Ring Oscillator Random Number Circuit Using Metastable States
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Solution Overview
Problem
Conventional random number generators using natural phenomena are bulky, power-intensive, and susceptible to external noise, making them unsuitable for miniaturization and integration into compact, high-performance devices.
Innovation Solution
A random number generator design featuring a loop of delay circuits, a pulse generation circuit, and a counter that generates true random numbers based on metastable states, allowing for a compact and low-power implementation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional random number generators use natural phenomena (thermal noise, radioactive rays), then true random numbers can be generated, but the circuit scale increases and power consumption increases
Solution Approach 1:
The patent extracts only the essential function of random number generation from complex natural phenomenon-based circuits. By using a simple ring oscillation circuit with delay elements and a counter, it eliminates unnecessary analog components (amplifiers, waveform shaping circuits) while preserving the core random number generation capability through digital metastable state exploitation
Solution Approach 2:
The patent replaces analog/mechanical random number generation methods (thermal noise, radioactive decay detection) with a digital electronic system. The ring oscillation circuit uses digital logic elements (delay circuits, flip-flops) to generate random numbers through metastable states, substituting physical natural phenomena with digital electronic behavior
2Reliability
If conventional random number generators use natural phenomena, then true random numbers can be generated, but power consumption increases
Solution Approach 1:
The patent replaces power-intensive analog random number generation circuits with a low-power digital ring oscillation circuit. The digital logic elements in the ring oscillator consume significantly less power than analog amplifiers and waveform shaping circuits, while the counter-based random number generation maintains true randomness through metastable state exploitation
Solution Approach 2:
The patent uses simple, low-cost digital logic elements (delay circuits, flip-flops, counters) that can be easily integrated into standard CMOS technology. These digital components are more economical and power-efficient than complex analog circuits, enabling random number generation in resource-constrained environments
3Reliability
If conventional random number generators use thermal noise, then random pulses can be generated, but susceptibility to external noise increases
Solution Approach 1:
The patent replaces analog thermal noise-based random number generation with a digital ring oscillation circuit. The digital system is inherently more immune to external noise interference because it operates with discrete logic levels and uses metastable states for random number generation, rather than relying on analog signal processing that is vulnerable to noise
4Reliability
If conventional random number generators use radioactive rays, then random pulses can be generated, but environmental negative effects occur
Solution Approach 1:
The patent completely eliminates radioactive materials and related components from the random number generation system. It extracts only the essential random number generation function and implements it using non-radioactive digital electronic components, thereby removing all environmental hazards associated with radioactive sources
Solution Approach 2:
The patent uses standard digital logic components that are environmentally safe and can be manufactured using conventional semiconductor fabrication processes. These components replace radioactive sources, eliminating long-term environmental concerns while maintaining random number generation capability
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 enables the creation of a high-performance, miniaturized random number generator with reduced power consumption, capable of producing uniform and reliable true random numbers.
Implementation Method 1
a substrate effect of a field effect transistor configuring a ring oscillation circuit is utilized to vary the ring oscillation circuit's oscillation frequency to generate a clock signal varying in frequency
Implementation Method 2
In the loop, a metastable state occurs having a longevity of '0', '1' or binarized to generate true random number data
Data Source
AI summary
A random number generator includes a ring oscillator having an EX-OR gate and four inverters together forming a loop. This loop enters stable state for a start signal having the low level and oscillates for the start signal having the high level. When the start signal has a pulse of a width shorter than the loop's delay time, output nodes responsively, sequentially enter metastable state hovering between the high and low levels. The metastable waveform becomes smaller with time and finally disappears. As metastable state cannot be controlled in longevity, it disappears at any random number node. A counter thus outputs a signal serving as true random number data depending on the longevity of the metastable state. A random number generator miniaturized and having reduced power consumption, and of high performance can thus be implemented.