Radiation-Hard Field-Programmable Gate Arrays Configuration Technique Using Silicon on Sapphire

Once largely the domain of space-borne applications, the effects of high energy charged particles on electronics systems are now also a concern for conventional terrestrial devices. The configuration memory within reconfigurable components, such as SRAM-based field-programmable gate arrays are particularly vulnerable to radiation-induced single event effects. We present a silicon on insulator (SOI)-based configuration memory system for use in a radiation hard reconfigurable system. A nonvolatile storage cell, able to be manufactured in a standard single polysilicon SOI CMOS process with no special layers, is combined with a Schmitt amplifier, which results in a final structure that exhibits two unique characteristics enhancing its resistance to radiation. First, it is impossible for a radiation-induced event to permanently flip the configuration state. Second, a partial de-programming resulting in a reduction in the magnitude of the storage cell voltage causes a large change in static current that can very easily be detected using a conventional sense amplifier. A simple current detector of the type used in conventional RAM circuits allows the configuration memory to be set up to exhibit self-correcting, or “auto-scrubbing” behavior. Failure estimates indicate a mean time between failures for a single cell to be in the order of 10³⁴ years.