Programmable Resistive Switch Circuits for Soft-Error-Immune Logic

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Solution Overview

Problem

Integrated circuits with volatile memory elements, such as SRAM and CRAM cells, face challenges with reduced read/write margins and increased susceptibility to soft error upsets due to smaller transistors, lower power supply voltages, and process, voltage, and temperature variations, which affect reliability and memory yield.

Innovation Solution

The use of non-volatile programmable resistive switch elements, formed with two-terminal electrochemical metallization memory devices in a 'back-to-back' configuration, which can be configured to conduct or block signals, replacing the need for multiple transistors and CRAM cells, providing immunity to soft error upsets and reducing standby current.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of moving object

If transistors are scaled to smaller sizes with lower threshold voltages and lower power supply voltages, then device density and integration are improved, but read/write margins for volatile memory elements decrease

Engineering Contradiction:

Improvedevice densityVSAvoidread/write margin

Core Design Contradiction:

Area of moving objectVSReliability

Solution Approach 1:

The patent changes the fundamental operating parameter of memory elements from volatile to non-volatile resistive switching. This allows the system to operate at lower voltages while maintaining sufficient signal margins through the high-contrast resistance states of the resistive switch elements, thereby resolving the contradiction between small device size and adequate read/write margins.

Inventive Principle:

Principle #35Parameter changes

2Area of moving object

If transistors are scaled to smaller sizes, then device density is improved, but susceptibility to soft error upsets increases

Engineering Contradiction:

Improvedevice densityVSAvoidsoft error upset susceptibility

Core Design Contradiction:

Area of moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent employs non-volatile resistive switch elements that retain their state without power, effectively creating a more robust memory element that is inherently immune to soft error upsets. The resistive switch elements maintain their resistance states through physical structural changes rather than fragile voltage states, thereby protecting against radiation-induced errors while enabling higher device density.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Use of energy by moving object

If memory elements operate at lower power supply voltages, then power consumption is reduced, but variation from process, voltage, and temperature changes increases

Engineering Contradiction:

Improvepower consumptionVSAvoidmemory element variation

Core Design Contradiction:

Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

The patent transitions from volatile memory elements to non-volatile resistive switch elements, fundamentally changing the operating parameters. The resistive switch elements exhibit superior PVT stability because their resistance states are determined by physical structural configurations rather than voltage levels, allowing operation at lower voltages without exacerbating variation effects from process, voltage, and temperature changes.

Inventive Principle:

Principle #35Parameter changes

4Ease of operation

If volatile memory elements are used, then configuration data can be loaded and supplied to transistors, but separate CRAM cells are required increasing device complexity

Engineering Contradiction:

Improveconfiguration data storageVSAvoidseparate CRAM cells

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent merges the memory function directly into the logic fabric by using non-volatile resistive switch elements that serve dual purposes: storing configuration data and controlling logic operations. This eliminates the need for separate CRAM cells and their associated read/write circuitry, thereby reducing device complexity while maintaining full configuration capability.

Inventive Principle:

Principle #5Merging (Combining)

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 solution reduces the circuit area, improves reliability by eliminating the need for separate CRAM cells, and enhances immunity to soft error upsets, while allowing for efficient configuration of logic functions with fewer components and lower voltage stress on transistors.

Implementation Method 1

The programmable switch elements may be formed using non-volatile resistive elements... two-terminal electrochemical metallization memory devices

Methodology Applied

Scientific EffectElectrochemical metallization: Electrochemiluminescence

Data Source

PatentUS10447275B2Integrated circuits with programmable non-volatile resistive switch elements

Publication Date: 2019.10.15 ALTERA CORP

AI summary

Integrated circuits with programmable resistive switch elements are provided. A programmable resistive switch element may include two non-volatile resistive elements connected in series and a programming transistor. The programmable resistive switch elements may be configured in a crossbar array and may be interposed within the user data path. Driver circuits may also be included for selectively turning on or turning off the switches by applying positive and optionally negative voltages.