Adaptive reference cells for a memory device

摘要

A memory device is provided with reference cells that can be adapted to the core cells of the memory device. An erase verify reference cell. is adapted to the core cells by changing the threshold voltage of the erase verify reference cell until substantially all the core cells pass an erase verification test. A program verify reference cell is then setup by changing the threshold voltage of the program reference cell by a desired change in voltage between erased and programmed states. A read reference cell is also setup by changing the threshold voltage of the read reference cell so that it is intermediate of the erase verify reference cell and the program verify reference cell.