A wide dynamic range single-chip SQUID magnetometer

A single-chip SQUID magnetometer is described and demonstrated that integrates a SQUID sensor with feedback circuitry on the same chip. This chip has a very large dynamic range, determined by the sensitivity of the input SQUID and by the current-carrying capacity of the input superconducting lines. This chip can eliminate the need for the sophisticated room temperature circuitry currently used with conventional analog SQUID magnetometers and replace these electronics with a simple bi-directional counter. Furthermore, on-chip multiplexing can be easily implemented for use in multi-channel systems where arrays of more than 100 sensors are required for magnetic imaging. In addition, due to its extremely wide dynamic range and high slew rate, a system based on this chip can be operated in a relatively high magnetic field environment without extensive magnetic shielding.<>