AN INTEGRATED SIDEBAND SEPARATING SIS MIXER FOR 200-280 GHz

Abstract

Separate waveguides for the signal and LO are connected via suspended striplines to a 2 x 1 mm quartz substrate which contains all the RE components of the sideband separating mixer: quadrature hybrid, LO power splitter, two LO couplers, and two SIS mixers. These components are realized in capacitivelyloaded coplanar waveguide, which minimizes stray coupling between adjacent components and coupling to undesired modes in the thick quartz substrate. Over the 200-280 GHz band, the mixer noise temperature was 50-150 K and the overall receiver noise temperature was 60-200 K (both measured outside the vacuum window). The sideband separation was . 9 dB, which we hope to improve by reducing leakage of LO power under the substrate into the signal port, and by improvin g the match of the cold termination of the fourth port of the input quadrature hybrid.