Clock-Synchronized Ring Oscillator Startup for Stable Entropy

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Solution Overview

Problem

Ring oscillators experience unpredictable startup behavior due to rapid temperature changes and circuit noise, leading to unstable oscillation frequencies, which compromises the predictability of entropy generation and information security.

Innovation Solution

Synchronizable ring oscillators are used, built with standard logic gates that are synchronized to a stable clock signal during a predetermined warm-up duration, allowing for predictable startup conditions and low-cost stabilization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a thermostat is used to stabilize the circuit temperature, then the startup behavior is stabilized, but the cost increases and analog circuits are required

Engineering Contradiction:
Improvestartup behavior stabilityVSAvoidcircuit complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical/thermal control system (thermostat) with an electronic control system. Specifically, it uses a ring oscillator coupled with a counter and control logic to electronically monitor and regulate the oscillation frequency, thereby stabilizing the startup behavior without requiring analog thermal control circuits.

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

Solution Approach 2:

The ring oscillator system performs self-regulation through the interaction between the oscillator frequency changes and the control logic. When the oscillation frequency deviates due to temperature changes, the counter detects this and the control logic automatically adjusts the circuit to restore stable operation, enabling the system to self-correct without external intervention.

Inventive Principle:
Principle #25Self-service

2Temperature

If dummy circuits are used to generate heat before the ring oscillator starts, then the startup temperature is improved, but the solution is inaccurate and does not ensure predictable startup conditions

Engineering Contradiction:
Improvestartup temperatureVSAvoidstartup predictability
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where the ring oscillator's output is fed into a counter that monitors the oscillation frequency. This feedback loop allows the system to detect temperature-induced frequency variations and automatically adjust the startup conditions to ensure predictable and stable oscillation frequency from the beginning of operation.

Inventive Principle:
Principle #23Feedback

3Temperature

If the ring oscillator is allowed to self-warm-up, then the circuit temperature increases, but predictable startup conditions are not ensured

Engineering Contradiction:
Improvecircuit temperatureVSAvoidwarm-up time
Core Design Contradiction:
TemperatureVSLoss of time

Solution Approach 1:

The patent applies preliminary action by pre-configuring the ring oscillator circuit with controlled warming elements and pre-establishing the feedback control mechanism before operation begins. This allows the circuit to undergo a controlled warm-up phase where the feedback system is already in place to monitor and regulate the oscillation frequency, ensuring predictable startup conditions are achieved faster and more reliably.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3502870B1Stabilizing the startup behavior of ring oscillators
Publication Date: 2024.08.07 THE BOEING CO
  • EP3502870B1 patent drawingFigure 1~2
  • EP3502870B1 patent drawingFigure 3A~3B
  • EP3502870B1 patent drawingFigure 3C

AI summary

A system (100) for providing security in a computer system (110) is provided. The system includes a ring oscillator (102) including a plurality of logic gates connected in a ring configuration. The system also includes logic circuits (101) to start the ring oscillator by a ring-enable signal and a clock signal provided to a clock input of at least one controlled logic gate of the plurality of logic gates. The clock signal controls the at least one controlled logic gate and thereby synchronizes the ring oscillator to the clock signal. The clock signal is provided to the clock input for a predetermined warm-up duration, and thereafter, the logic circuits restart and operate the ring oscillator without the clock signal.