Operation of the SUPARAMP at 33 GHz

Abstract

A 9‐mm degenerate parametric amplifier has been constructed using a linear series array of unbiased Josephson junctions as the active nonlinear element. We used a balanced diode mixer as a synchronous detector, with a single source serving both as the pump and as the mixer local oscillator. A stable net gain of 15 dB in an instantaneous bandwidth (FWHM) of 3.4 GHz has been achieved. We measured a system noise temperature of 220±5 K (DSB) with a SUPARAMP contribution of only 20±10 K. Output saturation, however, has been observed. This complicates the interpretation of our noise‐temperature measurements and may render them upper limits. Comparison is made with the results of an earlier 3‐cm SUPARAMP. The data are in substantial agreement with theoretical predictions.