Configuration Memory Scrubbing of SRAM-Based FPGAs Using a Mixed 2-D Coding Technique

SRAM-based field-programmable gate array (FPGA) vendors typically integrate error correction codes (ECCs) into the configuration memory to assist designers in implementing scrubbing mechanisms. In most cases, these ECC schemes guarantee the correction of single- and double-bit errors per configuration frame but fail to correct upsets with higher multiplicity in a single frame caused by a single event. This phenomenon has been observed in modern commercial-off-the-shelf FPGAs. Bit interleaving schemes are used in some FPGA families to scatter the multiple upsets into more than one frame, but this does not fully resolve the problem of uncorrectable errors. In this article, we propose a configuration memory scrubbing approach for SRAM-based FPGA devices, which combines the embedded ECC logic with an interframe, interleaved parity code to build a mixed 2-D coding technique. The proposed technique improves the multiple-bit error correction capabilities of the on-chip ECC scheme while keeping the error correction latency and hardware cost low. The scrubbing concept has been validated under heavy-ion irradiation, where it succeeded in correcting all the single and multiple upsets observed during the radiation experiment.