PT Journal
AU Burke, PJ
   Schoelkopf, RJ
   Prober, DE
   Skalare, A
   Karasik, BS
   Gaidis, MC
   McGrath, WR
   Bumble, B
   Leduc, HG
TI Spectrum of thermal fluctuation noise in diffusion and phonon cooled hot-electron mixers
SO Applied Physics Letters
JI Appl. Phys. Lett.
PY 1998
BP 1516
EP 1518
VL 72
IS 12
DE HEB mixer; thermal fluctuation noise; TFN
AB A systematic study of the intermediate frequency noise bandwidth of Nb thin-film superconducting hot-electron bolometers is presented. We have measured the spectrum of the output noise as well as the conversion efficiency over a very broad intermediate frequency range (from 0.1 to 7.5 GHz) for devices varying in length from 0.08 μm to 3 μm. Local oscillator and rf signals from 8 to 40 GHz were used. For a device of a given length, the spectrum of the output noise and the conversion efficiency behave similarly for intermediate frequencies less than the gain bandwidth, in accordance with a simple thermal model for both the mixing and thermal fluctuation noise. For higher intermediate frequencies the conversion efficiency decreases; in contrast, the noise decreases but has a second contribution which dominates at higher frequency. The noise bandwidth is larger than the gain bandwidth, and the mixer noise is low, between 120 and 530 K (double side band).
ER