Neural Network Device Stochastic Synaptic Weight Update

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Solution Overview

Problem

Conventional artificial intelligence systems require significant computational power and memory capacity to learn and store synaptic weights, making them inefficient for edge devices, especially when using continuous synaptic weights, and complex analog memory systems are needed for accurate representation.

Innovation Solution

A neural network device with a spiking neural network configuration that uses stochastic update rules for synaptic weights represented by discrete values, such as binary, allowing for efficient learning with small-scale circuitry by dividing synapse circuits into groups and using random number generators to control update probabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If continuous synaptic weights are used in spiking neural networks, then learning accuracy is improved, but memory capacity and device complexity increase significantly

Engineering Contradiction:
Improvelearning accuracyVSAvoidmemory capacity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent changes the representation parameter of synaptic weights from continuous values to discrete binary values (0 or 1). This parameter change fundamentally transforms the memory requirements and computational approach, enabling accurate learning in spiking neural networks while dramatically reducing memory capacity needs and device complexity.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs stochastic update rules that probabilistically modify synaptic weights based on spike timing relationships. Instead of requiring precise continuous weight storage, the system uses simple binary weights that are updated stochastically during learning, effectively replacing complex memory systems with simpler, more efficient components.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Measurement precision

If analog memory is used to store continuous synaptic weights, then representation accuracy is improved, but circuit complexity increases

Engineering Contradiction:
Improverepresentation accuracyVSAvoidcircuit complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical/analog memory system with a digital/stochastic update system. Instead of using analog memory components that require precise signal control and complex circuitry, the system uses binary weight representation with stochastic update rules implemented through simpler digital circuits and probability control mechanisms.

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

Solution Approach 2:

The patent fundamentally changes the storage parameter from continuous analog values to discrete binary values. This parameter transformation eliminates the need for complex analog memory circuits while maintaining learning accuracy through the stochastic update mechanism that captures essential temporal relationships between spikes.

Inventive Principle:
Principle #35Parameter changes

3Device complexity

If discrete synaptic weights are used, then device complexity is reduced, but learning precision deteriorates

Engineering Contradiction:
Improvecircuit complexityVSAvoidlearning precision
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent employs stochastic update rules that enable discrete weight systems to automatically adapt and refine their representations during learning. The probability control circuit and update mechanism allow the system to self-adjust synaptic weights based on spike timing relationships, compensating for the limitations of discrete representation and achieving precise learning outcomes.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent changes the update mechanism parameter from deterministic to stochastic. This allows discrete binary weights to evolve through probabilistic updates driven by temporal relationships between pre- and post-synaptic spikes, enabling the system to capture precise temporal information despite the discrete nature of the weights.

Inventive Principle:
Principle #35Parameter changes

4Device complexity

If stochastic update rules are used with discrete weights, then device complexity is reduced and power consumption is lowered, but update accuracy may be affected

Engineering Contradiction:
Improvecircuit complexityVSAvoidupdate accuracy
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent incorporates feedback mechanisms through the probability control circuit that monitors spike timing relationships and adjusts update probabilities accordingly. This feedback loop ensures that stochastic updates accurately reflect the temporal correlations between pre- and post-synaptic spikes, maintaining update accuracy while using simpler circuits and lower power.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The stochastic update mechanism serves itself by automatically adjusting weight values based on observed spike timing patterns. The system self-regulates the update process through probability control, ensuring accurate learning without requiring complex external control circuits or additional computational resources.

Inventive Principle:
Principle #25Self-service

Data Source

PatentUS20240296325A1Neural network device and synaptic weight update method
Publication Date: 2024.09.05 KK TOSHIBA
  • US20240296325A1 patent drawing
  • US20240296325A1 patent drawing
  • US20240296325A1 patent drawing

AI summary

A neural network device according to an embodiment includes a plurality of neuron circuits, a plurality of synapse circuits, and a plurality of random number circuits. Each of the random number circuits outputs a random signal. Each of the synapse circuits receives the random signal from one of the random number circuits and updates a synaptic weight with a probability generated on the basis of the received random signal. The synapse circuits are divided into synapse groups. Each of two or more synapse circuits belonging to a first synapse group receives the random signal output from a first random number circuit. Each of two or more synapse circuits outputting output signals to a first neuron circuit belongs to a synapse group differing from a synapse group, to which other synapse circuits outputting the output signal to the first neuron circuit, belong.