3:15 PM - 3:30 PM
[6p-S43-8] Digital flux-locked loop system equipped with sub-sampling technique for high-Tc rf-SQUID controlled by magnetic flux modulation
Keywords:high-Tc superconductor, SQUID, digital control
The digital flux-locked loop (FLL) system has been developed for an rf-SQUID to improve the high-frequency noise tolerance and the long-time stability. In this system, the reflected wave from the rf-SQUID is directly input into the analog-digital converter, and the in-phase/quadrature demodulation is carried out in the FPGA chip by means of a sub-sampling technique. In this study, the modulated magnetic flux was applied to the rf-SQUID, and its synchronized signal from the rf-SQUID was used for the feedback control of the FLL. The rf-SQUID was successfully operated with high stability and high noise-tolerance.