Partially Programmed Block Read Operations in Memory Arrays
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing memory devices face challenges in performing read operations on partially programmed blocks, where a mix of programmed and unprogrammed word lines can lead to voltage threshold drops, affecting the accuracy of data retrieval.
Innovation Solution
A controller applies distinct voltages to programmed and unprogrammed word lines during read operations, with a Vpass_erase signal of lower magnitude applied to unprogrammed lines to minimize voltage threshold drops, calculated based on the percentage of unprogrammed word lines in the block.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a standard read voltage is applied to all word lines during read operations, then the read operation can be performed uniformly across the memory block, but voltage threshold drops occur in partially programmed blocks leading to inaccurate data retrieval
Solution Approach 1:
The patent applies different pass voltages to different groups of word lines based on their programming status. Specifically, fully programmed word lines receive a first pass voltage, partially programmed word lines receive a second pass voltage, and unprogrammed word lines receive a third pass voltage. This local differentiation ensures that each word line group is treated according to its specific state, preventing voltage threshold drops and ensuring accurate data retrieval while maintaining operational feasibility.
2Measurement precision
If distinct voltages are applied to programmed and unprogrammed word lines to prevent voltage threshold drops, then data retrieval accuracy improves, but the control complexity and device complexity increase
Solution Approach 1:
The patent segments the word lines into distinct groups based on their programming status: fully programmed word lines, partially programmed word lines, and unprogrammed word lines. Each segment is assigned a specific pass voltage level. This segmentation approach simplifies the control logic by creating clear categories that can be managed independently, reducing the overall complexity compared to a continuous adjustment approach while still achieving accurate data retrieval.
Solution Approach 2:
The patent implements dynamic voltage adjustment where the pass voltage applied to word lines is not fixed but changes based on the programming status of each word line group. The controller dynamically selects appropriate pass voltages from multiple levels (first, second, and third pass voltages) depending on whether word lines are fully programmed, partially programmed, or unprogrammed. This dynamic approach optimizes read accuracy while managing complexity through systematic voltage level selection.
Data Source
AI summary
Apparatuses and methods for determining performing read operations on a partially programmed block are provided. One example apparatus can include a controller configured to apply a read voltage to a word line in an array of memory cells during a read operation on the word line, apply a first pass voltage to a number of programmed word lines in the array of memory cells during the read operation, and apply a second pass voltage to a number of unprogrammed word lines in the array of memory cells during the read operation.