For obvious safety reasons, automotive drive-by-wire technology mandates the need for ever increasing reliability levels in automotive electronics. Simultaneously, the ever increasing requirement to reduce costs mandates the use of commercial off-the-shelf semiconductor components in automotive electronic subsystems.
Semiconductor memory is and will continue to be an essential part of automotive electronics subsystems. The amount of semiconductor memory will inevitably grow in quantity, density, speed, and complexity as the requirements and intelligence of automotive electronics increases in future years.
One aspect of semiconductor memory reliability that has been studied intensively is its sensitivity to radiation.
Alpha particle radiation from radioactive contamination found in the packaging materials used in early semiconductor memories was eventually identified as a root cause of serious system failures in early computers. Luckily that issue was identified and mostly resolved well before the intense use of microelectronics in automobiles.
However a 1994 IBM study showed conclusively that the ground level soft error rate (SER) in memory due to cosmic ray induced neutron flux is significant and increases dramatically at higher altitudes such as in Denver (see below)
From these data it can be concluded that semiconductor memory failures induced by cosmic radiation are no longer an "aerospace problem." Such failure mechanisms must be accounted for in automotive electronics systems design. Reliability engineers must have accurate estimates of the sensitivity to radiation for the commercial memory devices they use in their designs. Thus, testing capabilities are required to accurately measure radiation sensitivity in modern memory devices.
The taskDigital locked loop (DLL) to synchronize the internal operation of the memory at its rated speed
Multiple blocks to interleave data for continuous transmission of data without gaps
Latency circuits to control the internal pipeline operations
Logic to generate bursts of either sequential or interleaved addresses from a single external starting address
Word-line and bit-line decoders to select cells in the array
Sense amplifiers to detect the data status during read cycles.
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The figure below shows a block diagram of a classic synchronous dynamic RAM (SDRAM) memory device architecture, whose features include:
Any test program that does not account for the normal operation of each of the above features will underestimate the radiation sensitivity of the memory device.