Temperature-Dependent Refresh Reads for NAND Memory Error Control
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Solution Overview
Problem
Conventional non-volatile memory systems face higher error rates and increased power consumption during the first read operation due to temperature variations, which are not adequately addressed by fixed refresh read rates.
Innovation Solution
Implementing a temperature-dependent refresh read rate to optimize power consumption by adjusting refresh read times based on current temperature, using control circuitry to determine and apply appropriate refresh rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed refresh read rate is used, then the memory device structure remains simple, but power consumption increases and error rates rise due to temperature variations
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed refresh read rate to a variable refresh read rate that adapts to temperature conditions. The control circuitry dynamically adjusts the refresh read rate based on temperature sensor feedback, increasing the rate at higher temperatures and decreasing it at lower temperatures, thereby optimizing power consumption across varying thermal environments
Solution Approach 2:
The patent changes the parameter of refresh read rate from a fixed value to a temperature-dependent variable. By modifying this critical parameter based on temperature conditions, the system achieves lower power consumption and reduced error rates without requiring complex additional hardware structures
2Device complexity
If a fixed refresh read rate is used, then the control circuitry remains simple, but error rates increase due to temperature variations
Solution Approach 1:
The patent implements feedback by incorporating a temperature sensor that continuously monitors the memory device temperature and provides input to the control circuitry. This feedback loop enables the system to detect temperature changes and adjust the refresh read rate accordingly, reducing error rates caused by thermal variations without requiring overly complex control structures
Solution Approach 2:
The system dynamically adjusts the refresh read rate based on real-time temperature conditions, transitioning from a static fixed rate to an adaptive variable rate that responds to thermal environment changes, thereby improving reliability across different temperature ranges
3Reliability
If a faster refresh read rate is used, then error rates decrease, but power consumption increases
Solution Approach 1:
The patent changes the refresh read rate parameter dynamically based on temperature conditions rather than using a constant high rate. At higher temperatures, the rate increases to maintain low error rates, while at lower temperatures, the rate decreases to reduce power consumption, achieving an optimal balance between reliability and energy efficiency
Solution Approach 2:
The system dynamically adjusts the refresh read rate according to thermal conditions, avoiding the need to maintain a constantly high rate. This dynamic adaptation allows the system to achieve low error rates when necessary while minimizing power consumption during stable, cooler conditions
Data Source
AI summary
Systems and methods for effecting a temperature dependent refresh read rate of a read operation of a block or sub-block of memory cells in a NAND string. The method includes initiating a refresh read cycle, determining a current temperature of the non-volatile memory device, and determining a refresh read rate corresponding to the current temperature. The refresh read is performed. The method further includes implementing a delay of a defined time period after the refresh read is performed, wherein the defined time period is based on the determined refresh read rate. If a new command is received before the delay has ended then the new command is performed, and if the delay has ended without a new command having been received then the method returns to the step of determining the current temperature.