TY  - JOUR
AU  - Trifonov, A.
AU  - Tong, C-Y E.
AU  - Blundell, R.
AU  - Ryabchun, S.
AU  - Gol'tsman, G.
PY  - 2015
DA  - 2015//
TI  - Probing the stability of HEB mixers with microwave injection
T2  - IEEE Trans. Appl. Supercond.
JO  - IEEE Trans. Appl. Supercond.
SP  - 2300404 (1 to 4)
VL  - 25
IS  - 3
KW  - NbN HEB mixer
KW  - stability
KW  - Allan-variance
AB  - Using a microwave probe as a tool, we have performed experiments aimed at understanding the origin of the output-power fluctuations in hot-electron-bolometer (HEB) mixers. We use a probe frequency of 1.5 GHz. The microwave probe picks up impedance changes of the HEB, which are examined upon demodulation of the reflected wave outside the cryostat. This study shows that the HEB mixer operates in two different regimes under a terahertz pump. At a low pumping level, strong pulse modulation is observed, as the device switches between the superconducting state and the normal state at a rate of a few megahertz. When pumped much harder, to approximate the low-noise mixer operating point, residual modulation can still be observed, showing that the HEB mixer is intrinsically unstable even in the resistive state. Based on these observations, we introduced a low-frequency termination to the HEB mixer. By terminating the device in a 50-Ω resistor in the megahertz frequency range, we have been able to improve the output-power Allan time of our HEB receiver by a factor of four to about 10 s for a detection bandwidth of 15 MHz, with a corresponding gain fluctuation of about 0.035%.
SN  - 1051-8223
UR  - http://ieeexplore.ieee.org/document/6966788/
UR  - https://doi.org/10.1109/TASC.2014.2374417
DO  - 10.1109/TASC.2014.2374417
N1  - exported from refbase (https://db.rplab.ru/refbase/show.php?record=1355), last updated on Thu, 13 May 2021 00:20:09 -0500
ID  - Trifonov_etal2015
ER  -