TY  - JOUR
AU  - Dong, H.
AU  - Zhang, G.
AU  - Wang, Y.
AU  - Zhang, Y.
AU  - Xie, X.
AU  - Krause, H.-J.
AU  - Braginski, A.
AU  - Offenhäusser, A.
TI  - Effect of voltage source internal resistance on the SQUID bootstrap circuit
JO  - Superconductor science and technology
VL  - 25
SN  - 0953-2048
CY  - Bristol
PB  - IOP Publ.
M1  - PreJuSER-21518
SP  - 015012
PY  - 2012
N1  - This work is supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant Nos KGCX2-YW-906 and KGCX2-EW-105).
AB  - The voltage-biased SQUID bootstrap circuit (SBC) is suitable for achieving simple and low-noise direct readout of dc SQUIDs. In practice, an ideal voltage bias is difficult to realize because of non-zero internal resistance R-in of the bias voltage source. In order to clearly observe the influence of R-in on the SBC parameters (namely the flux-to-current transfer coefficient (partial derivative I=partial derivative Phi)(SBC) and the dynamic resistance R-d(SBC))and the noise performance, we introduced an additional adjustable resistor R-ad at room temperature to simulate a variable R-in between the SQUID and the preamplifier. We found that the measured SQUID flux noise does not rise, even though R-ad increases significantly. This result demonstrates that a highly resistive connection can be inserted between the liquid-helium-cooled SQUID and the room-temperature readout electronics in the SBC scheme, thus reducing the conductive heat loss of the system. This work will be significant for developing multichannel SBC readout systems, e. g. for biomagnetism, and systems using SQUIDs as amplifiers, for example, in TES-array readout.
KW  - J (WoSType)
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000298413200025
DO  - DOI:10.1088/0953-2048/25/1/015012
UR  - https://juser.fz-juelich.de/record/21518
ER  -