Gain Enhancement in Inductively-Loaded Distributed SIS Junction Arrays

Due to their very low IF output capacitance, series-connected distributed SIS junction array mixers possess very wide IF bandwidth. However, careful control of parasitic inductance in the IF network is important in order to obtain a flat IF response in this class of wideband mixer. We have studied the effect of inductive loading on the operation of these mixers, both experimentally and theoretically. It is shown that over the range of IF where the reactive part of the load impedance is large, a higher mixer conversion gain accompanied by a lower noise temperature is observed.