A 211-275 GHz Sideband Separating SIS Mixer for APEX

Paper i proceeding, 2007

We present the results of the development and characterization of the sideband separating (2SB) SIS mixer for the APEX band 1, 211-275 GHz. All mixer components, except the IF hybrid, are integrated into a single mixer block. The sideband separation is achieved by using a quadrature scheme where a local oscillator (LO) pumps two identical SIS mixers. The RF power is divided using a waveguide branch line coupler and directed with 900 phase difference to the ends of the substrate, where each path is coupled to the mixer chip through a waveguide to microstrip transition. Preliminary tests of this 2SB mixer show a sideband suppression ratio of about 12 dB and a typical SSB noise temperature of 80K.