Over-sampling read operation for a flash memory device
AssigneeSamsung Electronics Co., Ltd.
InventorDong-Ku Kang
Life of this patent
Estimating the term…
Abstract
A flash memory device and a reading method are provided where memory cells are divided into at least two groups. Memory cells are selected according to a threshold voltage distribution. Data stored in the selected memory cells are detected and the data is latched corresponding to one of the at least two groups according to a first read operation. A second read operation detects and latches data of the memory cells corresponding to another one of the at least two groups. The data is processed through a soft decision algorithm during the second read operation.
Claims16
A read method of a non-volatile memory device including a plurality of memory cells programmed in a first state or a second state, the method comprising:
- detecting the plurality of memory cells via a first read voltage for distinguishing a threshold voltage of the plurality of memory cells between the first state and the second state;
- outputting first data being detected from the plurality of memory cells via the first read voltage;
- determining whether or not to perform an over-sampling read operation based on the first data;
- performing the over-sampling read operation to detect the plurality of memory cells via a second read voltage, wherein the second read voltage is disposed between the first read voltage and a threshold voltage corresponding to a peak point of the first state or the second state;
- outputting second data detected through the over-sampling read operation;
- and
- determining read data through a soft decision algorithm based on the first and second data.
A memory system comprising:
- a non-volatile memory device performing a normal read operation so as to output a first data and an over-sampling read operation so as to output a second data on a plurality of memory cells which are programmed in a first state or a second state;
- and
- a memory controller communicating with the non-volatile memory device and configured to control the non-volatile memory device to selectively perform the over-sampling read operation during a read operation, wherein the memory controller determines read data through a soft decision algorithm based on the first data and the second data when the over-sampling read operation is selected,
- wherein during the normal read operation, the plurality of memory cells are detected via a first read voltage,
- wherein during the over-sampling read operation, the plurality of memory cells are detected via a second read voltage which is disposed between the first read voltage and a threshold voltage corresponding to the peak point of the first state or the second state.
A method for reading a non-volatile memory device, the method comprising:
- performing a normal read operation on a plurality of memory cells via a first read voltage for distinguishing each of threshold voltages of the plurality of memory cells between a first state and a second state;
- performing an over-sampling read operation on the plurality of memory cells via a second read voltage being disposed between the first read voltage and a threshold voltage corresponding to the peak point of the first state or the second state;
- and
- performing a soft decision operation referring to a first read data derived from the normal read operation and a second read data derived from the over-sampling read operation.
A read method of a non-volatile memory device, the method comprising:
- performing a first normal read operation and a first over-sampling read operation on a first plurality of memory cells;
- outputting a first data derived from the first normal read operation in page unit and a second data derived from the first over-sampling read operation in page unit;
- performing a first soft decision operation referring to the first data and the second data read from the first plurality of memory cells;
- during the first soft decision operation, performing a second normal read operation and a second over-sampling read operation on a second plurality of memory cells.
Dependencies are inferred from the claim text.