Probing the Stability of HEB Mixers With Microwave Injection

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 demodula...

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Bibliographic Details
Published in:IEEE transactions on applied superconductivity 2015-06, Vol.25 (3), p.1-4
Main Authors: Trifonov, Andrey, Tong, Cheuk-Yu E., Blundell, Raymond, Ryabchun, Sergey, Gol'tsman, Gregory
Format: Article
Language:English
Subjects:
Allan variance
Demodulation
Devices
Fluctuation
Fluctuations
Frequency ranges
hot-electron-bolometer mixer
Microwave oscillators
Microwave probes
Mixers
Modulation
Probes
Receivers
relaxation oscillation
stability
Superconducting microwave devices
Superconductivity
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Summary: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%.
ISSN:1051-8223
1558-2515
DOI:10.1109/TASC.2014.2374417