Progressive Read-Level Offsets for Accurate Partial-Block Reads
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Solution Overview
Problem
Existing memory devices face challenges in accurately reading data from partial blocks due to variations in voltage threshold levels, leading to increased error rates and reduced data integrity, particularly when read-level voltage offsets are calibrated based on full blocks.
Innovation Solution
A progressive compensation method is employed to calibrate read-level voltages for partial blocks by using a partial block offset component that applies specific read-level voltage offsets determined from a partial block offset table, considering the unique characteristics of partial blocks, including identifying the last written page and word line type.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If read-level voltage offsets are calibrated based on full blocks, then full block read accuracy is maintained, but partial block read accuracy deteriorates due to voltage threshold level variations
Solution Approach 1:
The patent applies different read-level voltage offsets to different regions (full blocks vs. partial blocks) based on their unique characteristics. The partial block offset component identifies when a partial block is being read and applies specially calibrated voltage offsets for partial blocks, while full blocks use their own calibrated offsets. This local differentiation resolves the contradiction by ensuring each block type receives optimized read parameters.
Solution Approach 2:
The system dynamically adapts the read-level voltage offsets based on the block type being accessed. The partial block offset component determines whether a block is full or partial and adjusts the voltage offsets accordingly in real-time. This dynamic adjustment allows the system to maintain optimal read accuracy for both full and partial blocks without using a fixed calibration approach.
2Device complexity
If a single read-level voltage offset is used for all blocks, then device complexity is reduced, but read accuracy for partial blocks deteriorates
Solution Approach 1:
The patent segments the block management into distinct components: a full block offset component and a partial block offset component. Each component handles calibration and voltage offset application for its specific block type independently. This segmentation allows the system to maintain separate calibration data and processing logic for full and partial blocks, improving read accuracy without requiring complete redesign of the entire calibration system.
Solution Approach 2:
The partial block offset component acts as an intermediary between the read operation and the memory blocks. It intercepts read commands, identifies whether the block is partial or full, and selectively applies the appropriate voltage offsets. This intermediary approach adds minimal complexity while significantly improving read accuracy for partial blocks without affecting full block performance.
3Measurement precision
If progressive compensation method is applied to calibrate read-level voltages for partial blocks, then read accuracy is improved, but device complexity increases
Solution Approach 1:
The system performs preliminary identification of block type (full or partial) before executing the read operation. The partial block offset component analyzes the read command and block state in advance to determine the appropriate voltage offsets to apply. This preliminary action prevents read errors before they occur and simplifies the overall calibration process by avoiding the need for complex real-time adjustments during the read operation itself.
Data Source
AI summary
A command to read data stored in a block of a memory device is received. The block is determined to be a partial block based on the block having one or more unprogrammed pages. Based on the block being a partial block, a partial block offset table is accessed. The partial block offset table comprises a mapping between word line numbers and read-level voltage offsets for partial blocks. A last written page in the block is identified and a word line type is determined based on the last written page. A first read-level voltage offset for the block is determined from the partial block offset table based on the last written page and the word line type. The first read-level voltage offset is applied to the block before performing a read-level voltage calibration process that includes determining second read-level voltage offsets for the block.