Phase change memory device

摘要

A phase change memory device with memory cells is formed from a phase change memory element and a selection switch. A reference cell is formed from a similar phase change memory element and an associated selection switch and is associated to a group of memory cells to be read. An electrical quantity of the group of memory cells is compared with an analogous electrical quantity of the reference cell, thereby compensating for drift in the properties of the memory cells.

主权项

1. A system comprising:
a memory array comprising a number of phase change memory elements, the number of phase change memory elements arranged in groups with each group being coupled to a respective row line; a number of reference cells each including a reference phase change memory element, each of the number of reference cells being coupled only to a respective one of each of the groups through the respective row line for the group, the number of reference cells each having a substantially same structure to the phase change memory elements within the respective group; and a reading stage and reference column line switches, the system being configured to use the reference column line switches to couple the reading stage to the memory array, the system further configured to activate the reference column line switches in sequence to feed current from one of the number of reference cells coupled to a specific one of the respective row lines during a read operation occurring in the respective row line.