MASAR Column Architecture for Low-Energy Neural MAC Computation

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Solution Overview

Problem

Current machine learning and neural network models require significant memory and computational resources for large numbers of weights, leading to increased memory and energy costs due to the need for extensive data transfer and multiplication-accumulate operations in digital hardware implementations.

Innovation Solution

The implementation of a Multiply-Accumulate Successive Approximation (MASAR) column using a plurality of MASAR cells with multipliers, unit capacitors, and digital logic to perform digital multiplication and analog summation, enabling efficient MAC operations and reducing the need for analog-to-digital conversion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If digital hardware implementations are used for MAC operations, then computational power can be increased, but energy consumption and time costs increase significantly

Engineering Contradiction:
Improvecomputational powerVSAvoidenergy consumption
Core Design Contradiction:
PowerVSUse of energy by moving object

Solution Approach 1:

The patent combines multiple MAC operations and ADC conversion into a single integrated circuit architecture. The MASAR column performs both MAC computations and successive approximation register ADC conversion using shared hardware resources, eliminating the need for separate analog-to-digital conversion stages and reducing overall energy consumption while maintaining computational power.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The integrated circuit is designed with multi-functional processing elements that can perform both MAC operations and ADC conversion. The same computational units are reused for different functions throughout the computation pipeline, reducing hardware redundancy and lowering energy consumption per operation.

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

2Measurement precision

If the number of weights and layers in neural networks is increased, then model accuracy improves, but memory requirements and data transfer costs increase

Engineering Contradiction:
Improvemodel accuracyVSAvoidmemory requirements
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent integrates weight storage and computation functions within the same processing elements. Weights are stored locally in the MASAR column and used directly in MAC operations without requiring transfer to separate memory units, reducing memory bandwidth requirements and enabling larger models to be deployed with fewer external memory resources.

Inventive Principle:
Principle #5Merging (Combining)

3Measurement precision

If separate ADC conversion stages are added for each MAC operation, then digital output precision is improved, but device complexity and energy consumption increase

Engineering Contradiction:
Improvedigital output precisionVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges the ADC conversion function with the MAC computation by implementing successive approximation register ADC directly within the MASAR column. This integration allows multiple MAC results to be converted to digital format using a single shared ADC unit rather than requiring separate ADC stages for each operation, reducing device complexity while maintaining precision.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The SAR ADC conversion is performed continuously alongside the MAC computations in a pipelined manner. While MAC operations are being computed, the ADC conversion proceeds in parallel using the same hardware resources, ensuring that precision is maintained without adding sequential conversion stages that would increase complexity.

Inventive Principle:
Principle #20Continuity of useful action

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 reduces energy and time costs by allowing for parallel and serial multi-bit precision MAC computations, improving hardware efficiency for AI/ML applications by using the same processing elements for both MAC calculations and ADC conversion.

Implementation Method 1

a unit capacitor configured to store the result as analog charge

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 2

digital logic configured to perform analog summation of the analog charge of the unit capacitors

Methodology Applied
Scientific EffectCharge summation: Capacitance

Data Source

PatentUS20240223207A1Multiply-accumulate successive approximation devices and methods
Publication Date: 2024.07.04 ROBERT BOSCH GMBH
  • US20240223207A1 patent drawing
  • US20240223207A1 patent drawing
  • US20240223207A1 patent drawing

AI summary

A multiply-accumulate successive approximation (MASAR) column is provided. The MASAR column includes a plurality of MASAR cells, each including a multiplier configured to perform digital multiplication between an input activation received to an input and an operand to compute a result, and a unit capacitor configured to store the result as analog charge. The MASAR column further includes digital logic configured to perform analog summation of the analog charge of the unit capacitors of the plurality of MASAR cells to determine a digital output of the multiplication.