A DESIGN OF PLANAR MULTITURN FLUX TRANSFORMERS FOR RADIO-FREQUENCY SQUID MAGNETOMETERS

We propose a design for planar multi-turn flux transformer for radio f requency (rf) superconducting quantum interference device (SQUID) magn etometers. This transformer is integrated with a coplanar resonator, e .g., on a 1 cm(2) LaAlO3 substrate. Its pickup loop is connected with two input coils, separate for dc (low-frequency) and rf currents. A do uble-hole washer SQUID is coupled to these coils in a flip-chip config uration to form a magnetometer. The separation of rf and de current pa ths in the transformer made it possible to demonstrate the rf SQUID ma gnetometer operation. (C) 1998 American Institute of Physics.