Performance improvement approach for dependable computing system with optical voting circuit

This paper proposes a new voting method using light that makes possible the realization of a high-performance computing system equipped with both flexibility and dependability. Soft errors inside computers due to terrestrial radiation have become a problem in recent years. We have proposed a highly dependable triple voting-type computing system that can be used even in the strong radiation environment of space. While this system uses reconfigurable SRAM-based FPGA to achieve high flexibility, the system operation speed was limited by synchronization problems in voting circuits located on parallel buses, and by the bottleneck of a limited upper speed for the radiation-tolerant device used in the voting logic circuit. As a result, we study the use of a serial bus, and propose a voting circuit using light that is suitable for a high-speed serial bus. This optical voting circuit is highly compatible with the high-speed serial interfaces provided on recent FPGAs, and is easily configurable using existing optical communications devices. In operations tests using an optical communications module, we obtained voting performance at a 1 Gbit/s communication speed, and estimated that the upper speed limit for the test system is 2.14 Gbit/s. Use of a higher speed optical communication module and circuit optimization should make it possible to achieve even higher speeds. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 90(12): 35–46, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20422