Oscillation Generator Circuit With Asymmetric Delay Control
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Solution Overview
Problem
Existing random number generators face challenges in producing non-cloneable physical functions and ensuring sufficient randomness, particularly in applications requiring unique identifiers and cryptographic keys, due to limitations in controlling the number of oscillations before generator stoppage and imbalance between rise and fall times.
Innovation Solution
A circuit design incorporating symmetrical and asymmetrical delay lines with NAND gates and multiplexers, allowing for controllable oscillation generation and verification, using paired inverters for symmetrical delays and non-inverting logic elements for asymmetrical delays to manage rise and fall times, ensuring deterministic stopping conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If delay lines are used to generate oscillations, then random number generation capability is improved, but control over the number of oscillations before stoppage deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-configuring the delay lines with specific delay values before oscillation generation begins. The delay lines are designed with predetermined characteristics that control the oscillation behavior, allowing the system to achieve both randomness and可控性 (controllability) of oscillation count without real-time adjustment complexity
Solution Approach 2:
The patent implements feedback mechanisms where the oscillation output is monitored and fed back to control logic that can detect when oscillations have sufficient randomness. This feedback loop allows the system to stop oscillations at appropriate moments, providing control over the number of oscillations while maintaining random number generation quality
2Manufacturing precision
If asymmetrical delay elements are used, then rise and fall time differences are improved, but circuit complexity increases
Solution Approach 1:
The patent applies local quality by introducing asymmetry only in specific delay elements where it is needed to control rise and fall times, rather than making the entire circuit asymmetrical. This localized approach to creating time differences minimizes overall circuit complexity while achieving the desired timing precision for random number generation
Solution Approach 2:
The patent deliberately introduces asymmetry in the delay line configuration, using delay elements with different characteristics for rising and falling edges. This controlled asymmetry is essential for creating the timing variations needed for high-quality random number generation, while the asymmetry is carefully managed to avoid excessive circuit complexity
3Ease of operation
If multiple delay lines are used, then oscillation control is improved, but device area increases
Solution Approach 1:
The patent applies segmentation by dividing the delay control function into multiple separate delay lines, each with specific delay characteristics. This segmentation allows independent control of different oscillation parameters, improving oscillation control capability while the modular structure helps manage the overall area requirement through efficient layout and shared resources
Data Source
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AI summary
The invention relates to a circuit (20) for generating a number of oscillations comprising: a first branch including at least one delay line (21) providing symmetrical delays on rising and falling edges and at least one asymmetrical delay element (22) providing different delays on rising and falling edges; a second branch, looped back on the first and including at least one delay line (27) providing symmetrical delays on rising and falling edges.