Memory Controller Dynamic Read Voltage Adjustment
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Solution Overview
Problem
Current memory controllers face challenges in accurately correcting errors in read data from memory devices, particularly due to changes in threshold voltage distributions of memory cells over time, leading to inefficiencies in read operations.
Innovation Solution
A memory controller is designed with an error corrector, command generator, and read voltage controller that calculates cell difference probabilities and determines optimal read voltages based on cell distribution detection data, adjusting the interval between read voltages to improve data reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed read voltages are used for read operations, then the read operation is simple and fast, but error correction fails when threshold voltage distributions change over time
Solution Approach 1:
The patent implements dynamic read voltage adjustment by detecting cell distribution characteristics and calculating optimal read voltages based on detected threshold voltage distributions. The read voltage controller dynamically modifies read voltages according to detected cell states, transforming the fixed voltage system into an adaptive one that responds to changing memory conditions.
Solution Approach 2:
The system employs feedback mechanisms where cell distribution detection data from previous read operations is fed back to adjust subsequent read voltages. The error corrector's failure signal triggers a feedback loop that detects threshold voltage distributions and recalibrates read voltages, creating a closed-loop control system that continuously optimizes read accuracy.
2Measurement precision
If read voltages are dynamically adjusted based on cell distribution detection, then error correction accuracy improves, but read operation time increases
Solution Approach 1:
The system performs cell distribution detection in advance during idle periods or background operations, preparing detection data before it is needed for actual read operations. By pre-detecting threshold voltage distributions and calculating optimal read voltages beforehand, the system minimizes the time penalty during critical read operations.
Solution Approach 2:
The patent applies partial adjustment by modifying only the necessary read voltages based on detected cell distributions rather than recalculating all parameters. The system adjusts read voltages selectively based on the degree of distribution change, applying minimal necessary corrections to maintain accuracy while reducing processing overhead.
3Reliability
If the number of read voltages is increased to cover threshold voltage variations, then read accuracy improves, but the interval between read voltages becomes smaller and more complex
Solution Approach 1:
The system dynamically changes read voltage parameters (number of voltages and intervals) based on detected cell distribution characteristics. Instead of using a fixed large set of voltages, the system adjusts the number and spacing of read voltages according to the actual threshold voltage distribution width and shape, optimizing the balance between coverage and complexity.
Data Source
AI summary
A memory controller for performing soft decoding according to a Cell Difference Probability (CDP) calculated based on a cell distribution controls a memory device. The memory controller for controlling the memory device, the memory controller comprising: an error corrector configured to correct an error in read data received from the memory device; a command generator configured to output, in response to failing an error correction operation of the error corrector, a cell distribution detection command for detecting threshold voltage distributions of memory cells included in the memory device; and a read voltage controller configured to determine, based on cell distribution detection data that the memory device provides in response to the cell distribution detection command, a number of read voltages for a read operation to be performed in the memory device and an interval between neighboring ones among the read voltages.