A novel mm-wave SIS mixer comprising series-connected junction array and on-chip bias-T

Abstract

In this paper, we introduce a novel Superconductor-Insulator-Superconductor (SIS) mixer circuitry based on a series-connected junction (SJ) array. Unlike existing SJ designs, in which each junction is biased at the same DC current. This new design enables each junction to be DC-biased at the same voltage via a set of on-chip bias-T's. Thanks to this parallel DC biasing solution, this circuit design supports a so-called series-connected distributed junction (SDJ) array design, in which LO power non-uniformly spreads along the junction array both in amplitude and in phase. Using this SDJ array, we can realize mm-wave SIS mixers with octave RF band, 15 GHz-wide IF band and high dynamic range required for radio astronomical observation. Simulations of an 80-160GHz SIS mixer design have been made based on this design to support our arguments.