IEICE Transactions on Electronics
Online ISSN : 1745-1353
Print ISSN : 0916-8524
Special Section on Leading-Edge Technology of Superconductor Large-Scale Integrated Circuits
High-Speed Operation of 0.25-mV RSFQ Arithmetic Logic Unit Based on 10-kA/cm2 Nb Process Technology
Masamitsu TANAKAAtsushi KITAYAMAMasakazu OKADATomohito KOUKETSUTakumi TAKINAMIMasato ITOAkira FUJIMAKI
Author information
JOURNALS RESTRICTED ACCESS

2014 Volume E97.C Issue 3 Pages 166-172

Details
Abstract

We report the successful operation of a low-power arithmetic logic unit (ALU) based on a low-voltage rapid single-flux-quantum (LV-RSFQ) logic circuit, whereby a dc bias current is fed to circuits from lowered constant-voltage sources through small resistors. Both the static and dynamic energy consumptions are reduced because of the reduction in the amplitudes of voltage pulses across the Josephson junctions, with a trade-off of slightly slower switching speeds. The designed bias voltage was set to 0.25mV, which is one-tenth that of our standard RSFQ circuit design. We investigated several issues related to such low-voltage operation, including margins and timing design. To achieve successful operation, we tuned the circuit parameters in the logic gate design and carefully controlled the timing by considering the interference of pulse signals. We show test results for the low-voltage ALU in on-chip high-speed testing. The circuit was fabricated using the AIST Nb/AlOx/Nb Advanced Process with a critical current density of 10kA/cm2. We verified that arithmetic and logical operations were correctly implemented and obtained dc bias margins of 18% at a target clock frequency of 20GHz and achieved a maximum clock frequency of 28GHz with a power consumption of 28µW. These experimental results indicate energy efficiency of 3.6 times that of the standard RSFQ circuit design.

Information related to the author
© 2014 The Institute of Electronics, Information and Communication Engineers
Previous article Next article
feedback
Top