Path selection switch, 90-degree terahertz phase shifter and phased array radar

Abstract

The invention discloses a path selection switch, a 90-degree terahertz phase shifter and a phased array radar, and belongs to the technical field of communication and radar, the path selection switch comprises a plurality of transmission lines, the input ends of the plurality of transmission lines are connected to form a common node, and the output end of each transmission line is sequentially connected with a transistor and an impedance converter; the substrate of the transistor is grounded through the first resistor, the control end of the transistor is connected with the second resistor, the 90-degree terahertz phase shifter based on the path selection switch reduces the change of parasitic parameters in different phase shifting states, reduces the deterioration effect of the parasitic parameter change in different phase shifting states on the phase shifting precision, and improves the phase shifting precision. According to the 90-degree terahertz phase shifter, the phase shifting precision of the terahertz phase shifter is improved, the technical bottleneck that a high-precision terahertz phase shifter is sensitive to parasitic parameters is broken through, meanwhile, the 90-degree terahertz phase shifter has the advantages of being low in insertion loss and wide and flat, and the insertion loss performance and the phase shifting precision performance are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of communication and radar, and in particular to a path selection switch, a 90-degree terahertz phase shifter and a phased array radar. Background Art

[0002] Traditional terahertz phase shifters are mainly divided into two architectures: switch-line phase shifters based on PIN (PIN represents the structural type of transistor, P-type semiconductor, intrinsic semiconductor and N-type semiconductor) Schottky diodes and switch-line phase shifters based on MEMS (Micro-Electro-Mechanical Systems) technology. Terahertz phase shifters play an important role in communication and radar electronic systems, but the above two switch-line phase shifters have the problems of large structure volume, large insertion loss and low integration, which is not conducive to the miniaturization design of communication equipment.

[0003] In addition, the terahertz phase shifter is a core component of the radar system. Its phase shift accuracy restricts the performance of the radar system. The insertion loss of the terahertz phase shifter limits the sensitivity and detection distance of the radar system, and the phase shift accuracy of the terahertz phase shifter directly determines key performance indicators such as the beam pointing error and sidelobe suppression ratio of the radar system. The phase shift accuracy of the terahertz phase shifter is mainly limited by the parasitic parameters of the active device. When the phase shift state is switched, the parasitic parameters of the transistor device will also change, causing the phase shift value to deviate from the ideal phase shift value and deteriorating the phase shift accuracy. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a path selection switch, a 90-degree terahertz phase shifter and a phased array radar. The 90-degree terahertz phase shifter can reduce the parasitic parameter changes in different phase shift states and improve the phase shift accuracy of the terahertz phase shifter.

[0005] The present invention is achieved through the following technical solutions: In a first aspect, the present application provides a path selection switch, comprising a plurality of transmission lines, wherein input ends of the plurality of transmission lines are connected to form a common node, and output ends of the transmission lines are connected to a transistor and an impedance converter; The substrate of the transistor is grounded through a first resistor, and the control terminal of the transistor is connected to a second resistor; When the control terminal of the transistor is at a low level, the corresponding transmission line is turned on to transmit the radio frequency signal.

[0006] Preferably, the transistor is a CMOS transistor, a BJT, a FET, an IGBT, a PNP transistor, a PIN transistor or an NPN transistor.

[0007] Preferably, the gate of the transistor is the control terminal, the gate is connected to the second resistor, the source is grounded, the substrate is grounded through the first resistor, the drain is connected to the selection node of the transmission line, and the impedance converter is connected to the drain.

[0008] Preferably, the transmission line is wired in a reciprocating folding manner.

[0009] Preferably, the transmission line is a coplanar waveguide transmission line, a microstrip line or a stripline.

[0010] In a second aspect, the present application provides a 90-degree terahertz phase shifter. It includes a primary phase module and a secondary phase module connected in series; The first-level phase module includes two first-path selection switches with the same structure, and the two first-path selection switches are connected through a multi-section transmission line; The two-stage phase module includes two second path selection switches with the same structure, and the two second path selection switches are connected through a multi-section transmission line; The first path selection switch and the second path selection switch are the path selection switches, and the phase selection path of the first path selection switch is smaller than the phase selection path of the second path selection switch.

[0011] Preferably, the two path selection switches in the primary phase module or / and the secondary phase module are connected by a coplanar waveguide transmission line.

[0012] Preferably, the radio frequency signal is input from the first phase module and output through the second phase module after phase shifting; During the transmission process, the radio frequency signal is transmitted along the transmission line corresponding to the low level at the control end of the transistor.

[0013] Preferably, the first path selection switch is a single-pole three-throw switch, and the second path selection switch is a single-pole four-throw switch.

[0014] In a third aspect, the present application provides a terahertz phased array radar, including the 90-degree terahertz phase shifter.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: A path selection switch provided in the present application adopts parallel transmission line resonance technology, connects a transistor and an impedance converter at the output end of the transmission line, and reduces the insertion loss of the RF signal in the on state; secondly, adding a resistor between the substrate and the ground of the transistor, and adding a resistor at the control end of the transistor can improve the isolation performance of the path selection switch, and can also further reduce the insertion loss; in addition, an impedance converter is set at the output end of the transmission line to improve the isolation of the transistor in the off state and reduce the insertion loss of the path selection switch.

[0016] The present application provides a 90-degree terahertz phase shifter, which uses different path selection switches in two phase modules, thereby reducing the changes in parasitic parameters under different phase shift states, reducing the deterioration effect of the changes in parasitic parameters under different phase shift states on the phase shift accuracy, and improving the phase shift accuracy of the terahertz phase shifter, so as to break through the technical bottleneck of high-precision terahertz phase shifters being sensitive to parasitic parameters. At the same time, it has the advantages of low insertion loss and wide flatness, so that both insertion loss and phase shift accuracy performance are improved. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 This is a structural diagram of a 90-degree terahertz phase shifter of the present invention; Figure 2 It is a structural diagram of a single-pole triple-throw switch of the present invention; Figure 3 It is a structural diagram of a single-pole four-throw switch of the present invention; Figure 4 This is a working principle diagram of the 90-degree terahertz phase shifter of the present invention; Figure 5 The relative phase shift value and phase shift mean square error diagram of the 90-degree terahertz phase shifter of the present invention; Figure 6 This is a diagram of insertion loss and insertion loss mean square error of the 90-degree terahertz phase shifter of the present invention. DETAILED DESCRIPTION

[0017] The present invention will be further described in detail below in conjunction with the accompanying drawings, which are intended to explain the present invention rather than to limit it.

[0018] A path selection switch includes a plurality of transmission lines, the input ends of the plurality of transmission lines are connected to form a common node, and the output ends of the transmission lines are sequentially connected to transistors and impedance converters; The substrate of the transistor is grounded through a first resistor, and the control end of the transistor is connected to a second resistor. When the control end of the transistor is at a low level, the corresponding transmission line is turned on to transmit a radio frequency signal.

[0019] The path selection switch uses the common node as the RF signal input terminal and the selection node of each transmission line as the RF signal output terminal. The path selection switch adopts parallel transmission line resonance technology to make the transmission line equivalent to an inductor. The inductor resonates with the transistor to present a high-resistance state, so that the RF signal can pass more effectively in the on state, thereby reducing the insertion loss. The reduction in insertion loss means that the energy loss of the RF signal during the transmission process is reduced, thereby improving the efficiency and quality of RF signal transmission.

[0020] At the same time, as a switching element, the working state (on or off) of the transistor is determined by the control terminal signal. The first resistor is added between the substrate and the ground of the transistor, and the second resistor is added to the control terminal of the transistor. The introduction of these two resistors plays multiple roles. On the one hand, it helps to stabilize the working state of the transistor and prevent malfunctions caused by parasitic effects and noise interference; on the other hand, the resistors inhibit the transmission of the RF signal to the control terminal, further optimizing the transmission performance of the RF signal during the switching state transition. In particular, when the transistor is in the off state, the resonant circuit presents a high impedance state, ensuring the transmission of the RF signal to the output terminal, thereby reducing the attenuation of the RF signal.

[0021] In addition, setting an impedance converter at the selection node of the transmission line is another important component. The main function of the impedance converter is to match the impedance of the transistor selection node to the impedance level required by the subsequent circuit to reduce the RF signal reflection and insertion loss caused by impedance mismatch. This impedance matching design not only improves the isolation of the transistor in the off state, but also ensures the efficient transmission of the RF signal in the on state. By accurately adjusting the parameters of the impedance converter, the overall performance of the path selection switch can be further optimized to meet the needs of specific application scenarios.

[0022] The path selection switch achieves the performance characteristics of low insertion loss and high isolation of the path selection switch by adopting parallel transmission line resonance technology, adding resistors to the substrate and control end of the transistor, and setting an impedance transformer at the selection node, thereby realizing precise control and efficient transmission of radio frequency signals.

[0023] The transmission line is a coplanar waveguide transmission line, a microstrip line or a stripline, preferably a coplanar waveguide transmission line, which has a signal trace and a return path conductor. The radio frequency signal trace is located in the center and is surrounded by two adjacent external ground planes. This structure enables the coplanar waveguide transmission line to have lower dispersion and better electromagnetic compatibility at high frequencies, and is suitable for high-speed digital circuits and radio frequency integrated circuits.

[0024] The transmission line is wired in a reciprocating folding manner to reduce the area of ​​the path selection switch, and is applied to communication equipment, which is conducive to the miniaturization of the communication equipment; for example, the transmission line is arranged in a folded serpentine shape.

[0025] The transistor is a CMOS (Complementary Metal-Oxide-Semiconductor) transistor, a BJT (Bipolar Junction Transistor), a FET (Field Effect Transistor), an IGBT (Insulated Gate Bipolar Transistor), a PNP transistor, a PIN transistor or an NPN transistor, preferably a CMOS transistor.

[0026] The PNP transistor consists of three different semiconductor regions, and its structure is marked as PNP, that is, two P-type semiconductor regions sandwich an N-type semiconductor region. These three regions are called the emitter (the first P-type region), the base (N-type region), and the collector (the second P-type region).

[0027] The "NPN" in the NPN transistor represents the structural type of the transistor, namely N-type semiconductor-P-type semiconductor-N-type semiconductor, the middle layer is P-type semiconductor, and the two sides are N-type semiconductors.

[0028] The gate of the CMOS transistor is a control terminal, the gate is connected to the second resistor, the source is grounded, the substrate is grounded through the first resistor, the drain is connected to the selection node of the transmission line, and the impedance converter is connected to the drain.

[0029] The path selection switch is a single-pole multi-throw switch, for example, a single-pole three-throw switch SP3T, a single-pole four-throw switch SP4T, a single-pole five-throw switch, a single-pole six-throw switch, etc.

[0030] When the path selection switch is working, the control end of the transistor controls the conduction state of the path selection switch according to the control signal. When the control end of the transistor is at a low level, the corresponding transmission line is turned on, and the other transmission lines are disconnected. The RF signal is transmitted through the turned-on transmission line and output.

[0031] Correspondingly, see Figure 1 , the present application also provides a 90-degree terahertz phase shifter using the above-mentioned path selection switch, including a primary phase module and a secondary phase module connected in series; The first-level phase module includes two first-path selection switches with the same structure, and the two first-path selection switches are connected through a multi-section transmission line; The two-stage phase module includes two second path selection switches with the same structure, and the two second path selection switches are connected through a multi-section transmission line; The phase selection path of the first path selection switch is smaller than the phase selection path of the second path selection switch.

[0032] The number of transmission line segments between two path selection switches in the same phase module matches the number of selection nodes of the path selection switches. For example, in the same phase module, if the number of selection nodes of the path selection switches is N, the two path selection switches are connected using N transmission line segments.

[0033] The two first path selection switches are respectively the first path selection switch A and the first path selection switch B, and the two second path selection switches are respectively the second path selection switch A and the second path selection switch B. The connection method of the primary phase module and the secondary phase module is described below.

[0034] The common node of the first path selection switch A is used as the RF input port P IN , the multiple selection nodes of the first path selection switch A are respectively connected to the multiple selection nodes of the first path selection switch B through multiple transmission lines, the common node of the first path selection switch B is connected to the common node of the second path selection switch A, the multiple selection nodes of the second path selection switch A are respectively connected to the multiple selection nodes of the second path selection switch B through multiple transmission lines, and the common node of the second path selection switch B is used as the RF signal output port P OUT .

[0035] The transmission line between the two path selection switches is a coplanar waveguide transmission line, a microstrip line or a stripline, preferably a coplanar waveguide transmission line; the transmission line is wired in a reciprocating folding manner, and the transmission line is arranged in a folded serpentine shape to reduce the area of ​​the 90-degree terahertz phase shifter, which is conducive to the miniaturization of the 90-degree terahertz phase shifter.

[0036] Example 1 A 90-degree terahertz phase shifter comprises a primary phase module and a secondary phase module connected in series.

[0037] The primary phase module includes two single-pole three-throw switches SP3T (Single Pole, 3 Throw), the single-pole three-throw switch SP3T includes three phase selection paths, and the selection nodes of the two single-pole three-throw switches SP3T are connected through three sections of coplanar waveguide transmission lines; the secondary phase module includes two single-pole four-throw switches SP4T (Single Pole, 4 Throw), the single-pole four-throw switch SP4T includes four phase selection paths, and the selection nodes of the two single-pole four-throw switches SP4T are connected through four sections of coplanar waveguide transmission lines; The common node of a single-pole three-throw switch SP3T is connected to the common node of a single-pole four-throw switch SP4T, and the common node of another single-pole three-throw switch SP3T is used as the RF signal input terminal P 31 , the common node of another single-pole four-throw switch SP4T is used as the RF signal output terminal P 41 .

[0038] See also Figure 2 , single-pole three-throw switch SP3T, the selection node of the first phase selection path is connected to the CMOS transistor M5 and the impedance converter in sequence, and the output end of the impedance converter is used as the RF signal output end P 32 The selection node of the second phase selection path is connected to the CMOS transistor M6 and the impedance converter in sequence, and the output end of the impedance converter serves as the RF signal output end P 33 The selection node of the third phase selection path is connected to the CMOS transistor M7 and the impedance converter in sequence, and the output end of the impedance converter serves as the RF signal output end P 34 .

[0039] The gate of the CMOS transistor M5 is connected to a resistor R 12 The substrate is grounded through a resistor R9; the gate of the CMOS transistor M6 is connected to a resistor R 13 , the substrate passes through the resistor R 10 The gate of the CMOS transistor M7 is connected to a resistor R 11 , the substrate passes through the resistor R 14 Ground.

[0040] See also Figure 3 , single-pole four-throw switch SP4T, the selection node of the first phase selection path is connected to the CMOS transistor M1 and the impedance converter in sequence, and the output end of the impedance converter is used as the RF signal output end P 42 The selection node of the second phase selection path is connected to the CMOS transistor M2 and the impedance converter in sequence, and the output end of the impedance converter serves as the RF signal output end P 43 The selection node of the third phase selection path is connected to the CMOS transistor M3 and the impedance converter in sequence, and the output end of the impedance converter serves as the RF signal output end P 44 The selection node of the fourth phase selection path is connected to the CMOS transistor M4 and the impedance converter in sequence, and the output end of the impedance converter serves as the RF signal output end P 45 .

[0041] The gate of the CMOS transistor M1 is connected to resistor R5, and the substrate is grounded through resistor R1; the gate of the CMOS transistor M2 is connected to resistor R6, and the substrate is grounded through resistor R2; the gate of the CMOS transistor M3 is connected to resistor R7, and the substrate is grounded through resistor R3; the gate of the CMOS transistor M4 is connected to resistor R8, and the substrate is grounded through resistor R4.

[0042] When the above 90-degree terahertz phase shifter is working, the transmission path of the RF signal is as follows: The control terminal of the CMOS transistor M5 of the single-pole triple-throw switch is V5, the control terminal of the CMOS transistor M6 is V6, and the control terminal of the CMOS transistor M7 is V7.

[0043] When the control terminal V5 is at a low level, the control terminals V6 and V7 are at a high level, and the RF signal is output from the RF signal input terminal P 31 Input and transmit to the RF signal output terminal P 32 ; When the control terminal V6 is at a low level, the control terminals V5 and V7 are at a high level, and the RF signal is output from the RF signal input terminal P 31 Input and transmit to the RF signal output terminal P 33 ; When the control terminal V7 is at a low level, the control terminals V5 and V6 are at a high level, and the RF signal is output from the RF signal input terminal P 31 Input and transmit to the RF signal output terminal P 34 .

[0044] The control end of the CMOS transistor M1 of the single-pole four-throw switch is V1, the control end of the CMOS transistor M2 is V2, the control end of the CMOS transistor M3 is V3, and the control end of the CMOS transistor M4 is V4.

[0045] When the control terminal V1 is at a low level, the control terminals V2, V3 and V4 are at a high level, and the RF signal is output from the RF signal input terminal P 41 Input and transmit to the RF signal output terminal P 42 ; When the control terminal V2 is at a low level, the control terminals V1, V3 and V4 are at a high level, and the RF signal is output from the RF signal input terminal P 41 Input and transmit to the RF signal output terminal P 43 ; When the control terminal V3 is at a low level, the control terminals V1, V2 and V4 are at a high level, and the RF signal is output from the RF signal input terminal P 41 Input and transmit to the RF signal output terminal P 44 .

[0046] When the control terminal V4 is at a low level, the control terminals V1, V2 and V3 are at a high level, and the RF signal is output from the RF signal input terminal P 41 Input and transmit to the RF signal output terminal P 45 .

[0047] Figure 4 FIG. 4 is a working principle diagram of a 90-degree terahertz phase shifter. The phase shifting method of the 90-degree terahertz phase shifter is described below.

[0048] For ease of description, the selection nodes of each single-pole multi-throw switch are defined as follows: The two single-pole three-throw switches of the first-stage phase module are single-pole three-throw switch SP3TA and single-pole three-throw switch SP3TB.

[0049] The three selection nodes of the single-pole triple-throw switch SP3TA are nodes A1, A2, and A3; The three selection nodes of the single-pole triple-throw switch SP3TB are nodes B1, B2, and B3; The two single-pole four-throw switches of the secondary phase module are single-pole four-throw switch SP4TA and single-pole four-throw switch SP4TB respectively.

[0050] The four selection nodes of the single-pole four-throw switch SP4TA are nodes A4, A5, A6, and A7; The four selection nodes of the single-pole four-throw switch SP4TB are nodes B4, B5, B6, and B7 respectively.

[0051] The phases of the primary phase module include 28.125°, 16.875°, and 5.625°; the phases of the secondary phase module include 50.625°, 39.375°, 16.875°, and 5.625°. In the phase shifting process, the phase shifting is achieved by controlling the node conduction of the single-pole three-throw switch and the single-pole four-throw switch. Table 1 is a relationship table between the node status and the corresponding phase shift value.

[0052] Table 1

[0053] The 90-degree terahertz phase shifter of the present application controls the phase shift state of the terahertz phase shifter through a transistor to achieve a phase shift with a step of 5.625° within a 90° phase shift range. Due to the symmetry of the single-pole three-throw switch SP3T and the single-pole four-throw switch SP4T, the fluctuation of the parasitic parameters of the terahertz phase shifter in different states is reduced, thereby effectively improving the phase shift accuracy of the terahertz phase shifter.

[0054] The 90-degree terahertz phase shifter is simulated. Figure 5 The relative phase shift value and phase shift mean square error diagram of the 90-degree terahertz phase shifter. Figure 6 Insertion loss and insertion loss mean square error diagram of 90-degree terahertz phase shifter.

[0055] The 90-degree terahertz phase shifter can achieve a 5-bit phase shift function within a 90° range in the frequency range of 192.5-220 GHz (gigahertz), and the phase mean square error is less than 5.625, with high phase shift accuracy. At the same time, the insertion loss mean square error fluctuation is less than 0.5dB (decibel) in the frequency range of 190-220 GHz. The simulation results prove that the 90-degree terahertz phase shifter proposed in the present invention reduces the deterioration of the phase shift accuracy caused by the parasitic parameter changes caused by the phase shift state changes, effectively improves the phase shift accuracy in the sub-terahertz frequency band, and has the characteristics of low insertion loss and wide flatness.

[0056] The 90-degree terahertz phase shifter has the following advantages: 1. The 90-degree terahertz phase shifter adopts a path selection switch, which adopts parallel transmission line resonance technology to realize the resonance effect between transmission lines when the RF signal is on, reducing the insertion loss of the RF signal in the on state, thereby reducing the insertion loss of the entire terahertz phase shifter, which not only improves the efficiency of RF signal transmission, but also ensures the performance stability of the terahertz phase shifter in the high-frequency terahertz band.

[0057] 2. The two channel selection switches are connected by coplanar waveguide transmission lines, and the coplanar waveguide transmission lines are arranged in a folded manner. This arrangement not only retains the advantages of low loss and easy integration of coplanar waveguide transmission lines in high frequency bands, but also significantly reduces the space occupied by the transmission lines through the folding design, thereby realizing the miniaturization of the overall volume of the terahertz phase shifter. This is undoubtedly an important advantage for terahertz systems that require highly integrated and compact designs.

[0058] 3. A resistor is added between the transistor substrate and the ground of the path selection switch to improve the isolation performance of the substrate, reduce the leakage and reflection of the RF signal in the substrate, thereby reducing the insertion loss of the path selection switch and improving the isolation of the switch, thereby reducing the insertion loss of the entire terahertz phase shifter and improving the phase shift accuracy.

[0059] 4. A resistor is added to the gate of the transistor of the path selection switch, which effectively limits the path of the RF signal coupling to the control circuit through the gate, reduces the leakage of the RF signal to the control end, and not only improves the isolation performance of the path selection switch, but also reduces the insertion loss of the path selection switch, further reduces the overall insertion loss of the terahertz phase shifter, and improves the phase shift accuracy.

[0060] 5. An impedance converter is added to the RF output port of the path selection switch, so that the transistor can provide better isolation when it is in the off state, further reducing insertion loss and improving phase shift accuracy. This design not only improves the overall performance level of the terahertz phase shifter, but also enhances its adaptability and reliability in complex application scenarios.

[0061] Example 2 The present application also provides a terahertz phased array radar, comprising the 90-degree terahertz phase shifter of Example 1.

[0062] Example 3 The present application also provides a communication device, comprising the 90-degree terahertz phase shifter of Example 1.

[0063] Example 4 The present application also provides an electronic device, comprising the 90-degree terahertz phase shifter of Example 1.

[0064] The electronic device is a terahertz imaging device. Terahertz waves can penetrate non-metallic materials such as clothing and plastics, so terahertz imaging technology has great potential in the field of security inspection. As part of the imaging system, the terahertz phase shifter can optimize the phase characteristics of the signal, improve the resolution and clarity of the imaging, and thus more accurately identify contraband hidden in clothing or packages.

[0065] This electronic device is a biological detection device that can analyze the vibration mode of biological molecules through terahertz spectroscopy technology to achieve high-precision human tissue imaging and tumor detection. In this process, the terahertz phase shifter plays a role in adjusting the signal phase, improving the accuracy and reliability of detection.

[0066] The electronic device is a terahertz spectrum analysis system. As a part of the spectrum analysis system, the terahertz phase shifter can optimize the phase characteristics of the signal and improve the accuracy and sensitivity of the spectrum analysis.

[0067] The electronic device is an audio device, and the function of the terahertz phase shifter is mainly reflected in adjusting the phase of the audio signal, thereby producing a specific sound effect or improving the audio quality.

[0068] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A path selection switch, characterized in that: It includes a plurality of transmission lines, wherein the input ends of the plurality of transmission lines are connected to form a common node, and the output end of each transmission line is connected to a transistor and an impedance converter; The substrate of the transistor is grounded through a first resistor, and the control terminal of the transistor is connected to a second resistor; When the control terminal of the transistor is at a low level, the corresponding transmission line is turned on to transmit the radio frequency signal.

2. A path selection switch according to claim 1, characterized in that: The transistor is a CMOS transistor, a BJT, a FET, an IGBT, a PNP transistor, a PIN transistor or an NPN transistor.

3. A path selection switch according to claim 1, characterized in that: The gate of the transistor is a control terminal, the gate is connected to the second resistor, the source is grounded, the substrate is grounded through the first resistor, the drain is connected to the selection node of the transmission line, and the impedance converter is connected to the drain.

4. A path selection switch according to claim 1, characterized in that: The transmission line is wired in a reciprocating folding manner.

5. A path selection switch according to claim 1, characterized in that: The transmission line is a coplanar waveguide transmission line, a microstrip line or a stripline.

6. A 90-degree terahertz phase shifter, characterized in that: It includes a primary phase module and a secondary phase module connected in series; The first-level phase module includes two first-path selection switches with the same structure, and the two first-path selection switches are connected through a multi-section transmission line; The two-stage phase module includes two second path selection switches with the same structure, and the two second path selection switches are connected through a multi-section transmission line; The first path selection switch and the second path selection switch are the path selection switches according to any one of claims 1 to 6, and the phase selection path of the first path selection switch is smaller than the phase selection path of the second path selection switch.

7. The 90-degree terahertz phase shifter according to claim 6, characterized in that: The two path selection switches in the primary phase module or / and the secondary phase module are connected by a coplanar waveguide transmission line.

8. The 90-degree terahertz phase shifter according to claim 6, characterized in that: The RF signal is input from the first phase module and output through the second phase module after phase shifting; During the transmission process, the radio frequency signal is transmitted along the transmission line corresponding to the low level at the control end of the transistor.

9. The 90-degree terahertz phase shifter according to claim 6, characterized in that: The first path selection switch is a single-pole three-throw switch, and the second path selection switch is a single-pole four-throw switch.

10. A terahertz phased array radar, characterized in that: A 90-degree terahertz phase shifter comprising any one of claims 6 to 9.

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