Title :
Design and Performance of Digital SQUID with Sub-Flux Quantum Resolution
Author :
Hiroaki Myoren;Kouhei Takatoku;Masato Naruse;Tohru Taino
Author_Institution :
Grad. Sch. of Sci. &
fDate :
7/1/2015 12:00:00 AM
Abstract :
Digital SQUIDs based on the single flux quantum (SFQ) logic have attractive characteristics, such as wide dynamic range and high slew rate. However, the resolution of digital SQUIDs is limited to SFQ. To realize sub-flux quantum resolution for these SQUIDs, we have adopted two types of feedback combinations: one with the SFQ input/output for a main loop and the other with a mutually coupled loop. The main loop receives direct Φ0 feedback and sub-flux quantum feedback Φ0/n, where n is an integer, from the mutually coupled loop. We confirmed the correct operation of our device at a clock frequency of 1.25 GHz for a digital SQUID with a sub-Φ0 flux feedback resolution of Φ0/8 from circuit simulation. The slew rate is found to be 1.56×108 Φ0/s in this simulation (fc=1.25 GHz, n=8). The flux resolution for the digital SQUID shows improvement with increasing n and reached below 40 mΦ0 with n=210; however the slew rate is decreased with increasing n and reached 1.22×106 Φ0/s with fc=1.25 GHz and n=210.
Keywords :
"SQUIDs","Quality of service","Dynamic range","Clocks","Feedback loop","Inductance","Radiation detectors"
Conference_Titel :
Superconductive Electronics Conference (ISEC), 2015 15th International
DOI :
10.1109/ISEC.2015.7383444