High-speed operation of demultiplexer up to 56 GHz

A 1-to-4 demultiplexer (DEMUX) was designed based on Single Flux Quantum (SFQ) circuitry and high-speed operation was confirmed using on-chip testing. The circuit was designed with a binary-tree structure to enable high-speed operation. We also investigated timing between clock and data signals in detail. Monte Carlo simulation was applied to vary the design parameters pseudo-randomly and the spread of timing was obtained by circuit simulation. Even if the circuit parameters varied as a result of the fabrication process, proper timing was maintained by optimizing the length of Josephson transmission line. The 1-to-4 DEMUX we fabricated distributed data signals correctly at operating frequencies up to 56 GHz with a bias margin of +7%.