Memristive Crossbar Array Transistor Switching for Vector Processing

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Solution Overview

Problem

Current computing technologies face inefficiencies in vector-matrix processing, particularly in terms of accuracy and power consumption, which are critical for applications like data compression, neural networks, and encryption.

Innovation Solution

A memristive crossbar array with transistors is used to perform vector-matrix computations, where memristors at each junction allow for precise programming of conductance values, reducing sneak path currents and enhancing precision while minimizing power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If memristors are used in a crossbar array for vector-matrix processing, then computing speed and productivity are improved, but accuracy and power consumption become problematic

Engineering Contradiction:
Improvecomputing speedVSAvoidaccuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

Transistors are introduced as intermediary components between signal lines and memristors. Each transistor acts as a switch that selectively connects or disconnects the memristor from the signal lines, enabling precise control of current flow through each memristor during programming operations while minimizing leakage currents that would affect accuracy.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent implements feedback mechanisms through sense amplifiers and control circuits that monitor the state of memristors and adjust programming signals accordingly. This feedback loop ensures accurate programming of conductance values by compensating for variations in memristor characteristics and preventing errors from propagating through the crossbar array.

Inventive Principle:
Principle #23Feedback

2Productivity

If memristors are used in a crossbar array for vector-matrix processing, then computing speed is improved, but power consumption increases

Engineering Contradiction:
Improvecomputing speedVSAvoidpower consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

Transistors serve as intermediaries that enable selective activation of memristors. By using transistor switches to connect or disconnect memristors from signal lines, the system can activate only the necessary memristors for current computations, significantly reducing leakage current and power consumption compared to having all memristors continuously powered.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system employs periodic scanning and sequential activation of row and column lines in the crossbar array. Rather than continuously activating all lines, the system cycles through different line combinations to access different memristors, allowing inactive lines to be turned off and reducing overall power consumption while maintaining high computing speed.

Inventive Principle:
Principle #19Periodic action

3Measurement precision

If transistors are added to reduce sneak path currents, then accuracy is improved, but device complexity increases

Engineering Contradiction:
ImproveaccuracyVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The crossbar array is segmented into individual controllable units, each consisting of a transistor and a memristor. This segmentation allows independent control of each unit, enabling precise programming of conductance values while containing complexity at the local level. Each transistor-memristor unit can be controlled independently without affecting other units.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The transistor-memristor unit serves multiple functions: the transistor acts as both a switch for current control and as part of the computational element, while the memristor provides both storage and weight function. This multi-functionality reduces the need for separate dedicated components, thereby limiting the increase in device complexity despite the addition of transistors.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 significantly improves the accuracy and reduces power consumption in vector processing, outperforming traditional graphics processing units and leading to substantial performance increases and lower energy usage.

Implementation Method 1

programming the conductance values Gij in the crossbar junctions

Methodology Applied
Scientific EffectConductance programming: Electrical Resistance

Implementation Method 2

the current vector, I, flowing out of the crossbar array will be approximately IT=VTG, where V is the input voltage vector and G is the conductance matrix

Methodology Applied
Scientific EffectOhm's Law: Ohm's Law

Data Source

PatentUS10541026B2Memristive dot product engine for vector processing
Publication Date: 2020.01.21 HEWLETT PACKARD ENTERPRISE DEV LP
  • US10541026B2 patent drawing
  • US10541026B2 patent drawing
  • US10541026B2 patent drawing

AI summary

A memristive dot-product system for vector processing is described. The memristive dot-product system includes a crossbar array having a number of memory elements. Each memory element includes a memristor. Each memory element includes a transistor. The system also includes a vector input register. The system also includes a vector output register.