Infinite available gain in a 115 GHz SIS mixer

Abstract

We report the observation of infinite available conversion gain at 115 GHz with an SIS mixer. The output impedance can be smoothly changed from positive, through infinite, to negative. The mixer consists of a series array of N = 14 thermally recyclable Pb-alloy tunnel junctions in a reduced-height waveguide mount. The best mixer noise temperatures measured are consistent with a quantum noise temperature of Nh{stroke}ω/k. © 1981.