Title :
Dynamic characteristics of S-band DC SQUID amplifier
Author :
Prokopenko, Georgy V. ; Shitov, Sergey V. ; Lapitskaya, Irina L. ; Koshelets, Valery P. ; Mygind, Jesper
Author_Institution :
Inst. of Radio Eng. & Electron., Russian Acad. of Sci., Moscow, Russia
fDate :
6/1/2003 12:00:00 AM
Abstract :
A low-noise RF amplifier based on a dc SQUID (SQA) has been tested in the frequency range 3.0-4.6 GHz in the open-loop configuration. The following parameters have been measured for the single-stage balanced type SQA at 4.0 GHz: gain (12±1) dB, 3 dB bandwidth of 500 MHz and noise temperature (1.0±0.25) K. For the nonbalanced type SQA at 4.0 GHz gain was (15±1) dB, 3 dB bandwidth 200 MHz and noise temperature (0.5±0.25) K. The improved performance is obtained due to the increased characteristic voltage (≈420 μV) of the small-area (down to 0.7-0.9 μm2) high-quality Nb-AlOx-Nb SIS junctions. The saturation power (normalized to 1 GHz) referred to the input at 1 dB gain compression is estimated as ≈55 K*GHz at a bias voltage of 60 μV. The reasons for saturation of the SQA are discussed.
Keywords :
SQUIDs; aluminium compounds; differential amplifiers; niobium; superconducting device noise; superconducting microwave devices; superconductor-insulator-superconductor devices; 11 to 13 dB; 14 to 16 dB; 200 MHz; 3.0 to 4.6 GHz; 420 muV; 500 MHz; 60 muV; DC SQUID amplifier; Josephson devices; Nb-AlOx-Nb; S-band; characteristic voltage; dynamic characteristics; high-quality SIS junctions; low-noise amplifier; noise temperature; open-loop configuration; saturation power; single-stage balanced type; Bandwidth; Frequency; Gain measurement; Noise measurement; Performance gain; Radiofrequency amplifiers; SQUIDs; Temperature; Testing; Voltage;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
DOI :
10.1109/TASC.2003.814146
