Memory Write Driver Stress Voltage Reduction via Dynamic Ground Adjustment

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Solution Overview

Problem

The use of negative bit line techniques in memory devices increases the operation voltage range but results in high stress voltage for write drivers, leading to potential damage and shortened device lifetime due to fabrication variations.

Innovation Solution

A memory device design that includes a write controller, write driver, negative voltage generator, and protector, where the negative voltage generator generates a reference voltage lower than the ground voltage during specific logic states, and the protector adjusts the supply voltage to reduce stress on the write driver, thereby decreasing the voltage gap between input and ground terminals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If negative bit line techniques are used to increase operation voltage range, then write operation reliability is improved, but write driver stress voltage increases leading to potential damage

Engineering Contradiction:

Improvewrite operation reliabilityVSAvoidwrite driver stress voltage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A ground terminal voltage adjustment unit is introduced as an intermediary component between the negative bit line technique and the write driver. This unit dynamically adjusts the ground terminal voltage to compensate for the stress voltage caused by negative bit line operations, thereby protecting the write driver while maintaining the benefits of increased operation voltage range

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The ground terminal voltage is dynamically changed based on operation conditions. During normal operations, the ground terminal voltage is maintained at standard levels, but during write operations where stress voltage may occur, the ground terminal voltage is adjusted to reduce the voltage gap across the write driver, thus controlling stress voltage while preserving write operation reliability

Inventive Principle:

Principle #35Parameter changes

2Reliability

If negative bit line techniques are used to prevent write failures, then operation voltage range is increased, but device lifetime is shortened due to excessive stress voltage

Engineering Contradiction:

Improvewrite operation success rateVSAvoiddevice lifetime

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The ground terminal voltage adjustment unit provides beforehand cushioning by proactively adjusting the ground terminal voltage before or during write operations that may generate excessive stress voltage. This preventive measure cushions the write driver from damage accumulation, ensuring write operation success while extending device lifetime through reduced stress exposure

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS10692568B2Memory device capable of releasing stress voltage

Publication Date: 2020.06.23 M31 TECH

AI summary

A memory device includes: at least one memory cell; a bit line connected to the at least one memory cell; a write controller; a write driver receiving a logic signal from an output terminal of the write controller, and driving the bit line based on the logic signal; a negative voltage generator generating a reference voltage for receipt by a ground terminal of the write driver; and a protector connected to one of a power terminal and the output terminal of the write controller. The protector is capable of releasing stress voltage of the write driver.