Study On Thz Solid-state Mixer Based On The Planar Schottky Diode

Terahertz(THz)is a promising field of electromagnetic waves.At the beginning of the twenty-first century,more and more experts and scholars turned their research focus to the field of terahertz.Now,terahertz technology has been applied in medical,military,and many other fields.As an important component of the Terahertz system,the main function of the mixer is achieving spectrum shifting.However,when the frequency increases to terahertz band where stable and reliable source is difficult to obtain,harmonic mixer is a feasible solution.This paper will pay attention to the study of sub-harmonic mixer.A simulation method based on unit circuit was applied for 440 GHz sub-harmonic mixer design.The circuit was divided into some components with specific function,and each of them was designed independently.With all of the components we built up the whole circut for matching circuit design in the ADS.By using the Teratech AP4/G2/0P64 diode chip.we achieved a simulation result that the convert loss less than 10 dB in 40 GHz RF band.After that,the 440 GHz sub-harmonic mixer was machined in factory.And it's Up-convert tested under different local oscillator(LO)conditions.When set the LO frequency 222 GHz and 4.2mW driving power,it turns out double side band(DSB)convert loss less than 15 dB in 20 GHz IF band,and less than 13.7d B in 18 GHz IF band.With a flat and wide bandwidth,the best DSB convert loss tested is 11.5dB.As for the 330 GHz sub-harmonic mixer design we used the more advanced global circuit optimization.According to the experience,the whole circuit structure was divided into many transmission line structures,so all of the circuit structures can be used as design variables.The matching part was carried out directly,and we used the overall index of mixer to restrain its behavior.By using the same diode chip,we achieved a simulation result that the convert loss less than 7.7dB in 50 GHz RF band.Obviously,the method of global circuit optimization has more advantages.The terahertz mixer is an important component of the terahertz system.This research will provide experience and inspiration for the design of THz devices.