Non-volatile memory with improved sensing by reducing source line current
AssigneeSanDisk Technologies LLC
InventorRaul-Adrian Cernea
Life of this patent
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Abstract
One or more sense amplifiers for sensing the conduction current of non-volatile memory is controlled by signals that are timed by a reference sense amplifier having similar characteristics and operating conditions. In one aspect, a sensing period is determined by when the reference sense amplifier sensing a reference current detects an expected state. In another aspect, an integration period for an amplified output is determined by when the reference sense amplifier outputs an expected state. When these determined timings are used to control the one or more sense amplifiers, environment and systemic variations are tracked.
Claims14
In a non-volatile memory device having a plurality of memory cells to be sensed in parallel, each memory cell having a source electrode, and the plurality of memory cells having their source electrodes coupled together into a combined source line, a method of sensing comprising:
- (a) providing a predetermined demarcation current value to discriminate between two memory states;
- (b) sensing the plurality of memory cells in parallel;
- (c) identifying a high-current set of memory cells having conduction currents higher than said predetermined demarcation current value;
- (d) marking the high current set of memory cells;
- (e) inhibiting the conduction currents of the memory cells which have been marked;
- (f) repeating (b) to (e) for a predetermined number of times;
- and
- (g) sensing the plurality of memory cells in parallel in a final pass.
Dependencies are inferred from the claim text.