the resistor 5e and one end of the capacitor 3i are connected to the common connection point I to which one end of each of ~ 6d is respectively connected, the other end of the resistor 5e is connected to the fixed voltage terminal Vfix, and the other end of the capacitor 3i is connected. It is connected to ground potential.

At this time, the distributed constant lines 2a to 2d and 6
Each of a to d is composed of a stripline, a microstripline, a coplanar guideline, etc. having a length of λ / 4 or less, where λ is the wavelength of the high-frequency signal flowing through the high-frequency switch 10. The distributed constant lines 2a to 2h and 6a to 6d are so-called λ / 4 lines, but since they are actually affected by the inductance component and the stray capacitance, they should have a length of λ / 4 or less as described above. Composed.

Next, the operation of the high frequency switch 10 will be described. Direction of the diodes 4a to 4d, control voltages of the first to fourth control voltage terminals Vc1 to Vc4, and fixed voltage terminal Vf.
Table 2 shows the relationship between the control voltage of ix and the operation between the ports.

[0054]

[Table 2]

Here, the case where the first connection state is realized will be described. Second and fourth control voltage terminals Vc2, V
A positive control voltage + Vcc is applied to c4, and the first and third control voltage terminals Vc1 and Vc3 and the fixed voltage terminal Vfix are set to the ground potential, that is, 0 [V]. In this case, the control voltage applied from the second control voltage terminal Vc2 is the resistance 5
The voltage is dropped by b and 5e and applied as a forward bias voltage to the diode 4b. Similarly, diode 4
A voltage obtained by subtracting the voltage drop due to the resistors 5d and 5e from the control voltage applied from the fourth control voltage terminal Vc4 is also applied to d as the forward bias voltage. Therefore,
The diodes 4b and 4d are turned on, and the diode 4
The impedances of the series circuit of b and the capacitor 3d and the series circuit of the diode 4d and the capacitor 3h become zero at the operating frequency, and the connection points C and G are short-circuited to the ground potential.

On the other hand, since the connection point I is connected to the fixed voltage terminal Vfix via the resistor 5e, the diode 4
A reverse bias is applied to a by the amount of the voltage drop in the resistor 5e. Similarly, a reverse bias is applied to the diode 4c by the amount of the voltage drop in the resistor 5e. Therefore, the diodes 4a and 4c are turned off, and the capacitance of the series circuit of the diode 4a and the capacitor 3b and the capacitance of the series circuit of the diode 4c and the capacitor 3f can be maintained.

Here, the distributed constant lines 2a to 2d and 6a.
6d are designed to operate as an impedance inverting circuit at the operating frequency. Further, since the connection points C and G are short-circuited to the ground potential, the connection points A and E are connected to the distributed constant lines 2b and 2c, respectively. , 6a, 6c, the impedance becomes infinite. Therefore, since the connection points A and E are connected and the connection points C and G are short-circuited to the ground potential, only the first and third ports P1 and P3 are turned on.

To realize the second to fourth connection states, the control voltages shown in Table 2 may be applied to the first to fourth control voltage terminals Vc1 to Vc4.

As described above, according to the high frequency switch 10 of the second embodiment, a 4-port high frequency switch can be constructed.

The high-frequency signal flowing between the pair of ports flows only through one distributed constant line connected between the pair of ports. Therefore, the insertion loss can be halved as compared with the high frequency switch circuit configured by using the conventional 3-port high frequency switch in which the high frequency signal has passed through the two diodes, and the life of the elements constituting the high frequency switch is reduced. Can also be long. In addition, when used in mobile phones, for example, to reduce battery consumption,
It is possible to extend the call time and the standby time.

Furthermore, the first and second ports are symmetrical with respect to the connection to the third and fourth ports. Therefore, it can be suitably used as a changeover switch for a diversity antenna.

Further, among the control voltages applied to the first to fourth control voltage terminals and the fixed voltage terminal, at least two terminals can be set to the ground potential, and in that case, one type of voltage is used. For example, it is only necessary to apply a positive or negative control voltage. Therefore, the wiring pattern on the printed wiring board on which the high frequency switch is mounted can be simplified. In addition, it is possible to greatly contribute to miniaturization of electronic equipment in which the high frequency switch is incorporated.

The positive control voltage + Vcc may be changed to the ground potential, and the negative control voltage -Vcc may be added to the ground potential. In that case, the first in the high-frequency switch 1
In the connected state of the second and third control voltage terminals Vc
2, Vc3 is grounded, and the first and fourth control voltage terminals Vc
The negative control voltage -Vcc may be applied to 1 and Vc4.
The same applies when the second to fourth connection states of the high-frequency switch 1 and the first to fourth connection states of the high-frequency switch 10 are realized.

Further, in the first and second embodiments, the diodes 4a to 4d are connected in the directions shown in FIGS. 2 and 3, but they are connected in the opposite direction to the directions shown in FIGS. 2 and 3. Good. That is, in the first embodiment, the diode 4a
In the second embodiment, the diodes 4a to 4d are arranged so that the anodes of 4d to 4d are on the connection points A, C, F and H sides and the cathodes of the diodes 4a to 4d are on the connection points B, D, E and G sides.
Of the diode 4 on the side of connection points A, C, E, G
The diodes 4a to 4d may be connected so that the cathodes of a to 4d are on the connection points B, D, F, and H sides. In this case, since the polarities of the diodes are opposite to those in the first and second embodiments, the first to fourth control voltage terminals Vc1 to Vc4 and the fixed voltage terminals as shown in Tables 1 and 2 are obtained. Vfix
It suffices to select the control voltage to be applied to.

Further, the resistors 5a to 5e are connected to the first to fourth control voltage terminals Vc1 to Vc4 and the fixed voltage terminal Vfix.
To first to fourth control voltage terminals Vc1 to V applied to the high frequency switches 1 and 10 via the connection points B, D, F, H, and I from
Since it is provided to adjust the control voltage values of the c4 and the fixed voltage terminal Vfix, it may not be connected in some cases, and in that case, the connection point B,
D, F, H, and I are the first to fourth control voltage terminals Vc1 directly
~ Vc4 and fixed voltage terminal Vfix.

The distributed constant lines 6a to 6d may be high impedance lines.

Further, the capacitors 3a to 3i have a function of cutting direct current, and may not be connected depending on the case.

Next, a first modification of the high frequency switches 1 and 10 will be described. As shown by the broken lines in FIGS. 2 and 3, preferably, the capacitors 7a to 7d may be connected to the first to fourth ports P1 to P4 and the reference potential, respectively. In this case, the characteristic impedance can be corrected by selecting the capacitances of the capacitors 7a to 7d, whereby the high frequency switches 1 and 1 can be corrected.
It is possible to effectively reduce the insertion loss of 0 and the reflection loss. In addition, the lengths of the distributed constant lines 2a to 2d and 6a to 6d can be shortened, whereby the high frequency switches 1 and 10 can be downsized.

It is not always necessary to use all the capacitors 7a to 7d, and only one of them may be connected.

Next, second to fourth modifications applicable to the high frequency switch of the above embodiment will be described with reference to FIGS. 4 to 6. In the modified examples shown in FIGS. 4 to 6, each of the circuit elements described below is connected to an arbitrary diode among the diodes 4a to 4d. 4 to 6, the diodes 4a to
As a representative of 4d, the portion provided in the diode 4a will be described.

As shown in FIG. 4, in the second modification, a resistor 8 is connected in parallel with the diode 4a. When in the off state, the diode 4a functions as a capacitor in terms of direct current. Therefore, in the off state, the accumulated charges flow at the same time when the diode 4a is turned on, but in the configuration shown in FIG.
The accumulated charge is discharged to the resistor 8, and the switching operation of the diode 4a from the off state to the on state is facilitated.
In addition, it is possible to stabilize the reverse bias of the diode 4a when it is off.

In the third modification shown in FIG. 5, the distributed constant line 9 and the capacitor 11 connected in series are connected in parallel to the diode 4a. In this configuration, the parallel resonant circuit is configured by the capacitance of the diode 4a in the off state and the inductance of the distributed constant line 9. Therefore, the impedance of the diode 4a in the off state can be increased by adjusting the inductance of the distributed constant line 9 so that the resonance frequency of the parallel resonance circuit matches the frequency of the transmitted high frequency signal. As a result, the isolation characteristic of the diode 4a in the off state can be improved. In addition, the capacitor 11 is
It is provided to prevent direct current from bypassing.

The distributed constant line 9 is composed of a strip line, a micro strip line, a coplanar guide line, etc., and its length and impedance are selected so that the resonance frequency of the parallel resonance circuit matches the frequency of the high frequency signal. .

Further, when the capacitance in the off state of the diode 4a is small and the desired resonance frequency cannot be obtained, as a fourth modification, as shown in FIG. 6, a distributed constant is provided in parallel with the diode 4a. A capacitor 12 is connected in parallel with the line 9 and the capacitor 11 connected in series. In this configuration, the diode 4a
A parallel resonance circuit is configured by the combined capacitance of the capacitance in the off state and the capacitor 12 and the inductance component of the distributed constant line 9, and a desired resonance frequency can be obtained.

The first to fourth modifications can be combined with each other.

[0076]

According to the high frequency switch of the first and second aspects, a 4-port high frequency switch can be constructed.

The high frequency signal flowing between the pair of ports flows only through one distributed constant line connected between the pair of ports. Therefore, the insertion loss can be halved as compared with the high frequency switch circuit configured by using the conventional 3-port high frequency switch in which the high frequency signal has passed through the two diodes, and the life of the elements constituting the high frequency switch is reduced. Can also be long. In addition, when used in mobile phones, for example, to reduce battery consumption,
It is possible to extend the call time and the standby time.

Furthermore, the first and second ports are symmetrical with respect to the connection to the third and fourth ports. Therefore, it can be suitably used as a changeover switch for a diversity antenna.

According to the high frequency switch of the third aspect, the first
~ Of the control voltages applied to the fourth control voltage terminal, 2
Since the terminal can be set to the ground potential, in that case, it is only necessary to apply one kind of voltage, for example, a positive or negative control voltage. Therefore, the wiring pattern on the printed wiring board on which the high frequency switch is mounted can be simplified. In addition, it is possible to greatly contribute to miniaturization of electronic equipment in which the high frequency switch is incorporated.

Further, since two diodes are inserted in one bias circuit, the current consumption becomes small.

According to the high frequency switch of the fourth aspect, the first
-Since at least two terminals of the control voltages applied to the fourth control voltage terminal and the fixed voltage terminal can be set to the ground potential, in that case, one type of voltage, for example, positive or negative control All that is required is to apply a voltage. Therefore, the wiring pattern on the printed wiring board on which the high frequency switch is mounted can be simplified.
In addition, it is possible to greatly contribute to miniaturization of electronic equipment in which the high frequency switch is incorporated.

According to the high frequency switch of the fifth aspect, the values of the control voltage and the control current at the first to fourth control voltage terminals and the fixed voltage terminal can be easily adjusted by the resistance value of the resistor.

According to the high frequency switch of the sixth aspect, the characteristic impedance can be corrected by selecting the capacitance of the capacitor, whereby the insertion loss and the reflection loss can be effectively reduced. In addition, when the distributed constant line connected in parallel with the diode is provided, the length of the distributed constant line can be shortened, and thereby the high frequency switch can be downsized.

According to the high frequency switch of the seventh aspect, the electric charge accumulated in the electrostatic capacitance when the diode is in the off state is discharged to the resistor connected in parallel with the diode at the same time when the diode is in the on state. Therefore, the switching operation from the off state to the on state of the diode can be facilitated. In addition, it is possible to stabilize the reverse bias of the diode when it is off.

According to the high frequency switch of the eighth aspect, the parallel resonant circuit is constituted by the capacitance in the off state of the diode and the inductance of the distributed constant line connected in parallel with the diode. Therefore, by configuring the resonance frequency of this parallel resonance circuit to match the frequency of the high-frequency signal transmitted to the high-frequency switch,
The off-state impedance of the diode can be increased, and as a result, the isolation characteristic can be improved. In addition, the capacitor connected in series to the distributed constant line can prevent direct-current bypass to the circuit portion including the distributed constant line.

According to the ninth aspect of the high-frequency switch, the capacitance in the off state of the diode, the combined capacitance of the diode and the capacitor connected in parallel, and the distribution of the diode and the capacitor connected in parallel. A parallel resonant circuit is formed by the inductance of the constant line. Therefore, it is possible to obtain a desired resonance frequency and further improve the isolation characteristic.

[Brief description of drawings]

FIG. 1 is a schematic circuit diagram showing a schematic configuration of a first embodiment of a high frequency switch according to the present invention.

FIG. 2 is a circuit diagram of a first embodiment of a high frequency switch according to the present invention.

FIG. 3 is a circuit diagram of a second embodiment of the high frequency switch according to the present invention.

FIG. 4 is a circuit diagram for explaining a second modification of the high frequency switch.

FIG. 5 is a circuit diagram for explaining a third modification of the high frequency switch.

FIG. 6 is a circuit diagram for explaining a fourth modification of the high frequency switch.

FIG. 7 is a schematic configuration diagram for explaining a conventional high-frequency switch circuit.

FIG. 8 is a circuit diagram showing an example of a conventional 3-port high-frequency switch.

[Explanation of symbols]

 1, 10 high frequency switch 2a-2d, 6a-6d, 9 distributed constant line 4a-4d diode 5a-5e, 8 resistance 7a-7d, 11, 12 capacitor P1-P4 port Vc1-Vc4 control voltage terminal Vfix fixed voltage terminal

Claims (9)

[Claims] 1. A high frequency switch having first to fourth ports, wherein the first and second ports are connected to a third or fourth port, wherein the first and third ports are provided. Between the third and second ports, between the second and fourth ports, and between the fourth and
A high-frequency switch characterized in that distributed constant lines are connected between the first ports. 2. The high frequency switch according to claim 1, wherein diodes are respectively connected between the first to fourth ports and a reference potential. 3. The high frequency switch according to claim 2, wherein first to fourth control voltage terminals are connected between the diode and the reference potential, respectively. 4. A distributed constant line is connected in parallel to the diode, one end of each of the distributed constant lines is connected to a common connection point, and a fixed voltage terminal is connected to the common connection point. The high frequency switch according to claim 2 or 3. 5. At least one of a connection point between a diode connected to the first to fourth ports and a reference potential and at least one of the common connection points is connected to the first to fourth control via a resistor. The high frequency switch according to claim 3 or 4, wherein the high frequency switch is connected to a voltage terminal and a fixed voltage terminal. 6. The method according to claim 1, wherein at least one of the first to fourth ports is connected to the reference potential via a capacitor. High frequency switch. 7. The high frequency switch according to claim 2, further comprising a resistor connected in parallel to at least one of the diodes. 8. The high frequency switch according to claim 2, wherein a series circuit of a distributed constant line and a capacitor is connected in parallel with at least one of the diodes. 9. A distributed constant line and a series circuit of a capacitor are connected in parallel to at least one of the diodes, and a capacitor is connected in parallel to a series circuit of the distributed constant line and the capacitor. The high frequency switch according to any one of claims 2 to 7.