Memory Device In-Memory MAC Operations

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Solution Overview

Problem

The memory wall problem in large-scale datasets arises due to the significant speed difference between processors and memory, leading to performance limitations, especially when processing large datasets.

Innovation Solution

A computational method for a memory device that involves storing weight data in memory cells, generating memory cell currents based on input data and weight data, summing these currents on bit lines, converting them into analog-to-digital conversion results, and accumulating these results to obtain a computational outcome.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If traditional processor-memory architecture is used, then memory access speed is limited by the memory wall problem, but processor performance is bottlenecked by data retrieval speed

Engineering Contradiction:
Improvedata retrieval speedVSAvoidprocessor stall time
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The patent merges computing operations with memory storage by implementing in-memory MAC operations. The memory device performs both storage and computational functions within the same hardware structure, eliminating the need for data to be transferred between processor and memory. This integration directly addresses the memory wall problem by making the memory system computationally capable, thereby reducing processor stall time and improving overall data retrieval speed.

Inventive Principle:
Principle #5Merging (Combining)

2Productivity

If MAC operations are performed using traditional processor architecture, then computational accuracy is maintained, but energy consumption increases and computational efficiency decreases

Engineering Contradiction:
Improvecomputational efficiencyVSAvoidenergy consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent replaces traditional digital processor-based MAC operations with analog computational mechanisms implemented in memory. Instead of using digital logic gates and arithmetic units in the processor, the system uses analog current-based multiplication and accumulation directly in the memory array. This substitution significantly reduces energy consumption while maintaining computational efficiency, as the analog operations eliminate the need for repeated digital processing cycles.

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

3Productivity

If data is stored in traditional memory architecture, then storage capacity is achieved, but computational operations become inefficient due to data transfer limitations

Engineering Contradiction:
Improvecomputational efficiencyVSAvoidsystem architecture complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent implements multi-functionality by enabling the memory device to perform both data storage and computational operations simultaneously. The same memory array that stores weight data also performs MAC operations with input data, eliminating the need for separate computational hardware. This universal approach improves computational efficiency by keeping data and computations together, while the standardized memory cell structure keeps the architecture relatively simple despite the enhanced functionality.

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 enhances computational efficiency and reduces energy consumption by effectively performing Multiply Accumulate (MAC) operations within the memory device, thereby alleviating the memory wall problem.

Implementation Method 1

generating a plurality of memory cell currents in the plurality of first memory cells based on the weight data and the input data

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

converting the summed currents into a plurality of analog-to-digital conversion results

Methodology Applied
Scientific EffectAnalog-to-digital conversion:

Data Source

PatentUS20250157508A1Memory device and computation method thereof
Publication Date: 2025.05.15 MACRONIX INTERNATIONAL CO LTD
  • US20250157508A1 patent drawing
  • US20250157508A1 patent drawing
  • US20250157508A1 patent drawing

AI summary

The application discloses a memory device and a computation method thereof. A plurality of weight data are stored in a plurality of first memory cells of the memory device. A plurality of input data are input via a plurality of string select lines. A plurality of memory cell currents are generated in the plurality of first memory cells based on the weight data and the input data. The memory cell currents are summed on a plurality of bit lines coupled to the plurality of string select lines to obtain a plurality of summed currents. The summed currents are converted into a plurality of analog-to-digital conversion results. The plurality of analog-to-digital conversion results are accumulated to obtain a computational result.