Adaptive Read Voltage Tracking for Charge Leakage Mitigation
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Solution Overview
Problem
Solid-state storage devices face data errors due to charge leakage, which shifts read voltage levels over time, affecting the accuracy of data retrieval and requiring improved adaptive reference voltage tracking techniques to mitigate these effects.
Innovation Solution
Implementing adaptive read reference voltage tracking techniques that account for charge leakage by determining and applying reference voltage offsets or waiting for charge leakage to settle, ensuring accurate data retrieval by adjusting read reference voltages based on shifts over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If adaptive reference voltage tracking is performed immediately after programming, then productivity is improved by reducing wait time, but measurement precision deteriorates due to charge leakage affecting voltage readings
Solution Approach 1:
The patent applies preliminary action by implementing a settling time delay after programming before performing adaptive reference voltage tracking. This allows charge leakage to stabilize first, ensuring accurate voltage measurements without sacrificing too much productivity. The controller waits for a predetermined settling time period, then performs the tracking algorithm to determine updated reference voltages based on the stabilized charge distribution.
2Measurement precision
If charge leakage settling time is extended, then measurement precision improves by allowing charge stabilization, but productivity deteriorates due to increased wait time
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the settling time period based on different programming conditions, memory cell types, and temperature ranges. Rather than using a fixed delay, the controller modifies the settling time parameter to optimize the balance between charge stabilization accuracy and data retrieval efficiency for different operational scenarios.
Solution Approach 2:
The patent implements dynamics by making the settling time adaptive rather than static. The controller dynamically determines the appropriate settling duration based on real-time conditions, allowing the system to respond optimally to varying charge leakage characteristics while maintaining high productivity when conditions permit shorter waits.
3Reliability
If read reference voltages are adjusted frequently to track channel variations, then reliability improves by maintaining data accuracy, but device complexity increases due to additional tracking operations
Solution Approach 1:
The patent applies feedback by implementing an adaptive tracking algorithm that continuously monitors read operations and uses the results to adjust reference voltages. The system performs tracking reads, analyzes the distribution of read values, and updates reference voltages based on this feedback to maintain optimal data retrieval accuracy while avoiding excessive adjustments.
Data Source
AI summary
Adaptive read reference voltage tracking techniques are provided that employ charge leakage mitigation. An exemplary device for use with multi-level memory cells, comprises a controller configured to: after a predefined time interval that approximates a settling time after a programming of the multi-level memory cells until a charge leakage of one or more of the multi-level memory cells has settled, determine a plurality of read reference voltages for the multi-level memory cells using a post-programming adaptive tracking algorithm; and employ the plurality of read reference voltages to read data from the multi-level memory cells. The reference voltage offsets are optionally determined based on a shift in the read reference voltages after the predefined time interval since the programming of the multi-level memory cells.