A method to eliminate the event accumulation problem from a memory affected by multiple bit upsets

Errors caused by radiation are a major problem for memories that have to operate in harsh environments. To evaluate the effects of radiation, memories are normally tested by exposing them to known radiation sources and measuring the number and shape of observed errors. If during the testing, errors accumulate in the memory, some of them can occur on adjacent locations and be interpreted as a multiple bit upset (MBU) instead of several independent events. This error accumulation makes difficult to characterize the number of events and error patterns that have affected the system. This paper presents an analysis of the error accumulation problem that enables the selection of radiation time values which can ensure that the effects of error accumulation are below a predetermined threshold. A method is also proposed to extract the correct error information from data that include a limited amount of error accumulation effects, therefore eliminating the event accumulation problem. Both techniques can be helpful to optimize the radiation testing of memories.