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.
Claims21
A method of reading memory cells of a flash memory device, comprising:
- dividing memory cells in the flash memory device into at least two groups;
- selecting particular memory cells according to a threshold voltage distribution;
- detecting and latching data stored in of the selected memory cells corresponding to one of the at least two memory cell groups according to a first read operation;
- detecting and latching data of memory cells corresponding to another of the at least two groups according to a second read operation;
- and
- processing the data detected and latched according to the first read operation through a soft decision algorithm during the process of detecting and latching of the data according to the second read operation.
The method of clam 7 further comprising combining the data outputted based on the first and second read operations, respectively, with the data processed through the soft decision algorithm.
A reading method of a flash memory system, comprising:
- detecting memory cells selected through first read voltages between threshold voltage distributions;
- outputting first data detected from the first read voltages;
- determining whether or not to perform an over-sampling read operation;
- when the over-sampling read operation is selected, performing the over-sampling read operation to detect the selected memory cells through second read voltages within a range of the threshold voltage distributions;
- 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 reading method of a flash memory system, comprising:
- performing a normal read operation to detect memory cells selected by first read voltages defined between threshold voltage distributions,
- latching the detected memory cells as first data;
- performing an over-sampling read operation to detect the selected memory cells by second read voltages within a range of the threshold voltage distributions and latch them as second data;
- outputting the latched first and second data;
- and
- executing a soft decision algorithm with reference to the first and second data;
- and
- determining read data based on an output of said soft decision algorithm.
A memory system comprising:
- a multi-bit flash memory device having a plurality of memory cells, said memory device configured to perform a normal read operation and an over-sampling read operation, said normal read operation configured to detect selected memory cells within said multi-bit flash memory device by using first read voltages defined between threshold voltage distributions, said memory device further configured to output said read voltages as first data, said over-sampling read operation configured to detect the selected memory cells by using second read voltages within a range of the threshold voltage distributions, said second read voltages outputted as second data;
- and
- a memory controller communicating with said multi-bit flash memory device and configured to control said multi-bit flash memory device to selectively perform the over-sampling read operation in response to an outside request during a read operation, wherein said memory controller determines read data through a soft decision algorithm based on the first and second data when the over-sampling read operation is selected.
A memory system comprising:
- a multi-bit flash memory device having a plurality of memory cells, said multi-bit flash memory device configured to perform a normal read operation and an over-sampling read operation, said normal read operation detects selected memory cells from the plurality of memory cells by using first read voltages defined between threshold voltage distributions, said first read voltages outputted as first data, the over-sampling read operation detects the selected memory cells from the plurality of memory cells by using second read voltages within a range of the threshold voltage distributions, said second read voltages outputted as second data;
- and
- a memory controller communicating with said multi-bit flash memory device and configured to determine read data through execution of a soft decision algorithm based on the first and second data.
Dependencies are inferred from the claim text.