RNG Entropy Source Charge Pump for PVT-Stable Randomness
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Solution Overview
Problem
Random number generators (RNGs) are sensitive to process, voltage, and temperature (PVT) variations, leading to manufacturing inefficiencies, yield loss, and security risks due to insufficient entropy, necessitating improved entropy sources with enhanced randomness and dynamic range characteristics.
Innovation Solution
The implementation of a circuit with an entropy source that utilizes a deterministic feedback circuit with pre-delay and post-delay feedback paths to power on and off the entropy source efficiently, combined with a stochastic feedback circuit using a switched-capacitor stepper circuit and charge pump to adjust drive strength and voltage, thereby improving randomness and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entropy source is powered continuously to ensure sufficient entropy generation, then randomness is improved, but power consumption increases
Solution Approach 1:
The entropy source is powered periodically rather than continuously. A control circuit activates the entropy source for specific time intervals (less than half of the cycle) based on feedback signals, reducing power consumption while maintaining sufficient entropy generation through timed operation cycles
2Reliability
If the inverter drive strength is increased to improve entropy source performance, then randomness is enhanced, but power consumption increases
Solution Approach 1:
The inverter drive strength is made dynamic and adjustable rather than fixed. A charge pump circuit modifies the drive strength of inverters based on feedback signals, allowing the system to optimize performance for entropy generation while consuming less power during non-active periods
Solution Approach 2:
The drive strength parameter of the inverter is changed dynamically based on operational requirements. The charge pump adjusts voltage levels to modify inverter drive strength, enabling the system to achieve high randomness quality only when needed rather than maintaining maximum performance continuously
3Manufacturing precision
If feedback mechanisms are added to control entropy source operation, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
Feedback mechanisms are implemented to monitor and adjust entropy source operation. The system uses feedback signals from the entropy source output to control the timing and drive strength adjustments, compensating for PVT variations and improving manufacturing precision through closed-loop control
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 enhances the entropy source's randomness and dynamic range, reduces power consumption, and mitigates sensitivity to PVT variations, resulting in improved performance and security of RNGs.
Implementation Method 1
a charge pump to adjust drive strength and voltage
Data Source
AI summary
Techniques and mechanisms for facilitating random number generation with an entropy source. In an embodiment, the entropy source comprises two complementary metal-oxide-semiconductor (CMOS) inverters which are cross-coupled with each other between a first node and a second node. A third CMOS inverter of the entropy source includes an output terminal coupled to the first node, and an input terminal which is to receive an adjustment voltage that is based on a first signal at the first node. The first, second and third CMOS inverters are each coupled to a third node by which each is to draw power. The entropy source is to update the first signal based on the adjustment voltage. In another embodiment, the entropy source is coupled to a switched capacitor circuit which is to generate the adjustment voltage based on a feedback of the first signal.