Title :
Two-stage S-band DC SQUID amplifier
Author :
Prokopenko, G.V. ; Balashov, D.V. ; Shitov, S.V. ; Koshelets, V.P. ; Mygind, J.
Author_Institution :
Inst. of Radio Eng. & Electron., Acad. of Sci., Moscow, Russia
fDate :
6/1/1999 12:00:00 AM
Abstract :
A 6 mm/spl times/6 mm chip comprising two identical DC SQUID based amplifiers (SQAs) has been designed, fabricated and tested as a two-stage RF amplifier in a frequency range 3.5-4.0 GHz. Each SQA consists of a double washer type DC SQUID with novel integrated input resonant circuit. The reflection coefficient of both input and output of the SQA has been measured in the two stage configuration. To avoid SQA saturation at the wide band noise tests a tunable 40 MHz bandpass YIG-filter has been used. The following parameters of the two-stage SQA have been measured at the 3.65 GHz: gain of (17.5/spl plusmn/1) dB, 3 dB bandwidth of about 250 MHz, and noise temperature (4.0/spl plusmn/0.5)K what corresponds to intrinsic flux noise S/spl phi//sup 1/2//spl ap/0.6 /spl mu//spl Phi//sub 0/Hz/sup -1/2/ and energy sensitivity /spl epsiv//sub i//spl ap/75 /spl planck/ (7.8/spl middot/10/sup -33/ J/Hz). If the measured RF mismatch between the input/output of SQA and source signal/post-amplifier is taken into account a gain of (20.5/spl plusmn/1.5) dB and noise temperature as low as (2.5/spl plusmn/1.0) K (intrinsic flux noise S/spl phi//sup 1/2//spl ap/0.4 /spl mu//spl Phi//sub 0/Hz/sup -1/2/, energy sensitivity /spl epsiv//sub i//spl ap/47 /spl planck/) can be estimated.
Keywords :
SQUIDs; intermediate-frequency amplifiers; submillimetre wave mixers; submillimetre wave receivers; superconducting microwave devices; superconductor-insulator-superconductor mixers; 17.5 dB; 3.5 to 4 GHz; 6 mm; IF amplifier; RF mismatch; double washer type DC SQUID; energy sensitivity; integrated input resonant circuit; intrinsic flux noise; noise temperature; reflection coefficient; sub-MM wave receiver; tunable bandpass YIG-filter; two-stage RF amplifier; two-stage S-band DC SQUID amplifier; Acoustic reflection; Circuit testing; Energy measurement; Frequency; Gain measurement; Noise measurement; RLC circuits; Radiofrequency amplifiers; SQUIDs; Temperature sensors;
Journal_Title :
Applied Superconductivity, IEEE Transactions on