Single-balanced mixer circuit based on carbon nanotube schottky diode

Abstract

The application provides a single-balanced mixer circuit based on a carbon nanotube Schottky diode, comprising the following structure: one end of the carbon nanotube Schottky diode is connected with a 180-degree hybrid junction structure, and one end is connected with a fan-shaped open circuit line structure; a radio frequency input impedance matching network is located between a radio frequency input port and the 180-degree hybrid junction; a local oscillator input impedance matching network is located between a local oscillator input port and the 180-degree hybrid junction; the fan-shaped open circuit line structure is located between the carbon nanotube Schottky diode device and a 1 / 4 wavelength high-impedance microstrip line; the 1 / 4 wavelength high-impedance microstrip line is located between the fan-shaped open circuit line structure and an air bridge; the air bridge is transversely arranged on the radio frequency input impedance matching network; a thin film resistor and a plate capacitor are connected on a intermediate frequency output line. The mixer circuit provided by the application can realize lower conversion loss in a high frequency band, and greatly reduces the parasitic capacitance of the Schottky diode device and the substrate loss of the passive device.

Description

Technical Field

[0001] This invention specifically relates to a single-balanced mixer circuit based on a carbon nanotube Schottky diode, belonging to the field of semiconductor integrated circuit technology. Background Technology

[0002] Semiconductor-based carbon nanotubes possess a range of advantages, including high carrier mobility, extremely low intrinsic capacitance, ultra-high thermal conductivity, excellent radiation resistance, and ease of three-dimensional heterogeneous integration. Schottky diodes based on carbon nanotube materials exhibit extremely low parasitic capacitance and high cutoff frequencies. Millimeter-wave and terahertz radio frequency (RF) front-ends have significant application value in 5G / 6G communications, radar detection, and terahertz imaging. However, due to the relatively high operating frequencies of millimeter-wave and terahertz systems, extremely high demands are placed on the down-conversion circuitry in the receiver. Single-balanced mixer circuits, as a crucial solution for spectrum shifting modules in millimeter-wave and terahertz RF front-ends, require semiconductor devices with high cutoff frequencies and meticulous RF circuit design to achieve excellent conversion performance. Summary of the Invention

[0003] The purpose of this invention is to design and develop a single-balanced mixer circuit with low conversion loss based on carbon nanotube Schottky diode devices with high cutoff frequency, realize a low-loss 180° hybrid junction structure on a quartz substrate, and integrate an on-chip RC filter, thereby expanding the application potential of carbon-based integrated circuits in the fields of millimeter-wave and terahertz radio frequency front-ends.

[0004] To achieve the above objectives, the present invention adopts the following technical solution.

[0005] A single-balanced mixer circuit based on carbon nanotube Schottky diodes includes: a carbon nanotube Schottky diode, a 180° hybrid junction structure, an RF input impedance matching network, a local oscillator input impedance matching network, a thin-film resistor, a parallel-plate capacitor, a fan-shaped open-circuit structure, a quarter-wavelength high-impedance microstrip line, an air bridge, an RF input port, and an intermediate frequency output line. The single-balanced mixer circuit based on carbon nanotube Schottky diodes comprises two carbon nanotube Schottky diode devices; one end of each carbon nanotube Schottky diode device is connected to the 180° hybrid junction structure, and the other end is connected to the fan-shaped open-circuit structure. The circuit structures are connected; the RF input impedance matching network is located between the RF input port and the 180° hybrid junction; the local oscillator input impedance matching network is located between the local oscillator input port and the 180° hybrid junction; the fan-shaped open circuit structure is located between the carbon nanotube Schottky diode device and the 1 / 4 wavelength high impedance microstrip line; the 1 / 4 wavelength high impedance microstrip line is located between the fan-shaped open circuit structure and the air bridge; the air bridge spans across the RF input impedance matching network; the thin film resistor is connected in series on the intermediate frequency output line; the parallel plate capacitor is connected in parallel on the intermediate frequency output line.

[0006] The active layer of the carbon nanotube Schottky diode is a semiconductor carbon nanotube, and its arrangement includes a randomly arranged carbon nanotube network and a directionally arranged carbon nanotube array.

[0007] The two carbon nanotube Schottky diode devices are two identical carbon nanotube Schottky diode devices, and the electrodes connected to the 180° hybrid junction are different. The cathode of one carbon nanotube Schottky diode is connected to the 180° hybrid junction, and the anode of the other carbon nanotube Schottky diode is connected to the 180° hybrid junction.

[0008] The two carbon nanotube Schottky diode devices operate at zero bias voltage.

[0009] The 180° hybrid junction is a microstrip line unit-based structure with a characteristic impedance between 70 and 80 ohms in the operating frequency band.

[0010] The open-circuit fan structure and the quarter-wavelength high-impedance microstrip line are both based on microstrip line units. The open-circuit fan structure adopts a fan-shaped design, and the quarter-wavelength high-impedance microstrip line has a characteristic impedance of 100 ohms in the operating frequency band.

[0011] The radio frequency input impedance matching network and the local oscillator input impedance matching network are based on microstrip line units.

[0012] The material of the thin-film resistor is one of tantalum nitride, tantalum, and nickel-chromium.

[0013] The dielectric material of the parallel plate capacitor is aluminum oxide.

[0014] The metal materials constituting the 180° hybrid junction structure, RF input impedance matching network, local oscillator input impedance matching network, fan-shaped open-circuit structure, and 1 / 4 wavelength high-impedance microstrip line based on microstrip line technology include, but are not limited to, one of gold, copper, and aluminum.

[0015] Any of the aforementioned single-balanced mixer circuits based on carbon nanotube Schottky diodes further includes: a quartz substrate for carrying the carbon nanotube Schottky diode, a 180° hybrid junction structure, an RF input impedance matching network, a local oscillator input impedance matching network, a thin-film resistor, a planar capacitor, a fan-shaped open-circuit structure, a 1 / 4 wavelength high-impedance microstrip line, an air bridge, an RF input port, and an IF output line.

[0016] The thickness of the quartz substrate is less than or equal to 100 micrometers, and a gold backing structure is provided on the back side of the quartz substrate.

[0017] The advantages and technical effects of this invention are as follows:

[0018] This invention relates to a single-balanced mixer circuit based on carbon nanotube Schottky diodes. It utilizes a carbon nanotube Schottky diode with a high cutoff frequency as the core device to provide nonlinear characteristics, achieving a low-conversion-loss single-balanced mixer circuit. A low-loss 180° hybrid junction structure is designed based on microstrip line technology to achieve in-phase distribution of the RF signal and differential distribution of the local oscillator signal. A fan-shaped open-circuit structure and a 1 / 4-wavelength high-impedance microstrip line are designed based on microstrip line technology to form a high-frequency choke structure for transmitting the intermediate frequency (IF) signal, suppressing high-frequency signal leakage to the IF output port, and simultaneously achieving a miniaturized mixer design. Furthermore, this invention chooses to fabricate the carbon nanotube Schottky diode device and the single-balanced mixer circuit on a quartz substrate, reducing the transmission loss of passive components and the parasitic capacitance of the carbon nanotube Schottky diode device, thereby improving the conversion performance of the single-balanced mixer circuit. Attached Figure Description

[0019] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

[0020] Figure 1 This invention provides a schematic diagram of a single-balanced mixer circuit based on a carbon nanotube Schottky diode. Detailed Implementation

[0021] To make the objectives, content, and advantages of this invention clearer, the specific embodiments of this invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of this invention and should not be construed as limiting the scope of protection of this invention.

[0022] This embodiment specifically describes a single-balanced mixer circuit based on a carbon nanotube Schottky diode provided by the present invention.

[0023] Figure 1This is a schematic diagram of a carbon nanotube Schottky diode single-balanced mixer circuit provided by the present invention. The schematic diagram of the single-balanced mixer includes a carbon nanotube Schottky diode device 101, a carbon nanotube Schottky diode device 102, a 180° hybrid junction structure 103, an RF input impedance matching network 104, a local oscillator input impedance matching network 105, a fan-shaped open-circuit structure 106, a fan-shaped open-circuit structure 107, a 1 / 4 wavelength high-impedance microstrip line 108, a 1 / 4 wavelength high-impedance microstrip line 109, an air bridge 110, a thin film resistor 111, and a parallel plate capacitor 112.

[0024] The carbon nanotube Schottky diode device 101 is located between the 180° hybrid junction structure 103 and the fan-shaped open-circuit structure 106; the carbon nanotube Schottky diode device 102 is located between the 180° hybrid junction structure 103 and the fan-shaped open-circuit structure 107; the RF input impedance matching network 104 is located between the RF input port 113 and the 180° hybrid junction structure 103; the local oscillator input impedance matching network 105 is located between the local oscillator signal input port 115 and the 180° hybrid junction structure 103; and the fan-shaped open-circuit structure 106 is located between the carbon nanotube Schottky diode device 101 and the 1 / 4 wavelength high-impedance microstrip line 108. The open-circuit fan structure 107 is located between the carbon nanotube Schottky diode device 102 and the quarter-wavelength high-impedance microstrip line 109; the quarter-wavelength high-impedance microstrip line 108 is located between the open-circuit fan structure 106 and the air bridge 110; the quarter-wavelength high-impedance microstrip line 109 is located between the open-circuit fan structure 107 and the air bridge 110; the air bridge 110 spans across the RF input matching network 104; the thin-film resistor 111 is connected in series on the intermediate frequency output line 116; the parallel plate capacitor 112 is connected in parallel on the intermediate frequency output line 116, and the thin-film resistor 111 and the parallel plate capacitor 112 constitute an RC filter structure.

[0025] The active layer of the carbon nanotube Schottky diode device is a semiconductor carbon nanotube, and its arrangement is a directional carbon nanotube array.

[0026] The single-balanced mixer circuit based on carbon nanotube Schottky diodes uses two identical carbon nanotube Schottky diodes as its core device. The electrodes of the two carbon nanotube Schottky diodes connected to the 180° hybrid junction structure are different. The cathode of one carbon nanotube Schottky diode is connected to the 180° hybrid junction, and the anode of the other carbon nanotube Schottky diode is connected to the 180° hybrid junction. The two Schottky diodes operate, but are not limited to, at zero bias voltage.

[0027] The 180° hybrid junction structure based on microstrip line technology has a characteristic impedance between 70 and 80 ohms, preferably 70.7 ohms, within the operating frequency band. The fan-shaped open-circuit structure is designed in a fan shape.

[0028] The RF input impedance matching network and the local oscillator input impedance matching network are based on microstrip line units.

[0029] Both the fan-shaped open-circuit structure and the quarter-wavelength high-impedance microstrip line are based on microstrip line units, with the fan-shaped open-circuit structure employing a fan-shaped design. The quarter-wavelength high-impedance microstrip line has a characteristic impedance of 100 ohms in its operating frequency band.

[0030] The material of the thin-film resistor is one of tantalum nitride, tantalum, or nickel-chromium.

[0031] The dielectric material of the parallel plate capacitor is aluminum oxide.

[0032] For the 180° hybrid junction structure, RF input impedance matching network, local oscillator input impedance matching network, fan-shaped open-circuit structure, and 1 / 4 wavelength high-impedance microstrip line based on microstrip line technology, the metal material may include, but is not limited to, one of gold, copper, and aluminum.

[0033] The single-balanced mixer circuit based on carbon nanotube Schottky diodes also includes a quartz substrate for carrying the carbon nanotube Schottky diodes, a 180° hybrid junction structure, an RF input impedance matching network, a local oscillator input impedance matching network, thin-film resistors, planar capacitors, a fan-shaped open-circuit structure, a 1 / 4 wavelength high-impedance microstrip line, an air bridge, an RF input port, and an IF output line.

[0034] The single-balanced mixer circuit based on carbon nanotube Schottky diodes is fabricated on a quartz substrate. The advantage of using a quartz substrate as a substrate is that it can greatly reduce the parasitic parameters of carbon nanotube Schottky diodes and the losses of passive devices.

[0035] After the top layer circuit is fabricated, the quartz substrate needs to be thinned to a thickness of less than or equal to 100 micrometers, which is to reduce the transmission loss of the microstrip line. A back gold structure is fabricated on the back side of the quartz substrate, which is to provide a reference ground for the microstrip line structure of the top layer. The material of the back gold structure is one of gold, copper and aluminum.

[0036] This invention employs a carbon nanotube Schottky diode with a high cutoff frequency to design a single-balanced mixer circuit, achieving low conversion loss at high frequencies. A low-loss 180° hybrid junction structure based on microstrip line technology is designed to achieve in-phase equal power distribution of RF signals and differential equal power distribution of local oscillator signals. A fan-shaped open-circuit structure and a 1 / 4-wavelength high-impedance microstrip line, also based on microstrip line technology, constitute a high-frequency choke structure for transmitting intermediate frequency (IF) signals and suppressing high-frequency signal leakage to the IF output port 117 (see [reference]). Figure 1 This invention achieves the design of a miniaturized mixer. Furthermore, by fabricating carbon nanotube Schottky diode devices and single-balanced mixer circuits on a quartz substrate, the transmission losses of passive devices and the parasitic capacitance of the carbon nanotube Schottky diode devices are reduced, thereby improving the frequency conversion performance of the single-balanced mixer circuit and mitigating its single-balanced mixing losses. This results in significant technological advancements and economic benefits.

[0037] The above embodiments are merely illustrative of the technical concept and features of the present invention, and are preferred embodiments. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and they should not be construed as limiting the scope of protection of the present invention. All equivalent transformations or modifications made according to the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A single-balanced mixer circuit based on a carbon nanotube Schottky diode, characterized in that, The single-balanced mixer circuit includes a carbon nanotube Schottky diode, a 180° hybrid junction structure, an RF input impedance matching network, a local oscillator input impedance matching network, a thin-film resistor, a planar capacitor, a fan-shaped open-circuit structure, a 1 / 4 wavelength high-impedance microstrip line, an air bridge, an RF input port, and an IF output line. The single-balanced mixer circuit based on carbon nanotube Schottky diodes includes two carbon nanotube Schottky diode devices. One end of each carbon nanotube Schottky diode device is connected to the 180° hybrid junction structure, and the other end is connected to the fan-shaped open-circuit structure. The RF input impedance matching network is located between the RF input port and the 180° hybrid junction structure. The local oscillator input impedance matching network is located between the local oscillator input port and the 180° hybrid junction structure. The fan-shaped open-circuit structure is located between the carbon nanotube Schottky diode device and the 1 / 4 wavelength high-impedance microstrip line. The 1 / 4 wavelength high-impedance microstrip line is located between the fan-shaped open-circuit structure and the air bridge. The air bridge spans across the RF input impedance matching network. The thin-film resistor is connected in series on the intermediate frequency output line. The parallel plate capacitor is connected in parallel on the intermediate frequency output line.

2. The single-balanced mixer circuit based on a carbon nanotube Schottky diode according to claim 1, characterized in that, The active layer of the carbon nanotube Schottky diode is a semiconductor carbon nanotube, and its arrangement includes a randomly arranged carbon nanotube network and a directionally arranged carbon nanotube array.

3. The single-balanced mixer circuit based on a carbon nanotube Schottky diode according to claim 1, characterized in that, The two carbon nanotube Schottky diode devices are two identical carbon nanotube Schottky diode devices, and the electrodes of the carbon nanotube Schottky diode devices connected to the 180° hybrid junction structure are different. The cathode of one carbon nanotube Schottky diode is connected to the 180° hybrid junction structure, and the anode of the other carbon nanotube Schottky diode is connected to the 180° hybrid junction structure.

4. The single-balanced mixer circuit based on a carbon nanotube Schottky diode according to claim 3, characterized in that, The two carbon nanotube Schottky diode devices operate at zero bias voltage.

5. The single-balanced mixer circuit based on a carbon nanotube Schottky diode according to claim 1, characterized in that, The 180° hybrid junction structure is based on a microstrip line unit and has a characteristic impedance between 70 and 80 ohms in the operating frequency band.

6. The single-balanced mixer circuit based on a carbon nanotube Schottky diode according to claim 1, characterized in that, Both the open-circuit fan structure and the quarter-wavelength high-impedance microstrip line are based on microstrip line units. The open-circuit fan structure adopts a fan-shaped design, and the quarter-wavelength high-impedance microstrip line has a characteristic impedance of 100 ohms in the operating frequency band.

7. The single-balanced mixer circuit based on a carbon nanotube Schottky diode according to claim 1, characterized in that, The RF input impedance matching network and the local oscillator input impedance matching network are based on microstrip line units.

8. The single-balanced mixer circuit based on a carbon nanotube Schottky diode according to claim 1, characterized in that, The material of the thin-film resistor is one of tantalum nitride, tantalum, or nickel-chromium.

9. The single-balanced mixer circuit based on a carbon nanotube Schottky diode according to claim 1, characterized in that, The dielectric material of the parallel plate capacitor is aluminum oxide.

10. The single-balanced mixer circuit based on a carbon nanotube Schottky diode according to claim 1, characterized in that, The metallic materials constituting the 180° hybrid junction structure, RF input impedance matching network, local oscillator input impedance matching network, fan-shaped open-circuit structure, and 1 / 4 wavelength high-impedance microstrip line include, but are not limited to, one of gold, copper, and aluminum.

11. The single-balanced mixer circuit based on a carbon nanotube Schottky diode according to any one of claims 1 to 10, characterized in that, Also includes: A quartz substrate is used to support the carbon nanotube Schottky diode, 180° hybrid junction structure, RF input impedance matching network, local oscillator input impedance matching network, thin film resistor, planar capacitor, fan-shaped open circuit structure, 1 / 4 wavelength high impedance microstrip line, air bridge, RF input port, and intermediate frequency output line.

12. The single-balanced mixer circuit based on a carbon nanotube Schottky diode according to claim 11, characterized in that, The thickness of the quartz substrate is less than or equal to 100 micrometers, and a gold backing structure is provided on the back side of the quartz substrate.

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