FeFET In-Memory Computing for Cosine Distance Search

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Solution Overview

Problem

Current von Neumann computer architectures for cosine-based operations in artificial intelligence applications face significant energy consumption and delay issues, and existing in-memory computing solutions for cosine distance calculations are scarce and not applicable to wider applications like binary neural networks.

Innovation Solution

An in-memory computing architecture utilizing two FeFET-based storage arrays, Translinear circuits, and a WTA circuit, where each storage array stores different vectors and outputs inner products and sum of squares, allowing for efficient cosine distance calculations with reduced energy consumption and delay through the use of FeFET and resistor structures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If traditional von Neumann computer architecture is used for cosine-based operations, then computation can be performed, but energy consumption and delay are significant

Engineering Contradiction:
Improveenergy consumptionVSAvoidcomputational efficiency
Core Design Contradiction:
Use of energy by moving objectVSProductivity

Solution Approach 1:

The patent merges storage and computation functions into a unified in-memory computing architecture. FeFET-based storage cells simultaneously store vector data and perform multiplication operations, while Translinear circuits compute inner products and sum of squares directly in memory, eliminating the need to transfer data between CPU and memory and thus reducing energy consumption and computational delay

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent replaces the traditional von Neumann architecture with an in-memory computing system that uses FeFET-based storage cells and Translinear circuits to perform computations directly in memory. This substitution of the computational mechanism enables parallel processing of cosine similarity calculations for multiple vectors simultaneously, dramatically improving productivity while reducing energy consumption

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If in-memory computing cell is designed for Hamming code calculation, then delay and energy consumption are solved, but applicability to wider scenarios like binary neural network is limited

Engineering Contradiction:
ImproveapplicabilityVSAvoidcalculation accuracy
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent designs an in-memory computing architecture that is universally applicable to multiple scenarios including binary neural networks and hyperdimensional computing. The FeFET-based storage cells and Translinear circuits can compute both Hamming distances and cosine similarities, making the system versatile for different AI applications while maintaining calculation accuracy through precise analog computation

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

Solution Approach 2:

The patent achieves versatility by changing the computation parameter from Hamming distance to cosine similarity while using the same in-memory computing hardware. By adjusting the mathematical operations performed by Translinear circuits (computing inner products and sum of squares instead of bit differences), the system adapts to different application requirements without sacrificing reliability

Inventive Principle:
Principle #35Parameter changes

3Productivity

If existing in-memory computing cell is used for approximate cosine similarity calculation, then some computation is enabled, but implementation is not applicable to wider applications

Engineering Contradiction:
Improvesearch efficiencyVSAvoidapplication range
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent implements continuous analog computation throughout the in-memory computing process. Translinear circuits continuously compute inner products and sum of squares for all storage vectors simultaneously, and the WTA circuit continuously identifies the maximum value, enabling efficient nearest neighbor search while maintaining the capability to handle various application scenarios through parameter adjustment

Inventive Principle:
Principle #20Continuity of useful action

Data Source

PatentUS20240069780A1In-memory computing architecture for nearest neighbor search of cosine distance and operating method thereof
Publication Date: 2024.02.29 ZHEJIANG UNIV
  • US20240069780A1 patent drawing
  • US20240069780A1 patent drawing
  • US20240069780A1 patent drawing

AI summary

Disclosed are an in-memory computing architecture for a nearest neighbor search of a cosine distance and an operating method thereof. The in-memory computing architecture comprises two FeFET-based storage arrays, Translinear circuits and a WTA circuit, and the two storage arrays are a first storage array and a second storage array, respectively; wherein each of the storage cells comprises a FeFET and a resistor which are electrically connected; an input vector is inputted into the first storage array for outputting the inner product X of the input vector multiplied by all the storage vectors in the first storage array; the second storage array outputs the sum of squares Y of all vector elements in the storage vectors; the output values of the first storage array and the second storage array are respectively inputted into the Translinear circuits through current mirrors; and the Translinear circuits output X2/Y to the WTA circuit.