The SQUID Bootstrap Circuit (SBC) consists of a mutually coupled dc-SQUID and a feedback coil. The SQUID and the coil are connected in series. The feedback coil, which can be made of a superconductor or of a normal metal, can be either integrated on the SQUID chip, or be placed separately next to the SQUID. Together, both SQUID and coil form a novel two-terminal device, which will be named SBC. The invention combines the advantages of both, APF and NC and avoids certain drawbacks thereof. With the help of this new design, the current or voltage -Phi characteristics of SQUID will be asymmetric and the equivalent dynamic resistance will be changed.