Noise Properties of Digital SQUID Using Double Relaxation Oscillation SQUID Comparator With Relaxation Oscillation Resonant Circuit

作者：Myoren Hiroaki^*; Kobayashi Ryota; Kumagai Kenji; Naruse Masato; Taino Tohru

来源：IEEE Transactions on Applied Superconductivity, 2017, 27(4): 1602205.

DOI：10.1109/TASC.2017.2677422

• Digital SQUID
• double relaxation oscillation SQUID
• single flux quantum logic
• SFQ feedback

We designed a digital superconducting quantum interference device (SQUID) system that contains a double relaxation oscillation SQUID (DROS) as a magnetic flux comparator that is connected to an additional relaxation oscillation (RO) circuit with mutually coupled inductances. In the designed digital SQUID, the RO circuit works as a resonator and increases the relaxation oscillation frequency without decreasing the input current of dc/SFQ converters. Numerical simulation shows that the digital SQUID system can operate up to 7 GHz. A fabricated digital SQUID using a DROS comparator with an RO circuit provides correct digital SQUID operation. For a magnetometer using the digital SQUID system, we can realize a magnetic field noise less than 1 pT/root Hz with a small signal bandwidth of more than 10 MHz.

• 出版日期2017-6