Terahertz ultra-wideband single-pole single-throw high-speed switch

Abstract

The application discloses a terahertz ultra-wideband single-pole single-throw high-speed switch, and relates to a waveguide transmission line technology. The scheme is proposed for the high insertion loss and other problems in the prior art. A coupling line module is arranged for coupling connection between a signal input end and a signal output end; a switch module is arranged for turning on or turning off the coupling line module; the coupling line module is provided with a folded coupling line structure and a folded pseudo virtual line structure; the folded coupling line structure is used for signal coupling transmission; the folded pseudo virtual line structure is symmetrically arranged with the folded coupling line structure and is used for assisting electromagnetic coupling to improve the working frequency of the switch. The pseudo virtual line technology introduced can additionally participate in electromagnetic field coupling and change pole distribution and frequency response of a circuit, so that the working frequency of the circuit is improved. In addition, the structure itself has the characteristics of low insertion loss, and a control transistor gate does not need to be additionally applied with a large bias resistor, so that the switching speed of the switch is significantly improved.

Description

Technical Field

[0001] This invention relates to waveguide transmission line technology, and more particularly to a terahertz ultrawideband single-pole single-throw high-speed switch. Background Technology

[0002] Wireless communication technology has experienced rapid development over the past few decades, profoundly changing people's lifestyles. Today, the demand for wireless communication systems with higher transmission rates and greater access capacity is increasingly strong, but existing technologies are limited by the limited spectrum and channel resources in the low-frequency band, making it difficult to meet this growing demand. However, the terahertz band still has abundant spectrum resources waiting to be developed. Terahertz waves refer to electromagnetic waves with frequencies ranging from 0.1 to 10 THz, a frequency range between millimeter waves and infrared radiation, and also a transitional region between electronics and photonics. Terahertz technology can be widely used in communications, radar, medical detection, and other fields.

[0003] Single-pole single-throw (SPS) switches have a wide range of applications in wireless communication systems. They can function as passive modulators in on / off keyed transmitters, or as a core component of single-pole double-throw (SPS) switches in time-division duplex RF transceivers, enabling signal path switching. In both applications, low insertion loss and high isolation are crucial. Specifically, on / off keyed modulation requires additional fast switching speeds to support high data rates; while time-division duplex RF transceivers require high linearity to prevent signal saturation compression.

[0004] Some terahertz single-pole single-throw switch structures, such as Figure 1 and Figure 2 As shown, this structure consists of several main coupling lines located on the upper metal layer and auxiliary coupling lines located on the lower metal layer between the main coupling lines. RF signals are typically input from one of the main coupling lines and output from another. This structure is constrained by the characteristic impedance of the coupling lines and the required metal spacing between them, limiting design freedom and making it difficult to simultaneously achieve low insertion loss and high isolation. Furthermore, the coupling lines are relatively long, typically around 100 micrometers, and require a certain distance from the return ground plane on both sides, resulting in additional area overhead.

[0005] Specifically, the following problems exist when applying it:

[0006] 1. Traditional low-loss RF switches use a quarter-wavelength transmission line structure, which significantly increases the occupied area. Furthermore, the loss of the quarter-wavelength transmission line increases in the terahertz band, making it less suitable for use in ordinary CMOS integrated circuit processes.

[0007] 2. Conventional coupled-line switches are constrained by the characteristic impedance of the coupled lines and the required metal spacing between the coupled lines, making it difficult to simultaneously achieve low insertion loss and high isolation.

[0008] 3. The lack of additional electromagnetic coupling and parasitic capacitance compensation results in limited operating frequency and bandwidth, making it unable to support ultra-high frequency and ultra-wideband applications.

[0009] 4. In order to achieve lower insertion loss, a larger gate bias resistor is selected, which leads to a larger RC time constant, thereby reducing the switching speed. Summary of the Invention

[0010] The purpose of this invention is to provide a terahertz ultra-wideband single-pole single-throw high-speed switch to solve the problems existing in the prior art.

[0011] The terahertz ultra-wideband single-pole single-throw high-speed switch described in this invention includes a coupling line module for coupling connection between the signal input terminal and the signal output terminal; and a switch module for turning the coupling line module on or off.

[0012] The coupling line module is provided with a folded coupling line structure and a folded pseudo-virtual line structure; the folded coupling line structure is used for signal coupling and transmission; the folded pseudo-virtual line structure is symmetrically arranged with the folded coupling line structure and is used to assist electromagnetic coupling to improve the switching operating frequency.

[0013] The coupling line module includes an upper metal layer, a lower metal layer, and a return ground plane stacked from top to bottom;

[0014] The upper metal layer is provided with a folded and symmetrical first coupling line and a first pseudo-virtual line; one end of the first coupling line is connected to the first pad through a signal input line, and the other end is connected to the corresponding end of the first pseudo-virtual line; the other end of the first pseudo-virtual line is connected to the return ground plane through a metal via; the connection end of the first coupling line and the first pseudo-virtual line is connected to one end of the first equipotential line, and the other end of the first equipotential line is connected to the return ground plane through a metal via;

[0015] The lower metal layer is provided with a folded and symmetrically structured second coupling line and a second pseudo-virtual line; one end of the second coupling line is connected to the second pad via a metal via, and the other end is connected to the corresponding end of the second pseudo-virtual line; the other end of the second pseudo-virtual line is connected to the return ground plane via a metal via; the connection end of the second coupling line and the second pseudo-virtual line is connected to one end of the second equipotential line, and the other end of the second equipotential line is connected to the return ground plane via a metal via;

[0016] The first coupling line is located above the second coupling line, together forming the folded coupling line structure;

[0017] The first pseudo-virtual line is located above the second pseudo-virtual line, together forming the folded pseudo-virtual line structure;

[0018] The return ground plane has a defect in the middle to surround the folded coupling line structure and the folded pseudo-virtual line structure;

[0019] The first pad is used to connect the signal input terminal; the second pad is used to connect the signal output terminal.

[0020] The second coupling line has a wider linewidth than the first coupling line; the second pseudo-virtual line has a wider linewidth than the first pseudo-virtual line.

[0021] The switch module has the following structure:

[0022] The drain of the first transistor is connected to the signal input terminal and the signal input line, the gate of the first transistor is connected to the switch control signal through the first resistor, and the source of the first transistor is grounded.

[0023] The drain of the second transistor is connected to the signal output terminal and the signal output line, the gate of the second transistor is connected to the switch control signal through the second resistor, and the source of the second transistor is grounded.

[0024] The signal input line has a first terminal in the middle for connecting to the drain of the first transistor; the signal output line has a second terminal in the middle for connecting to the drain of the second transistor.

[0025] The terahertz ultra-wideband single-pole single-throw high-speed switch described in this invention has the advantage that the introduced pseudo-virtual line technology can additionally participate in electromagnetic field coupling and change the pole distribution and frequency response of the circuit, thereby increasing the circuit's operating frequency. Furthermore, because the structure itself has low insertion loss, the control transistor gate does not require an additional large bias resistor, thus significantly improving the switching speed of the switch. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of a single-pole single-throw switch in the prior art.

[0027] Figure 2 This is a schematic diagram of the structure of a coupling line module in the prior art.

[0028] Figure 3 This is a schematic diagram of the structure of a terahertz ultrawideband single-pole single-throw high-speed switch described in this invention.

[0029] Figure 4 This is a schematic diagram of the coupling line module described in this invention.

[0030] Figure 5 yes Figure 4 Rear view of the structure shown.

[0031] Figure 6 yes Figure 4 The three-dimensional structure shown Figure 1.

[0032] Figure 7 yes Figure 4 The three-dimensional structure shown Figure 2 .

[0033] Figure 8 yes Figure 4 The diagram shows the structure after the pads and the upper metal layer are hidden.

[0034] Figure 9 yes Figure 4 The diagram shows the structure after the underlying metal layer is hidden.

[0035] Figure 10 This is the equivalent circuit diagram of a terahertz ultra-wideband single-pole single-throw high-speed switch described in this invention.

[0036] Figure 11 This is a simulation diagram of the S-parameters of a terahertz ultrawideband single-pole single-throw high-speed switch described in this invention.

[0037] Figure 12 This is a simulation diagram of the isolation effect of a terahertz ultra-wideband single-pole single-throw high-speed switch described in this invention.

[0038] Figure 13 This is a simulation diagram of the input 1dB compression point and output 1dB compression point of a terahertz ultrawideband single-pole single-throw high-speed switch described in this invention.

[0039] Figure 14 This is a simulation diagram of the switching speed of a terahertz ultra-wideband single-pole single-throw high-speed switch described in this invention.

[0040] Figure label:

[0041] 110 - Signal input line, 111 - First terminal, 120 - First coupling line, 130 - First pseudo-virtual line, 140 - Signal output line, 141 - Second terminal, 150 - First equipotential line;

[0042] 210 - Second coupling line, 220 - Second pseudo-virtual line, 230 - Second equipotential line;

[0043] 300 - Return flow plane, 310 - Defect;

[0044] 410 - First pad, 420 - Second pad;

[0045] 800 - Main coupling line; 900 - Auxiliary coupling line;

[0046] M1 - First transistor, M2 - Second transistor;

[0047] R1 - First resistor, R2 - Second resistor;

[0048] Vctrl - Switch control signal;

[0049] R0ff - the equivalent resistance of the first or second transistor;

[0050] C0ff - the equivalent capacitance of the first or second transistor;

[0051] L1 - Equivalent inductance of the first coupled line, L2 - Equivalent inductance of the second coupled line;

[0052] L1` - the equivalent inductance of the first pseudo-virtual line, L2` - the equivalent inductance of the second pseudo-virtual line;

[0053] The coupling coefficients of K0-L1 and L2, K1-L1 and L1', and K2-L2 and L2'. Detailed Implementation

[0054] like Figures 3 to 9 As shown, the terahertz ultra-wideband single-pole single-throw high-speed switch described in this invention uses a coupling line module for coupling connection between the signal input terminal and the signal output terminal; the switch module is used to turn the coupling line module on or off.

[0055] The coupling line module includes a folded coupling line structure and a folded pseudo-virtual line structure. The folded coupling line structure is used for signal coupling and transmission. The folded pseudo-virtual line structure is symmetrically arranged with the folded coupling line structure to assist electromagnetic coupling and improve the switching operating frequency. Based on the folded design, the coupling line in this invention has a length and width of only about 50 micrometers, and a shorter distance from the return ground on both sides, effectively reducing the area required for circuit implementation.

[0056] The coupling line module includes an upper metal layer, a lower metal layer, and a return ground plane 300, which are stacked from top to bottom.

[0057] The upper metal layer is provided with a folded and structurally symmetrical first coupling line 120 and a first pseudo-virtual line 130. One end of the first coupling line 120 is connected to the first pad 410 via a signal input line 110, and the other end is connected to the corresponding end of the first pseudo-virtual line 130. The other end of the first pseudo-virtual line 130 is connected to the return ground plane 300 via a metal via. The connection end of the first coupling line 120 and the first pseudo-virtual line 130 is connected to one end of a first equipotential line 150, and the other end of the first equipotential line 150 is connected to the return ground plane 300 via a metal via.

[0058] The lower metal layer is provided with a folded and structurally symmetrical second coupling line 210 and a second pseudo-virtual line 220. One end of the second coupling line 210 is connected to the signal output line 140 via a metal via, thereby connecting to the second pad 420, and the other end is connected to the corresponding end of the second pseudo-virtual line 220. The other end of the second pseudo-virtual line 220 is connected to the return ground plane 300 via a metal via. The connection end of the second coupling line 210 and the second pseudo-virtual line 220 is connected to one end of the second equipotential line 230, and the other end of the second equipotential line 230 is connected to the return ground plane 300 via a metal via.

[0059] The first coupling line 120 is located above the second coupling line 210, together forming the folded coupling line structure.

[0060] The first pseudo-virtual line 130 is located above the second pseudo-virtual line 220, together forming the folded pseudo-virtual line structure.

[0061] The return ground plane 300 has a defect 310 in the middle to surround the folded coupling line structure and the folded pseudo-virtual line structure.

[0062] The first pad 410 is used to connect to the signal input terminal. The second pad 420 is used to connect to the signal output terminal.

[0063] The second coupling line 210 has a wider linewidth than the first coupling line 120. The second pseudo-virtual line 220 has a wider linewidth than the first pseudo-virtual line 130.

[0064] The switch module has the following structure:

[0065] The drain of the first transistor M1 is connected to the signal input terminal and the signal input line 110. The gate of the first transistor M1 is connected to the switch control signal Vctrl through the first resistor R1. The source of the first transistor M1 is grounded.

[0066] The drain of the second transistor M2 is connected to the signal output terminal and the signal output line 140. The gate of the second transistor M2 is connected to the switch control signal Vctrl through the second resistor R2. The source of the second transistor M2 is grounded.

[0067] The signal input line 110 has a first terminal 111 in the middle for connecting to the drain of the first transistor M1. The signal output line 140 has a second terminal 141 in the middle for connecting to the drain of the second transistor M2.

[0068] like Figure 10As shown, the working principle of the terahertz ultra-wideband single-pole single-throw high-speed switch described in this invention is as follows: By adjusting the length and shape of each part of the first coupling line 120 and the second coupling line 210, the equivalent inductance and equivalent distributed parallel capacitance of the coupling lines, as well as the coupling strength between the coupling lines, can be changed, achieving a wider operating bandwidth and lower losses. By changing the length and width of the defect 310, the spacing between the return ground plane and the coupling lines and their corresponding pseudo-virtual lines can be changed, thereby adjusting the size of the equivalent distributed parallel capacitance of the coupling lines and pseudo-virtual lines, and achieving adjustment of the circuit's operating frequency and bandwidth. In the on state, each transistor is equivalently modeled as Roff and Coff connected in parallel. Although both ends of L1' and L2' are short-circuited to ground, the coupling coefficients K1 and K2 are still effective, which is determined by the inherent characteristics of the electromagnetic field. K1 and K2 help push the poles to higher frequency bands, thereby reducing insertion loss at high frequencies. Coff, together with L1, L2, and the distributed parasitic capacitance between the coupling lines, constitute a high-order resonant circuit, which can effectively extend the bandwidth.

[0069] By employing a topology using folded coupling lines and pseudo-virtual lines, this invention ultimately achieves a terahertz ultrawideband single-pole single-throw high-speed switch with low insertion loss, high isolation, high linearity, and ultrawideband performance. Its technical effects are as follows: Figures 11 to 14 As shown.

[0070] like Figure 11 and Figure 12 As shown, the terahertz switch in this invention, operating within an ultra-wideband frequency range of 110–210 GHz, exhibits an input return loss of 10.5–16.7 dB, an output return loss of 10.6–17.2 dB, an insertion loss of 2.3–3.3 dB, and an isolation of 22.5–23 dB. Figure 13 As shown, the terahertz switch at a frequency of 140 GHz has an input 1dB compression point of 11.6 dBm and a corresponding output 1dB compression point of 7.7 dBm. Figure 14 As shown, the terahertz switch takes 35ps to turn on and 31ps to turn off when the input signal is 140GHz and 0dBm. Therefore, it can support high-speed OOK modulation applications with a maximum speed of 14Gbps or more.

[0071] In summary, the main advantages of the terahertz switch of the present invention include:

[0072] 1. High operating frequency and wide bandwidth

[0073] The proposed folded coupling line structure is a distributed matching structure. The transistor, coupling line, and the distributed parasitic capacitance between the coupling lines form a high-order resonant cavity, which can effectively extend the bandwidth and is more suitable for broadband design. Furthermore, a pseudo-virtual line structure is introduced, which can additionally couple the electromagnetic field and change the pole distribution of the circuit, moving the poles to high frequencies to optimize circuit performance at high frequencies, making it more suitable for terahertz circuit design.

[0074] 2. The circuit requires a small area to implement.

[0075] The proposed folded coupling line and pseudo-virtual line structure is more compact than the traditional coupling line structure, reducing the area requirement by about 30%, effectively reducing the area required for circuit implementation, and making it easier to integrate with other systems, thereby reducing manufacturing costs.

[0076] 3. It simultaneously exhibits low insertion loss and high isolation.

[0077] Traditional quarter-wavelength transmission line switches suffer from reduced isolation when optimizing insertion loss. The proposed folded coupling line and pseudo-virtual line structures, due to their simple and compact structure and low-loss characteristics, do not require additional optimization of insertion loss, thus achieving both low insertion loss and high isolation.

[0078] 4. Fast switching speed

[0079] To achieve lower insertion loss, traditional switches typically require a large resistor of over 3000 ohms connected in series with the gate of the control transistor. This increases the RC time constant of the circuit and reduces the switching speed. In this invention, the series resistance of the control transistor's gate is only 500 ohms. Without significantly increasing the insertion loss, this effectively reduces the RC time constant of the circuit and significantly improves the switching speed, enabling it to support high-speed modulation applications.

[0080] For those skilled in the art, various other corresponding changes and modifications can be made based on the technical solutions and concepts described above, and all such changes and modifications should fall within the protection scope of the claims of this invention.

Claims

1. A terahertz ultra-wideband single-pole single-throw high-speed switch, comprising a coupling line module for coupling connection between a signal input terminal and a signal output terminal; and a switch module for turning the coupling line module on or off. Its features are, The coupling line module is provided with a folded coupling line structure and a folded pseudo-virtual line structure; the folded coupling line structure is used for signal coupling and transmission; the folded pseudo-virtual line structure is symmetrically arranged with the folded coupling line structure and is used to assist electromagnetic coupling to improve the switching operating frequency; The coupling line module includes an upper metal layer, a lower metal layer, and a return ground plane (300) stacked from top to bottom. The upper metal layer is provided with a folded and structurally symmetrical first coupling line (120) and a first pseudo-virtual line (130); one end of the first coupling line (120) is connected to the first pad (410) through a signal input line (110), and the other end is connected to the corresponding end of the first pseudo-virtual line (130); the other end of the first pseudo-virtual line (130) is connected to the return ground plane (300) through a metal via; the connection end of the first coupling line (120) and the first pseudo-virtual line (130) is connected to one end of the first equipotential line (150), and the other end of the first equipotential line (150) is connected to the return ground plane (300) through a metal via. The lower metal layer is provided with a folded and structurally symmetrical second coupling line (210) and a second pseudo-virtual line (220); one end of the second coupling line (210) is connected to the signal output line (140) through a metal via, thereby connecting to the second pad (420), and the other end is connected to the corresponding end of the second pseudo-virtual line (220); the other end of the second pseudo-virtual line (220) is connected to the return ground plane (300) through a metal via; the connection end of the second coupling line (210) and the second pseudo-virtual line (220) is connected to one end of the second equipotential line (230), and the other end of the second equipotential line (230) is connected to the return ground plane (300) through a metal via. The first coupling line (120) is located above the second coupling line (210), together forming the folded coupling line structure; The first pseudo-virtual line (130) is located above the second pseudo-virtual line (220), together forming the folded pseudo-virtual line structure; The return ground plane (300) has a defect (310) in the middle to surround the folded coupling line structure and the folded pseudo-virtual line structure; The first pad (410) is used to connect the signal input terminal; the second pad (420) is used to connect the signal output terminal; The switch module has the following structure: The drain of the first transistor M1 is connected to the signal input terminal and the signal input line (110), the gate of the first transistor M1 is connected to the switch control signal Vctrl through the first resistor R1, and the source of the first transistor M1 is grounded. The drain of the second transistor M2 is connected to the signal output terminal and the signal output line (140). The gate of the second transistor M2 is connected to the switch control signal Vctrl through the second resistor R2. The source of the second transistor M2 is grounded.

2. The terahertz ultra-wideband single-pole single-throw high-speed switch according to claim 1, characterized in that, The line width of the second coupling line (210) is greater than that of the first coupling line (120); the line width of the second pseudo-virtual line (220) is greater than that of the first pseudo-virtual line (130).

3. The terahertz ultra-wideband single-pole single-throw high-speed switch according to claim 2, characterized in that, The signal input line (110) has a first terminal (111) in the middle for connecting to the drain of the first transistor M1; the signal output line (140) has a second terminal (141) in the middle for connecting to the drain of the second transistor M2.

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