Laser Fault Detection Cells for Fast IC Tamper Shutdown

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Solution Overview

Problem

Laser fault injection attacks degrade data security by causing incorrect timing or data flipping in integrated circuits, compromising their operations.

Innovation Solution

A fault-injection protection circuit with a detection circuit and detection cells having unequal pull-up and pull-down capabilities, arranged close to the protected circuit, rapidly detects laser faults and disables the circuit to prevent unauthorized access.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a detection circuit with unequal pull-up and pull-down capabilities is placed close to the protected circuit, then the detection speed and accuracy improve, but the device complexity increases

Engineering Contradiction:

Improvelaser fault detection accuracyVSAvoidcircuit complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The protection system is segmented into independent detection cells positioned at specific locations around the protected circuit. Each detection cell operates autonomously with unequal pull-up/pull-down capabilities, allowing localized fault detection without requiring a complex centralized detection system.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The detection circuit employs cells with asymmetric pull-up and pull-down capabilities specifically positioned at critical locations within laser spot diameter distance from the protected circuit. This local asymmetry creates differential responses to laser-induced faults, enhancing detection accuracy at specific vulnerable points without complicating the entire circuit.

Inventive Principle:

Principle #3Local quality

2Speed

If the detection circuit is arranged at a distance less than laser spot diameter from the protected circuit, then the detection responsiveness improves, but the manufacturing precision requirements increase

Engineering Contradiction:

Improvefault detection speedVSAvoiddetection cell positioning precision

Core Design Contradiction:

SpeedVSManufacturing precision

Solution Approach 1:

The detection cells are pre-positioned at predetermined locations that are less than one laser spot diameter away from potential attack points on the protected circuit. This preliminary positioning ensures that when a laser fault injection occurs, the detection cells are already in optimal position to detect the fault immediately, eliminating the need for real-time positioning adjustments.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Multiple detection cells are strategically placed in advance around the protected circuit to create overlapping detection zones. This redundancy provides a cushion against positioning variations during manufacturing, ensuring that at least one detection cell will be within the effective detection range regardless of minor manufacturing tolerances.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS12608508B2Fault-injection protection circuit for protecting against laser fault injection

Publication Date: 2026.04.21 EMEMORY TECH INC

AI summary

A fault-injection protection circuit includes a circuit under protection and a detection circuit. The detection circuit includes a detection cell having unequal pull-up capability and pull-down capability, and is arranged at a distance less than a laser spot diameter from the circuit under protection. The detection circuit is used to generate an alarm signal upon detecting a laser fault injection.