METHOD AND APPARATUS FOR IMPLEMENTING SELF-REFERENCING READ OPERATION FOR PCRAM DEVICES

摘要

A method of implementing a self-referencing read operation for a PCRAM array includes applying a stimulus to a bit line (212) associated with a selected phase change element (PCE) (206) to be read; comparing a first voltage on a node (516) of the bit line with a second voltage on a delay node (518), wherein the second voltage represents a delayed voltage with respect to the first voltage due to a resistance/capacitance time constant associated therewith; and determining whether, during the read operation, the first voltage drops below the value of the second voltage; wherein in the event the first voltage drops below the value of the second voltage during the read operation, the PCE (206) is determined to be programmed to an amorphous state and in the event the first voltage does not drop below the value of the second voltage, the PCE (206) is determined to be programmed to a crystalline state.