Non-volatile Memory Reference Circuit Area Reduction

Solution Overview

Problem

The existing ReRAM designs require multiple polysilicon resistive elements to generate various reference currents, leading to increased circuit area and manufacturing complexity and cost.

Innovation Solution

A non-volatile semiconductor memory device configuration that reduces circuit area by sharing fixed resistance elements among multiple reference cells, using a series of fixed resistance elements coupled in parallel with reference word lines, allowing different resistance paths to be formed by selecting specific reference word lines, thereby generating various reference currents efficiently.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple polysilicon resistive elements are used to generate various reference currents, then different reference currents can be generated, but the circuit area increases

Engineering Contradiction:

Improveability to generate various reference currentsVSAvoidcircuit area

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

Multiple reference cells share a common set of fixed resistance elements. Instead of each reference cell having its own separate resistance elements, the fixed resistance elements are shared among multiple reference cells, reducing the total number of resistance elements needed while still enabling generation of various reference currents through different switching combinations.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The fixed resistance elements serve multiple functions by being shared across multiple reference cells. The same resistance elements are used to generate reference currents for different reference cells, making the resistance elements universal components that perform multiple roles in the circuit.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If multiple polysilicon resistive elements are used to generate various reference currents, then different reference currents can be generated, but the manufacturing complexity increases

Engineering Contradiction:

Improveability to generate various reference currentsVSAvoidmanufacturing complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Multiple reference cells share a common set of fixed resistance elements. Instead of each reference cell having its own separate resistance elements, the fixed resistance elements are shared among multiple reference cells, reducing the total number of resistance elements needed while still enabling generation of various reference currents through different switching combinations.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

Different reference currents are generated by changing the switching state of the reference cell transistors rather than by using different physical resistance elements. The resistance values are selected through parameter changes in the transistor switching configuration, simplifying the manufacturing process.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If multiple polysilicon resistive elements are used to generate various reference currents, then different reference currents can be generated, but the manufacturing cost increases

Engineering Contradiction:

Improveability to generate various reference currentsVSAvoidmanufacturing cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

Multiple reference cells share a common set of fixed resistance elements. Instead of each reference cell having its own separate resistance elements, the fixed resistance elements are shared among multiple reference cells, reducing the total number of resistance elements needed while still enabling generation of various reference currents through different switching combinations.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The fixed resistance elements serve multiple functions by being shared across multiple reference cells. The same resistance elements are used to generate reference currents for different reference cells, making the resistance elements universal components that perform multiple roles in the circuit.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Adaptability or versatility

If fixed resistance elements are arranged in series, then various resistance paths can be formed, but the circuit area increases

Engineering Contradiction:

Improveability to form various resistance pathsVSAvoidcircuit area

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

Multiple reference cells share a common set of fixed resistance elements arranged in series. The series arrangement allows different combinations of resistance elements to be selected by switching, forming various resistance paths without requiring separate series chains for each reference cell.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The resistance paths are dynamically selected through switching of reference cell transistors rather than being fixed. This allows the same physical resistance elements to be reconfigured into different series combinations based on which reference cell is active, providing adaptability without increasing physical circuit area.

Inventive Principle:

Principle #15Dynamics

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 configuration reduces the number of fixed resistance elements needed, minimizing circuit area and manufacturing complexity while maintaining high accuracy and speed in generating reference currents.

Implementation Method 1

a variable resistance memory element coupled to one end of the cell transistor... The non-volatile semiconductor memory device utilizes variations in the resistance of the variable resistance memory element to store data

Methodology Applied

Scientific EffectResistive switching: Electrical Resistance

Implementation Method 2

a plurality of fixed resistance elements coupled in series... One end of the resistance path in which the plurality of fixed resistance elements are arranged is coupled to a first reference data line

Methodology Applied

Scientific EffectElectrical resistance: Electrical Resistance

Data Source

PatentUS9153625B2Non-volatile semiconductor memory device

Publication Date: 2015.10.06 PANASONIC SEMICON SOLUTIONS CO LTD

AI summary

A non-volatile semiconductor memory device includes a plurality of series-coupled fixed resistance elements, a plurality of reference cell transistors, and reference word lines coupled to gates of the reference cell transistors, a first reference data line coupled to one end of a resistance path in which a plurality of fixed resistance elements are arranged, and a second reference data line coupled in common to one ends of the reference cell transistors. The other end of each of the reference cell transistors is coupled to one of coupling points of the fixed resistance elements or the other end of the resistance path.