System and method for updating a reading threshold voltage based on symbol transition information
First Claim
1. A method for updating a reading threshold voltage applied to control gates of memory cells in a flash memory device while reading symbols from the flash memory device, the method comprising:
- in response to one or more first host read commands received from a host device, obtaining symbol transition information corresponding to symbol read errors identified while reading data from flash memory cells in the flash memory device in accordance with the one or more first host read commands and the current value of the reading threshold voltage;
determining a reading threshold voltage offset, based at least in part on;
a first factor based on a plurality of probability values determined from the symbol transition information;
a second factor based on a current count of program-erase cycles; and
a third factor based on a word line zone value for a word line zone of the flash memory device containing the flash memory cells from which the data was read in response to the one or more first host read commands;
generating an updated reading threshold voltage, to be applied to the control gates of memory cells in the flash memory device while reading symbols from the flash memory device, in accordance with the reading threshold voltage offset and the current value of the reading threshold voltage; and
in response to one or more second host read commands, different from the one or more first host read commands received from the host device, reading data from the flash memory cells in accordance with the one or more second host read commands and the updated reading threshold voltage.
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Accused Products
Abstract
The various implementations described herein include systems, methods and/or devices that may enhance the reliability with which data can be stored in and read from a memory. The method includes obtaining symbol transition information corresponding to symbol read errors identified while reading data from flash memory cells in a flash memory device. The method further includes determining a reading threshold voltage offset, based at least in part on: a plurality of probability values determined from the symbol transition information; a current count of program-erase cycles; and a word line zone value for a word line zone containing the flash memory cells. Additionally, the method includes generating an updated reading threshold voltage in accordance with the reading threshold voltage offset and the current value of the reading threshold voltage.
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Citations
22 Claims
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1. A method for updating a reading threshold voltage applied to control gates of memory cells in a flash memory device while reading symbols from the flash memory device, the method comprising:
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in response to one or more first host read commands received from a host device, obtaining symbol transition information corresponding to symbol read errors identified while reading data from flash memory cells in the flash memory device in accordance with the one or more first host read commands and the current value of the reading threshold voltage; determining a reading threshold voltage offset, based at least in part on; a first factor based on a plurality of probability values determined from the symbol transition information; a second factor based on a current count of program-erase cycles; and a third factor based on a word line zone value for a word line zone of the flash memory device containing the flash memory cells from which the data was read in response to the one or more first host read commands; generating an updated reading threshold voltage, to be applied to the control gates of memory cells in the flash memory device while reading symbols from the flash memory device, in accordance with the reading threshold voltage offset and the current value of the reading threshold voltage; and in response to one or more second host read commands, different from the one or more first host read commands received from the host device, reading data from the flash memory cells in accordance with the one or more second host read commands and the updated reading threshold voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A controller for updating a reading threshold voltage applied to control gates of memory cells in a flash memory device while reading symbols from the flash memory device, the controller comprising:
a memory controller with interfaces to the flash memory device and a host, configured to; in response to one or more first host read commands received from a host device, obtain symbol transition information corresponding to symbol read errors identified while reading data from flash memory cells in the flash memory device in accordance with the one or more first host read commands and the current value of the reading threshold voltage; determine a reading threshold voltage offset, based at least in part on; a first factor based on a plurality of probability values determined from the symbol transition information; a second factor based on a current count of program-erase cycles; and a third factor based on a word line zone value for a word line zone of the flash memory device containing the flash memory cells from which data was read in response to the first host read commands; generate an updated reading threshold voltage, to be applied to the control gates of memory cells in the flash memory device while reading symbols from the flash memory device, in accordance with the reading threshold voltage offset and the current value of the reading threshold voltage; and in response to one or more second host read commands, different from the one or more first host read commands received from the host device, read data from the flash memory cells in accordance with the one or more second host read commands and the updated reading threshold voltage. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
Specification