CN-122026866-A - W-band switch line MMIC phase shifter based on alignment CNT Schottky diode

CN122026866ACN 122026866 ACN122026866 ACN 122026866ACN-122026866-A

Abstract

The invention discloses a W-band switch line MMIC phase shifter based on an alignment CNT Schottky diode. The phase shifter comprises a substrate, a radio frequency input port, a radio frequency output port, two transmission paths with different physical lengths, a switch selection network and a direct current bias circuit. The switch selection network adopts aligned carbon nanotube Schottky diode and is configured at the input end and the output end of the transmission path. The direct current bias circuit is used for applying complementary control voltage to drive the switch selection network to enable the selected paths to be simultaneously conducted at two ends, and the unselected paths to be simultaneously cut off at two ends, so that discrete switching of phases is realized. The invention utilizes the high-frequency characteristic of the aligned carbon nanotube device in combination with the double-end complementary selection topology, effectively solves the problem that the amplitude unbalance and the phase precision are difficult to be compatible in the W wave band, remarkably inhibits the signal leakage and parasitic resonance of the non-conductive branch, and has the advantages of low insertion loss, high isolation, compact layout area and the like.

Inventors

Zhuo Murong
WANG DEFU
ZHANG ZHIYONG
PENG LIANMAO

Assignees

北京邮电大学
北京元芯碳基集成电路研究院
北京大学
北京华碳元芯电子科技有限责任公司

Dates

Publication Date: 20260512
Application Date: 20251222

Claims (8)

1. A W-band switch line MMIC phase shifter based on aligned CNT schottky diodes, comprising: The device comprises a substrate, a radio frequency input port (105) and a radio frequency output port (106) which are integrated on the substrate, and two transmission paths which are respectively a first transmission path and a second transmission path and are connected between the radio frequency input port (105) and the radio frequency output port (106), wherein the two transmission paths have physical length differences and preset electric length differences; the switch selection network comprises an input end switch group and an output end switch group which are formed by a plurality of aligned carbon nanotube Schottky diodes and are respectively arranged at the input end and the output end of the first transmission path and the second transmission path; And the direct current bias circuit is used for providing control voltage for the switch selection network, and the complementary control voltage is applied by the direct current bias circuit, so that one transmission path is simultaneously conducted and the other transmission path is cut off by the switch selection network at the input end and the output end, and the discrete switching of the phase is realized at the radio frequency output port (106).
2. The W-band switch line MMIC phase shifter based on aligned CNT schottky diodes of claim 1, wherein the switch selection network comprises four aligned carbon nanotube schottky diodes, specifically connected in the following manner: The first diode (D1) and the second diode (D2) are connected in series on the first transmission path, and the polarity directions of the first diode and the second diode are consistent, wherein the first diode (D1) is positioned at one side close to the radio frequency input port (105), and the second diode (D2) is positioned at one side close to the radio frequency output port (106); The third diode (D3) and the fourth diode (D4) are connected in series on the second transmission path, have the same polarity direction and have opposite polarities with the diodes on the first transmission path, wherein the third diode (D3) is positioned at one side close to the radio frequency input port (105), and the fourth diode (D4) is positioned at one side close to the radio frequency output port (106); The first transmission path is a shorter extension line path, the second transmission path is a longer extension line path, and the difference of the electrical lengths of the two paths corresponds to 180-degree phase difference of the working frequency band.
3. The W-band switch line MMIC phase shifter based on aligned CNT schottky diodes according to claim 2, characterized in that the dc bias circuit is configured to drive the first diode (D1) and the second diode (D2) on while turning off the third diode (D3) and the fourth diode (D4) when a first polarity control voltage is applied, and to drive the third diode (D3) and the fourth diode (D4) on while turning off the first diode (D1) and the second diode (D2) when a second polarity control voltage is applied, the gated transmission path forming a low-impedance path at both input and output and the ungated transmission path forming a high-impedance isolation at both input and output.
4. The W-band switch line MMIC phase shifter based on the aligned CNT Schottky diode according to claim 2 is characterized in that the first transmission path and the second transmission path are of a coplanar waveguide structure, the coplanar waveguide comprises central trunk conductors (103 and 109) and radio frequency signal ground wires (101 and 104) positioned on two sides, the aligned CNT Schottky diode is connected across the fracture of the central trunk conductors of the coplanar waveguide to form a serial path, and electrodes of the diode and a metal layer of the coplanar waveguide are prepared in the same process flow to form an integrated structure.
5. The W-band switch line MMIC phase shifter based on aligned CNT schottky diodes according to claim 1, wherein the dc bias circuit comprises an input dc bias circuit (108) and an output dc bias circuit (107), the dc bias circuits each comprising a choke inductance and a choke capacitance, the choke capacitance being arranged on the bias branch for introducing a dc control signal into the diode control node while preventing the dc signal from entering the rf main channel, the choke inductance for preventing the rf signal from leaking to the dc supply.
6. The W-band switch line MMIC phase shifter based on aligned CNT schottky diode according to claim 1, wherein the first and second transmission paths are mirror-symmetrical in layout, and the trace widths, corner structures and ground rails of the first and second transmission paths are designed with equivalent loss balancing so that the insertion loss difference between the two phase states is minimized.
7. The aligned CNT schottky diode based W-band switch line MMIC phase shifter of claim 1 wherein the substrate is a high resistance silicon substrate.
8. The aligned CNT schottky diode based W-band switch line MMIC phase shifter of claim 1 wherein the aligned carbon nanotube schottky diode electrode structure and schottky contact process is optimized for W-band radio frequency applications with low parasitic capacitance and high cut-off frequency characteristics.

Description

W-band switch line MMIC phase shifter based on alignment CNT Schottky diode Technical Field The invention belongs to the technical field of microwave millimeter wave integrated circuits, and particularly relates to a W-band switch line MMIC phase shifter based on an alignment CNT Schottky diode. Background Along with the development of wireless communication and radar detection technology to a high frequency band, a W-band (75-110 GHz) becomes one of core working frequency bands of a millimeter wave phased array system due to the advantages of short wavelength, high resolution, abundant frequency band resources and the like. In phased array transmit-receive front-ends, phase shifters are key components to control beam steering and waveform synthesis, which require high accuracy of phase control in very small chip areas while maintaining low insertion loss and good port matching. Particularly for a large-scale array, the amplitude consistency, the phase precision and the layout compactness of the phase shifting unit directly determine the sidelobe level, the beam pointing precision and the system power consumption of the whole antenna array. The existing W-band phase shifter mainly adopts topological structures such as reflection type, loading linear type, vector synthetic type and switch linear type. Although the reflective phase shifter and the vector synthesis phase shifter have higher design freedom, a complex coupling structure and multiple branches are often introduced in a W wave band, so that the chip area is expanded and the insertion loss is larger. In contrast, a switch line (Switched-line) phase shifter has the advantages of clear topology and easiness in digital discrete control, and is a preferred structure for realizing 180-degree and other large-span phase shifting. However, the performance of the switching line phase shifter is highly dependent on the high frequency characteristics of the rf switching device and the layout design of the transmission line. The prior art at present mainly has the following defects and bottlenecks: First, radio frequency switching devices based on conventional semiconductor materials (e.g., silicon, gallium arsenide, etc.) face severe physical limitations in the W-band. The on-resistance (R on) and the off-capacitance (C off) of the traditional transistor or diode in the millimeter wave frequency range are difficult to reduce simultaneously, so that a remarkable parasitic effect exists in the switching device. The non-ideal characteristic not only increases the insertion loss of the phase shifter, but also can cause serious unbalance of the transmission loss in the two states of 0 degree and 180 degrees, thereby introducing amplitude mismatch and phase error and deteriorating the amplitude consistency of the system. Second, conventional switch-line phase shifters often employ long leads and complex crossover structures at the circuit structure level. In the W-band, the long-distance metal interconnection and the asymmetric layout can introduce additional line loss and parasitic inductance, so that in-band fluctuation is aggravated. To compensate for the loss, existing schemes sometimes have to add active amplification stages, which in turn increase power consumption and thermal management difficulties, making high density integration challenging. Although novel nanomaterials such as carbon nanotubes (Carbon Nanotube, CNT) have proved to have extremely high carrier mobility and cut-off frequency potential, current research has focused on principle verification or low frequency prototyping at the device physical level. In the W-band, there is a lack of a monolithic microwave integration (Monolithic Microwave Integrated Circuit, MMIC) scheme to deep synergize the carbon nanotube device with microwave passive networks (e.g., coplanar waveguide CPW), bias circuits, and fabrication processes. The existing new material device is difficult to solve engineering problems such as device and layout matching, radio frequency and direct current decoupling, process consistency and the like in an actual circuit, and a mature and mass-producible phase shift unit reference path cannot be provided for the front end of a future carbon-based phased array. In summary, how to overcome the loss bottleneck of the existing semiconductor switch at high frequency and solve the problem that new material devices lack circuit-level verification and engineering structures in the W-band, and design a W-band phase shifter which has low loss, high precision, small area and easy cascade integration is a technical problem to be solved in the field of the current millimeter wave integrated circuits. Disclosure of Invention Aiming at the defects of unbalanced amplitude and large loss of the existing W-band phase shifter, the invention provides a W-band switch line MMIC phase shifter based on an aligned CNT Schottky diode, so as to solve the defects in the prior art. The invention provides a W-band s