  Superconducting circuits, like Adiabatic Quantum-Flux-Parametron (AQFP),
offer exceptional energy efficiency but face challenges in physical design due
to sophisticated spacing and timing constraints. Current design tools often
neglect the importance of constraint adherence throughout the entire design
flow. In this paper, we propose SuperFlow, a fully-customized RTL-to-GDS design
flow tailored for AQFP devices. SuperFlow leverages a synthesis tool based on
CMOS technology to transform any input RTL netlist to an AQFP-based netlist.
Subsequently, we devise a novel place-and-route procedure that simultaneously
considers wirelength, timing, and routability for AQFP circuits. The process
culminates in the generation of the AQFP circuit layout, followed by a Design
Rule Check (DRC) to identify and rectify any layout violations. Our
experimental results demonstrate that SuperFlow achieves 12.8% wirelength
improvement on average and 12.1% better timing quality compared with previous
state-of-the-art placers for AQFP circuits.
