Currently, semiconductor integrated circuits are facing challenges related to high integration density and excessive power consumption. As a promising solution, superconducting integrated circuits are attracting attention. Among them, the Adiabatic Quantum-Flux-Parametron (AQFP) circuit is notable for its significantly reduced power consumption due to its adiabatic switching operations.
The Direct-Coupled AQFP (DQFP) circuit is a miniaturized version of the AQFP that eliminates the need for a superconducting transformer, which does not follow scaling laws in future deep-submicron superconducting processes. Our goal is to design large-scale circuits with reduced area by using a specific type of DQFP, called the Dual-rail DQFP (D2QFP). D2QFP employs dual-rail signal lines, which enable efficient logic operation without additional overhead.
In this study, we designed a DQFP demultiplexer (DEMUX) and designed a tree-structured decoder using this DEMUX. The proposed decoder exhibits excellent scalability and demonstrates superior performance compared to conventional AQFP-based decoders, in terms of circuit area and number of Josephson junctions. We also simulated a 4-bit decoder and verified its correct functionality.