Digital Timer Neuromorphic STDP Synapse Timing

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Solution Overview

Problem

Neuromorphic systems with Spike Time Dependent Plasticity (STDP) synapse and Leaky Integrate and Fire (LIF) models face computational inefficiencies in software simulations, leading to long processing times even with few modeled synapses and neurons, such as in handwritten number recognition tasks.

Innovation Solution

Implementing hardware-based digital timers with multi-bit digital values in neuromorphic systems to generate time signals, update parameters, and emulate neuron spike shapes, thereby enhancing processing speed and stability by converting parallel operations to serial and minimizing errors in spike shape emulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If software simulation is used to model STDP synapse and LIF neuron, then the system can be implemented with standard computing resources, but the computing operation takes a long time

Engineering Contradiction:
Improveprocessing speedVSAvoidcomputational time
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The patent replaces software-based computational mechanisms with hardware-based digital timer mechanisms. Digital timers physically count clock cycles to generate time signals, eliminating the need for software loops and mathematical computations. This mechanical-to-electronic substitution achieves approximately 10³ times speedup in processing operations.

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

Solution Approach 2:

The patent creates hardware copies of temporal computation functions. Instead of software algorithms calculating elapsed time, physical digital timer circuits replicate this function by directly counting clock cycles. Multiple timers can operate in parallel to handle multiple neurons and synapses simultaneously, enabling hardware acceleration of neuromorphic simulations.

Inventive Principle:
Principle #26Copying

2Productivity

If parallel operations are used in neuromorphic system, then processing capacity increases, but errors in spike shape emulation increase

Engineering Contradiction:
Improveprocessing capacityVSAvoidspike shape emulation accuracy
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent segments the parallel computation into independent temporal phases handled by digital timers. Each timer operates independently to track elapsed time for specific neurons or synapses, allowing parallel execution while maintaining precise temporal control. This segmentation enables parallel processing without compromising spike timing accuracy.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses digital timers to preliminarily establish precise time references before spike events occur. By pre-synchronizing all timers to the same clock source and using them to generate time signals in advance, the system ensures accurate temporal coordination across parallel operations, eliminating emulation errors.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If more learning cycles are performed, then learning accuracy improves, but processing time increases

Engineering Contradiction:
Improvelearning accuracyVSAvoidprocessing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces software-based learning cycle computations with hardware-based digital timer operations. Each learning cycle uses digital timers to rapidly establish time relationships between pre- and post-synaptic spikes, enabling thousands of learning cycles to be completed in practical timeframes while maintaining accurate STDP learning.

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

Data Source

PatentUS11003984B2Timing sequence for digital STDP synapse and LIF neuron-based neuromorphic system
Publication Date: 2021.05.11 SAMSUNG ELECTRONICS CO LTD
  • US11003984B2 patent drawing
  • US11003984B2 patent drawing
  • US11003984B2 patent drawing

AI summary

Methods and systems are provided for operating a neuromorphic system for generating neuron and synapse activities. The method includes: preparing at least one digital timer in the neuromorphic system, each of the at least one digital timers including multi-bit digital values; generating time signals using the at least one digital timer; emulating an analog waveform of a neuron spike; updating parameters of the neuromorphic system using the time signals and the current values of the parameters; presetting, using a processor, the digital values of the at least one digital timer to initial values when the spike input is provided to the node; and updating, using the processor, the digital values of the at least one digital timer with a specified amount when there is an absence of a spike input to the node.