Flash Memory Read Voltage Adjustment via Tracking Data Comparison
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Solution Overview
Problem
Non-volatile data storage devices, such as flash memory devices, face errors in reading data due to threshold voltage shifts caused by factors like data retention and program disturb, leading to inaccuracies in retrieving stored information.
Innovation Solution
The system updates read voltages by comparing the count of bits in tracking data stored in the memory to the count of bits in the representation of tracking data read from the memory, allowing for adjustments to be made to the read voltages to compensate for shifted threshold voltages, thereby improving data reading accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If read voltages are used to read data from flash memory cells, then data can be retrieved, but errors occur due to threshold voltage shifts from data retention and program disturb
Solution Approach 1:
The system reads tracking data from memory cells and compares the read values with expected values. Based on this feedback, it determines threshold voltage shifts and adjusts read voltages accordingly to compensate for drift, thereby maintaining accurate data reading despite threshold voltage changes over time
Solution Approach 2:
The system dynamically adjusts read voltage parameters based on detected threshold voltage shifts. By changing the read voltage values in response to measured drift, the system compensates for threshold voltage changes and maintains accurate data retrieval
2Reliability
If error correction coding is used to correct reading errors, then data accuracy improves, but power consumption increases
Solution Approach 1:
The system performs preliminary adjustment of read voltages by tracking threshold voltage shifts and proactively compensating for them. This preliminary correction reduces the need for power-intensive error correction coding during normal operation, as data is read with already-adjusted voltages that account for expected drift
Data Source
AI summary
A method includes reading a representation of tracking data from at least a portion of a non-volatile memory. The method further includes adjusting a read voltage based on a comparison between a number of bits in tracking data as compared to a count of bits in the representation of the tracking data.