US Patent 11309018 Stable memory cell identification for hardware security

A method includes setting an output of each memory cell in an array of memory cells to a same first value, decreasing power to the array of memory cells and then increasing power to the array of memory cells. Memory cells in the array of memory cells with outputs that switched to a second value different from the first value are then identified in response to decreasing and then increasing the power. A set of memory cells is then selected from the identified memory cells to use in hardware security.