Dynamic Read Time Adjustment for NAND Flash Memory
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The increasing bit-line capacitance in NAND flash memory devices due to smaller geometries leads to longer read times, causing bit flips and reducing data access efficiency, as sense amplifiers become more sensitive to voltage differentials, necessitating longer read times to accurately convert analog charge levels to digital values.
Innovation Solution
Implementing a tunable read time (tREAD) mechanism that allows adjustment based on performance parameters such as raw bit error rate (RBER) and error correction code (ECC) capabilities, enabling proactive or reactive changes to read time to maintain data accuracy and speed, independent of hardware design, through protocols like early status, stage duration, and status disregard.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sense amplifiers are made more sensitive to distinguish small voltage differentials, then measurement precision is improved, but read time increases
Solution Approach 1:
The patent implements dynamic read time adjustment by monitoring raw bit error rate (RBER) and program/erase cycle counts, then proactively or reactively changing the read time parameter. This allows the system to adapt read time based on actual device conditions rather than using a fixed conservative value, thereby reducing unnecessary wait time while maintaining data accuracy.
Solution Approach 2:
The system changes the read time parameter based on monitored performance metrics. By adjusting this critical parameter dynamically, the patent resolves the contradiction between maintaining precise voltage differential detection and minimizing read time, allowing the system to operate efficiently at different stages of the device lifecycle.
2Manufacturing precision
If smaller cell geometries are used, then manufacturing precision is improved, but bit-line capacitance increases causing more bit flips
Solution Approach 1:
The patent implements proactive adjustment by monitoring program/erase cycle counts and predicting when RBER will increase due to smaller geometry effects. Before bit flips actually occur, the system adjusts read time or triggers ECC processing to prevent data corruption, rather than waiting for errors to manifest.
Solution Approach 2:
The system continuously monitors RBER and uses this feedback to adjust read parameters and trigger ECC processing when necessary. This closed-loop feedback mechanism allows the system to maintain data reliability despite the increased bit-line capacitance from smaller geometries.
3Reliability
If read time is increased to compensate for smaller geometries, then reliability is improved, but productivity deteriorates
Solution Approach 1:
The patent makes read time a dynamic parameter that adjusts based on monitored RBER and device age. Instead of always using the conservative long read time required for small geometries, the system uses shorter read times when conditions permit, thereby maintaining productivity while ensuring reliability when needed.
Solution Approach 2:
By changing the read time parameter based on monitored performance metrics and device lifecycle stage, the patent resolves the contradiction between reliability and productivity. The system uses appropriate read time values dynamically, avoiding unnecessary delays while maintaining data accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces read times by up to 50% while maintaining accuracy, utilizing stronger ECC capabilities to compensate for increased bit errors, and dynamically adjusts read times to accommodate changing device performance over its lifecycle.
Implementation Method 1
analog charge level can be stored in each cell. A sense amplifier connected to the array senses and converts the charge level from an analog format to a digital format
Data Source
AI summary
A method includes initiating a read process for a memory array of an electronic memory device to make data available at an I/O buffer of the electronic memory device for access by a controller. A method includes signaling completion of a read process prior to completion of one or more stages of the read process at a memory array.