Memory Die Temperature Compensation Across Program-Erase Cycles
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Solution Overview
Problem
Conventional memory sub-systems face challenges in accurately compensating for temperature variations across program erase cycles, leading to increased raw bit error rates due to inadequate temperature compensation values, which are not effectively updated to account for die-to-die variations and result in a large lookup table size.
Innovation Solution
A memory sub-system that generates and updates a fitting equation using slope and intercept parameters to determine temperature compensation values, reducing the size of the lookup table and accounting for die-to-die variations by periodically optimizing these parameters based on measured cross-temperature values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional temperature compensation methods are used with fixed lookup tables, then the implementation is simple, but the lookup table size becomes large and memory consumption increases
Solution Approach 1:
The patent transforms the fixed lookup table approach into a dynamic parameter-based system. Instead of storing comprehensive temperature compensation values for all conditions, the system uses a fitting equation with parameters (slope, intercept, curvature) that are periodically updated based on measured cross-temperature values. This reduces memory consumption while maintaining compensation accuracy across varying program-erase cycles and temperature conditions.
Solution Approach 2:
The patent introduces dynamic updating of compensation parameters through periodic optimization. The fitting equation parameters are not static but are periodically refined based on actual measured cross-temperature values from the memory die. This dynamic adaptation allows the system to maintain accuracy over time and across different operational conditions without requiring a large static lookup table.
2Stability of the object's composition
If temperature compensation values are not updated across program erase cycles, then the system operation is stable, but bit error rates increase due to die-to-die variations
Solution Approach 1:
The patent implements a feedback mechanism where cross-temperature values are periodically measured and used to optimize the fitting equation parameters. This closed-loop approach allows the system to adapt to die-to-die variations and drift in temperature characteristics over time, maintaining reliability without compromising operational stability. The periodic updates ensure the compensation remains accurate while the system continues to operate stably between updates.
3Measurement precision
If a large lookup table is used to account for all temperature and program erase cycle conditions, then temperature compensation accuracy is improved, but memory footprint increases
Solution Approach 1:
The patent replaces the large lookup table with a compact fitting equation model that uses a small number of parameters (slope, intercept, curvature). These parameters capture the essential temperature compensation behavior across all conditions. By periodically updating these parameters based on measured cross-temperature values, the system maintains high compensation accuracy while using minimal memory resources compared to a comprehensive lookup table.
Solution Approach 2:
The patent extracts the essential temperature compensation characteristics from complex multi-dimensional data (temperature × program-erase cycles) and represents them through a simplified fitting equation with a few key parameters. This extraction process captures the dominant compensation behavior while eliminating the need to store all possible condition combinations, dramatically reducing memory footprint while preserving accuracy.
Data Source
AI summary
A first analysis of each respective die of a multi-die memory device is performed. An equation to determine a respective temperature compensation (tempco) value for each respective die based on a number of program erase cycles (PECs) of the respective die based on the first analysis s determined. The equation for use in processing memory access requests directed to the respective die is stored. Whether to update the equation directed to the respective die based on a second analysis of the respective die is determined.