Non-volatile memory (nvm) with dynamically adjusted reference current

A memory system, comprising:

• a non-volatile memory array comprising a plurality of bit cells;
• a sense amplifier coupled to the non-volatile memory array and configured to sense a current from a selected bit cell of the non-volatile memory array and compare the sensed current to a reference current to determine a logic state stored in the selected bit cell;
• and
• a controller coupled to the non-volatile memory array and sense amplifier and configured to:
• perform a program or erase operation on at least a portion of the memory array to change a logic state of at least one bit cell of the portion of the non-volatile memory array;
• determine a number of program or erase pulses applied to the at least one bit cell during the program or erase operation to achieve the change in logic state;
• and
• when the number of program or erase pulses exceeds a pulse count threshold, adjust the reference current of the sense amplifier for a subsequent program or erase operation,
• wherein the pulse count threshold corresponds to a predetermined temperature range.

In a non-volatile memory system, a method comprising:

• performing a program or erase operation by applying program or erase pulses to a memory cell until the memory cell achieves a target logic state, wherein after each program or erase pulse, a verify is performed to determine whether the target logic state has been achieved, wherein performing the verify includes providing a verify reference current to a sense amplifier for comparison with a sensed current from the memory cell at a verify gate voltage to determine whether the target logic state has been achieved;
• comparing a number of program or erase pulses applied to the memory cell to achieve the target logic state to a threshold value;
• when the number of program or erase pulses exceeds the threshold value, adjusting the verify reference current;
• performing a subsequent program or erase operation to achieve the target logic state, wherein verification during the subsequent program or erase operation includes providing the adjusted verify reference current to the sense amplifier for comparison with the sensed current from the memory cell at the verify gate voltage;
• sensing a temperature of the non-volatile memory system;
• and
• obtaining the threshold value from storage circuitry based on the sensed temperature, wherein the threshold value corresponds to a predetermined temperature range which includes the sensed temperature.

A memory system, comprising:

• a non-volatile memory array comprising a plurality of bit cells;
• and
• a controller coupled to the non-volatile memory array and configured to:
• determine whether at least one of programming performance or erasing performance of the non-volatile memory array has degraded beyond a corresponding degradation threshold;
• and
• when the at least one of the programming performance or erasing performance of the non-volatile memory array has degraded beyond the corresponding degradation threshold, adjusting a verify reference current that is provided to a sense amplifier during a program verification or an erase verification, wherein the controller is configured to determine a number of erase pulses required to erase a first bit cell of the plurality of bit cells and determine a number of program pulses required to program a second bit cell of the plurality of bit cells, wherein the controller is configured to determine whether at least one of the programming or erasing performance has degraded beyond the corresponding degradation threshold based on at least one of the number of erase pulses or the number of program pulses.