Research On 220GHz Monolithic Integrated IQ Image Rejection Mixing Technology

Mixers are one of the key circuits for frequency shifting in the front-end of solidstate transceiver systems,and there are more researchers who have studied the imagerejection mixers because they can suppress the mirror signal to make the communication signal cleaner and the circuit structure more compact.And with the development of science and technology,low-frequency resources are gradually utilized completely,so the frequency application is shifted up to the terahertz band.In this thesis,based on solid-state terahertz technology,the terahertz image-rejection mixing technology is studied using gallium arsenide(GaAs)monolithic integration process line,which includes the mixer principle,monolithic integration process flow and the image rejection mixer design method,and a monolithic integration image rejection mixer with a center frequency of 220 GHz is developed.The main contents of this thesis are summarized as follows:(1)Terahertz sub-harmonic image rejection mixing technique.In this thesis,the physical structure and nonlinear characteristics of the planar Schottky diode used in the mixer are analyzed from the principle,and the three-dimensional model of the mixer diode is built.The thesis analyzes the principle of mixer and harmonic mixer,and according to the principle of image rejection,the working principle and design idea of the image rejection mixer are analyzed,and the design is finally completed.(2)3dB quadrature branch waveguide coupling technology.According to the analysis of the working principle of the image rejection mixer,this thesis adopts the "quadrature dual coupling" structure at the RF and local oscillator.The study of coupler phase and amplitude unevenness affects the performance of the quadrature two-way mixer and thus the overall image rejection system.(3)Monolithic integration technology based on gallium arsenide(GaAs)process.A 220 GHz monolithic integrated IQ image rejection mixer is developed using a domestic GaAs monolithic integration process line.By integrating the mixing diode and microstrip circuit on the same substrate GaAs substrate,the overall circuit integration and the image rejection mixer performance are demonstrated.This thesis completes the processing and assembly of the design based on the domestic GaAs monolithic integration process,and the test results are as follows: When the local oscillation frequency is 112 GHz,the frequency conversion loss is better than15 dB in the range of 210-240 GHz,and the best value is 6dB;when the local oscillation frequency is 110 GHz,the image rejection ratio is better than 10 dB in the frequency band of 206-225 GHz,and the best value is 27.5dB.