Research On Terahertz Frequency Multiplying And Mixing Technology Based On Schottky Diodes

In the electromagnetic spectrum,terahertz waves are located between millimeter waves and light waves,with many special characteristics.Due to the wide potential application in electronic information,security imaging,biomedicine and aerospace remote sensing,terahertz technology has become a research hotspot in recent years.At present,terahertz frequency multiplying technology is the main way to obtain terahertz signals,and terahertz mixing technology is the core content of terahertz transceiver system.Therefore,in this thesis,terahertz frequency multiplying and mixing technology are studied.The main contends are as following.To begin with,two 220 GHz frequency triplers based on hybrid integration and monolithic integration processes are designed and manufactured.In the 220 GHz frequency tripler based on hybrid integration technology,the domestic Schottky diode with four anode-junctions in series is utilized.Furthermore,the segmented design method is used to provide superior performance for each unit circuit,and the circuit is simulated using a combination of three-dimensional electromagnetic simulation software and harmonic balance circuit simulation software.The designed frequency tripler prototype is manufactured and assembled,and the measured results reveal that the output power of the frequency multiplier is basically better than 2 m W with an input power of 70 m W in the frequency band of 193-245 GHz.The maximum power output is up to 2.57 m W.The measured return losses are in good agreement with the simulated results.The second 220 GHz frequency tripler based on monolithic integrated technology uses the interdigital structure diode innovatively proposed by our team,and the number of diode is designed to be 8 to increase power capacity.Using HS-HGDM,each unit circuit except for the direct-current(DC)biased low-pass filter is split into the most basic transmission line units to enhance the simulation optimization space at once.As described above,the three-dimensional electromagnetic simulation software and harmonic balance circuit simulation software are combined to simulate the circuit,and waveguide chokes are added to the input and output waveguide ports to reduce the interconnection loss.The measured results show that the output power of the designed frequency multiplier is better than 3.2 m W within 203-232 GHz.The maximum output is 11.9 m W at 210 GHz.The simulated and measured return losses are in good agreement.Then,a 560 GHz subharmonic mixer based on monolithic integrated technology is developed.According to domestic technology and mixer specifications,a suitable reverse parallel Schottky diode is designed.In the design process,the unit circuits with superior performance are firstly optimized,and the semi-global and semi-partial design method is adopted,i.e.,each unit circuit is split except the intermediate frequency(IF)low-pass filter.These circuits are thereafter simulated using the above described field circuit joint simulation method.The final simulation results show that when the IF frequency is fixed at 2 GHz and the local oscillator(LO)power is fixed at 3 m W,the single side band(SSB)conversion loss of the mixer is less than 8 d B in the radio frequency(RF)band of 515-600 GHz,and the optimal conversion loss is 6.8 d B at533.5 GHz.In the RF band of 520-600 GHz,the corresponding RF port return loss is better than 10 dB.