NONVOLATILE MEMORY DEVICES, MEMORY SYSTEMS AND METHODS OF PERFORMING READ OPERATIONS
First Claim
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1. A method of operating a non-volatile memory device, comprising:
- during a read operation directed to a nonvolatile memory cell having a positive threshold voltage and being connected between a selected word line and a selected bit line, applying a positive read voltage to the selected word line and a first control signal to a page buffer connected to the selected bit line, wherein the first control signal defines a first read operation interval comprising a first discharge interval, a first pre-charge interval, a first developing interval, and a first sensing interval; and
during a read operation directed to the memory cell having a negative threshold voltage, applying a negative read voltage to the selected word line and a second control signal to the page buffer different from the first control signal, wherein the second control signal defines a second read operation interval longer in duration than the first read operation interval and comprising a second discharge interval, a second pre-charge interval, a second developing interval, and a second sensing interval.
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Abstract
Within a non-volatile memory device, a read operation directed to a nonvolatile memory cell having a positive threshold voltage applies a positive read voltage to a selected word line and a first control signal to a page buffer connected to a selected bit line, but if the memory cell has a negative threshold voltage the read operation applies a negative read voltage to the selected word line and a second control signal to the page buffer different from the first control signal.
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Citations
21 Claims
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1. A method of operating a non-volatile memory device, comprising:
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during a read operation directed to a nonvolatile memory cell having a positive threshold voltage and being connected between a selected word line and a selected bit line, applying a positive read voltage to the selected word line and a first control signal to a page buffer connected to the selected bit line, wherein the first control signal defines a first read operation interval comprising a first discharge interval, a first pre-charge interval, a first developing interval, and a first sensing interval; and during a read operation directed to the memory cell having a negative threshold voltage, applying a negative read voltage to the selected word line and a second control signal to the page buffer different from the first control signal, wherein the second control signal defines a second read operation interval longer in duration than the first read operation interval and comprising a second discharge interval, a second pre-charge interval, a second developing interval, and a second sensing interval. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method of operating a non-volatile memory device, comprising:
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during a read operation directed to a memory cell connected between a selected word line and a selected bit line and applying a positive read voltage to the selected word line, applying a bit line voltage to the selected bit line at a first time relative to a time at which the positive read voltage is applied to the selected word line; and during a read operation directed to the memory cell and applying a negative read voltage to the selected word line, applying the bit line voltage to the selected bit line at a second time later than the first time, such that application of the bit line voltage occurs during an interval wherein the negative read voltage is transitioning from an initial word line voltage to a negative target voltage. - View Dependent Claims (17)
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18. A method of reading data stored in a non-volatile memory cell according to a defined threshold voltage distribution, the memory cell being connected between a selected word line and a selected bit line and the method comprising:
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determining whether the threshold voltage distribution is positive or negative; if the threshold voltage distribution is positive, applying a positive read voltage to the selected word line during a first read operation interval including a first discharge interval, a first pre-charge interval, a first developing interval, and a first sensing interval; and if the threshold voltage is negative, applying a negative read voltage to the selected word line during a second read operation interval different from the first read operation interval and including a second discharge interval, a second pre-charge interval, a second developing interval, and a second sensing interval. - View Dependent Claims (19, 20)
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21-33. -33. (canceled)
Specification