Wide Range SQUID Amplifier with Proportional Feedback for Flux Quanta Counting Scheme

• Published in: IEEE transactions on applied superconductivity Vol. 30; no. 5; p. 1
• Main Authors: Wang, Yongliang, Xie, Xiaoming, Zhang, Guofeng, Dong, Hui, Zhang, Shulin, Rong, Liangliang, Pei, Yi Feng, Qiu, Longqing, Wu, Jun, Wang, Yong
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.08.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Circuits; Electric potential; Feedback amplifiers; Flux; Flux-quanta counting; Frequency locked loops; Geomagnetic field; Magnetic fields; Magnetic measurement; Measurement errors; Sensors; SQUID readout; SQUIDs; Superconducting quantum interference devices; Transfer functions; Transient analysis; Voltage; Voltage measurement; wide range amplifier
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2020.2976596

To implement a Flux Quanta Counting (FQC) scheme in the wide range magnetic field measurement using Superconducting Quantum Interference Device (SQUID), we present a SQUID Proportional Feedback Amplifier (PFA) circuit. It is a simplified version of the direct readout Flux-Locked Loop (FLL) electronics without integrator. It achieved a periodically repeated (with a period of {1\Phi_{0}} ), quasi-linear flux-to-voltage characteristics with an input range extended to {2\Phi_{0}} . Its working point is reset spontaneously with {1\Phi_{0}} of flux jump caused by the over range flux input. The resultant wide range measurement is achieved by the synthesis of the PFA voltage output and the flux jumps recorded using the FQC scheme. We simulated and experimentally verified the working principles of SQUID PFA. The FQC scheme using SQUID PFA was demonstrated with measurements in both shielded and unshielded environment. SQUID PFA is simple and easy-to-operate suited for applications in the Earth's magnetic field