Nonvolatile Memory Wordline Driving via Precharged Drive Line

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Solution Overview

Problem

In nonvolatile memory devices, the time taken to apply voltages to floating gate transistors affects the operation time, and existing methods struggle to efficiently manage the high voltages required for programming, reading, and verifying operations, leading to inefficiencies in word line driving.

Innovation Solution

A nonvolatile memory device with a word line coupled to a memory cell, a drive line, and a switch configured to electrically connect the word line and drive line, where the drive line is precharged to a higher precharge voltage than the bias voltage applied to the word line, allowing efficient charging and maintaining the pass voltage during operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the drive line is charged to a high precharge voltage before connecting to the word line, then the word line charging speed is improved, but the voltage stability during operation deteriorates

Engineering Contradiction:

Improveword line charging speedVSAvoidvoltage stability

Core Design Contradiction:

SpeedVSStability of the object's composition

Solution Approach 1:

The drive line is precharged to a high voltage level before being connected to the word line through the switch. This preliminary charging action stores energy in the drive line's capacitance, which is then rapidly transferred to the word line when the switch closes, achieving fast charging without requiring continuous high-voltage pumping during the operation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses periodic switching between the precharged drive line and the word line to maintain voltage levels. The switch periodically connects the drive line to the word line to top up the voltage, rather than maintaining a continuous connection, which improves voltage stability while preserving charging speed.

Inventive Principle:

Principle #19Periodic action

2Stability of the object's composition

If continuous high-voltage pumping is used to maintain word line voltage, then voltage stability is improved, but energy consumption increases

Engineering Contradiction:

Improvevoltage stabilityVSAvoidenergy consumption

Core Design Contradiction:

Stability of the object's compositionVSUse of energy by moving object

Solution Approach 1:

The precharged drive line serves itself as a voltage reservoir, automatically maintaining the word line voltage through periodic connection rather than requiring continuous external pumping. The stored energy in the drive line's capacitance is reused to maintain voltage, reducing the need for continuous energy input from the voltage pump.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

Instead of continuously pumping high voltage, the system recovers and reuses the energy stored in the drive line's capacitance. The precharged drive line periodically replenishes the word line voltage, effectively recovering and reusing energy that would otherwise be continuously consumed by high-voltage pumping circuits.

Inventive Principle:

Principle #34Discarding and recovering

3Speed

If the drive line is precharged to a higher voltage than the bias voltage, then operation speed is improved, but the complexity of voltage management increases

Engineering Contradiction:

Improveoperation speedVSAvoidvoltage management complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The drive line acts as an intermediary between the voltage pump and the word line. It is precharged to a high voltage by the pump, then isolated and used to rapidly charge the word line through the switch. This intermediary approach simplifies voltage management by decoupling the continuous pumping operation from the rapid charging requirement, allowing each component to operate independently at its optimal voltage level.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 enables rapid and efficient charging of the word line to the required voltage levels, reducing the need for continuous high-voltage pumping and maintaining voltage stability, thereby enhancing the operation speed and efficiency of the memory device.

Implementation Method 1

a voltage generator coupled to the drive line and configured to charge the drive line to a precharge voltage

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

a switch coupled between the word line and the drive line, and configured to electrically connect the word line and the drive line

Methodology Applied

Scientific EffectElectrical Conduction: Conduction (electrical)

Data Source

PatentUS8040736B2Non-volatile memory device, computing system and wordline driving method

Publication Date: 2011.10.18 SAMSUNG ELECTRONICS CO LTD

AI summary

A nonvolatile memory device including a memory cell; a word line coupled to the memory cell; a drive line; a switch coupled between the word line and the drive line, and configured to electrically connect the word line and the drive line; and a voltage generator coupled to the drive line and configured to charge the drive line to a precharge voltage. The precharge voltage is higher than a bias voltage applied to the word line during a corresponding operation on the memory cell.