Bipolar Transistor Array PUF for Secure Component Identification
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Solution Overview
Problem
Existing physical unclonable functions (PUFs) are either considered weak in a cryptographic sense or lack alternatives, particularly in silicon-based forms, which are desirable due to semiconductor technology familiarity but require more robust identification methods.
Innovation Solution
A method and circuit utilizing an array of bipolar transistors with common base, collector, and emitter contacts, where a challenge is responded to by increasing the total collector or emitter current to detect instability in the transistors, generating a unique response for component identification, effectively distinguishing the component from clones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If SRAM-based PUF is used, then silicon-based identification is achieved, but cryptographic strength is weak
Solution Approach 1:
The patent changes the operating parameters of bipolar transistors by increasing total collector or emitter current from a first level to a second level, inducing electro-thermal instability that generates unique, repeatable responses based on individual transistor characteristics, thereby achieving cryptographically strong identification while maintaining silicon-based manufacturability
2Reliability
If optical PUF systems are used, then unique identification is achieved, but silicon-based implementation is not realized
Solution Approach 1:
The patent substitutes optical measurement systems with electrical measurement systems by using bipolar transistors in an electrical circuit configuration, where electro-thermal instability is detected through electrical current measurements, thereby achieving unique identification through silicon-based electronic components rather than optical systems
3Reliability
If magnetic PUF or coating-based PUF is used, then identification capability is achieved, but semiconductor integration is limited
Solution Approach 1:
The patent utilizes electro-thermal instability in bipolar transistors by changing operational parameters (current levels) to induce instability, generating unique identification responses that are inherently integrated into semiconductor fabrication processes, thereby achieving both identification capability and seamless semiconductor integration
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 provides a robust and unique identification method for components, leveraging the electro-thermal instability of bipolar transistors to create a repeatable and secure challenge-response pair, enhancing security by utilizing the unique switching effects in transistor arrays.
Implementation Method 1
detecting instability in each of a group of the transistors
Data Source
AI summary
A method of identifying a component by a response to a challenge is disclosed, the component comprising an array of bipolar transistors connectable in parallel so as to have a common collector contact, a common emitter contact and a common base contact, the challenge comprising a value representative of a total collector current value, the method comprising: receiving the challenge; supplying the total collector current to the common collector contact; detecting instability in each of a group of the transistors; and determining the response in dependence on the group. A circuit configured to operate such a method is also disclosed.