Basic Research On Terahertz Broadband Frequency Converter Based On Diode Monolithic

The terahertz frequency band is between macroelectronics and microphotonics.As the preferred frequency band for 6G high-speed communication technology,terahertz is a popular research direction in the academic circle in recent years.As a critical frequencyshifting device,mixers are widely used in terahertz systems.This thesis starts with the basic principles of Schottky diodes and subharmonic mixers,and focuses on two integration methods: hybrid integration and monolithic integration,performed the following work:Establish and revise the physical model and SPICE model of anti-parallel Schottky diodes,based on which the subharmonic mixer is studied.Using the joint simulation method of HFSS and ADS,combined with the basic principles of field and circuit,a220 GHz subharmonic mixer is designed,and the optimal frequency conversion loss is7.9d B.Also,the experimental and simulation results are fitted,and the diode’s parasitic parameters are corrected.Facing the demand for broadband receiving technology in 220 GHz terahertz highspeed communication systems,the design method of broadband mixer is studied in order to improve the system transmission rate.Starting from the efficiency of RF feed-in,a broadband RF transition probe was designed and applied to the 220 GHz broadband subharmonic mixer,and two single mixers and one IQ mixer were developed.After experimental tests,broadband The bandwidth of the mixer reaches 40 GHz,and the optimal frequency conversion loss is 8.28 d B,and the processed and assembled IQ mixer can also show the same performance;the experimental test shows that the optimal value of the frequency conversion loss of the developed ultra-wideband mixer is 6.8 d B,and the bandwidth reaches 70 d B.Modify the existing Schottky diode model,design a monolithic integration model of an antiparallel diode,and a passive unit model of a mixer on a gallium arsenide substrate,optimize and restore a 220 GHz monolithic On-chip sub-harmonic mixer,and complete the processing and assembly of the mixer.The experimental test shows that the frequency conversion loss is basically better than 14 d B in the frequency range of 195GHz～245GHz,and the optimal frequency conversion loss is 9.9d B.This study lays the foundation for further research on monolithic integrated mixers.