IEEE Transactions on Microwave Theory and Techniques
Design and Performance of a 600–720-GHz Sideband-Separating Receiver Using ${\hbox{AlO}}_{x}$ and AlN SIS Junctions
Fausto Patricio Mena, J. Kooi, Andrey M. Baryshev, C. F. J. Lodewijk, T. Zijlstra, Ronald Hesper, G. Gerlofsma, T. M. Klapwijk, W. Wild
Abstract
We present the design, modeling, construction, and characterization of a sideband separating heterodyne receiver that covers the frequency range from 600 to 720 GHz. The receiver has been constructed using waveguide technology in the split-block technique. The core of the mixer consists of a quadrature hybrid, two directional couplers to inject the local oscillator signal, two superconductor-insulator-superconductor (SIS) junctions, three signal-termination loads, and two planar IF/bandpass-filter/dc-bias circuits. The instrument that we have constructed presents excellent performance as demonstrated by two important figures of merit: receiver noise temperature and sideband ratio. Across the entire band, the uncorrected single-sideband noise temperature is below 500 K and reaches 190 K at the best operating point. The sideband ratio is greater than 10 dB over most of the frequency operating range. Superconducting junctions containing AlO∞- and AlN-tunnel barriers were tested.