This innovation provides reconfigurable circuitry and 2-Gb of error-corrected or 1-Gb of triple-redundant digital memory in a small package. RTIMS uses circuit stacking of heterogeneous components and radiation shielding technologies. A reprogrammable field-programmable gate array (FPGA), six synchronous dynamic random access memories, linear regulator, and the radiation mitigation circuits are stacked into a module of 42.7×42.7×13 mm. Triple module redundancy, current limiting, configuration scrubbing, and single-event function interrupt detection are employed to mitigate radiation effects. The novel self-scrubbing and single event functional interrupt (SEFI) detection allows a relatively “soft” FPGA to become radiation tolerant without external scrubbing and monitoring hardware.
RTIMS enables significant reductions in the size and mass of mission memory arrays, and is a radiation-tolerant memory suitable for both GEO and LEO space missions through the use of new package-level radiation shielding technology and triple modular redundancy (TMR) FPGA techniques. RTIMS also provides a simplified interface to a large SDRAM (synchronous dynamic random access memory) array with built-in logic for timing reads, writes, and refresh cycles.
Mission flexibility is added by operating the memory array in the TMR architecture with 1 Gb of storage or in an EDAC (Error Detection And Correction) mode where part of the memory is used to detect and correct errors with 2 Gb of storage (corrects single bit errors and detects double bit errors). This allows RTIMS to be used effectively on many types of missions, because it can be configured for the “harshness” of the expected environment. RTIMS enables in-flight reconfigurability by using SRAM (static random access memory)-based FPGA technology.
The design overcomes both hardware and software errors that may be detected after launch during mission operations. This reduces overall mission risk, which is increasingly important as flight system development times and budgets decrease. It also allows RTIMS to adapt to changing mission conditions.
The design increases system reliability by distributing the radiation mitigation structure to each component instead of to a singlepoint failure at the system level. The mitigation techniques significantly simplify system design. RTIMS is well suited for deployment in real-time data processing, reconfigurable computing, and memory-intensive applications.
This work was done by Tak-kwong Ng and Jeffrey A. Herath for Langley Research Center. LAR-17257-1
