Memory Controller Read-Voltage Screening for NAND Data Retention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing memory technologies face challenges in efficiently determining and addressing data retention states in NAND-type memory devices, leading to bit flipping and data loss due to electron escape and read disturb issues, which are not effectively managed by current error correction methods like LDPC, resulting in high read errors and inefficient data scrub processes.
Innovation Solution
A memory controller and system that utilize a first read voltage to determine data retention states by counting bits flipped and successfully read bits, comparing these results to preset thresholds, enabling quick data migration without complex decoding processes, thus reducing power consumption and I/O transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex decoding processes like LDPC are used to correct read errors, then data reliability is improved, but processing time and power consumption increase
Solution Approach 1:
The patent performs preliminary read operations at multiple voltage levels (first read voltage and second read voltage) before determining data retention state. By pre-obtaining statistical results from these preliminary reads, the system can quickly determine whether data migration is needed without performing complex decoding processes, thus reducing processing time while maintaining reliability
Solution Approach 2:
The patent replaces complex software-based decoding mechanisms (like LDPC) with a simpler hardware-based statistical comparison approach. Instead of using complex error correction algorithms, the system uses statistical results from preliminary reads and compares them against thresholds to determine data retention state, substituting complex computational mechanics with simpler statistical mechanics
2Reliability
If traditional error correction methods are used, then data integrity is maintained, but power consumption increases
Solution Approach 1:
The patent performs partial read operations only at specific voltage levels (first read voltage greater than mean threshold voltage of intermediate state, and second read voltage within preset voltage difference) rather than performing complete decoding. This partial action approach maintains data integrity assessment while significantly reducing power consumption compared to full LDPC decoding
Solution Approach 2:
The patent substitutes power-intensive LDPC decoding with low-power statistical comparison. By using hardware-based statistical result comparison against preset thresholds, the system maintains data integrity determination with minimal power consumption, replacing complex computational energy consumption with simple comparison logic
3Reliability
If comprehensive data scrubbing is performed to address data retention issues, then data reliability is improved, but I/O transmission and processing complexity increase
Solution Approach 1:
The patent segments the data scrubbing process into distinct phases: first obtaining statistical results at a first read voltage (greater than mean threshold voltage of intermediate state), then obtaining results at a second read voltage (within preset voltage difference). This segmentation allows systematic analysis of data retention at different voltage levels, improving reliability assessment while managing processing complexity through structured approach
Solution Approach 2:
The patent performs preliminary statistical result collection at multiple voltage levels before making data retention determinations. By pre-obtaining and storing these statistical results, the system can later quickly compare against thresholds without reperforming complex analyses, reducing overall processing complexity while maintaining comprehensive data reliability checking
Data Source
AI summary
Memory controllers, devices, systems, operating methods thereof, and storage media are provided. In one aspect, a memory controller includes a processor configured to: obtains a statistical result of a physical page corresponding to a first read voltage. The statistical result includes at least one of a first number of bits flipped between two read results of the physical page corresponding to the first read voltage and a read voltage having a voltage difference of less than a preset voltage with the first read voltage, or a second number of bits of the physical page successfully read using the first read voltage. The first read voltage is greater than a mean value of a threshold voltage interval corresponding to an intermediate storage state of the physical page. The process is further configured to determine a data retention state of the physical page according to the statistical result.