基于超导HEB混频器的太赫兹超宽带耦合电路设计  

Design of Terahertz Ultra-wide Band Coupling Circuit Based on Superconducting Hot Electron Bolometer Mixer

作　　者：李春[1] 秦雷[1] 李淼[1] 蒋玲[1] 

机构地区：[1]南京林业大学信息科学技术学院,南京210037

出　　处：《微波学报》2014年第1期64-67,71,共5页Journal of Microwaves

基　　金：国家自然科学基金(31200541);江苏省自然科学基金(BK2012417);教育部留学回国人员科研基金

摘　　要：超导HEB(Hot Electron Bolometer)热电子混频器是1THz以上灵敏度最高的相干探测器,为了进一步提高其灵敏度,有效减小射频信号在传输路径中的损耗,实现超导HEB混频器的超宽带混频功能,设计高耦合效率的射频匹配电路尤为重要。首先提出了混频器耦合电路的理论模型,然后采用三维电磁场仿真软件HFSS和类似于准光学天线的集总源法,设计了一种超宽带、低损耗的太赫兹信号耦合电路,对超导HEB混频器的嵌入阻抗在整个0.9～1.3THz的工作频带范围内进行了详细的分析。系统研究了低通滤波器中高低阻抗线结构,波导到微带转换中存在的高次模对射频信号传输的影响,并模拟仿真了实验中可能出现的磨片厚度误差对嵌入阻抗的影响。分析结果表明,该混频器的嵌入阻抗为35Ω-j10Ω左右,在整个工作频带内变化缓慢,能够实现超宽频带匹配,混频器的相对工作带宽可达到36%,仿真结果和理论模型计算结果完全一致。该研究结果对研制超宽带高灵敏度的超导HEB混频器具有很好的指导意义。Superconducting hot electron bolometer mixer which is the highest sensitive coherent detector above 1 THz. In order to further improve the sensitivity and effectively reduce the loss of RF signal in the transmission path in ultra-wide band, it is important to design a RF matching circuit with high coupling efficiency. This paper firstly presents a theoretical model for the feed point matching impedance, and employs a 3D electromagnetic simulation software （HFSS） to design an ul- tra-broad-band and low-loss THz signal coupling circuit based on lumped-port source method similar to quasi optical antenna. Embedding impedance of the superconducting HEB mixer in the 0.9 ~ 1.3 THz has been studied in detail. The effect of low pass filter composed of high- and low- impedance lines, high-order modes in the probe structure from waveguide to micros- trip, and chip thickness on the embedding impedance are investigated. In particular, we study the influence of slice tolerance of substrate thickness and feed-point size on the embedding impedance. The mixer embedding impedance is simulated to be around 35Ω-j10Ω in the whole operation band. The mixer relative bandwidth can reach 36%. The simulation results are in good agreement with the calculated results according to the theoretical model. The calculation results provide helpful instruc- tion for the future development of ultra-wide band and highly sensitive superconducting HEB mixer.

关 键 词：超导HEB混频器 嵌入阻抗 宽带匹配 高次模 嵌入阻抗耦合模型 

分 类 号：TN773[电子电信—电路与系统]