Spectrum of thermal fluctuation noise in diffusion and phonon cooled hot-electron mixers
作者:
P. J. Burke,
R. J. Schoelkopf,
D. E. Prober,
A. Skalare,
B. S. Karasik,
M. C. Gaidis,
W. R. McGrath,
B. Bumble,
H. G. LeDuc,
期刊:
Applied Physics Letters
(AIP Available online 1998)
卷期:
Volume 72,
issue 12
页码: 1516-1518
ISSN:0003-6951
年代: 1998
DOI:10.1063/1.121044
出版商: AIP
数据来源: AIP
摘要:
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 &mgr;m to 3 &mgr;m. 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). ©1998 American Institute of Physics.
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