Patent ID: 7660152
Filing Date: 2010-02-09
Classification: G11C

Abstract:
1. A method of implementing a self-referencing read operation for a phase change random access memory (PCRAM) array, the method comprising: applying a stimulus to a bit line associated with a selected phase change element (PCE) to be read; comparing a first voltage on a node of the bit line with a second voltage on a delay node, wherein the second voltage on the delay node 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 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 during the read operation, the PCE is determined to be programmed to a crystalline state.