Two-stage integrated SQUID amplifier with series array output

Author

Welty, R.P. ; Martinis, J.M.

Author_Institution

Dept. of Electr. & Comput. Eng., Colorado Univ., Boulder, CO, USA

Volume

3

Issue

1

fYear

1993

fDate

3/1/1993 12:00:00 AM

Firstpage

2605

Lastpage

2608

Abstract

A two-stage integrated DC superconducting quantum interference device (SQUID) amplifier has been fabricated which uses a compact series array of 100 DC SQUIDs as the readout device for a low-noise single SQUID. The output noise is dominated by the amplified noise of the input SQUID and substantially exceeds the input noise of a good room-temperature preamp. The input stage is a low-inductance double-loop SQUID with energy sensitivity of approximately 30-h (equivalent flux noise phi /sub n/ approximately=0.3 mu phi /sub 0// square root Hz), with an input transformer having input inductance L/sub in/ approximately=0.25 mu H and net coupling to the SQUID of k/sup 2/ approximately=0.1. The bandwidth extends from DC to about 390 kHz. The series array has an output voltage swing of 3-4 mV, providing a dynamic range of over 50 dB at full bandwidth. The results suggest the general utility of series SQUID arrays as readout devices for SQUIDs.<>

Keywords

SQUIDs; amplifiers; electron device noise; superconducting integrated circuits; 0 to 390 kHz; 390 kHz; DC SQUIDs; dynamic range; input stage; integrated SQUID amplifier; low-inductance double-loop SQUID; low-noise single SQUID; output noise; readout device; series array output; superconducting quantum interference device; Bandwidth; Circuit noise; Coils; Dynamic range; Inductance; NIST; Noise level; SQUIDs; Temperature sensors; Voltage;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/77.233523

Filename

233523