A chip-based non-magnetic simultaneous transmit and receive (STAR) duplexer for terahertz communication and sensing integration

Abstract

The present invention discloses a non-magnetic simultaneous transmit and receive (STAR) duplexer for terahertz communication and sensing integration, which includes a dielectric substrate, a microstrip stepped impedance filter, varactor diodes, terahertz signal input / output ports, modulation signal input ports, ground ports, and a Y-shaped microstrip transmission line connection. Through the design of distributed parameter circuits, the present invention overcomes the problem of mismatch of the non-magnetic STAR duplexer with lumped parameter circuits at high frequencies. The main structure of the present invention is composed of a microstrip circuit. The ports connecting the external modulation signal and the ground port include lumped element filters. The overall structure is simple and easy to process and integrate.

Description

Technical Field

[0001] The present invention relates to the technical field of millimeter-wave communication, and particularly to a non-magnetic simultaneous transmit and receive duplexer for terahertz communication and sensing integration. Background Art

[0002] As one of the key technologies for 6G, the communication and sensing integrated network will deploy a large number of intelligent nodes. However, dynamic deployment will lead to a complex wireless environment, causing signal interference with each other. The transmit and receive interference between antennas is an internal factor restricting the performance of communication and sensing integration, and also the main factor restricting the improvement of communication and sensing integration performance. The in-band full-duplex technology is a potential method to solve the antenna transmit and receive interference problem. It can transmit and receive electromagnetic waves simultaneously at the same frequency. The core of the technology is to suppress self-interference. In the optical and microwave fields, a simultaneous transmit and receive duplexer requires materials such as ferrite to apply a permanent magnetic bias to obtain a non-reciprocal transmission effect. It is large in volume and cannot be integrated, and is not compatible with commercial integrated circuit technology, which is not conducive to the miniaturization design of terahertz communication and sensing integrated systems. Therefore, the research on on-chip non-magnetic simultaneous transmit and receive duplexers is crucial.

[0003] In recent years, foreign research teams have successfully achieved a non-reciprocal effect without an external magnetic bias by using time-space modulation technology, pointing the way for the design of on-chip non-magnetic simultaneous transmit and receive duplexers in the terahertz band. The general implementation method is as follows: Discretely load a low-frequency time-varying modulation signal on a certain medium, and control the frequency, amplitude, and initial phase of the modulation signal to achieve non-reciprocal propagation of electromagnetic waves. Taking a circulator as an example, time modulation is embodied as three-way equal-phase difference modulation signals, and space modulation is embodied as a rotationally symmetric resonant structure. When no modulation is applied, the overall structure shows a superposition degenerate state of a clockwise circulator and a counterclockwise circulator. When modulation is applied, one of the states can be reflected through the phase increasing direction of the applied modulation signal, playing a role similar to that of ferrite, breaking time-reversal symmetry, and realizing the function of the circulator. Existing on-chip non-magnetic non-reciprocal devices are mainly designed for 5G. For example, the on-chip non-magnetic isolator designed by Zang Jiawei et al. in 2020 has an operating frequency of about 2.6 GHz. At lower frequencies, there is more experience as a reference for the design of RF devices. In addition, because of the larger electrical length, the processing and testing of devices are more convenient. However, in the sub-millimeter wave and terahertz bands, the design and processing technology difficulties brought about by the higher frequency have also led to no reports on on-chip non-magnetic simultaneous transmit and receive duplexers in the terahertz band. Summary of the Invention

[0004] The purpose of the present invention is to provide a non-magnetic simultaneous transmit and receive duplexer for terahertz communication and sensing integration in view of the deficiencies of the prior art.

[0005] The purpose of the present invention is achieved by the following technical solutions:

[0006] A magnetic-free simultaneous transmit and receive (STAR) duplexer for terahertz communication and sensing integration, comprising a dielectric substrate, a microstrip stepped impedance filter, varactor diodes, terahertz signal input / output ports, modulation signal input ports, ground ports, and a Y-shaped microstrip transmission line connection; there are three groups of the microstrip stepped impedance filters, namely the first microstrip stepped impedance filter, the second microstrip stepped impedance filter, and the third microstrip stepped impedance filter; there are three groups of the varactor diodes, namely the first varactor diode, the second varactor diode, and the third varactor diode; there are three groups of the terahertz signal input / output ports, namely the first terahertz signal input / output port, the second terahertz signal input / output port, and the third terahertz signal input / output port; the center of the top of the dielectric substrate is the connection point of the microstrip transmission line, which is a Y-shaped microstrip transmission line connection; the first microstrip stepped impedance filter, the second microstrip stepped impedance filter, and the third microstrip stepped impedance filter are respectively externally connected to the first terahertz signal input / output port, the second terahertz signal input / output port, and the third terahertz signal input / output port; one side of the first varactor diode, the second varactor diode, and the third varactor diode facing the center of the structure is connected to the ground port through a microstrip stub, and the side facing outside the structure is connected to the modulation signal input port through a microstrip stub.

[0007] Further, the dielectric substrate is a quartz substrate with a thickness of 50 μm.

[0008] Further, the first microstrip stepped impedance filter, the second microstrip stepped impedance filter, and the third microstrip stepped impedance filter are stepped impedance filters and have exactly the same structure, and are respectively composed of three microstrip lines with different electrical lengths and different impedances connected in series.

[0009] Further, the length of the first microstrip line is 0.24 mm, the width is 0.05 mm, the length of the second microstrip line is 0.5 mm, the width is 0.91 mm, and the length of the third microstrip line is 0.2 mm, the width is 0.1 mm.

[0010] Further, the varactor diodes are single-tube flip-chip GaAs diodes with a die diameter of 1 μm.

[0011] Further, there are 3 groups of the modulation signal input ports, namely the first modulation signal input port, the second modulation signal input port, and the third modulation signal input port.

[0012] Further, the first modulation signal input port, the second modulation signal input port, and the third modulation signal input port introduce control signals through low-pass filters; the first ground port, the second ground port, and the third ground port are grounded through low-pass filters.

[0013] Further, the low-pass filter is composed of lumped elements, including two inductors with inductances of L1 = 0.3 nH and L2 = 0.3 nH respectively, and a capacitor with capacitance of C = 0.2 pF.

[0014] Further, there are 3 groups of grounding ports, namely the first grounding port, the second grounding port, and the third grounding port.

[0015] Further, the Y-shaped microstrip transmission line connection is connected to three circulator sub-structures. The included angles between the three sub-structures are 120° to each other and they are congruent in structure.

[0016] The present invention has the following effects:

[0017] (1) Through the design of the distributed parameter circuit, the present invention overcomes the problem of the non-magnetic simultaneous and co-frequency duplexer of the lumped parameter circuit being mismatched at high frequencies.

[0018] (2) The main structure of the present invention is composed of a microstrip circuit. The ports connecting the external modulation signal and the grounding ports include lumped element filters. The overall structure is simple and easy to process and integrate.

[0019] (3) The present invention does not require an external magnetic bias or magnetic material, has a small size, is convenient for processing, has a high isolation degree, and operates in the millimeter-wave terahertz frequency band, facilitating integration with other on-chip terahertz devices. Description of the Drawings

[0020] Figure 1 is a schematic structural diagram of a non-magnetic simultaneous and co-frequency duplexer for terahertz communication and sensing integration according to the present invention.

[0021] Figure 2 is a schematic diagram of the low-pass filter according to the present invention.

[0022] Figure 3 is a schematic diagram of the echo loss, insertion loss, and isolation simulation curves of a non-magnetic simultaneous and co-frequency duplexer for terahertz communication and sensing integration with any terahertz signal input / output port as the input port according to the embodiment.

[0023] Reference numerals in the figures: 1. First terahertz signal input / output port; 2. Second terahertz signal input / output port; 3. Third terahertz signal input / output port; 4. First microstrip stepped impedance filter; 5. Second microstrip stepped impedance filter; 6. Third microstrip stepped impedance filter; 7. First modulation signal input port; 8. Second modulation signal input port; 9. Third modulation signal input port; 10. First varactor diode; 11. Second varactor diode; 12. Third varactor diode; 13. First grounding port; 14. Second grounding port; 15. Third grounding port; 16. Y-shaped microstrip transmission line connection. Detailed implementation mode

[0024] The technical solution of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0025] As Figure 1 shown, a non-magnetic simultaneous and co-frequency duplexer for terahertz communication and sensing integration provided in this embodiment includes a dielectric substrate, a microstrip stepped impedance filter, varactor diodes, terahertz signal input / output ports, modulation signal input ports, ground ports, and a Y-shaped microstrip transmission line connection. There are three groups of the microstrip stepped impedance filters, namely the first microstrip stepped impedance filter 4, the second microstrip stepped impedance filter 5, and the third microstrip stepped impedance filter 6; there are three groups of the varactor diodes, namely the first varactor diode 10, the second varactor diode 11, and the third varactor diode 12; there are three groups of the terahertz signal input / output ports, namely the first terahertz signal input / output port 1, the second terahertz signal input / output port 2, and the third terahertz signal input / output port 3; there are 3 groups of the modulation signal input ports, namely the first modulation signal input port 7, the second modulation signal input port 8, and the third modulation signal input port 9; there are three groups of the ground ports, namely the first ground port 13, the second ground port 14, and the third ground port 15.

[0026] The center of the top of the dielectric substrate is the connection point of the microstrip transmission line, which is the Y-shaped microstrip transmission line connection 16, connecting three circulator substructures. The included angles of the three substructures are 120° to each other and are congruent in structure.

[0027] The first microstrip stepped impedance filter 4, the second microstrip stepped impedance filter 5, and the third microstrip stepped impedance filter 6 have exactly the same structure and are respectively composed of three sections of microstrip lines connected in series. The length of the first section of microstrip line from the inside out is 0.24 mm, the width is 0.05 mm, the length of the second section of microstrip line is 0.5 mm, the width is 0.91 mm, and the length of the third section of microstrip line is 0.2 mm, the width is 0.1 mm.

[0028] The first microstrip stepped impedance filter 4, the second microstrip stepped impedance filter 5, and the third microstrip stepped impedance filter 6 are respectively externally connected to the first terahertz signal input / output port 1, the second terahertz signal input / output port 2, and the third terahertz signal input / output port 3, and the port impedance is 50 Ω.

[0029] The first varactor diode 11, the second varactor diode 12, and the third varactor diode 13 have exactly the same structure. The side facing the center of the structure is connected to the ground port through a microstrip stub with a length of 0.775 mm and a width of 0.125 mm, and the side facing the outside of the structure is connected to the modulation signal input port through a microstrip stub with a length of 0.775 mm and a width of 0.125 mm.

[0030] The first modulation signal input port 7, the second modulation signal input port 8, and the third modulation signal input port 9 introduce a control signal through a low-pass filter as shown in Figure 2 .

[0031] The first ground port 13, the second ground port 14, and the third ground port 15 are grounded through a low-pass filter as shown in Figure 2 .

[0032] The low-pass filter is composed of lumped elements, and its structure is as shown in Figure 2 . The two inductors are L1 = 0.3 nH and L2 = 0.3 nH respectively, and the capacitor is C = 0.2 pF.

[0033] The dielectric substrate is a quartz substrate with a thickness of 50 μm. The microstrip metal structure on the substrate is made of gold with a thickness of 2 μm. The varactor diode is a single-tube flip-chip GaAs diode with a die diameter of 1 μm.

[0034] A method for implementing a magnetic-free simultaneous and co-frequency duplexer for terahertz communication and sensing integration provided in this embodiment: By loading three sinusoidal modulation signals with an amplitude of 2.6 V, an initial phase increasing counterclockwise (by Figure 1 ) by 120° in sequence, and a frequency of 5.25 GHz, and a reverse bias voltage of 2.6 V at the first modulation signal input port 7, the second modulation signal input port 8, and the third modulation signal input port 9, the time-reversal symmetry of the system is broken through the action of the first varactor diode 11, the second varactor diode 12, and the third varactor diode 13, achieving a non-reciprocal effect.

[0035] When a circulator is deployed with the first terahertz signal input / output port 1 as the input port, the second terahertz signal input / output port 2 as the transmission port, and the third terahertz signal input / output port 3 as the isolation port, the simulation curves of the return loss, insertion loss, and isolation of the circulator are as shown in Figure 3 . When the operating frequency is 140 GHz, the return loss is 15.097 dB, the insertion loss is 10.577 dB, and the isolation is 15.011 dB. Since the entire circulator structure has C3 symmetry, when the circulator is deployed with the second terahertz signal input / output port 2 as the input port, the third terahertz signal input / output port 3 as the transmission port, and the first terahertz signal input / output port 1 as the isolation port, and when the circulator is deployed with the third terahertz signal input / output port 3 as the input port, the first terahertz signal input / output port 1 as the transmission port, and the second terahertz signal input / output port 2 as the isolation port, the simulation curves of the return loss, insertion loss, and isolation of the circulator are also as shown in Figure 3 .

[0036] In addition, the present invention does not require an external magnetic bias or magnetic materials, has a small structure, is convenient for processing, has a high isolation degree, and operates in the millimeter-wave terahertz frequency band, which is convenient for integration with other on-chip terahertz devices.

[0037] The above are only the preferred embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any modification and replacement based on the technical solutions and inventive concepts provided by the present invention should be covered by the protection scope of the present invention.

Claims

1. A non-magnetic simultaneous transmit and receive duplexer for terahertz communication and sensing integration, characterized in that: It includes a dielectric substrate, a microstrip stepped impedance filter, varactor diodes, terahertz signal input and output ports, modulation signal input ports, ground ports, and a Y-shaped microstrip transmission line connection; there are three groups of the microstrip stepped impedance filters, namely the first microstrip stepped impedance filter, the second microstrip stepped impedance filter, and the third microstrip stepped impedance filter; there are three groups of the varactor diodes, namely the first varactor diode, the second varactor diode, and the third varactor diode; there are three groups of the terahertz signal input and output ports, namely the first terahertz signal input and output port, the second terahertz signal input and output port, and the third terahertz signal input and output port; the center of the top of the dielectric substrate is the connection point of the microstrip transmission line, which is a Y-shaped microstrip transmission line connection; the first microstrip stepped impedance filter, the second microstrip stepped impedance filter, and the third microstrip stepped impedance filter are respectively externally connected to the first terahertz signal input and output port, the second terahertz signal input and output port, and the third terahertz signal input and output port; one side of the first varactor diode, the second varactor diode, and the third varactor diode facing the center of the structure is connected to the ground port through a microstrip stub, and the side facing outside the structure is connected to the modulation signal input port through a microstrip stub; The first microstrip stepped impedance filter, the second microstrip stepped impedance filter, and the third microstrip stepped impedance filter are stepped impedance filters and have the same structure, and are respectively composed of three microstrip lines with different electrical lengths and different impedances connected in series; There are 3 groups of the modulation signal input ports, namely the first modulation signal input port, the second modulation signal input port, and the third modulation signal input port; The first modulation signal input port, the second modulation signal input port, and the third modulation signal input port introduce control signals through low-pass filters; the first ground port, the second ground port, and the third ground port are grounded through low-pass filters.

2. The non-magnetic simultaneous transmit and receive duplexer for terahertz communication and sensing integration according to claim 1, characterized in that: The dielectric substrate is a quartz substrate with a thickness of 50 μm.

3. The non-magnetic simultaneous transmit and receive duplexer for terahertz communication and sensing integration according to claim 1, characterized in that: The length of the first microstrip line is 0.24 mm, the width is 0.05 mm, the length of the second microstrip line is 0.5 mm, the width is 0.91 mm, and the length of the third microstrip line is 0.2 mm, the width is 0.1 mm.

4. The non-magnetic simultaneous transmit and receive duplexer for terahertz communication and sensing integration according to claim 1, characterized in that: The varactor diode selects a single-tube flip-chip GaAs diode with a die diameter of 1 μm.

5. The non-magnetic simultaneous transmit and receive duplexer for terahertz communication and sensing integration according to claim 1, characterized in that: The low-pass filter is composed of lumped elements, including two inductors, the two inductors are L1 = 0.3 nH and L2 = 0.3 nH respectively, and the capacitor is C = 0.2 pF.

6. A non-magnetic simultaneous transmit and receive duplexer for terahertz communication and sensing integration according to claim 1, characterized in that: There are 3 groups of grounding ports, namely the first grounding port, the second grounding port, and the third grounding port.

7. A non-magnetic simultaneous transmit and receive duplexer for terahertz communication and sensing integration according to claim 1, characterized in that: The Y-shaped microstrip transmission line is connected to three circulator sub-structures. The included angles of the three sub-structures are 120° to each other and are congruent in structure.

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