An Accurate Method for Determining the IF Noise in SIS Heterodyne Receivers

We present a new method to determine the contribution of the IF-amplifier chain to the overall noise performance of an SE-based receiver. Using simulated I-V and IF power characteristics, we show that the standard method used to date to evaluate the IF noise can underestimate the contribution because of non-negligible curvature in the post-gap SIS I-V characteristic. We demonstrate that the new method is not susceptible to the post-gap curvature, and discuss its benefits and limitations to the accurate and precise evaluation of IF noise contributions.