Digit-Serial MAC Accelerator Zero-Digit Gating

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Deep convolutional neural networks (DCNNs) require efficient hardware accelerators to perform computationally expensive operations like convolutions and dot products, which are power-intensive and costly when using general-purpose hardware, especially in mobile and consumer electronics where real-time constraints and power consumption are concerns.

Innovation Solution

A digit-serial Multiply Accumulate (MAC) hardware accelerator is developed, integrating digit-serial architectures within a bit-parallel stream-computation framework, using word-level unfolding techniques to adapt the architecture and eliminate input parallel-to-serial converters, and incorporating pre-processing logic for gating multipliers based on zero-value digit detection to reduce power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If general-purpose hardware is used to perform DCNN operations, then computational flexibility is maintained, but power consumption increases and processing speed decreases

Engineering Contradiction:
Improvepower consumptionVSAvoidprocessing speed
Core Design Contradiction:
PowerVSProductivity

Solution Approach 1:

The hardware accelerator is segmented into specialized functional units including digit-serial multipliers, accumulation units, and gating circuits that process DCNN operations in a divided, modular manner. This segmentation allows each unit to be optimized for specific computational tasks, achieving high throughput while maintaining low power consumption through efficient resource utilization.

Inventive Principle:
Principle #1Segmentation

2Area of stationary object

If digit-serial architecture is used in MAC hardware accelerators, then area occupation is reduced, but computational throughput may be affected

Engineering Contradiction:
Improvearea occupationVSAvoidcomputational throughput
Core Design Contradiction:
Area of stationary objectVSProductivity

Solution Approach 1:

The digit-serial architecture employs periodic clock gating where multipliers are activated only during specific clock cycles when non-zero digits are present. This periodic action pattern allows the hardware to process data serially over time rather than requiring all multipliers to be active simultaneously, significantly reducing area occupation while maintaining computational throughput through time-multiplexed operation.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system dynamically adjusts the operation of multipliers based on the actual data being processed. Pre-processing logic analyzes input digits and dynamically gates multipliers to operate only when needed, transforming a static hardware configuration into a dynamic system that adapts to data characteristics, thereby optimizing both area usage and throughput.

Inventive Principle:
Principle #15Dynamics

3Loss of energy

If pre-processing logic with gating circuits is added to control multipliers, then power consumption is reduced, but device complexity increases

Engineering Contradiction:
Improvepower consumptionVSAvoiddevice complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

Pre-processing logic is implemented to analyze input digits and generate gating control signals before the main multiplication operation occurs. This preliminary action identifies which multipliers need to be activated and prepares control signals in advance, allowing the main computational units to operate efficiently without unnecessary switching activity, thereby reducing power consumption while keeping the added complexity minimal and localized to the control logic.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentUS11740870B2Convolutional network hardware accelerator device, system and method
Publication Date: 2023.08.29 STMICROELECTRONICS SRL
  • US11740870B2 patent drawing
  • US11740870B2 patent drawing
  • US11740870B2 patent drawing

AI summary

A Multiple Accumulate (MAC) hardware accelerator includes a plurality of multipliers. The plurality of multipliers multiply a digit-serial input having a plurality of digits by a parallel input having a plurality of bits by sequentially multiplying individual digits of the digit-serial input by the plurality of bits of the parallel input. A result is generated based on the multiplication of the digit-serial input by the parallel input. An accelerator framework may include multiple MAC hardware accelerators, and may be used to implement a convolutional neural network. The MAC hardware accelerators may multiple an input weight by an input feature by sequentially multiplying individual digits of the input weight by the input feature.