Low-Voltage Attack Detector With Multi-Region Flag Hold
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Solution Overview
Problem
Existing hardware security systems for semiconductor chips are vulnerable to semi-invasive attacks, particularly low voltage attacks that can cause malfunctions without direct physical access, leading to exposure of sensitive information.
Innovation Solution
A low voltage attack detector system utilizing a bandgap reference (BGR) circuit with PMOS transistors and bipolar junction transistors, along with a power on reset (POR) circuit, to detect abnormal voltage levels and maintain a high-level detection flag signal even when the power supply voltage drops to a region where analog circuits malfunction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a bandgap reference (BGR) circuit is used to detect low voltage, then the detection accuracy is improved, but the circuit malfunctions when voltage drops to a certain level
Solution Approach 1:
The voltage detection function is segmented into multiple independent detection circuits: a first detection circuit using BGR for normal voltage range detection, a second detection circuit using a first comparator for low voltage range detection, and a third detection circuit using a second comparator for very low voltage range detection. Each circuit operates independently within its optimal voltage range, eliminating the malfunction problem when voltage drops.
Solution Approach 2:
Different detection circuits use different reference voltage parameters adapted to their respective detection ranges. The BGR circuit uses a first reference voltage suitable for normal operation, while the comparator circuits use second and third reference voltages respectively suited for low and very low voltage detection, allowing accurate detection across the entire voltage spectrum.
2Device complexity
If a single detection circuit is used, then the device complexity is reduced, but the detection coverage across different voltage regions is insufficient
Solution Approach 1:
The voltage detection function is segmented into multiple independent detection circuits: a first detection circuit using BGR for normal voltage range detection, a second detection circuit using a first comparator for low voltage range detection, and a third detection circuit using a second comparator for very low voltage range detection. Each circuit operates independently within its optimal voltage range, eliminating the malfunction problem when voltage drops.
Solution Approach 2:
The voltage detection device achieves multi-functionality by integrating three different detection circuits that collectively cover the entire voltage operating range. The system can detect normal voltage, low voltage, and very low voltage conditions, making it universally applicable across all operational scenarios.
3Ease of operation
If the detection flag signal level changes with voltage, then the circuit responds to voltage changes, but the detection signal cannot be maintained in abnormal voltage regions
Solution Approach 1:
The detection circuits are designed to activate in advance before the voltage reaches critical failure levels. The first comparator detects when voltage enters the low voltage range and generates a second detection signal, while the second comparator detects very low voltage conditions and generates a third detection signal, allowing the system to take preliminary protective actions before complete failure occurs.
Solution Approach 2:
The detection circuits provide continuous feedback about the voltage status through distinct detection signals. The first detection circuit provides feedback on normal voltage, the second provides feedback on low voltage conditions, and the third provides feedback on very low voltage conditions, enabling the system to continuously monitor and respond to voltage changes.
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
Effectively prevents system operation in abnormal power supply regions, ensuring security by maintaining a high-level detection flag signal and enabling timely system disabling or reset, thus preventing data exposure and hacking attempts.
Implementation Method 1
a low voltage detector configured to output a low voltage detection flag signal having a high level when a first power supply voltage reaches a first voltage level using a bandgap reference (BGR) circuit
Implementation Method 2
a first resistor and a bipolar junction transistor (BJT) connected in series between the first power supply voltage and a second power supply voltage
Implementation Method 3
a comparator including a first input terminal connected to a first node between the first resistor and the BJT and a second input terminal connected to a second node between the second resistor and the third resistor
Data Source
AI summary
A low voltage attack detector includes: a low voltage detector configured to output a low voltage detection flag signal having a high level when a first power supply voltage reaches a first voltage level using a bandgap reference (BGR) circuit including a PMOS transistor and a first bipolar junction transistor (BJT) connected in series between the first power supply voltage and a second power supply voltage; a BGR operation region detector configured to output a malfunction detection flag signal having a high level when the first power supply voltage reaches a second voltage level lower than the first voltage level; and a logic gate configured to output a final low voltage detection flag signal having a high level when at least one of the low voltage detection flag signal and the malfunction detection flag signal has a high level.