Title :
Advanced version of two-stage dc SQUID-based amplifier
Author :
Kirichenko, D.E. ; Pavolotskij, A.B. ; Prokhorova, I.G. ; Saigirev, O.V. ; Mezzena, R. ; Vitale, S. ; Maslennikov, Y.V. ; Beljaev, A.V.
Author_Institution :
Dept. of Phys., Moscow State Univ., Russia
fDate :
6/1/1999 12:00:00 AM
Abstract :
An advanced version of a two stage dc SQUID-based low frequency amplifier and its measured signal and noise parameters are presented in this report. An effective input inductance of about 2.9 /spl mu/H, a SQUID´s inductance of about 11 pH, an effective coupling k/sup 2/ of about 0.24 and a white noise level of about 0.87 /spl mu//spl Phi//sub 0//Hz/sup 1/2/ at 4.2 K were achieved. The gradiometric scheme, a modified distributed damping filter and a modified geometry of coupling transformers have been used to suppress the influences of the external noise and resonances in the SQUID microstructure.
Keywords :
DC amplifiers; SQUID magnetometers; quantum noise; superconducting device noise; white noise; 4.2 K; advanced version; coupling transformers; effective coupling; effective input inductance; gradiometric scheme; low frequency amplifier; modified distributed damping filter; modified geometry; noise parameters; resonance suppression; signal parameters; two-stage DC SQUID-based amplifier; white noise level; Damping; Filters; Frequency measurement; Geometry; Inductance; Low-frequency noise; Low-noise amplifiers; Noise measurement; Transformers; White noise;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
