Time-dependent compensation currents in non-volatile memory read operations
First Claim
1. A method of reading data from non-volatile storage, comprising:
- reading a first non-volatile storage element of a first string of non-volatile storage elements to determine whether said first non-volatile storage element is programmed to at least one predetermined state;
reading a second non-volatile storage element of a second string of non-volatile storage elements to determine whether said second non-volatile storage element is programmed to said at least one predetermined state;
reading a third non-volatile storage element of a third string of non-volatile storage elements using at least one compensation current and a first sampling period if at least one of said first non-volatile storage element and said second non-volatile storage element is programmed to said at least one predetermined state; and
reading said third non-volatile storage element using a second sampling period if said first non-volatile storage element and said second non-volatile storage element are not programmed to said at least one predetermined state.
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Accused Products
Abstract
Shifts in the apparent charge stored on a floating gate of a non-volatile memory cell can occur because of coupling of an electric field based on the charge stored in adjacent floating gates. The shift in apparent charge can lead to erroneous readings by raising the apparent threshold voltage, and consequently, lowering the sensed conduction current of a memory cell. The read process for a selected memory cell takes into account the state of one or more adjacent memory cells. If an adjacent memory cell is in one or more of a predetermined set of programmed states, a compensation current can be provided to increase the apparent conduction current of the selected memory cell. An initialization voltage is provided to the bit line of the programmed adjacent memory cell to induce a compensation current between the bit line of the programmed adjacent memory cell and the bit line of the selected memory cell.
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Citations
16 Claims
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1. A method of reading data from non-volatile storage, comprising:
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reading a first non-volatile storage element of a first string of non-volatile storage elements to determine whether said first non-volatile storage element is programmed to at least one predetermined state; reading a second non-volatile storage element of a second string of non-volatile storage elements to determine whether said second non-volatile storage element is programmed to said at least one predetermined state; reading a third non-volatile storage element of a third string of non-volatile storage elements using at least one compensation current and a first sampling period if at least one of said first non-volatile storage element and said second non-volatile storage element is programmed to said at least one predetermined state; and reading said third non-volatile storage element using a second sampling period if said first non-volatile storage element and said second non-volatile storage element are not programmed to said at least one predetermined state. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of reading data from non-volatile storage, comprising:
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reading a first non-volatile storage element of a first string of non-volatile storage elements; reading a second non-volatile storage element of a second string of non-volatile storage elements using compensation and a first sampling period if said first non-volatile storage element is programmed to a first predetermined state; reading said second non-volatile storage element using compensation and a second sampling period if said first non-volatile storage element is programmed to a second predetermined state; and reading said second non-volatile storage element using a third sampling period if said first non-volatile storage element is not programmed to said first predetermined state or said second predetermined state. - View Dependent Claims (9, 10, 11)
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12. A method of reading non-volatile storage, comprising:
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determining which non-volatile storage elements of a set of non-volatile storage elements are programmed to at least one predetermined state, said non-volatile storage elements of said set being coupled to a first word line and consecutive bit lines; for each non-volatile storage element determined not to be in said at least one predetermined state and having at least one adjacent non-volatile storage element of the set that is determined to be in said at least one predetermined state, reading said each non-volatile storage element using compensation and a first sampling period; and for each non-volatile storage element determined not to be in said at least one predetermined state and not having at least one adjacent non-volatile storage element in said at least one predetermined state, reading said each non-volatile storage element using a second sampling period. - View Dependent Claims (13, 14, 15, 16)
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Specification