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Author Khosropanah, P.; Merkel, H.; Yngvesson, S.; Adam, A.; Cherednichenko, S.; Kollberg, E.
Title A distributed device model for phonon-cooled HEB mixers predicting IV characteristics, gain, noise and IF bandwidth Type Conference Article
Year 2000 Publication Proc. 11th Int. Symp. Space Terahertz Technol. Abbreviated Journal
Volume Issue Pages 474-488
Keywords HEB mixer numerical model, diffusion cooling channel, diffusion channel, distributed HEB model, distributed model
Abstract A distributed model for phonon-cooled superconductor hot electron bolometer (HEB) mixers is given, which is based on solving the one-dimensional heat balance equation for the electron temperature profile along the superconductor strip. In this model it is assumed that the LO power is absorbed uniformly along the bridge but the DC power absorption depends on the local resistivity and is thus not uniform. The electron temperature dependence of the resistivity is assumed to be continuous and has a Fermi form. These assumptions are used in setting up the non-linear heat balance equation, which is solved numerically for the electron temperature profile along the bolometer strip. Based on this profile the resistance of the device and the IV curves are calculated. The IV curves are in excellent agreement with measurement results. Using a small signal model the conversion gain of the mixer is obtained. The expressions for Johnson noise and thermal fluctuation noise are derived. The calculated results are in close agreement with measurements, provided that one of the parameters used is adjusted.
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Publisher Place of Publication (down) University of Michigan, Ann Arbor, MI USA Editor
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Notes Approved no
Call Number Serial 893
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Author Cherednichenko, S.; Kroug, M.; Merkel, H.; Kollberg, E.; Loudkov, D.; Smirnov, K.; Voronov, B.; Gol'tsman, G.; Gershenzon, E.
Title Local oscillator power requirement and saturation effects in NbN HEB mixers Type Conference Article
Year 2001 Publication Proc. 12th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 12th Int. Symp. Space Terahertz Technol.
Volume Issue Pages 273-285
Keywords NbN HEB mixers, LO power, local oscillator power, saturation effect, dynamic range
Abstract The local oscillator power required for NbN hot-electron bolometric mixers (P LO ) was investigated with respect to mixer size, critical temperature and ambient temperature. P LO can be decreased by a factor of 10 as the mixer size decreases from 4×0.4 µm 2 to 0.6×0.13 µm 2 . For the smallest volume mixer the optimal local oscillator power was found to be 15 nW. We found that for such mixer no signal compression was observed up to an input signal of 2 nW which corresponds to an equivalent input load of 20,000 K. For a constant mixer volume, reduction of T c can decrease optimal local oscillator power at least by a factor of 2 without a deterioration of the receiver noise temperature. Bath temperature was found to have minor effect on the receiver characteristics.
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Publisher Place of Publication (down) San Diego, CA, USA Editor Jet Propulsion Laboratory, California Inst.it.u.t.e of Technology
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Notes Approved no
Call Number Serial 318
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Author Kroug, M.; Cherednichenko, S.; Choumas, M.; Merkel, H.; Kollberg, E.; Hübers, H.-W.; Richter, H.; Loudkov, D.; Voronov, B.; Gol'Tsman, G.
Title HEB quasi-optical heterodyne receiver for THz frequencies Type Conference Article
Year 2001 Publication Proc. 12th Int. Symp. Space Terahertz Technol. Abbreviated Journal
Volume Issue Pages 244-252
Keywords HEB mixer, NbN, MgO, conversion gain bandwidth, noise temperature
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Publisher Place of Publication (down) San Diego, CA, USA Editor
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Notes Approved no
Call Number Serial 319
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Author Merkel, H. F.; Khosropanah, P.; Sigfrid Yngvesson, K.; Cherednichenko, S.; Kroug, M.; Adam, A.; Kollberg, E.
Title An active zone small signal model for hot-electron bolometric mixers Type Conference Article
Year 2001 Publication Proc. 12th Int. Symp. Space Terahertz Technol. Abbreviated Journal
Volume Issue Pages 55
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Publisher Place of Publication (down) San Diego, CA, USA Editor
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Notes Approved no
Call Number RPLAB @ s @ losses_in_contacts_merkel Serial 320
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Author Cherednichenko, S.; Kollberg, E.; Angelov, I.; Drakinskiy, V.; Berg, T.; Merkel, H.
Title Effect of the direct detection effect on the HEB receiver sensitivity calibration Type Conference Article
Year 2005 Publication Proc. 16th Int. Symp. Space Terahertz Technol. Abbreviated Journal
Volume Issue Pages 235-239
Keywords HEB, mixer, direct detection effect
Abstract We analyze the scale of the HEB receiver sensitivity calibration error caused by the so called “direct detection effect”. The effect comes from changing of the HEB parameters when whey face the calibration loads of different temperatures. We found that for HIFI Band 6 mixers (Herschel Space Observatory) the noise temperature error is of the order of 8% for 300K/77K loads (lab receiver) and 2.5% for 100K/10K loads (in HIFI). Using different approach we also predict that with an isolator between the mixer and the low noise amplifiers the error can be much smaller.
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Publisher Place of Publication (down) Göteborg, Sweden Editor
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Notes Approved no
Call Number Serial 360
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