Research On Terahertz High Harmonic Mixing Technique

The unique advantange of terahertz in communication,imaging,and detection has make terahertz wave become the research focus.The study of terahertz transceiver system has promoted the development of terahertz technology.As the important stage of receivers,the mixer plays a significant role in the performance of the system.The harmonic mixer can reduce the difficulty of local oscillator fabricating,and be helpful for the miniaturization of receiver system and of great significance for the application of terahertz technology.This paper introduces the development of teraterhz harmonic mixer,and the theory of Schottky barrier diode and harmonic mixing.The planar Schottky barrier diode is structurally stable,easy to integrate,and can works at room temperature,has high cut-off frequency,which makes it a core device in terahertz receiver system.In addition,the modeled planar Schottky barrier diode,combined with the S-parameter and the intrinsic model of the diode model in the electromagnetic environment,are used to characterize the linear,nonlinear characteristics and the high frequency parasitic effect.In order to achieve the goal of broadband frequency conversion,this paper uses an improved filter structure,so that the filter has a wider stopband,better rectangular coefficient.The method of structure joint simulation solves the problem that the poor accuracy of high frequency circuit simulation.The simulation reveals that the mixers have good conversion loss and wide working bandwidth.In the band from 330 to 500 GHz,the conversion loss of fourth harmonic mixer is well below 18 dB,and the best point is 8.8dB;the eighth harmonic mixer's conversion loss is below 23 dB from 330 to 500 GHz,and the best point is 14 dB.The measurement shows in the band from 360 to 490 GHz,the conversion loss of fourth harmonic mixer is well below 25 dB,and the best point is 14.7dB;the eighth harmonic mixer's conversion loss is below 42 dB from 417 to 457 GHz,and the best point is 32 dB.This paper provides some reference and experience for the research work of the terahertz frequency harmonic mixer.In future,the research plans to relize the better flatness of conversion loss,analize and test the noise temperature.