Poster Presentation

Development of a Wide-IF SIS Mixer for the 150 GHz Heterodyne Receiver

Author(s): Jiman Kang (KASI/UST)

Presenter: Jiman Kang (KASI/UST)

We present the design, fabrication, and experimental validation of a wide-IF (8–16 GHz) SIS mixer developed for a 150-GHz heterodyne receiver. The device employs four series-connected Nb/AlOx/Nb junctions and an RF embedding network that combines microstrip–CPW structure with a quarter-wavelength shunt stub, an RF coupling capacitor, and a broadband RF choke for IF routing. The RF embedding impedance is controlled near the optimum impedance (~ 31 Ω), enabling stable operation with minimized noise and flat conversion gain across the IF band. Full-circuit simulations using SuperMix guided the layout and impedance optimization. The mixer chip was fabricated using a photolithographic trilayer process at ASIAA and was evaluated in a 4-K test cryogenic receiver using hot/cold-load Y-factor measurements. Experimental results demonstrate a peak double-sideband (DSB) conversion gain of approximately 6 dB at 154 GHz LO frequency, a minimum receiver noise temperature of about 25 K at 159 GHz, and an average noise temperature of 43 K across the 8–16 GHz IF band. These results confirm that the proposed mixer achieves wide-IF operation while maintaining low noise performance, making it suitable for next-generation wideband astronomical and spectroscopic receivers requiring high instantaneous bandwidth and survey efficiency.