Method and apparatus for improving data integrity using threshold voltage recalibration

1. A method able to recalibrate threshold voltage, comprising:

identifying a reference page storing at a predefined location in a block of a non-volatile (“NV”) memory after receiving a read command;

reading first reference data from the reference page by a reader in response to a first threshold voltage;

generating a first bit error rate (“BER”) based on comparison between the first reference data and a predefined known data pattern;

calculating a second threshold voltage in accordance with the first threshold voltage if the first BER is greater than a predefined BER target; and

setting reference threshold voltage to the second threshold voltage when the second BER is less than the predefined BER target.

2. The method of claim 1 , further comprising:

reading second reference data from the reference page by the reader in response to the second threshold voltage; and

generating a second BER based on comparison between the second reference data and the predefined known data pattern.

3. The method of claim 2 , further comprising calculating a third threshold voltage in accordance with the second threshold voltage if the second BER is greater than the predefined BER target.

4. The method of claim 2 , further comprising setting reference threshold voltage to the second threshold voltage when the second BER is equal to the predefined BER target.

5. The method of claim 2 , further comprising setting reference threshold voltage to the second threshold voltage when the second BER is less than the predefined BER target.

6. The method of claim 1 , further comprising storing the reference page containing a checkerboard data pattern at the predefined location in the block of the NV memory after receiving a command to write the block.

7. The method of claim 1 , wherein identifying the reference page storing at the predefined location in the block of the NV memory includes identifying a first reference page containing checkerboard data pattern from a flash memory based solid state drive (“SSD”).

8. The method of claim 1 , wherein the calculating a second threshold voltage in accordance with the first threshold voltage includes determining a new threshold voltage based on a predefined midpoint voltage incremental process.

9. A method for modifying threshold voltage, comprising:

identifying a data page in a block of a non-volatile (“NV”) memory after receiving a command to read the block;

reading a first predefined set of data from the data page by a reader in response to a first threshold voltage;

generating a first bit error rate (“BER”) based on a predefined direct-current (“DC”) balance coding scheme;

calculating a second threshold voltage in accordance with the first threshold voltage if the first BER is greater than a predefined BER target;

reading a second predefined set of data from the data page by the reader in response to the second threshold voltage; and

generating a second BER based on the predefined DC balance coding scheme.

10. The method of claim 9 , further comprising calculating a third threshold voltage in accordance with the second threshold voltage if the second BER is greater than the predefined BER target.

11. The method of claim 9 , further comprising setting reference threshold voltage to the second threshold voltage when the second BER is equal to the predefined BER target.

12. The method of claim 9 , further comprising setting reference threshold voltage to the second threshold voltage when the second BER is less than the predefined BER target.

13. The method of claim 9 , wherein generating a first BER based on a predefined DC balance coding scheme includes counting one's (1's) and zero's (0's) in the first predefined set of data formatted in a eight(8) bits/ten (10) bits DC balance coding scheme.

14. A method configured to optimize threshold voltage, comprising:

identifying a data page in a block of a non-volatile (“NV”) memory after receiving a command to read the data page;

reading a first data from the data page by a reader in response to a first threshold voltage and counting number of one's (1's) within the first data ;

fetching a counting metadata associated with the data page from the block and identifying an original count from the counting metadata;

generating a first bit error rate (“BER”) based on comparison between the number of 1's in the first data and the original count; and

calculating a second threshold voltage in accordance with the first threshold voltage if the first BER is greater than a predefined BER target.

15. The method of claim 14 , further comprising:

reading a second data from the data page by the reader in response to the second threshold voltage;

counting number of one's (1's) within the second data; and

generating a second BER based on comparison between the number of 1's in the second data and the original count.

16. The method of claim 15 , further comprising calculating a third threshold voltage in accordance with the second threshold voltage if the second BER is greater than the predefined BER target.

17. The method of claim 15 , further comprising setting reference threshold voltage to the second threshold voltage when the second BER is equal to the predefined BER target.

18. The method of claim 15 , further comprising setting reference threshold voltage to the second threshold voltage when the second BER is less than the predefined BER target.