%0 Journal Article
%T An investigation of the performance of the superconducting HEB mixer as a function of its RF embedding impedance
%A Loudkov, D.
%A Tong, C-Y E.
%A Blundell, R.
%A Kaurova, N.
%A Grishina, E.
%A Voronov, B.
%A Gol’tsman, G.
%J IEEE Trans. Appl. Supercond.
%D 2005
%V 15
%N 2
%F Loudkov_etal2005
%O exported from refbase (https://db.rplab.ru/refbase/show.php?record=1464), last updated on Mon, 17 May 2021 16:40:07 -0500
%X We have conducted an investigation of the optimal embedding impedance for a waveguide superconducting hot-electron bolometric (HEB) mixer. Three mixer chip designs for 800 GHz, offering nominal embedding resistances of 70 /spl Omega/, 35 /spl Omega/, and 15 /spl Omega/, have been developed. We used both High Frequency Structure Simulator (HFSS) software and scale model impedance measurements in the design process. We subsequently fabricated HEB mixers to these designs using 3-4 nm thick NbN thin film. Receiver noise temperature measurements and Fourier Transform Spectrometer (FTS) scans were performed to determine the optimal combination of embedding impedance and normal-state resistance for a 50 Ohm IF load impedance. A receiver noise temperature of 440 K was measured at a local oscillator frequency 850 GHz for a mixer with normal state resistance of 62 /spl Omega/ incorporated into a circuit offering a nominal embedding impedance of 70 /spl Omega/. We conclude from our data that, for low noise operation, the normal state resistance of the HEB mixer element should be close to the embedding impedance of the mixer mount.
%K waveguide NbN HEB mixers
%R 10.1109/TASC.2005.849879
%U https://doi.org/10.1109/TASC.2005.849879
%P 472-475