REALIZATION OF HIGH-TC DC SQUIDS - CHARACTERIZATION ON A BROAD RANGE OF TEMPERATURE

The analysis of different types of Josephson junctions allows us to de pict temperature dependences of the critical current I(C)(T), the Jose phson penetration depth lambda(J)(T) and main SQUID parameters. We sho w that a DC SQUID can operate on a broad range of temperature, with a current modulation equal to phi0/L in the limit beta much greater than 1. The analysis is given within the RSJ model. For this purpose, the usual DC SQUID current biasing circuit is replaced by a voltage contro lled system which detects current modulation. This voltage biasing is compatible with modulation technique usually applied to reduce the 1/f noise level of the junctions.