JPH05315803A - Rf switch - Google Patents

Abstract

PURPOSE:To make the circuit small by integrating the RF switch and a directional coupler. CONSTITUTION:When a signal is outputted to an output terminal 102, a voltage lower than a pinch-off voltage is supplied to a gate terminal of a field effect transistor(TR) 104 to set a part between a drain and a source of the field effect TR to be a high resistance state, and a signal inputted from an input terminal 101 is outputted to an output terminal 102 via a microstrip line 106 having a length of 1/4 wavelength. In this case, part of an input signal is outputted to an auxiliary output terminal 112 connecting to one terminal of an auxiliary microstrip line 107 electromagnetically coupled with the microstrip line 106. When no output is desired for the output terminal 102, a gate terminal of the field effect TR 104 connects to ground. Thus, the impedance when viewing the output terminal 102 from the input terminal 101 is close to infinite.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an R used in a high frequency circuit.
Regarding the F switch.

[0002]

2. Description of the Related Art In recent years, communication devices have been downsized, and there has been an increasing demand for downsizing of components and modules that make up the communication devices.

A conventional RF switch will be described below with reference to the drawings. As shown in FIG. 7, the conventional RF switch has an input terminal 701, a first output terminal 702, a second output terminal 703, and a first field effect transistor 70.
4, second field effect transistor 705, first microstrip line 706, second microstrip line 707, control voltage terminals 710, 711, resistors 714,
715.

Regarding the conventional RF switch composed of the above components, the relationship and operation of each component will be described below.

In the conventional RF switch, the input terminal 701 is used.
The signal input from the first output terminal 702 and not the second output terminal 703, or
It is possible to switch between two states of outputting only to the output terminal 703 of the above and not outputting to the first output terminal 702.

First, when a signal is output to the first output terminal 702 but not to the second output terminal 703, the gate terminal of the first field effect transistor 704 is controlled via the resistor 714. A voltage lower than the pinch-off voltage of the first field effect transistor 704 is applied from the voltage terminal 710 to make the drain terminal and the source terminal of the first field effect transistor 704 have a high resistance state, and the input terminal 7
The signal input from 01 is output to the first output terminal 702 via the microstrip line 706 having a length of ¼ wavelength of the signal. At this time, the gate terminal of the second field effect transistor 705 is grounded via the resistor 715 and the control voltage terminal 711, and the gate terminal and the source terminal of the second field effect transistor 705 become equipotential and the second electric field A low resistance state is established between the drain terminal and the source terminal of the effect transistor 705. When the resistance between the drain terminal and the source terminal of the second field effect transistor 705 becomes low, one end of the microstrip line 707 having a length of ¼ wavelength of the signal approaches the grounded state and the input terminal The impedance when the second output terminal 703 is viewed from 701 becomes nearly infinite, and no signal is transmitted to the second output terminal 703.

When the signal is output to the second output terminal 703 but not to the first output terminal 702, the resistor 71 is connected to the gate terminal of the second field effect transistor 705.
5, a voltage lower than the pinch-off voltage of the second field effect transistor 705 is applied from the control voltage terminal 711 to bring the drain terminal and the source terminal of the second field effect transistor into a high resistance state, and the input terminal 701 The further input signal is output to the second output terminal 703 through the microstrip line 707 having a length of ¼ wavelength of the signal. At this time, the gate terminal of the first field-effect transistor 704 is grounded via the resistor 714 and the control voltage terminal 710, the gate terminal and the source terminal of the first field-effect transistor 704 become equipotential, and the first electric field A low resistance state is established between the drain terminal and the source terminal of the effect transistor 704. First field effect transistor 704
When the resistance between the drain terminal and the source terminal of is in a low resistance state, one end of the microstrip line 706 having a length of ¼ wavelength of the signal approaches the state of being grounded, and
When the first output terminal 702 is viewed from the input terminal 701, the impedance becomes close to infinity, and the first output terminal 7
No signal is transmitted to 02.

[0008]

However, in the above-mentioned conventional configuration, in order to monitor the signal level, it is necessary to add a directional coupler to the front stage or the rear stage of the RF switch, which hinders miniaturization of the circuit. Had a problem.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide an RF switch having a directional coupler built therein so as to help miniaturize the circuit.

[0010]

In order to achieve the above object, the RF switch of the present invention comprises a field-effect transistor whose source is grounded or drain-grounded, and an input signal which has external connection terminals at both ends. The microstrip line is composed of a microstrip line having a length of 4 wavelengths and an auxiliary microstrip line electromagnetically coupled to the microstrip line and having external connection terminals at both ends and having a length of 1/4 wavelength or less of an input signal. It has a configuration in which one end of the line is connected to a drain terminal and a source terminal of the field effect transistor which are not grounded.

[0011]

According to the present invention, the circuit can be miniaturized by integrating the RF switch and the directional coupler, which are conventionally separate, in the above-mentioned configuration without largely changing the configuration of the RF switch.

[0012]

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the RF switch of this embodiment has an input terminal 101, an output terminal 102, a field effect transistor 104, a microstrip line 106, an auxiliary microstrip 107, a control voltage terminal 110 and an auxiliary output terminal 112. It is composed of a resistor 114.

Regarding the RF switch composed of the above components, the relationship and operation of each component will be described below. In the present embodiment shown in FIG. 1, it is possible to switch between two states in which the signal input from the input terminal 101 is output to the output terminal 102 or is not output. First, when outputting a signal to the output terminal 102, a voltage lower than the pinch-off voltage of the field effect transistor 104 is applied to the gate terminal of the field effect transistor 104 from the control voltage terminal 110 via the resistor 114 to generate an electric field. A high resistance state is established between the drain terminal and the source terminal of the effect transistor, and the signal input from the input terminal 101 has a length of ¼ wavelength of the signal.
It outputs to the output terminal 102 via 6. At this time, a part of the input signal is output to the auxiliary output terminal 112 connected to one end of the auxiliary microstrip line 107 electromagnetically coupled to the microstrip line 106.

When no output is made to the output terminal 102, the gate terminal of the field effect transistor 104 is a resistor 114.
Also, the gate terminal and the source terminal of the field effect transistor 104 become equipotential, and are grounded via the control voltage terminal 110, and a low resistance state is established between the terminal of the field effect transistor 104 and the source terminal. When the resistance between the drain terminal and the source terminal of the field effect transistor 104 becomes a low resistance state, one end of the microstrip line path 106 having a length of ¼ wavelength of the signal comes close to the grounded state and the input terminal 101 When looking at the output terminal 102, the impedance becomes almost infinity, and the output terminal 102
No signal is transmitted to. In the above embodiment,
Set the length of the microstrip line 106 to 1/4 of the signal.
Although the length of the wavelength is used, the same effect can be obtained even if the length is ¼ wavelength or less.

Although the auxiliary output terminal is provided only at one end of the auxiliary microstrip line 107 in the above embodiment, the same effect can be obtained by providing the auxiliary output terminal at both ends of the auxiliary microstrip line 107. ..

(Second Embodiment) A second embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 2, the RF switch of this embodiment has an input terminal 201, a first output terminal 202, a second output terminal 203, a first field effect transistor 204, and a second field effect transistor 205. , First microstrip line 206, first auxiliary microstrip line 207, second microstrip line 208, second auxiliary microstrip line 209, control voltage terminal 21
0, 211, a first auxiliary output terminal 212, a second auxiliary output terminal 213, and resistors 214, 215.

Regarding the RF switch composed of the above components, the relationship and operation of each component will be described below. In the second embodiment of the present invention shown in FIG. 2, the input terminal 2
The signal input from 01 is output only to the first output terminal 202 and is not output to the second output terminal 203, or is output only to the second output terminal 203 and is output to the first output terminal 202. It is possible to switch between two states of not outputting. First, when a signal is output to the first output terminal 202 and is not output to the second output terminal 203,
At the gate terminal of the first field effect transistor 204,
A voltage lower than the pinch-off voltage of the first field-effect transistor 204 is applied from the control voltage terminal 210 through the resistor 214 to make the drain terminal and the source terminal of the first field-effect transistor have a high resistance state, and the input terminal 201
The input signal is the first signal having a length of 1/4 wavelength of the signal.
The signal is output to the first output terminal 202 via the microstrip line 206. At this time, a part of the input signal is output to the first auxiliary output terminal 212 connected to one end of the first auxiliary microstrip line 207 electromagnetically coupled to the first microstrip line 206. The gate terminal of the second field effect transistor 205 is grounded via the resistor 215 and the control voltage terminal 211, and the gate terminal and the source terminal of the second field effect transistor 205 become equipotential, and the second field effect transistor 205. There is a low resistance state between the drain terminal and the source terminal of. When the resistance between the drain terminal and the source terminal of the second field effect transistor 205 becomes low, one end of the second microstrip line 208 having the length of ¼ wavelength of the signal approaches the state of being grounded. , The impedance when the second output terminal 203 is viewed from the input terminal 201 becomes nearly infinite, and no signal is transmitted to the second output terminal 203.
When the signal is output to the second output terminal 203 and not to the first output terminal 202, the gate terminal of the second field effect transistor 205 is connected to the control voltage terminal 211 through the resistor 215, 2 field effect transistor 20
A voltage lower than the pinch-off voltage of 5 is applied to bring the drain terminal and the source terminal of the second field effect transistor into a high resistance state, and the signal input from the input terminal 201 has a length of ¼ wavelength of the signal. The signal is output to the second output terminal 203 via the second microstrip line 208. At this time, part of the input signal is output to the second auxiliary output terminal 213 connected to one end of the second auxiliary microstrip line 209 electromagnetically coupled to the second microstrip line 208. The gate terminal of the first field effect transistor 204 is grounded via the resistor 214 and the control voltage terminal 210, and the gate terminal and the source terminal of the first field effect transistor 204 become equipotential, and the first field effect transistor 204 There is a low resistance state between the drain terminal and the source terminal of. First field effect transistor 204
When the resistance between the drain terminal and the source terminal is low, one end of the first microstrip line 206 having the length of ¼ wavelength of the signal approaches the grounded state, and the first terminal from the input terminal 201 The impedance when looking at the output terminal 202 of is close to infinity, and no signal is transmitted to the first output terminal 202. In the above embodiment, the length of the macrostrip line is set to 1/4 of the signal.
Although the length of the wavelength is used, the same effect can be obtained even if the length is ¼ wavelength or less.

Although the auxiliary output terminal is provided only at one end of the first auxiliary microstrip line 207 and the second auxiliary microstrip line 209 in the above embodiment, the auxiliary output terminal is provided at the first auxiliary microstrip line 209. The same effect can be obtained by providing the strip line 207 and the second auxiliary microstrip line 209 at both ends. (Embodiment 3) A third embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 3, the RF switch of this embodiment comprises an input terminal 301, an output terminal 302, a field effect transistor 304, a control voltage terminal 310, a resistor 314, inductors 318 and 319, and capacitors 322 and 323. ing.

Regarding the RF switch composed of the above components, the relationship and operation of each component will be described below. In addition, in the third embodiment of the present invention shown in FIG.
It is possible to switch between two states in which the signal input from 1 is output to the output terminal 302 or is not output. First, when outputting a signal to the output terminal 302, a voltage lower than the pinch-off voltage of the field-effect transistor 304 is applied to the gate terminal of the field-effect transistor 304 through the resistor 314 and the control voltage terminal 310, and the field-effect transistor 304 receives the field effect. A signal input from the input terminal 301 with a high resistance state between the drain terminal and the source terminal of the transistor 304 is a capacitor 322, 323, an inductor 31.
The signal of 8 and 319 is output to the output terminal 302 through the low-pass filter that changes the phase of the signal by 1/4 wavelength.

When no output is made to the output terminal 302, the gate terminal of the field effect transistor 304 is a resistor 314.
Further, the field effect transistor 304 is grounded through the control voltage terminal 310, the gate terminal and the source terminal of the field effect transistor 304 are equipotential, and the drain terminal and the source terminal of the field effect transistor 304 are in a low resistance state. When the resistance between the drain terminal and the source terminal of the field effect transistor 304 becomes low, the capacitors 322, 323, the inductor 31
As one end of the low-pass filter that changes the phase of the signal composed of 8 and 319 by 1/4 wavelength approaches the grounded state, the impedance when the output terminal 302 is seen from the input terminal 301 becomes nearly infinite. , Output terminal 30
No signal is transmitted to 2.

In the above embodiment, the low-pass filter is composed of two elements each of the capacitor and the inductor. However, the low-pass filter is provided with one or more elements each of the capacitor and the inductor, and the phase of the signal is The same effect can be obtained even if the number of elements is changed as long as it is configured to change 1/4 wavelength.

(Embodiment 4) A fourth embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 4, the RF switch of this embodiment has an input terminal 401, a first output terminal 402, a second output terminal 403, a first field effect transistor 404, and a second field effect transistor 405. , Control voltage terminal 41
0, 411, resistors 414, 415, inductor 418,
419, 420, 421, capacitors 422, 423
424.

Regarding the RF switch including the above components, the relationship and operation of each component will be described below. In the fourth embodiment of the present invention shown in FIG. 4, the input terminal 4
The signal input from 01 is output only to the first output terminal 402 and is not output to the second output terminal 403, or is output only to the second output terminal 403 and is output to the first output terminal 402. It is possible to switch between the two states of not performing.

First, when a signal is output to the first output terminal 402 but not to the second output terminal 403, the resistor 41 is connected to the gate terminal of the first field effect transistor 404.
4, a voltage lower than the pinch-off voltage of the first field effect transistor 404 is applied from the control voltage terminal 410 to bring the drain terminal and the source terminal of the first field effect transistor 404 into a high resistance state, and the input terminal The signal input from 401 is passed through a low-pass filter configured by capacitors 422, 423, inductors 418, 419 to change the phase of the signal by ¼ wavelength, and then the first output terminal 4
Output to 02. The gate terminal of the second field effect transistor 405 is grounded via the resistor 415 and the control voltage terminal 411, the gate terminal and the source terminal of the second field effect transistor 405 become equipotential, and the second field effect transistor 405. There is a low resistance state between the drain terminal and the source terminal of. Second field effect transistor 405
When the resistance between the drain terminal and the source terminal is low, the capacitors 423 and 424 and the inductors 420 and 4
As one end of the low-pass filter that changes the phase of the signal constituted by 21 by 1/4 wavelength approaches a state in which it is grounded, the impedance when the second output terminal 403 is seen from the input terminal 401 is close to infinity. Therefore, no signal is transmitted to the second output terminal 403.

When the signal is output to the second output terminal 403 but not to the first output terminal 402, the resistor 41 is connected to the gate terminal of the second field effect transistor 405.
5, a voltage lower than the pinch-off voltage of the second field effect transistor 405 is applied from the control voltage terminal 411 to bring the drain terminal and the source terminal of the second field effect transistor into a high resistance state, and the input terminal 401 The input signals are capacitors 423, 424, inductor 42
The signal of 0,421 is output to the second output terminal 403 through the low-pass filter that changes the phase of the signal by 1/4 wavelength.

The gate terminal of the first field effect transistor 404 is grounded via the resistor 414 and the control voltage terminal 410, the gate terminal and the source terminal of the first field effect transistor 404 are at the same potential, and the first electric field A low resistance state is established between the drain terminal and the source terminal of the effect transistor 404. When the resistance between the drain terminal and the source terminal of the first field effect transistor 404 becomes low, a low-pass filter for changing the phase of the signal formed by the capacitors 422 and 423 and the inductors 418 and 419 by ¼ wavelength is used. As one end approaches the grounded state, the impedance when the first output terminal 402 is seen from the input terminal 401 becomes close to infinity, and the first output terminal 40
No signal is transmitted to 2.

In the above embodiment, the low-pass filter is composed of two capacitors and two inductors. However, the low-pass filter is provided with one or more capacitors and one inductor, and the phase of the signal in the entire low-pass filter is changed. 1
If the configuration is such that the wavelength is changed by / 4 wavelength, the same effect can be obtained even if the number of elements is changed. (Embodiment 5) Hereinafter, a fifth embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 5, the RF switch of this embodiment has an input terminal 501, an output terminal 502, a field effect transistor 504, a microstrip line 506, an auxiliary microstrip line 507, a control voltage terminal 510, and an auxiliary output terminal 512. , Resistor 514, capacitors 522, 5
It is composed of 23.

Regarding the RF switch composed of the above components, the relationship and operation of each component will be described below. In the fifth embodiment of the present invention shown in FIG. 5, the input terminal 5
The signal input from 01 is output to the output terminal 502, or
Alternatively, it is possible to switch between two states of not outputting. First, when outputting a signal to the output terminal 502, a voltage lower than the pinch-off voltage of the field-effect transistor 504 is applied to the gate terminal of the field-effect transistor 504 via the resistor 514 via the resistor 514, and A low-pass filter that sets a high resistance state between the drain terminal and the source terminal and changes the phase of the signal input from the input terminal 501 by a quarter wavelength by the capacitors 522 and 523 and the microstrip line 506. And output to the output terminal 502. At this time, a part of the input signal is output to the auxiliary output terminal 512 connected to one end of the auxiliary microstrip line 507 electromagnetically coupled to the microstrip line 506.

When no output is made to the output terminal 502, the gate terminal of the field effect transistor 504 is a resistor 514.
The gate terminal and the source terminal of the field effect transistor 504 are equipotential, and the drain terminal and the source terminal of the field effect transistor 504 are in a low resistance state. When the resistance between the drain terminal and the source terminal of the field effect transistor 504 becomes low, one end of a low-pass filter configured to change the phase of the signal constituted by the capacitors 522 and 523 and the microstrip line 506 by ¼ wavelength is generated. As it approaches the grounded state, the impedance when the output terminal 502 is viewed from the input terminal 501 becomes nearly infinite, and no signal is transmitted to the output terminal 502. In the above embodiment, the low-pass filter is composed of one microstrip line and two capacitors. However, the low-pass filter includes one or more microstrip lines and one or more capacitors, and the entire low-pass filter has a signal. The same effect can be obtained even if the number of elements is changed as long as the phase is changed by 1/4 wavelength.

Although the auxiliary output terminal is provided only at one end of the auxiliary microstrip line 507 in the above embodiment, the same effect can be obtained by providing the auxiliary output terminal at both ends of the auxiliary microstrip line 507. ..

(Embodiment 6) A sixth embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 6, the RF switch of this embodiment has an input terminal 601, a first output terminal 602, a second output terminal 603, a first field effect transistor 604, and a second field effect transistor 605. , First microstrip line 606, first auxiliary microstrip line 607, second microstrip line 608, second auxiliary microstrip line 609, control voltage terminal 61
0, 611, first auxiliary output terminal 612, second auxiliary output terminal 613, resistors 614, 615, capacitor 62.
2, 623, 624.

Regarding the RF switch composed of the above components, the relationship and operation of each component will be described below. In the sixth embodiment of the present invention shown in FIG. 6, the input terminal 6
The signal input from 01 is output only to the first output terminal 602 and is not output to the second output terminal 603, or
The first output terminal 60 outputs only to the second output terminal 603.
It is possible to switch between two states of not outputting to 2.

First, when a signal is output to the first output terminal 602 but not to the second output terminal 603, the gate terminal of the first field effect transistor 604 is controlled via the resistor 614. A voltage lower than the pinch-off voltage of the first field effect transistor 604 is applied from the voltage terminal 610 so that the drain terminal and the source terminal of the first field effect transistor are in a high resistance state, and the signal input from the input terminal 601 is , The capacitors 622 and 623 and the first macrostrip line 606, and the first pass through a low-pass filter that changes the phase of the signal by ¼ wavelength.
To the output terminal 602 of the. At this time, part of the input signal is output to the first auxiliary output terminal 612 connected to one end of the first auxiliary microstrip line 607 electromagnetically coupled to the first microstrip line 606. Second
The gate terminal of the field effect transistor 605 is a resistor 6
15 and the control voltage terminal 611 to be grounded, the gate terminal and the source terminal of the second field effect transistor 605 become equipotential, and the drain terminal and the source terminal of the second field effect transistor 605 have a low resistance state. Become. When the drain terminal and the source terminal of the second field effect transistor 605 are in a low resistance state, the capacitor 623,
One end of a low-pass filter configured to change the phase of a signal constituted by 624 and the second microstrip line 608 by ¼ wavelength approaches a state in which it is grounded, and the input terminal 601 to the second output terminal 603 are connected to each other. The impedance when viewed is close to infinity, and no signal is transmitted to the second output terminal 603.

A signal is output to the second output terminal 603 to output the first signal.
Of the second field effect transistor 605, a resistor 615 is connected to the gate terminal of the second field effect transistor 605.
After that, a voltage lower than the pinch-off voltage of the second field effect transistor 605 is applied from the control voltage terminal 611, a high resistance state is established between the drain terminal and the source terminal of the second field effect transistor, and the input terminal The signal input from 601 has the phase of the signal formed by the capacitors 623 and 624 and the microstrip line 608 at 1 /
It is output to the second output terminal 603 through a low-pass filter that changes four wavelengths. At this time, a part of the input signal is output to the second auxiliary output terminal 613 connected to one end of the second auxiliary microstrip line 609 electromagnetically coupled to the third microstrip line 608. The gate terminal of the first field-effect transistor 604 is grounded via the resistor 614 and the control voltage terminal 610, and the gate terminal and the source terminal of the first field-effect transistor 604 become equipotential. A low resistance state exists between the drain terminal and the source terminal of 604. When the resistance between the drain terminal and the source terminal of the first field effect transistor 604 becomes low, the capacitors 622, 62
3 and the first microstrip line 606, one end of a low-pass filter that changes the phase of the signal by 1/4 wavelength approaches a grounded state, and the input terminal 6
The impedance when the first output terminal 602 is viewed from 01 becomes nearly infinite, and no signal is transmitted to the first output terminal 602.

In the above embodiment, the low-pass filter is composed of one microstrip line and two capacitors, but one or more microstrip lines are used.
Even if the number of elements is changed, the same effect can be obtained as long as the low pass filter is provided with one or more capacitors and the phase of the signal is changed by ¼ wavelength.

Although the auxiliary output terminal is provided only at one end of the first auxiliary microstrip line 607 and the second auxiliary microstrip line 609 in the above embodiment, the auxiliary output terminal is provided as the first auxiliary microstrip line. Line 607 and second auxiliary microstrip line 6
Even if it is provided at both ends of 09, the same effect can be obtained.

Although the field effect transistor is used with the source terminal grounded in the above embodiment, the drain terminal may be grounded and the roles of the source terminal and the drain terminal may be exchanged in the circuit of the above embodiment. The same effect can be obtained.

[0044]

As is apparent from the above-described embodiments, according to the present invention, a field-effect transistor grounded at the source or the drain and an external connection terminal at both ends of the field-effect transistor having a length of ¼ wavelength of the input signal are provided. It consists of a microstrip line and an auxiliary microstrip line electromagnetically coupled to the microstrip line and having external connection terminals at both ends and having a length of ¼ wavelength or less of the input signal. By connecting the drain terminal and the source terminal of the transistor that are not grounded, it is possible to realize an excellent RF switch in which a directional coupler can be built in the RF switch without changing the configuration of the RF switch. Is.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an RF switch according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram of an RF switch according to a second embodiment of the present invention.

FIG. 3 is a circuit diagram of an RF switch according to a third embodiment of the present invention.

FIG. 4 is a circuit diagram of an RF switch according to a fourth embodiment of the present invention.

FIG. 5 is a circuit diagram of an RF switch according to a fifth embodiment of the present invention.

FIG. 6 is an RF switch circuit diagram of a sixth embodiment of the present invention.

FIG. 7 is a circuit diagram of a conventional RF switch.

[Explanation of symbols]

104, 304, 504 Field effect transistor 205, 404, 604 First field effect transistor 205, 405, 605 Second field effect transistor 106, 506 Microstrip line 107, 507 Auxiliary microstrip line 206, 606 First micro Strip line 207, 607 First auxiliary microstrip line 208, 608 Second microstrip line 209, 609 Second auxiliary microstrip line 318, 319, 418, 419, 420, 421
Inductors 322, 323, 422, 423, 424, 522, 5
23,622,623324 capacitors

Claims (6)

[Claims] 1. A field effect transistor in which either a source terminal or a drain terminal is grounded, a microstrip line having an external connection terminal at both ends and having a length of ¼ wavelength of an input signal, and the microstrip line. And an auxiliary microstrip line having a length of ¼ wavelength or less of the input signal, which is electromagnetically coupled with external connection terminals at both ends,
An RF switch in which one end of the microstrip line is connected to a non-grounded terminal of the drain terminal and the source terminal of the field effect transistor. 2. A first field effect transistor having a source terminal or a drain terminal grounded, a second field effect transistor having a source terminal or a drain terminal grounded, and external connection terminals at both ends. A first microstrip line having a length of 1/4 wavelength of the input signal, and a second microstrip line having a length of 1/4 wavelength of the input signal having external connection terminals at both ends, A first and a second auxiliary microstrip line having a length equal to or less than 1/4 wavelength of a signal and having external connection terminals at both ends, wherein the external connection terminal at one end of the first microstrip line is An external connection terminal common to the external connection terminal at one end of the second microstrip line, and the drain of the first field effect transistor at the other end of the first microstrip line. An ungrounded terminal of the terminal and the source terminal is connected, and an ungrounded terminal of the drain terminal and the source terminal of the second field effect transistor is connected to the other end of the second microstrip line, An RF switch formed by electromagnetically coupling the first and second auxiliary microstrip lines to the first microstrip line and the second microstrip line, respectively. 3. A field effect transistor whose source terminal or drain terminal is grounded, at least one element or more of an inductor, at least one element or more of a capacitor whose one end is grounded, and a first external connection terminal. A second external connection terminal, wherein at least one element of the inductor is connected in series between the first external connection terminal and the second external connection terminal, and at least one element of the capacitor is provided. An RF switch which is connected in parallel and which is connected to the second external connection terminal and a drain terminal or a source terminal of the field effect transistor which is not grounded. 4. A first field effect transistor having a source terminal or a drain terminal grounded, a second field effect transistor having a source terminal or a drain terminal grounded, and at least one element or more. An inductor, a capacitor having at least one element grounded at one end, a first external connection terminal, a second external connection terminal, and a third external connection terminal, and the first external connection terminal and the first external connection terminal At least one element of the inductor is connected in series with a second external connection terminal, and at least one element of the capacitor is connected in parallel, and the first external connection terminal and the first field effect transistor are connected. Of the drain terminal and the source terminal, which are not grounded, are connected to each other, and at least one element is provided between the second external connection terminal and the third external connection terminal. Child or more of the inductors are connected in series, and at least one or more of the capacitors are connected in parallel, and the third external connection terminal, the drain terminal or the source terminal of the second field effect transistor are not grounded. An RF switch that connects terminals. 5. A field effect transistor in which one of a source terminal and a drain terminal is grounded, a microstrip line having external connection terminals at both ends, and an external connection terminal electromagnetically coupled to the microstrip line. And an auxiliary microstrip line having a length of ¼ wavelength or less of an input signal, and a capacitor having at least one element of which one end is grounded, and the capacitor is connected in parallel to one end or both ends of the microstrip line. An RF switch in which one end of the microstrip line is connected to a non-grounded terminal of a drain terminal and a source terminal of the field effect transistor. 6. A first field effect transistor having a source terminal or a drain terminal grounded, a second field effect transistor having a source terminal or a drain terminal grounded, and external connection terminals at both ends. And a second microstrip line having external connection terminals at both ends, and a second microstrip line having a length equal to or less than a quarter wavelength of an input signal and having external connection terminals at both ends. 1
And a second auxiliary microstrip line, and a capacitor having one end of at least one element grounded,
An external connection terminal at one end of the first microstrip line is used as a common external connection terminal with an external connection terminal at one end of the second microstrip line, and the first connection terminal is provided at the other end of the second microstrip line. An ungrounded terminal of the drain terminal and the source terminal of the field effect transistor is connected, and the drain terminal and the source terminal of the second field effect transistor which are not grounded are connected to the other end of the first microstrip line. A terminal is connected, and the first and second auxiliary microstrip lines are electromagnetically coupled to each of the first microstrip line and the second microstrip line, and one end or both ends of the first microstrip line. The capacitor is connected in parallel to the second microstrip line, and the capacitor is connected to one end or both ends of the second microstrip line. RF switch that is connected in parallel to Yapashita.