Ternary Memory Fixed-Weight Codewords for Voltage Drift Sensing
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Solution Overview
Problem
Existing memory devices face challenges in maintaining accurate data storage due to threshold voltage drift in ternary memory cells, which affects sensing accuracy, and existing techniques for generating fixed weight codewords for binary memory cells are not compatible with ternary cells.
Innovation Solution
A memory device generates fixed weight codewords by strategically dividing data sets into sub-messages, inverting portions of the codewords based on a coding scheme, and storing them in ternary memory cells to set reference voltages dynamically, allowing for accurate data retrieval despite threshold voltage drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fixed weight codeword techniques are used for binary memory cells, then sensing accuracy is improved, but the technique is not compatible with ternary memory cells
Solution Approach 1:
The patent modifies the codeword generation technique by changing the state distribution parameters from binary (0 or 1) to ternary (0, 1, or 2), creating fixed weight codewords adapted for three-state memory cells while maintaining the sensing accuracy benefits
Solution Approach 2:
The patent divides the data set into sub-messages and generates separate codewords for each sub-message, allowing the fixed weight technique to be applied systematically to ternary memory cells through segmented processing
2Productivity
If ternary memory cells are used to increase storage capacity, then productivity is improved, but threshold voltage drift causes sensing accuracy to deteriorate
Solution Approach 1:
The patent applies fixed weight codeword generation before storing data in ternary memory cells, pre-compensating for threshold voltage drift effects and establishing a reference framework that maintains sensing accuracy throughout the storage process
Solution Approach 2:
The patent uses the fixed weight codewords as reference signals that provide feedback for dynamic reference voltage adjustment, enabling continuous compensation for threshold voltage drift and maintaining accurate state detection
Data Source
AI summary
Methods, systems, and devices for fixed weight codewords for ternary memory cells are described. A memory device may generate a codeword from a set of data bits and invert a portion of the codeword so that the codeword is associated with a target distribution of programmable states. After inverting the portion of the codeword, the memory device store the codeword in a set of ternary cells according to a coding scheme. The memory device may read the codeword from the set of ternary cells and select one or more reference voltages for the set of ternary cells based on the target distribution for the codeword and the states of the ternary cells.