Enhanced voltage swing of rapid-single-flux-quantum distributed output amplifier equipped with double-stack superconducting quantum interference devices

Yoshinao Mizugaki; Komei Higuchi; Hiroshi Shimada

doi:10.1587/elex.16.20190331

This article has now been updated. Please use the final version.

Enhanced voltage swing of rapid-single-flux-quantum distributed output amplifier equipped with double-stack superconducting quantum interference devices

Yoshinao Mizugaki, Komei Higuchi, Hiroshi Shimada

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Keywords: Superconducting integrated circuits, single flux quantum, Josephson effects, niobium, cryogenic electronics

JOURNAL FREE ACCESS Advance online publication

Article ID: 16.20190331

DOI https://doi.org/10.1587/elex.16.20190331

The final version of this article is now available: Vol. 16 (2019), No. 14 pp. 20190331-20190331

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Abstract

We report the enhanced voltage swing of a rapid-single-flux-quantum (RSFQ) distributed amplifier by replacing a single superconducting quantum interference device (SQUID) with a double-stack-SQUID (DSS). A DSS is composed of two stacked 2-junction SQUIDs sharing one sensing inductor. Thanks to its stack structure, a DSS is expected to generate twofold output voltage. We have designed a 12-stage RSFQ distributed amplifier equipped with DSSs. The maximum output voltage swing reached 10.2 mV in simulation. Test chips were fabricated using a 25-μA/μm² Nb integration process. In measurements, a test chip was cooled in a liquid helium bath. The experimental output voltage swing was up to 8.34 mV.

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