Memory Controller Read Retry Voltage Offset Segmentation
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Solution Overview
Problem
The reliability of memory systems deteriorates due to the widening threshold voltage distribution of memory cells over time, leading to read operation failures and error correction issues, which existing technologies fail to adequately address.
Innovation Solution
A memory system that generates specific read voltages based on initial voltages and offset voltages to perform read operations on multi-bit memory cells, using a state counter to count data bits corresponding to threshold voltage states and extract the number of memory cells in threshold voltage regions, thereby improving data extraction and error handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If read operations are performed using initial read voltages on multi-bit memory cells, then data can be read from the memory cells, but the widening threshold voltage distribution causes read errors and reliability deterioration
Solution Approach 1:
The patent segments the threshold voltage distribution into multiple regions by introducing multiple read voltages (first read voltage and second read voltage) with different offset voltages. Each read voltage targets a specific threshold voltage region, allowing separate counting and analysis of memory cells in different regions. This segmentation enables accurate measurement of the widening threshold voltage distribution while maintaining reliable data reading.
Solution Approach 2:
The patent changes the voltage parameter by applying different offset voltages to generate multiple read voltages from the initial read voltage. By varying the offset voltage, the read voltages are adjusted to match different threshold voltage regions, enabling accurate detection of memory cell states despite threshold voltage widening over time.
2Measurement precision
If multiple read voltages with offset voltages are generated to address threshold voltage distribution, then measurement precision improves, but device complexity increases
Solution Approach 1:
The state counter is designed to perform multiple functions: it counts data bits corresponding to different threshold voltage states and also extracts the number of memory cells in each threshold voltage region by calculating differences between counts. This multi-functionality reduces the need for separate dedicated circuits, thereby limiting the increase in device complexity while achieving precise threshold voltage region detection.
Solution Approach 2:
The patent introduces a state counter as an intermediary component that mediates between the multiple read voltages and the final data output. The state counter processes the data from multiple read operations and extracts threshold voltage distribution information, serving as a bridge that simplifies the overall system architecture while enabling precise measurements.
3Ease of manufacture
If the threshold voltage distribution is allowed to widen naturally over time, then manufacturing simplicity is maintained, but read operation reliability deteriorates
Solution Approach 1:
The patent performs preliminary action by conducting multiple read operations with different offset voltages before final data output. By proactively measuring the threshold voltage distribution and using the state counter to extract accurate information, the system compensates for threshold voltage widening without requiring complex manufacturing processes or additional hardware modifications.
Data Source
AI summary
There are provided a memory system and an operating method thereof. A memory system includes: a plurality of storage regions, each including a plurality of memory cells; and a controller configured to provide a plurality of read retry sets, determine an applying order of the plurality of read retry sets based on characteristics of a read error occurred in a first storage region among the plurality of storage regions, and apply at least one of the read retry sets, based on the applying order, for a read retry operation performed on the first storage region.