Design considerations for a radiation hardened nonvolatile memory

摘要

The SA3823 64K EEPROM was developed for both weapon and space applications. The circuit was designed for fabrication in a CMOS /SNOS (Complementary Metal Oxide Semiconductor/Silicon Nitride Oxide Semiconductor) process since this process offers maximum radiation hardness for nonvolatile circuits. Specific aspects of the circuit design were influenced by each of the radiation environments of concern. Total dose radiation effects were a factor in the memory cell and sense amplifier designs. Power distribution to the various latches was designed to tolerate the photocurrents generated during a transient radiation pulse. Single event upset (SEU) concerns were accounted for in the design of the latches and the control logic. The SA3823 is a 8K x 8 bit EEPROM which is partitioned into 128 pages with 64 bytes in each page. Data is programmed into the memory one page at a time. Writing data into the memory is a two step process: loading 64 bytes into the data-in latches and then programming the latched data into a page of the memory.