PHASE CHANGE MEMORY DEVICE

摘要

A phase change memory device is provided to change a reference voltage according to a change of a bit line clamp voltage, thereby regularly controlling margins of a sensing voltage. A reference voltage controller(100) comprises as follows. A reference current controlling resistance unit(110) controls a sensing current of a reference cell array. A sensing current-to-voltage converter(120) converts an output current of the resistance unit into a second sensing voltage. A reference voltage fine controller outputs a reference control signal corresponding to a change of the second sensing voltage. A reference variable driver variably drives a level of a first reference voltage according to a second reference voltage and a reference control signal.