Boltzmann Machine Circuit Using Thermal Noise for Local Minimum Escape

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Solution Overview

Problem

Conventional Boltzmann machines face challenges in efficiently changing the amplitude of random noise due to large circuit scales and random noise generation, making it difficult to prevent solutions from falling into local minimum values.

Innovation Solution

The implementation of a Boltzmann machine with circuit units that include adders, comparison units, and digital arithmetic units capable of generating weighted input signals, using thermal noise and DA converters to vary the amplitude of random noise, allowing for a small-scale circuit to control the probability of output changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a random noise generator is used to change the probability of lattice output, then the temperature parameter can be adjusted, but the circuit scale becomes large and the noise amplitude control becomes difficult

Engineering Contradiction:
Improvetemperature parameter adjustmentVSAvoidcircuit scale
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent changes the parameter representation from direct analog noise amplitude control to digital domain control. By converting the temperature parameter to digital form and using digital-to-analog conversion only where necessary, the system achieves parameter adjustability while reducing circuit complexity. The digital random number generator and digital arithmetic operations replace the need for large-scale analog noise generation circuits.

Inventive Principle:
Principle #35Parameter changes

2Temperature

If conventional analog noise generation is used, then temperature control is possible, but the noise amplitude cannot be appropriately changed due to random magnitude

Engineering Contradiction:
Improvetemperature parameter controlVSAvoidnoise amplitude control
Core Design Contradiction:
TemperatureVSEase of operation

Solution Approach 1:

The patent replaces the analog mechanical noise generation system with a digital system. Instead of using analog circuits to generate and control noise amplitude, the invention uses digital random number generation combined with digital arithmetic operations. The digital-to-analog converter is used only at the final stage where precise amplitude control is needed, allowing easy adjustment of noise amplitude through digital parameter setting rather than complex analog circuit tuning.

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

3Reliability

If simulated annealing is implemented with conventional circuits, then local minimum prevention is achieved, but the circuit scale increases

Engineering Contradiction:
Improvelocal minimum preventionVSAvoidcircuit scale
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the simulated annealing function into modular digital components: a digital random number generator, digital arithmetic units for weighted sum calculation, and digital comparison units. Each circuit unit processes one lattice point independently, allowing the system to maintain reliability for local minimum prevention while keeping individual circuit blocks small and manageable. The modular structure enables scalable implementation without proportionally increasing overall circuit complexity.

Inventive Principle:
Principle #1Segmentation

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 enables the effective variation of random noise amplitude with a small-scale circuit, enhancing the ability to escape local minima and achieve optimal solutions by stochastically changing the energy state.

Implementation Method 1

a first comparator that compares a thermal noise with a reference voltage to output a binary digital random signal

Methodology Applied
Scientific EffectThermal noise:

Implementation Method 2

a first DA converter that converts the digital random signal to an analog random signal, and varies a magnitude of the analog random signal

Methodology Applied
Scientific EffectDigital-to-Analog conversion:

Implementation Method 3

a second comparator that input the analog random signal as the threshold signal, and compares the output signal of the adder with the threshold signal to generate the binary output signal with a predetermined probability function

Methodology Applied
Scientific EffectThermal noise:

Data Source

PatentUS11074493B2Boltzmann machine, method for controlling boltzmann machine, and information processing device having boltzmann machine
Publication Date: 2021.07.27 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD
  • US11074493B2 patent drawing
  • US11074493B2 patent drawing
  • US11074493B2 patent drawing

AI summary

Boltzmann machine includes a plurality of circuit units each having an adder that adds weighted input signals and a comparison unit that compares an output signal of the adder with a threshold signal to output a binary output signal; and digital arithmetic units each generating the weighted input signals by weighting the binary output signal of the circuit units with a weight. The comparison unit has a first comparator that compares a thermal noise with a reference voltage to output a binary digital random signal, a DA converter that converts the digital random signal to an analog random signal and varies a magnitude of the analog random signal, and a second comparator that compares the output signal of the adder with the analog random signal to generate the binary output signal with a predetermined probability function.