NOISE CHARACTERISTICS OF A NBN HOT-ELECTRON MIXER AT 2.5 THZ

The noise temperature of a NbN phonon cooled hot-electron mixer has be en measured at a frequency of 2.5 THz for various operating conditions . We obtained for optimal operation a double sideband mixer noise temp erature of approximate to 14000 K and a system conversion loss of appr oximate to 23 dB at intermediate frequencies up to 1 GHz. The dependen ces of the mixer noise temperature on the bias voltage, local oscillat or power, and intermediate frequency were consistent with the phenomen ological description based on the effective temperature approximation.