We have developed a novel coplanar resonator serving as a tank circuit for radio frequency washer superconducting quantum interference devices (SQUIDs). Two coplanar lines surrounded the circular flux concentrator washer, 13.4 mm in diameter. The SQUID, 3.5 mm in diameter, was coupled to the concentrator in the flip-chip configuration. All parts were fabricated from single-layer epitaxial YBa2Cu3O7
films on LaAlO3
substrates. In this layout, the resonant frequency could be set between 600 and 850 MHz. With SQUID loops of 100×100 μm2
(SQUID) inductance Ls = 150 pH
or 10×500 μm2 (Ls = 260 pH),
we determined at 77 K white flux noise levels Sϕ1/2
respectively. Both figures corresponded to the field resolution of about 30 fT/.
© 1997 American Institute of Physics.