Non-Volatile Memory Common-Voltage Sensing Across Data States
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Solution Overview
Problem
Existing non-volatile memory systems face challenges in reducing errors during data reading operations, particularly when using the same word line voltage for both program-verify and read operations, which can lead to inaccuracies in sensing different current levels for various data states.
Innovation Solution
Implementing a non-volatile memory system that uses a common word line voltage for both program-verify and read operations, allowing for sensing different current levels in response to the same voltage, thereby reducing errors by ensuring accurate data state detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If different word line voltages are used for program-verify and read operations, then sensing accuracy for different data states is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by designing a single word line voltage structure that serves multiple functions: it is used for both program-verify operations and read operations. The sense amplifiers are designed to be versatile, able to sense different current levels corresponding to multiple data states (0, 1, 2, 3) using the same voltage structure, thereby eliminating the need for separate voltage control circuits for different operations.
Solution Approach 2:
The patent utilizes parameter changes by varying the current level sensing rather than changing the word line voltage. The sense amplifiers detect different current levels (e.g., first current level for data state 0, second current level for data state 1, etc.) while maintaining a common word line voltage structure. This allows the system to distinguish between multiple data states through current level differentiation rather than voltage differentiation.
2Device complexity
If a unified voltage structure is used for program-verify and read operations, then device complexity is reduced, but error rate in data reading increases
Solution Approach 1:
The patent introduces sense amplifiers as intermediary components that bridge the word line voltage structure and the data state detection. These sense amplifiers act as mediators that translate current level differences into detectable signals, enabling accurate data state identification without requiring separate word line voltages. The sense amplifiers compensate for the simplified voltage structure by providing the necessary signal conditioning and differentiation.
Solution Approach 2:
The patent implements feedback mechanisms where the sense amplifiers continuously monitor current levels during both program-verify and read operations. This feedback information is used to determine the data state and can be used to adjust subsequent operations, ensuring high reliability in data reading while maintaining the simplified unified voltage structure.
Data Source
AI summary
A memory system has been described that uses the same word line voltage for verifying and reading multiple (or all) data states such that both program-verify and read operations comprise sensing for different current levels in response to the same word line voltage.