Crossbar Array Write Precision via Sneak Current Compensation

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Solution Overview

Problem

In highly integrated crossbar arrays using resistance-variable type memory elements, the precision of write operations is deteriorated due to sneak currents, making it difficult to finely adjust synaptic binding strengths effectively.

Innovation Solution

A write method that measures the sneak current generated when a write voltage is applied to a selected resistance-variable type memory element and regenerates it to be added to the write current, ensuring precise write operations by compensating for the sneak current influence.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a write voltage is applied to a selected resistance-variable type memory element in a highly integrated crossbar array, then the write operation can be performed, but a sneak current is generated that deteriorates the write precision

Engineering Contradiction:

Improvewrite operation speedVSAvoidwrite precision

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by measuring the sneak current before the actual write operation and holding this measurement result. This allows the system to prepare the compensation current in advance, so when the write operation is performed, the sneak current's influence has already been accounted for, thereby maintaining write precision without sacrificing operation speed.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback by measuring the sneak current generated during the write operation and using this measurement to regenerate and add the sneak current to the write current. This closed-loop feedback mechanism ensures that the write precision is maintained by continuously compensating for the sneak current's influence based on actual measurements.

Inventive Principle:

Principle #23Feedback

2Quantity of substance

If the crossbar array is highly integrated to improve scalability, then the number of memory elements increases, but the sneak current influence becomes more significant and write precision deteriorates

Engineering Contradiction:

Improvenumber of memory elementsVSAvoidwrite precision

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The feedback principle is applied by measuring the sneak current in the highly integrated crossbar array and using this measurement to compensate for the sneak current's influence during write operations. This allows the system to maintain write precision even as the number of memory elements increases and sneak current becomes more significant.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent converts the harmful sneak current into a beneficial element by measuring it and regenerating it to be added to the write current. This approach transforms the previously harmful sneak current into a useful compensation mechanism that actually improves write precision in highly integrated crossbar arrays.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Ease of operation

If the sneak current is not compensated, then the write operation is simpler and faster, but the write precision and fine adjustment capability of synaptic strength deteriorate

Engineering Contradiction:

Improvewrite operation simplicityVSAvoidsynaptic strength adjustment precision

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent applies feedback by measuring the sneak current and using this measurement to compensate for its influence on write precision. This feedback mechanism enables fine adjustment of synaptic strength by ensuring that the write current accurately reflects the intended value without being degraded by sneak current effects.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent introduces an intermediary mechanism (sneak current measurement and regeneration circuit) that mediates between the simple write operation and the precision requirement. This intermediary measures and compensates for the sneak current, allowing both operational simplicity and write precision to coexist.

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 enhances the precision of write operations in crossbar arrays by eliminating the impact of sneak currents, allowing for more accurate fine adjustments of synaptic strengths, especially in synaptic crossbar arrays using resistance-variable type memory elements.

Implementation Method 1

The resistance-variable type memory element 30 memorizes different resistance states by applying voltages or currents

Methodology Applied

Scientific EffectResistive switching: Electrical Resistance

Data Source

PatentUS11676662B2Crossbar array apparatus and write method thereof

Publication Date: 2023.06.13 WINBOND ELECTRONICS CORP

AI summary

A crossbar array apparatus suppressing deterioration of write precision due to a sneak current is provided. A synapse array apparatus includes a crossbar array configured by connecting resistance-variable type memory elements, a row selecting/driving circuit, a column selecting/driving circuit, and a writing unit performing a write operation to a selected resistance-variable type memory element. The writing unit measures the sneak current generated when applying a write voltage to a selected row line before applying the write voltage, and then the writing unit performs the write operation to the selected resistance-variable type memory element by applying a write voltage having a sum of the measured sneak current and a current generated for performing the write operation.