Reading a phase change memory
View Patent ↗A phase change memory cell may be read by driving a current through the cell higher than its threshold current. A voltage derived from the selected column may be utilized to read a selected bit of a phase change memory. The read window or margin may be improved in some embodiments. A refresh cycle may be included at periodic intervals.
1. A system comprising:
a processor; and
a memory including phase change memory cells connected to a bit line and a sense amplifier to sense a triggered cell, said memory including a reference generator connected to said bit line, said reference generator to alter a level from said bit line.
2. A system of claim 1 wherein said cells include a nonprogrammable chalcogenide threshold device.
3. The system of claim 1 wherein said memory includes address lines coupled to said cells and a reference generator coupled to an address line including a cell to be sensed.
4. The system of claim 3 wherein said reference generator to store a reference level on said line.
5. The system of claim 4 wherein said reference generator to reduce the level of a signal from said line.
6. The system of claim 5 wherein the sense amplifier to compare said reduced level signal to the reference level.
7. The system of claim 5 wherein the sense amplifier to compare the signal to the reference after the level of the signal is increased from the reduced level.