Research On Terahertz Frequency-Multiplied Technology Based On Schottky Diodes

Terahertz technology has broad application prospects in the areas of broadband communications,medical imaging,security inspections,and astronomical exploration.In recent years,it has become a research hotspot.Due to the lack of stable,reliable,and effective terahertz sources,the development of terahertz technology is greatly limited.Therefore,in the research of terahertz technology,the problem of terahertz source is the bottleneck.Terahertz solid-state frequency-multiplied sources based on semiconductor devices have the advantages of small size,high reliability,and easy integration,so the have become the main methods for obtaining terahertz waves.In this paper,based on the in-depth study of the working principle of planar Schottky diodes,a complete working model of diodes is firstly established based on the three-dimensional physical structure of the diodes and the intrinsic SPICE parameters.Then,the difference between load-pull method and harmonic wave load impedance optimization method is studied in the extraction of the optimum embedding impedance of the working model.It's found that their results tend to be consistent and two methods can be nested in actual use,although the algorithm and process are different.The followed is to design a 160 GHz broadband doubler and a 220 GHz high efficiency doubler by a method of frequency multiplier synthesis design combining partial design and overall design and a method of filed-circuit cooperative design.Finally,the designed frequency multipliers are tested by the test platform.The measured results of the 160 GHz wideband doubler show that the frequency doubler has about 8% conversion efficiency in the 140~180 GHz frequency band driven by 100 mW input power,and the average output power is about 8 mW.The conversion efficiency in the 135~190 GHz frequency band exceeds 4%,and the 3dB bandwidth is about 34%.Under 174 mW input power,the maximum output power is 17.8mW at 166 GHz.The frequency doubler works under the self-bias conditions,and no external bias voltage is needed.The best self-bias resistance is no more than 100?.Compared with the frequency multiplier in the same frequency band at home and abroad,the 160 GHz frequency doubler designed in this paper has reached a relatively advanced level in performance.The measured results of the 220 GHz high-efficiency doubler show that when the bias voltage is-4V and the frequency multiplier is driven by 33 mW input power,the maximum output power of 2.5mW is obtained at 220 GHz,and the frequency multiplication efficiency is 7.5%.The simulation shows that the frequency doubler will have greater output power and frequency doubling efficiency under the larger input power.The research results of this dissertation have accumulated experience in design of terahertz band wideband and high-efficiency frequency multpliers,and will provide reference for the design of subsequent higher frequency band multpliers.