Sensitive high-T _c superconducting (HTS) heterodyne receivers are envisioned as promising technologies for terahertz (THz) communication and sensing applications due to the lack of power efficient sources in the band. HTS device properties, particularly the noise temperature, are dependent on complicated factors that include multiple noise sources as well as the interaction between Josephson junction and radio-frequency (RF) networks. We report investigations on the device properties of an HTS THz mixer in the presence of nonlinear thermal fluctuation and series junction array. By using the three-port analysis method, it is observed that the Planck and quantum noises representing nonlinear thermal fluctuation plays a significant role in the cases of smaller fluctuation parameters and higher signal frequencies. The influence of series junction array on mixer performance is also studied, which shows that there is an optimum junction number dependent on the normalized RF source impedance. The measured results of a broadband antenna-coupled HTS single-junction mixer agree well with that obtained by numerical simulation. The results predict that noise performance, conversion gain and operating bandwidth would be considerably improved if a series junction array with a suitable junction number is used for heterodyne mixing.

高感度T _c由于该频段中缺乏高效功率源，超导（HTS）外差式接收器被设想为太赫兹（THz）通信和传感应用的有前途的技术。HTS设备的性能，尤其是噪声温度，取决于复杂的因素，其中包括多个噪声源以及约瑟夫森结与射频（RF）网络之间的相互作用。我们报告了在存在非线性热波动和串联结阵列的情况下对HTS THz混频器的器件性能进行的调查。通过使用三端口分析方法，可以观察到代表非线性热波动的普朗克和量子噪声在较小的波动参数和较高的信号频率的情况下起着重要作用。还研究了串联结阵列对混频器性能的影响，这表明存在一个取决于归一化RF源阻抗的最佳结数。宽带天线耦合HTS单结混频器的测量结果与数值模拟结果吻合良好。结果预测，如果将具有合适结数的串联结阵列用于外差混合，则噪声性能，转换增益和工作带宽将得到显着改善。