Automated Passive-Transmission-Line Routing Tool for Single-Flux-Quantum Circuits Based on A* Algorithm

Masamitsu TANAKA  Koji OBATA  Yuki ITO  Shota TAKESHIMA  Motoki SATO  Kazuyoshi TAKAGI  Naofumi TAKAGI  Hiroyuki AKAIKE  Akira FUJIMAKI  

IEICE TRANSACTIONS on Electronics   Vol.E93-C   No.4   pp.435-439
Publication Date: 2010/04/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E93.C.435
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Frontiers of Superconductive Electronics)
Category: Digital Applications
single-flux-quantum circuit,  computer-aided design,  wire router,  passive transmission line,  

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We demonstrated an automated passive-transmission-line routing tool for single-flux-quantum (SFQ) circuits. The tool is based on the A* algorithm, which is widely used in CMOS LSI design, and tuned for microstrip/strip lines formed in the SRL 4-Nb layer structure. In large-scale SFQ circuits with 10000-20000 Josephson junctions, such as microprocessors, 80-90% of the wires can be automatically routed in about ten minutes. We verified correct operation above 40 GHz for an automatically routed 44 switch circuit from on-chip high-speed tests. The resulting circuit size and operating frequency were comparable to those of a manually designed result. We believe that the tool is useful for large-scale SFQ circuit design using conventional fabrication processes.