Journal of Applied Physics
Operation of the SUPARAMP at 33 GHz
R. Y. Chiao, P. T. Parrish
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.