Title :
Improved sensitivity of planar microwave based RF-SQUIDs using a cryogenic HEMT preamplifier
Author :
Fontana, G. ; Mezzena, R. ; Vitale, S. ; Cerdonio, M. ; Muck, M. ; Hallmanns, G. ; Heiden, C.
Author_Institution :
Dipartimento di Fisica, Trento Univ., Italy
fDate :
3/1/1993 12:00:00 AM
Abstract :
The design and performance of a planar microwave RF-SQUID (superconducting quantum interference device) read out by a cryogenic high-electron-mobility-transistor (HEMT) preamplifier are described. The SQUID sensor consists of a planar half-wavelength microstrip resonator, into which the SQUID loop is integrated. The SQUID is operated at a pump frequency of 1.7 GHz. The cryogenic preamplifier uses a microwave HEMT, located close to the SQUID sensor. Measurements of the flux noise and the fractional step rise parameter were carried out in the temperature range between 4.2 K and 1.5 K. In an open loop, a flux noise of 2*10/sup -6/ Phi /sub 0// square root Hz was measured at 4.2 K, resulting in an energy resolution of about 100 h. The design of a 3-GHz magnetometer is also described, and the preliminary results of the measurements are reported.<>
Keywords :
SQUIDs; electron device noise; magnetometers; microstrip components; microwave amplifiers; microwave measurement; preamplifiers; solid-state microwave circuits; superconducting microwave devices; 1.5 to 4.2 K; 1.7 GHz; 3 GHz; SQUID sensor; cryogenic HEMT preamplifier; energy resolution; flux noise; fractional step rise parameter; magnetometer; microwave HEMT; planar half-wavelength microstrip resonator; planar microwave RF-SQUID; pump frequency; 1f noise; Cryogenics; Energy measurement; HEMTs; Noise measurement; Preamplifiers; SQUIDs; Superconducting device noise; Superconducting devices; Superconducting microwave devices;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
