Characterization of an On-Chip Magnetic Shielding Technique for Improving SFQ Circuit Performance

An on-chip magnetic shielding technique was characterized on several DC-SQUIDs to prepare the next generation of complex digital RSFQ circuits designed by the FLUXONICS foundry. The maximal frequency of operation of a toggle flip-flop cell was used as a criteria to validate the concept. It goes from...

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Bibliographic Details
Published in:IEEE transactions on applied superconductivity 2016-04, Vol.26 (3), p.1-5
Main Authors: Collot, R., Febvre, P., Kunert, J., Meyer, H.-G, Stolz, R., Issler, J. L.
Format: Article
Language:English
Subjects:
Computer architecture
Engineering Sciences
Integrated circuit modeling
Josephson junctions
Magnetic fields
Magnetic flux
Magnetic shielding
Micro and nanotechnologies
Microelectronics
Microprocessors
Rapid single flux quantum
RSFQ
SQUID
superconducting electronics
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Summary:An on-chip magnetic shielding technique was characterized on several DC-SQUIDs to prepare the next generation of complex digital RSFQ circuits designed by the FLUXONICS foundry. The maximal frequency of operation of a toggle flip-flop cell was used as a criteria to validate the concept. It goes from a simulated value of 52 GHz (46 ± 2 GHz experimentally), for a McCumber parameter β c = 1 with J C = 1 kA/cm2 in the absence of external magnetic field, down to 29 GHz in the presence of an external field of 88 μT. The shielding technique consists of surrounding a circuit by one or several superconducting niobium loops with the same layers as for the SFQ circuit. The loops are connected to the ground plane with vias. It is shown experimentally that the local magnetic field is reduced by a factor of 4 for the best shielded configuration, which limits the reduction of the maximal frequency of operation in presence of external magnetic field.
ISSN:1051-8223
1558-2515
DOI:10.1109/TASC.2016.2542117