Nonvolatile Memory Cross-Bar Array Dot Product Calculation
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Solution Overview
Problem
Existing memory technologies face challenges in efficiently performing simultaneous calculations of multiple dot products without the need for storage elements, particularly in nonvolatile memory cross-bar arrays using memristive devices.
Innovation Solution
A nonvolatile memory cross-bar array is designed with multiple junctions formed by intersecting row and column lines, where each junction includes controls with transistors and resistive memory elements, allowing for independent programming and vector application to calculate the sum of multiple dot products directly from collected currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional memory technologies are used to perform dot product calculations, then storage elements are required, but this increases device complexity and reduces operational speed
Solution Approach 1:
The patent extracts the storage function from the calculation process by using resistive memory elements that inherently store data through their resistance states. The memory elements themselves perform the dot product calculation through their electrical characteristics, eliminating the need for separate storage elements and reducing device complexity while maintaining high operational speed.
Solution Approach 2:
The resistive memory elements serve multiple functions simultaneously: they store data (memory function) and perform analog multiplication (calculation function). This multi-functionality allows the same hardware components to both store matrix values and participate in dot product calculations, reducing the need for additional storage elements and improving operational speed.
2Measurement precision
If storage elements are used for calculating dot products, then calculation accuracy is maintained, but this increases the requirement for memory circuits
Solution Approach 1:
The resistive memory elements perform the calculation function themselves through their inherent electrical characteristics. The resistance states directly represent data values and the current flow through multiple memory elements naturally performs the multiplication and addition operations, eliminating the need for external memory circuits while maintaining calculation accuracy.
Solution Approach 2:
The patent replaces traditional electronic calculation mechanisms with electrical conduction mechanisms. Instead of using active memory circuits to perform calculations, the passive resistive memory elements use their resistance properties to naturally perform analog multiplication, and the current summation performs addition, eliminating complex memory circuits while maintaining precision.
3Productivity
If multiple dot products are calculated simultaneously, then productivity is improved, but this requires complex control mechanisms
Solution Approach 1:
The patent segments the calculation into multiple independent dot product operations that can be performed simultaneously in parallel. Each dot product is calculated independently through separate current collection paths, allowing multiple operations to proceed concurrently without interfering with each other, thus improving productivity while keeping control mechanisms relatively simple.
Solution Approach 2:
The patent merges multiple dot product calculations into a unified current collection process. The currents from multiple parallel calculations are collected simultaneously through shared column lines and summed at the read circuit, allowing multiple operations to be performed at once without requiring separate control mechanisms for each operation, thereby improving productivity.
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 enables simultaneous calculation and summation of multiple dot products without the need for storage elements, improving operational speed and eliminating the requirement for memory circuits, while maintaining flexibility for various matrix operations.
Implementation Method 1
Resistive memory elements often referred to as memristors are devices that may be programmed to different resistive states by applying electrical voltage or currents to the memristors
Implementation Method 2
a current collection line to collect currents from the controls of the first set and the second set through their respective column lines and output a result current corresponding to a sum of a first dot product and a second dot product
Data Source
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AI summary
Provided in one example is a nonvolatile memory cross-bar array. The array includes: a number of junctions formed by a number of row lines intersecting a number of column lines; a first set of controls at a first set of the junctions coupling between a first set of the row lines and a first set of the column lines; a second set of controls at a second set of the junctions coupling between a second set of the row lines and a second set of the column lines; and a current collection line to collect currents from the controls of the first set and the second set through their respective column lines and output a result current corresponding to a sum of a first dot product and a second dot product.