△Design of SQUID Magnetometer With On-Chip Flux Locked-Loop Circuit

Myoren Hiroaki, Kosuke Okabe, Kamiya Ryotaro +2 more

Ryo Matsunawa, Kosuke Okabe, Masato Naruse +2 more

Hiroaki Myoren, M. Goto, Tohru Taino +5 more

Double relaxation oscillation SQUID (DROS) combined with an on-chip superconducting digital flux locked-loop (FLL) circuit has been proposed. In this study, we described superconducting digital FLL circuit which consists of an 8-bit up/down counter and an 8-bit R-2R ladder D/A converter. The circuit was designed using 4-Junction Logic (4JL)-gates which are driven by a two phase power supply. In the up/down counter, we employed binary carry lookahead (BCL) circuits for high-speed operation. Logic simulations for the BCL 8-bit up/down counter showed correct operation up to 4 GHz, assuming a 2.5 kA/cm/sup 2/ Nb/Al-AlO/sub x//Nb junction technology. From simulation results high slew rate of 10/sup 7//spl Phi//sub 0//s and dynamic range of 2.5/spl Phi//sub 0/ can be expected.

Fujimaki, Tamura, Imamura +1 more

Y. Zhang, H. R. Yi, Jürgen Schubert +3 more

We propose a design for planar multi-turn flux transformer for radio frequency (rf) superconducting quantum interference device (SQUID) magnetometers. This transformer is integrated with a coplanar resonator, e.g., on a 1 cm2 LaAlO3 substrate. Its pickup loop is connected with two input coils, separate for dc (low-frequency) and rf currents. A double-hole washer SQUID is coupled to these coils in a flip-chip configuration to form a magnetometer. The separation of rf and dc current paths in the transformer made it possible to demonstrate the rf SQUID magnetometer operation.

Jakob Flokstra, A. Martínez, Evert Pieter Houwman +4 more