Proceedings of the Second European Workshop on Low Temperature Electronics
J. Phys. IV France 06 (1996) C3-411-C3-416
DC SQUID Amplifier for NMR Experiments on Small SamplesO. Hubert, Y. Monfort, J. Lepaisant, C. Gunther and D. Bloyet
Groupe de Recherches en Informatique, Image et Instrumentation de Caen (G.R.E.Y.C.), URA 1526 CNRS, ISMRA, 6 Boulevard du Maréchal Juin, 14050 Caen Cedex, France
Law noise preamplifiers are required for the detection of the magnetic resonance of small size samples or at low magnetic fields. According to calculations based on the "en, in" model. SQUlD based amplifiers are more suitable to NMR experiments on small samples than semiconductor amplifiers. We propose an amplification method by frequency transposition using a DC SQUID. Such a system can be run over a broad range of frequency as the noise impedance of the stages subsequent to the SQUID is continually optimised. The measurements are in good agreement with our theoretical model, based on a simplified voltage to flux SQUID characteristic.
© EDP Sciences 1996