Digital Ring Oscillator Random Bit Generation with Fixed Points

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Solution Overview

Problem

Existing random number generators using analog noise sources and hybrid analog/digital circuits are difficult to implement, and the selection of suitable ring oscillators is limited due to the requirement of no fixed points, which restricts the use of a broader class of oscillators for generating random bit sequences.

Innovation Solution

A device with a digital ring oscillator circuit having an odd number of cascaded inverters or logic circuits, allowing for oscillation and the generation of random signals with a fixed point, where the presence of a fixed point does not harm the randomness, enabling a larger class of oscillators to be used, including those with fixed points, and reducing energy consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If analog noise sources are used to generate random numbers, then the quality of randomness is improved, but the implementation complexity and cost increase due to hybrid analog/digital circuits

Engineering Contradiction:
Improvequality of randomnessVSAvoidimplementation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces analog noise sources with a digital ring oscillator circuit that uses thermal and quantum mechanical processes within semiconductor components to generate phase fluctuations and jitter. This substitution eliminates the need for hybrid analog/digital circuits while maintaining randomness quality, as the digital circuit inherently captures thermal noise through phase variations in the oscillation signal.

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

Solution Approach 2:

The patent changes the parameter of interest from analog voltage levels to digital phase/timing relationships. By measuring phase differences between clock signals at different nodes of the ring oscillator, the system captures randomness through temporal parameter variations rather than analog amplitude variations, enabling pure digital implementation while preserving randomness quality.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If ring oscillators without fixed points are used, then the selection of oscillator circuits is limited, but the implementation follows existing protocols

Engineering Contradiction:
Improveselection of oscillator circuitsVSAvoidcomplexity of fixed point analysis
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent converts the previously harmful fixed point condition into a beneficial feature. By proving that fixed points do not compromise randomness quality and can even reduce energy consumption, the invention expands the usable class of ring oscillators to include those with fixed points, thereby increasing design flexibility without requiring complex fixed point analysis or exclusion procedures.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Ease of manufacture

If special Fibonacci or Galois ring oscillators are used, then the randomness generation follows established methods, but the hardware outlay and design flexibility increase

Engineering Contradiction:
Improvehardware outlayVSAvoiddesign flexibility
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent establishes a universal framework for random number generation using any digital ring oscillator circuit, regardless of whether it is a Fibonacci, Galois, or other configuration. The method works with any odd number of cascaded inverters or logic circuits, making the solution universally applicable to diverse oscillator designs while maintaining simplicity and reducing hardware requirements compared to specialized implementations.

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

4Reliability

If continuous oscillation is maintained to ensure randomness, then the statistical quality of random bits is improved, but the energy consumption increases

Engineering Contradiction:
Improvestatistical quality of random bitsVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent employs periodic sampling of the oscillation signal rather than continuous processing. By capturing random phase information at periodic intervals and using latch circuits to store the sampled values, the system maintains statistical quality of random bits while significantly reducing energy consumption compared to continuous oscillation and processing.

Inventive Principle:
Principle #19Periodic 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

The solution allows for easy implementation and efficient generation of random bit sequences with high statistical quality, suitable for low-cost, exclusively digital logic circuits, particularly in CMOS technology, and can be implemented in FPGA or ASIC forms, reducing the need for complex calculations to exclude fixed points.

Implementation Method 1

For example, thermal or quantum mechanical processes within the semiconductor components used to implement the oscillator result in phase fluctuations or jitter, which cause random internal signal or potential profiles.

Methodology Applied
Scientific EffectThermal processes: Thermal Radiation

Implementation Method 2

For example, thermal or quantum mechanical processes within the semiconductor components used to implement the oscillator result in phase fluctuations or jitter, which cause random internal signal or potential profiles.

Methodology Applied
Scientific EffectQuantum mechanical processes:

Data Source

PatentEP2183726B1Device and method for generating a random bit sequence
Publication Date: 2014.06.04 SIEMENS AG
  • EP2183726B1 patent drawingFigure 1
  • EP2183726B1 patent drawingFigure 2
  • EP2183726B1 patent drawingFigure 3

AI summary

The invention relates to a device (1) for generating a random bit sequence with a digital ring oscillator circuit (2) comprising logic components, said circuit comprising an input node (3) and an output node (4), wherein the digital ring oscillator circuit (2) is designed such that oscillation occurs during a change of state of a logic start signal (ST) coupled on the input node (3), said oscillation having a fixed point, and wherein on the output node (4) a random signal (OS) can be tapped having an arbitrary level curve.