Magnetically coupled quantum-flux-latch with wide operation margins

Abstract

We have been developing adiabatic quantum-flux-parametron (AQFP) circuits as an ultra-lowpower superconductor logic for energy-efficient computing. In a previous study, we proposed and demonstrated a quantum-flux-latch (QFL), which is a compact and compatible latch for AQFP logic. The QFL is composed of an AQFP buffer gate and a storage loop, which are directly connected to each other. However, the operation margins were not sufficiently wide due to a trade-off between the operation margins of the storage loop and that of the buffer gate. In this present study, we propose a magnetically coupled QFL (MC-QFL), where the storage loop and the buffer gate are physically separated and magnetically coupled to each other to eliminate the trade-off in the operation margins. The simulation results showed that the critical parameter margin of the MC-QFL is twice as large as that of the previously designed QFL. For comparison, we fabricated and demonstrated both the previously designed QFL and the newly designed MC-QFL. The measurement results showed that the MC-QFL has wider operation margins compared with the previously designed QFL.

A random-access-memory cell based on quantum flux parametron with three control lines

“…However, for the generous use of the advantage of the AQFP circuits, reduction of the energy consumption of the memories is essential. Although flip-flops based on AQFP circuits have been proposed in previous study [15][16][17], their circuit area is not small enough for making high-density large-scale memories. Any RAMs for large-scale memories compatible with AQFP circuits have not been realized yet.…”