Phase change memory having temperature budget sensor

A memory comprising:

• an array of phase change memory cells;
• a temperature budget sensor for detecting a temperature budget based on an integration of a temperature of the array over time, the temperature budget sensor including a phase change material in a partially crystalline and partially amorphous state and adapted to be initialized by slightly setting the phase change material;
• and
• a circuit for periodically comparing a signal from the phase change material of the temperature budget sensor to a reference signal and refreshing the array of phase change memory cells based on the comparison.

A memory device comprising:

• an array of phase change memory cells;
• means for monitoring a temperature budget of the array of memory cells based on an integration of a temperature of the array over time, the means for monitoring comprising a phase change material;
• means for initializing the means for monitoring by slightly setting the phase change material;
• and
• means for refreshing the array of memory cells in response to the temperature budget exceeding a predefined threshold.

A method for operating a resistive memory, the method comprising:

• resetting a phase change material of a temperature budget sensor;
• slightly setting the phase change material of the temperature budget sensor to initialize the temperature budget sensor;
• and
• monitoring, by the temperature budget sensor, a temperature budget of the resistive memory based on an integration of a temperature of the resistive memory over time.

A method for operating a memory, the method comprising:

• setting a phase change memory cell to a partially crystalline and partially amorphous state;
• periodically comparing a signal from the memory cell to a reference signal, the signal from the memory cell indicating a temperature budget of the memory based on an integration of a temperature of the memory over time;
• and
• refreshing a plurality of phase change memory cells storing data in response to the comparison,
• wherein setting the phase change memory cell to the partially crystalline and partially amorphous state comprises fully resetting the memory cell and then slightly setting the memory cell.

A method for operating a memory, the method comprising:

• setting a phase change memory cell to a partially crystalline and partially amorphous state;
• periodically comparing a signal from the memory cell to a reference signal, the signal from the memory cell indicating a temperature budget of the memory based on an integration of a temperature of the memory over time;
• and
• refreshing a plurality of phase change memory cells storing data in response to the comparison,
• wherein setting the phase change memory cell to the partially crystalline and partially amorphous state comprises partially resetting the memory cell.

A resistive memory device comprising:

• a plurality of resistive memory cells;
• a temperature budget sensor for detecting a temperature budget based on an integration of a temperature of the resistive memory device over time, the temperature budget sensor comprising a phase change material and adapted to be initialized by slightly setting the phase change material;
• and
• a circuit for periodically comparing a signal from the temperature budget sensor to a reference signal and refreshing the resistive memory cells based on the comparison.