Digital Sensor Calibration Device for Security and Performance
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Solution Overview
Problem
Digital circuits are vulnerable to attacks that exploit out-of-specifications operating conditions, leading to faulty computations and security breaches, as existing protection methods often result in low circuit performance due to arbitrarily set alarm thresholds.
Innovation Solution
A calibration device optimizes the alarm threshold to minimize the probability of false positives and false negatives by dynamically adjusting the digital sensor's parameters, ensuring greater performance and security by confining the alarm threshold within smaller margins relative to the critical path propagation delay and clock period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the alarm threshold is set arbitrarily in broad intervals to protect the digital circuit, then security is improved, but circuit performance deteriorates due to lower clock frequency operation
Solution Approach 1:
The patent applies parameter changes by optimizing the alarm threshold from an arbitrary value to a precisely calibrated value. The calibration device determines the optimal alarm threshold based on the actual propagation delay characteristics of the critical path, changing the threshold parameter from a conservative estimate to an optimized value that minimizes false positives while maintaining security detection capability.
Solution Approach 2:
The patent replaces the mechanical/system-level approach of using broad safety margins with a measurement-based calibration approach. Instead of relying on conservative timing estimates, the system uses a calibration device to measure actual propagation delays and set precise thresholds, substituting empirical engineering practice with systematic calibration.
2Reliability
If the alarm threshold is set conservatively with broad margins, then false positives are reduced, but the clock frequency must be lowered reducing overall circuit performance
Solution Approach 1:
The calibration device enables the digital sensor system to self-calibrate by automatically determining the optimal alarm threshold based on its own actual propagation delay characteristics. The system serves itself by measuring its own timing parameters and configuring its threshold accordingly, eliminating the need for conservative external estimates.
Solution Approach 2:
The patent implements feedback by using the measured propagation delay information to adjust the alarm threshold setting. The calibration device measures the actual timing characteristics and feeds this information back to optimize the threshold, creating a closed-loop system that adapts to actual circuit behavior rather than relying on open-loop conservative estimates.
3Reliability
If the propagation delay in the data path is increased to allow stable data arrival, then setup time violations are avoided, but the critical path delay increases reducing circuit speed
Solution Approach 1:
The patent applies dynamics by making the alarm threshold adaptive rather than fixed. The threshold is dynamically calibrated based on actual propagation delay measurements, allowing the system to adapt to varying operating conditions and actual circuit behavior rather than relying on static conservative estimates.
Solution Approach 2:
The calibration device performs preliminary action by determining the optimal alarm threshold before the digital sensor operates in its final application. This pre-calibration ensures that the threshold is optimally set based on actual circuit characteristics, preventing both false positives and false negatives from the outset.
Data Source
AI summary
There is provided a calibration device for calibrating a digital sensor (3), said digital sensor being configured to protest a target digital circuit (30) fed by a clock signal having a clock period by triggering an alarm depending on a condition between said clock signal and an optimal alarm threshold, said optimal alarm threshold being determined by minimizing a quantity depending on the probability of occurrence of false positives and on the probability of occurrence of false negatives.