JP2962771B2 - Phase shifter - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a path length switching type phase shifter in which two transmission lines having different path lengths are switched by a switch, and particularly to an improvement in loss characteristics in the phase shifter. It is about.

[Conventional technology]

There are various types of path length switching type phase shifters that change the phase of the radio wave by switching the propagation path of the radio wave. Here, a field effect transistor (hereinafter referred to as FET) formed on a semiconductor substrate such as silicon or GaAs is used. ) Will be described as an example of a semiconductor phase shifter that changes the phase of a microwave by switching the path of a microstrip line formed on the same semiconductor substrate using a switch.

FIG. 11 shows, for example, GFShade, “Monolithic X-Ba
nd Phase Shifter "GaAs IC Symposiuml981 pp.37
FIG. 2 is a schematic diagram for explaining the principle of the conventional semiconductor phase shifter shown in FIG. In the figure, (1) is an input line, (2)
Is an output line, (3) is a first branch line having an electrical length θ ₁ ,
(4) the second branch lines of the electric length theta _2, (5) a first single-pole double-throw switch (hereinafter, referred to as SPDT switch),
(6) is a second SPDT switch. In FIG. 11, since the first and second SPDT switches (5) and (6) are switched to the first branch line (3) side, the radio wave incident from the input line (1) is θ _1st phase delay
And appears on the output line (2) through the branch line (3). Here, the first and second SPDT switches (5) and (6)
Is switched to the side of the second branch line (4), the radio wave becomes θ ₂
After passing through the second branch line (4) in response to the phase delay, the signal appears on the output line (2). Therefore, the first,
By switching the second SPDT switches (5) and (6), the electric wave difference Δθ (Δθ = θ ₂ −θ ₁ ) between the first and second branch lines (3) and (4) is obtained. The phase changes and a phase shifter is formed.

FIG. 12 is a perspective view showing a configuration of the semiconductor phase shifter. In the figure, (1) to (6) are the same as those shown in FIG. 11, (7) is a semiconductor substrate, (8)
(9) denotes first and second FETs constituting the first SPDT switch (5), and (10) and (11) denote third and fourth FETs constituting the second SPDT switch (6). It is. Also, (1
2) (13) and (14) are the first, second, third and fourth F, respectively.
These are the drain electrode, gate electrode and source electrode of ET (8) (9) (10) (11). A bias voltage is applied to the gate electrode (13) from a bias terminal (16) via a bias resistor (15). The first, second, third and fourth FEs
For the switch operation of T (8) (9) (10) (11),
Normally, the drain electrode (12) and the source electrode (14) are used at the same potential in a DC manner, but a circuit for this is omitted in FIG. Now, assuming that the drain electrode (12) and the source electrode (14) have the same DC potential, for example, 0V, the voltage applied to the gate electrode (13) is switched to 0V and the pinch-off voltage, so that the drain electrode ( Between the 12) and the source electrode (14), a single-pole single-throw switch operates to pass and cut off radio waves. Therefore, the first and second FETs (8)
(9) and two FETs each of the third and fourth FETs (10) and (11) are arranged with a common drain electrode, and one of the two FETs has a gate bias voltage of 0 V ,
The other is a pinch-off voltage, and by simultaneously switching the above-mentioned bias voltage, constitutes an SPDT switch composed of two single-pole single-throw switches. Using this SPDT switch, the first branch line (3) and the second branch line (4)
By switching between three different propagation paths, it is possible to operate as a phase shifter in the same manner as described with reference to FIG.

In the conventional phase shifter as described above, the amount of phase shift is determined by the difference between the lengths of the first and second branch lines (3) and (4). Accurate phase shift characteristics can be obtained.

[Problems to be solved by the invention]

However, the conventional phase shifter as described above requires two switches at the input end and the output end of the propagation line to switch the propagation path, and the switching element such as the FET has a radio wave propagation path. In this case, there is a problem that the insertion loss due to the switch is large.

The present invention has been made to solve the above problems, and has as its object to obtain a low-loss phase shifter.

[Means for solving the problem]

The phase shifter according to the first aspect of the present invention includes two phase shifters having different path lengths.
Switch the two transmission lines with a switch and
In a path length switching type phase shifter having a phase shift amount of 180 degrees, an input terminal, an output terminal, one end is connected to the input terminal, and the other end is connected to the output terminal at a required frequency of about 180. And a second transmission line having an electrical length of approximately 360 degrees at a required frequency, one end of which is connected to the input terminal and the other end of which is connected to the output terminal. A single-pole single-throw switch, comprising one semiconductor element and having one end grounded at one end where cut-off and conduction are switched by a bias voltage from the input terminal of the first transmission line at a required frequency. The other end of a second single-pole single-throw switch, which is connected to a position approximately 90 degrees apart, is made of one semiconductor element, and has one end grounded at one end where cut-off and conduction are switched by a bias voltage, is connected to the second transmission line. Approximately 90 degrees from the above input terminal at the required frequency The first position
Either the first single-pole single-throw switch or the second single-pole single-throw switch connected to the transmission line that transmits radio waves from the input terminal, of the transmission line and the second transmission line. A means for applying a bias voltage to the first single-pole single-throw switch and the second single-pole single-throw switch so that one of the single-pole single-throw switches is turned off and the other single-pole single-throw switch is turned on. And formed by a microwave integrated circuit or a monolithic microwave integrated circuit.

The phase shifter according to the invention of claim 2 is characterized in that the semiconductor element is a field effect transistor.

The phase shifter according to the third aspect of the present invention is a phase shifter having two different path lengths.
Switch the two transmission lines with a switch and
In a path length switching type phase shifter having a phase shift amount of 180 degrees, an input terminal, an output terminal, one end is connected to the input terminal, and the other end is connected to the output terminal at a required frequency of about 180. A second transmission line having an electrical length of approximately 360 degrees at a required frequency and having one end connected to the input terminal and the other end connected to the output terminal; One end of one diode has an open end.
A low-impedance line formed of a quarter wavelength line is connected to form a short-circuit point at one terminal, and the other terminal is connected to the input terminal of the first transmission line at a required frequency of approximately 90%.
A first diode switch having a first bias terminal by connecting a high-impedance line formed of a quarter-wave line with an open end to one terminal forming the short-circuit point. A low impedance line formed by an open quarter-wave line is connected to one terminal of one diode to form a short-circuit point at the one terminal, and the other terminal is connected to the second transmission line. A second bias terminal which is connected to a position approximately 90 degrees away from the input terminal at a required frequency at a required frequency, and is connected to a high impedance line formed of a 1/4 wavelength line having an open end at one terminal where the short-circuit point is formed. Is connected to the first transmission line or the second transmission line, and a high-impedance line formed of an open-ended quarter-wave line is connected to the first or second transmission line. Formed with 4 wavelength lines Connect the impedance line to form a short-circuit point to the open end, the further distal end opened to an open end forming a short-circuit point of the high impedance line
A third bias terminal provided by connecting a high-impedance line formed of a quarter-wave line, and transmitting a radio wave from the input terminal among the first transmission line and the second transmission line. And the first bias terminal so that one of the first diode switch and the second diode switch connected to the other transmission line is turned off and the other diode switch is turned on. Means for applying a bias voltage to the first diode switch and the second diode switch between the third bias terminal and the second bias terminal and between the third bias terminal, respectively, the microwave integrated circuit or the monolithic It is characterized by being formed by a microwave integrated circuit.

[Action]

In the phase shifter configured as described above, the position of the first transmission line and the position of the second transmission line that appear high impedance when viewed from the input terminal and the output terminal when the switch that switches between cutoff and conduction is in the conduction state , Respectively, for example, when the switch connected to the first transmission line is turned off and the switch connected to the second transmission line is turned on, the second terminal from the input terminal and the output terminal is turned off. The impedance seen from the switch side of the transmission line becomes high impedance, that is, an open state.
Since the influence of the switch on the transmission line is negligible, the radio wave passes through the first transmission line. When the switch is switched between cutoff and conduction, the radio wave passes through the second transmission line. As described above, when the switch is switched between cutoff and conduction, the two transmission lines are switched without inserting a switch into the transmission line through which the radio wave passes, and the phase of the radio wave is changed.

〔Example〕

FIG. 1 is a schematic diagram for explaining an embodiment of the phase shifter of the present invention. Here, the technical idea of the present invention will be described by taking as an example a path length switching type 180-degree phase shifter in which two transmission lines having different path lengths having a difference of about 180 degrees at a predetermined frequency are switched by a switch. explain. In the figure, (17) is the input terminal of the phase shifter, (18) is the output terminal of the phase shifter, (19) and (20) have one end connected to the input terminal (17), and the other end connected to the output terminal (18). ) Connected to the first transmission line having an electrical length of approximately 180 degrees at the predetermined frequency and a second transmission line having an electrical length of approximately 360 degrees at the predetermined frequency. A first switch provided between the input terminal (17) of the transmission line (19) and the ground at an electric length of approximately 90 degrees at the predetermined frequency and the ground, and (22) a second switch (20) ) Is a second switch provided between the input terminal (17) and a position having an electrical length of approximately 90 degrees at the predetermined frequency and ground. Here, the first switch (21) and the second switch (22) are for switching between cutoff and conduction.

 Next, the operation will be described.

2 and 3 are explanatory diagrams of the operation of the embodiment of the phase shifter of the present invention shown in FIG. FIG. 2A shows the case where the first switch (21) is turned off and the second switch (22) is turned on, and FIG. 2B is an equivalent circuit showing the operation at this time. In this case, the effect of the first switch (21) can be neglected, and the second switch (22) can be considered as a short circuit. Therefore, it can be expressed as shown in FIG. (17) and the impedance seen from the output terminal (18) to the second switch (22) is high impedance, that is, in an open state, so that the radio wave receives a 180 ° phase delay and the first transmission line (19). Pass through. Also,
FIG. 3 (a) shows a case where the first switch (21) is turned on and the second switch (22) is turned off, and FIG. 3 (b) is an equivalent circuit showing the operation at this time. In this case,
The first switch (21) can be considered a short circuit and the second switch (21)
Since the effect of the switch (22) is negligible, it can be expressed as shown in FIG. 3 (b). The impedance seen from the input terminal (17) and the output terminal (18) to the first switch (21) is Since the radio wave has a high impedance, that is, an open state, the radio wave passes through the second transmission line (20) with a phase delay of 360 degrees. Therefore, by switching the first switch (21) and the second switch (22) to cut-off and conduction, the propagation phase of the radio wave changes by 180 degrees, and a 180-degree phase shifter can be configured.

FIG. 4 is a perspective view showing a specific structure of one embodiment of the phase shifter of the present invention shown in FIG. 1. In this embodiment, a semiconductor element and a line are formed using the same semiconductor substrate. An example is shown for a monolithic structure. In the figure, (23) is the FE forming the first switch (21).
T, (24) is the FET forming the second switch (22), (2
5) (26) and (27) are the drain electrode, gate electrode, and source electrode of FETs (23) and (24), (28) is a via hole, (29) is a bias resistor, (30) is a bias terminal, (31) is a capacitor. Here, a drain electrode (25) of the FET (23) is connected to the first transmission line (19), a source electrode (27) is grounded via a via hole (28), and a gate electrode (25). 26) is connected to a bias terminal (30) via a bias resistor (29). A capacitor (31) having one end grounded via a via hole (28) is connected between the bias resistor (29) and the bias terminal (30).
The leakage of radio waves to 0) is prevented. Similarly, FET
The drain electrode (25) of (24) is connected to the second transmission line (20), and the source electrode (27) is connected to the via hole (2).
The gate electrode (26) is connected to the bias terminal (30) via the bias resistor (29). A capacitor (31) having one end grounded via a via hole (28) is connected between the bias resistor (29) and the bias terminal (30). Prevents leaks.

The operation of the above embodiment is the same as that of the embodiment of the phase shifter of the present invention shown in FIG. 1 described above, and the gate bias of the FET (23) and the FET (24) is changed.
By switching between 0V and the pinch-off voltage, the first switch (21) and the second switch (22) can be switched between cut-off and conduction, and the radio wave path can be switched to the first transmission line (19).
And the second transmission line (20) to change the propagation phase to 180
Degrees, and a 180-degree phase shifter can be configured.

As described above, in the phase shifter of the present invention, two transmission lines can be switched without inserting a switch in the transmission line through which radio waves pass, and a low-loss phase shifter can be obtained. There is. Here, the 180-degree phase shifter shown in the above-described embodiment is difficult to obtain a low-loss phase shifter of a type other than the conventional path length switching type. It is considered high. Further, in this embodiment, the semiconductor element and the line have a monolithic structure constituted by using the same semiconductor substrate, so that a small-sized semiconductor phase shifter can be obtained and the number of semiconductor elements used can be reduced. .

In the above description, an example of a monolithic phase shifter in which a semiconductor element and a line are formed on the same substrate has been described. However, the present invention is not limited to this, and the present invention is not limited to this. As a semiconductor device, a PIN diode (3
Using a diode such as 2), a dielectric substrate (3
A microwave IC having a discrete hybrid structure using 3) may be used. In Fig. 5, (34) (35)
Are a high impedance line and a low impedance line formed by open-ended quarter wavelength lines, and the high impedance line (34) and the low impedance line (35) are
This is a circuit for applying a bias to the PIN diode (32). Here, in the circuit for applying the bias, the connection point of the PIN diode (32) is equivalently regarded as ground, and the one to which the PIN diode (32) is not connected is a floating ground. Therefore, by applying a bias to the PIN diode (32) from the bias terminal (30) and changing the bias, switching can be made between cut-off and conduction. There is an effect that two transmission lines can be switched, and a low-loss phase shifter can be obtained. Further, in this embodiment, when a bias is applied to the diode, DC cut is not required for the line, and there is an effect that the loss can be reduced.

FIG. 6 is a perspective view showing another embodiment of the phase shifter according to the present invention. This embodiment is provided with a configuration for improving the cutoff state of the switch. In the figure,
(36) is an inductor for resonance, and the inductor (36)
With the source electrodes of FET (23) and FET (24) (2
Each FET (23) between the 7) and the drain electrode (25)
(24) is a circuit configuration loaded in parallel. Inductor (3
6) By loading FETs (23) and (24) in parallel, FE
This has the effect of canceling the capacitance of T and improving the cutoff state of the switch.

FIG. 7 is a schematic diagram for explaining another embodiment of the phase shifter of the present invention. In this embodiment, a configuration for canceling the reflection by the first switch (21) or the second switch (22) in the cutoff state is added. Reference numeral (37) denotes a reflection compensating element connected to the input line (1) located at an electrical distance of an odd multiple of approximately 90 degrees from the first switch (21) or the second switch (22).
Here, as the reflection compensating element (37), for example, a distributed constant circuit composed of a line whose tip is open or short-circuited, or a MI
A lumped constant circuit composed of an M capacitor or the like is used. With such a configuration, it is possible to effectively match both the first switch (21) and the second switch (22) simply by loading one reflection compensating element (37), and to obtain the reflection characteristic. This is effective in obtaining a phase shifter having a good phase shifter.

The operation of the embodiment shown in FIGS. 6 and 7 is the same as that of the embodiment shown in FIG. 4, and has an effect that a low-loss phase shifter can be obtained.

In the above description, a 180-degree phase shifter of a path length switching type in which two transmission lines having different path lengths having an electrical length difference of about 180 degrees at a predetermined frequency are switched by a switch has been described as an example. Hereinafter, as a reference example, a case where the present invention is applied to a phase shifter in which the difference in electric length is set to another value will be described.

 Next, a reference example will be described.

FIG. 8 is a schematic diagram for explaining a reference example of a phase shifter in which the difference between the electrical lengths is set to an arbitrary value Δθ. In the figure, (22a) and (22b) are approximately 90 at a predetermined frequency from the input terminal (17) and the output terminal (18) of the second transmission line (20).
A second switch and a third switch provided between the electrical length position and the ground. Here, the first
The switch (21), the second switch (22a), and the third switch (22b) switch between interruption and conduction.
Here, a predetermined electrical length difference Δθ is set between the connection point of the second switch (22a) and the third switch (22b) on the second transmission line (20). Note that the position of the electrical length of approximately 90 degrees at a predetermined frequency may be a position of an electrical length that is an odd multiple of 90 degrees.

9 and 10 are explanatory diagrams of the operation of the phase shifter of the reference example shown in FIG. FIG. 9A shows the first switch (21).
, The second switch (22a), the third switch (22
FIG. 9 (b) is an equivalent circuit showing the operation at this time, where b) is a conduction state. In this case, the effect of the first switch (21) can be ignored, and the second switch (22)
a), since the third switch (22b) can be considered as a short circuit, it can be represented as shown in FIG. 9 (b), and the second switch (22) is connected from the input terminal (17) and the output terminal (18). twenty two
a) Since the impedance seen from the third switch (22b) side is high impedance, that is, in an open state, the radio wave passes through the first transmission line (19) with a phase delay of 180 degrees. FIG. 10 (a) shows that the first switch (21) is turned on, the second switch (22a), and the third switch (22b).
And FIG. 10 (b) is an equivalent circuit showing the operation at this time. In this case, the first switch (21) can be considered as a short circuit, and the effects of the second switch (22a) and the third switch (22b) can be neglected. From the input terminal (17) and the output terminal (18) to the first switch (21).
Since the impedance seen from the side becomes high impedance, that is, it is in an open state, the radio wave receives the phase delay of (180 + θ) degrees and passes through the second transmission line (20). Therefore, the first switch (21), the second switch (22) and the third switch (22)
By switching the switch (22b) to cut-off / conduction, the propagation phase of the radio wave changes by θ degrees, and a θ-phase shifter having an arbitrary value can be configured.

The specific configuration of the above-described reference example can be the same as that of the embodiment shown in FIGS. 4 to 7, so that the configuration diagram is omitted here.

Also, needless to say, the above-described reference example has the same effect as the above-described embodiment, and it is possible to switch between two transmission lines without inserting a switch in a transmission line through which a radio wave passes, thereby achieving low-loss transfer. There is an effect that a phaser can be obtained.

〔The invention's effect〕

As described above, according to the present invention, the first single-pole single-throw switch and the second single-pole single-throw switch each including one semiconductor element and having one end grounded at one end where cutoff and conduction are switched by a bias voltage are provided. Each of the first transmission line and the second transmission line is connected to a position approximately 90 degrees apart from the input terminal at a required frequency to transmit a radio wave from the input terminal of the first transmission line and the second transmission line. One of the first single-pole single-throw switch and the second single-pole single-throw switch connected to the transmission line to be turned off is turned off, and the other single-pole single-throw switch is turned off. Since a bias voltage is applied to the first single-pole single-throw switch and the second single-pole single-throw switch so as to make the switch conductive, all switches constituting the phase shifter are loaded in parallel on the transmission line, and radio waves are transmitted. The switch connected to the transmission line to be transmitted Ji always be open, with only two semiconductor devices, it low losses due to a good integrated circuit mass productivity
There is an effect that a 180 degree phase shifter can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining an embodiment of the phase shifter of the present invention. FIGS. 2 and 3 are operation explanatory diagrams of the embodiment of the phase shifter of the present invention shown in FIG. FIG. 4 is a perspective view showing the configuration of the embodiment of the phase shifter of the present invention shown in FIG. 1, FIG. 5 is a perspective view showing the configuration of another embodiment of the phase shifter of the present invention, and FIG. FIG. 7 is a perspective view showing the configuration of still another embodiment of the phase shifter of the present invention, FIG. 7 is a schematic diagram for explaining still another embodiment of the phase shifter of the present invention, and FIG. FIGS. 9 and 10 are schematic diagrams for explaining an example phase shifter, FIGS. 9 and 10 are explanatory diagrams of the operation of the phase shifter of the reference example shown in FIG. 8, and FIG. 11 illustrates a conventional phase shifter. FIG. 12 is a schematic diagram for explaining the operation of the conventional phase shifter. In the figure, (1) is an input line, (2) is an output line,
(3) is a first branch line, (4) is a second branch line,
(5) is the first SPDT switch, (6) is the second SPDT switch, (7) is the semiconductor substrate, (8) and (9) are the first and second SPDT switches.
FETs, (10) and (11) are the third and fourth FETs, (12) and (13)
(14) is the drain electrode, gate electrode, source electrode, (1
5) is a bias resistor, (16) is a bias terminal, (17) is an input terminal, (18) is an output terminal, (19) is a first transmission line, (20) is a second transmission line, and (21). Is a first switch, (22) and (22a) are second switches, (22b) is a third switch, (23) and (24) are FETs, (25), (26), and (27) are drain electrodes and gates. (28) via hole, (29) bias resistor, (30) bias terminal, (31) capacitor, (32) PIN diode, (3)
3) is a dielectric substrate, (34) is a high impedance line, (3)
5) is a low impedance line, (36) is an inductor, (3
7) is a reflection compensation element. In the drawings, the same reference numerals indicate the same or corresponding parts.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Shuji Urasaki 5-1-1, Ofuna, Kamakura City, Kanagawa Prefecture Inside the Electronic Systems Research Laboratory, Mitsubishi Electric Corporation (72) Inventor Kenji Ito 5-1-1, Ofuna, Kamakura City, Kanagawa Prefecture No. 1 In Electronic Systems Research Laboratory, Mitsubishi Electric Co., Ltd. (72) Inventor Kenji Mimatsu 5-1, 1-1 Ofuna, Kamakura City, Kanagawa Prefecture, Japan Electronic Systems Research Laboratory, Mitsubishi Electric Corporation (72) Inventor Tomonori Shigematsu Kamakura, Kanagawa Prefecture 5-1-1 of Ofuna In Electronic Systems Research Laboratory, Mitsubishi Electric Corporation (56) References JP-A-63-123201 (JP, A) JP-A-59-196603 (JP, A) JP-A-1-305601 ( JP, A) U.S. Pat. No. 3,313,367 (US, A) Morikita Electrical Engineering Series 3 "Microwave Engineering-Fundamentals and Principles" by Masamitsu Nakajima, P84-86

Claims (3)

(57) [Claims] 1. A phase shifter of a path length switching type having a phase shift amount of 180 degrees at a required frequency by switching two transmission lines having different path lengths by a switch. A first transmission line connected to the input terminal, the other end having an electrical length of approximately 180 degrees at a required frequency connected to the output terminal, and one end connected to the input terminal;
The other end is approximately 360 at the required frequency connected to the output terminal.
A second transmission line having an electrical length of
A single-pole, single-throw switch, one end of which is grounded at one end where cut-off and conduction are switched by a bias voltage, is separated from the input terminal of the first transmission line by approximately 90 degrees at a required frequency. Position, and one end of a second single-pole single-throw switch, which is made of one semiconductor element and has one end grounded at one end where cut-off and conduction are switched by a bias voltage, is connected to the second end.
The transmission line is connected to the input terminal at a required frequency of approximately 90 degrees from the input terminal, and the transmission line that transmits the radio wave from the input terminal is selected from the first transmission line and the second transmission line. One of the first single-pole single-throw switch and the second single-pole single-throw switch is connected such that the single-pole single-throw switch is turned off and the other single-pole single-throw switch is turned on. A phase shifter comprising means for applying a bias voltage to the first single-pole single-throw switch and the second single-pole single-throw switch, and formed by a microwave integrated circuit or a monolithic microwave integrated circuit. 2. The phase shifter according to claim 1, wherein said semiconductor element is a field effect transistor. 3. A path length switching type phase shifter having a phase shift amount of 180 degrees at a required frequency by switching two transmission lines having different path lengths by a switch, wherein an input terminal, an output terminal, and one end are provided. A first transmission line connected to the input terminal, the other end having an electrical length of approximately 180 degrees at a required frequency connected to the output terminal, and one end connected to the input terminal;
The other end is approximately 360 at the required frequency connected to the output terminal.
A second transmission line having an electrical length of one degree and a low-impedance line formed of a 1/4 wavelength line with an open end connected to one terminal of one diode to form a short-circuit point at the one terminal. The other terminal was connected to the input terminal of the first transmission line at a position approximately 90 degrees apart from the input terminal at a required frequency, and the one end where the short-circuit point was formed was formed by a 1/4 wavelength line having an open end. The first diode switch provided with a first bias terminal by connecting a high impedance line, and the low impedance line formed by a 1/4 wavelength line having an open end connected to one terminal of one diode. A short-circuit point is formed at one terminal, and the other terminal is connected to the input terminal of the second transmission line at a position approximately 90 degrees apart from the input terminal at a required frequency. of
A second diode switch provided with a second bias terminal by connecting a high impedance line formed of a 波長 wavelength line, and a 波長 wavelength switch having an open end on the first transmission line or the second transmission line; A high impedance line formed by a line is connected, a low impedance line formed by a 1/4 wavelength line with an open end is connected to an open end thereof, and a short-circuit point is formed at the open end, and a short-circuit point of the high impedance line is formed. And a third bias terminal provided by connecting a high-impedance line formed of a 1/4 wavelength line with an open end to the open end formed with the first transmission line and the second transmission line. One of the first diode switch and the second diode switch connected to the transmission line for transmitting the radio wave from the input terminal is turned off, and the other diode switch is turned off. The first diode switch and the second diode switch are connected between the first bias terminal and the third bias terminal and between the second bias terminal and the third bias terminal, respectively, so as to make the diode switch conductive. A phase shifter comprising: means for applying a bias voltage; and formed by a microwave integrated circuit or a monolithic microwave integrated circuit.