On the Optimization of Cryogenic Mixers

Measurements on cooled mm-wave Schottky diode mixers are presented. From embedding impedance measurements and knowledge about the diode properties a theoretical analysis is performed, which in general agrees well with the experiments. It is shown that it is possible to design a mixer with optimum noise properties with the lower sideband rejected by the backshort. It is also shown that correlation effects are important for the noise properties and that parametric effects cannot be neglected.