Power Glitch Detection Circuit Using Delayed Dual Threshold Paths
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Solution Overview
Problem
Existing power glitch detection circuits, such as those described in US7085979B2, rely on a single power supply and resistor divider for glitch detection, which are susceptible to glitches and struggle to distinguish between normal supply ripples and malicious hacker attacks, necessitating an improved method to identify real hacker glitches.
Innovation Solution
A glitch detection circuit utilizing a glitch sense threshold generator that generates positive and negative glitch threshold signals through parallel paths with path delay circuits and comparators, operating in a stable analog domain to distinguish between normal supply ripples and hacker attacks, with adjustable sensitivity through trimmable resistances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single power supply and resistor divider are used for glitch detection, then the device complexity is reduced, but the ability to distinguish between normal supply ripples and malicious hacker attacks deteriorates
Solution Approach 1:
The detection circuit is segmented into multiple independent paths (first path and second path) with different delay characteristics. Each path processes the power supply signal differently, allowing the system to compare signals with varying time delays and distinguish between normal ripples and malicious glitches based on their temporal patterns.
Solution Approach 2:
The invention adds a time dimension to the detection by introducing path delay circuits that create temporal differences between signal paths. This transforms a simple voltage comparison into a spatiotemporal analysis, enabling the detection circuit to identify glitches based on their rise time characteristics rather than just voltage magnitude.
2Measurement precision
If a lower threshold is used for glitch detection, then the detection sensitivity is improved, but the false positive rate increases due to normal supply ripples
Solution Approach 1:
The detection system dynamically adapts to different signal characteristics by using multiple paths with different delay characteristics. The system can adjust its detection behavior based on the temporal patterns observed in the signals, allowing it to maintain high sensitivity while filtering out normal supply ripples that exhibit different temporal behavior than malicious glitches.
Solution Approach 2:
The invention changes the detection parameter from simple voltage threshold comparison to include time delay characteristics. By introducing path delay circuits, the system detects glitches based on both voltage magnitude and temporal patterns, effectively changing the detection parameters to distinguish between normal ripples and malicious attacks.
3Device complexity
If the detection circuit operates in the same digital supply domain, then the circuit simplicity is maintained, but the detection reliability deteriorates due to susceptibility to glitches
Solution Approach 1:
The invention introduces an intermediary mechanism (path delay circuit) between the power supply signal and the comparison operation. This intermediary processes the signal in a controlled manner, creating delayed versions that can be safely compared without being directly susceptible to the same glitches affecting the original signal, thereby improving detection reliability.
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 circuit effectively identifies and distinguishes between normal supply ripples and malicious power glitches, providing accurate detection and storing the results until a reset signal is applied, even when the digital supply voltage disappears, thus enhancing security against hacker attacks.
Implementation Method 1
a path delay circuit coupled to the glitch sense threshold generator and comprising a first path and a second path located in parallel, wherein the first path provides a first output of a slow signal path of the digital supply to be detected that is used as the positive glitch threshold signal and the second path provides a second output of a slow signal path of the digital supply to be detected that is used as the negative glitch threshold signal
Implementation Method 2
a comparator circuit coupled to the path delay circuit and arranged to receive the digital supply to be detected and respectively compare the digital supply to be detected with the first output of a slow signal path and the second output of a slow signal path
Data Source
Figure 1~3
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AI summary
A glitch detection circuit (200) is arranged detect a glitch on a digital supply (150) and comprises a glitch sense threshold generator (132), a path delay circuit (133) comprising two parallel paths, wherein the first path provides a first output of a slow signal path of the digital supply to be detected that is used as a positive glitch threshold signal (530) and the second path provides a second output of a slow signal path of the digital supply to be detected that is used as a negative glitch threshold signal (540). A comparator circuit (134) is arranged to compare the digital supply to be detected with the first output of a slow signal path and the second output of a slow signal path; wherein the output of the comparator circuit indicates a power glitch on the digital supply in response to the positive or negative glitch threshold signals.