Non-Volatile Memory Read Voltage Optimization

Solution Overview

Problem

Non-volatile memory devices face challenges in reducing power consumption during read operations, particularly when many storage elements are in an erased state, leading to increased battery consumption and heat buildup in portable electronic devices.

Innovation Solution

A method is introduced to reduce power consumption by determining the programming state of storage elements on unselected word lines and applying lower voltages to unprogrammed lines, while maintaining higher voltages for programmed lines to ensure accurate reading without causing read disturbs, thereby optimizing voltage usage during read operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If higher voltages are applied to all word lines during read operations, then read accuracy is improved, but power consumption increases

Engineering Contradiction:

Improveread accuracyVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent applies different voltage levels to different word lines based on their programming state. Programmed word lines receive a first voltage level while unprogrammed word lines receive a second, lower voltage level. This local differentiation allows the system to maintain read accuracy where needed while reducing power consumption in areas where it is not required.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent dynamically adjusts the voltage applied to word lines based on real-time detection of programming states. The system determines whether storage elements on unselected word lines are programmed or unprogrammed and adapts the voltage levels accordingly during read operations, making the voltage application flexible and adaptive rather than static.

Inventive Principle:

Principle #15Dynamics

2Use of energy by moving object

If lower voltages are applied to reduce power consumption, then energy usage is reduced, but read accuracy deteriorates and read disturbs increase

Engineering Contradiction:

Improveenergy usageVSAvoidread accuracy

Core Design Contradiction:

Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The patent applies different voltage levels to different word lines based on their programming state. Programmed word lines receive a first voltage level while unprogrammed word lines receive a second, lower voltage level. This local differentiation allows the system to maintain read accuracy where needed while reducing power consumption in areas where it is not required.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent dynamically adjusts the voltage applied to word lines based on real-time detection of programming states. The system determines whether storage elements on unselected word lines are programmed or unprogrammed and adapts the voltage levels accordingly during read operations, making the voltage application flexible and adaptive rather than static.

Inventive Principle:

Principle #15Dynamics

3Device complexity

If uniform voltage is applied to all word lines, then circuit design is simplified, but power consumption cannot be optimized

Engineering Contradiction:

Improvecircuit designVSAvoidpower consumption

Core Design Contradiction:

Device complexityVSUse of energy by moving object

Solution Approach 1:

The patent applies different voltage levels to different word lines based on their programming state. Programmed word lines receive a first voltage level while unprogrammed word lines receive a second, lower voltage level. This local differentiation allows the system to maintain read accuracy where needed while reducing power consumption in areas where it is not required.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent dynamically adjusts the voltage applied to word lines based on real-time detection of programming states. The system determines whether storage elements on unselected word lines are programmed or unprogrammed and adapts the voltage levels accordingly during read operations, making the voltage application flexible and adaptive rather than static.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS7606079B2Reducing power consumption during read operations in non-volatile storage

Publication Date: 2009.10.20 SANDISK TECHNOLOGIES LLC

AI summary

Power consumption in a non-volatile storage device is reduced by providing reduced read pass voltages on unselected word lines during a read operation. A programming status of one or more unselected word lines which are after a selected word line on which storage elements are being read is checked to determine whether the unselected word lines contain programmed storage elements. When an unprogrammed word line is identified, reduced read pass voltages are provided on that word line and other word lines which are after that word line in a programming order. The programming status can be determined by a flag stored in the word line, for instance, or by reading the word line at the lowest read state. The unselected word lines which are checked can be predetermined in a set of word lines, or determined adaptively based on a position of the selected word line.