Dual-Mode Reconfigurable PUF Circuit for Stable IoT Responses

Solution Overview

Problem

Existing PUF technologies suffer from low reliability due to process variations and environmental factors, leading to unstable responses, particularly in SRAM and inverter modes, which compromise security and integrity in IoT applications.

Innovation Solution

A reconfigurable PUF with two PUF functions, comprising 2m×n PUF cells, a sequential control module, row selection module, and amplification modules, allows operation in both SRAM and inverter modes, utilizing PMOS and NMOS transistors to stabilize responses and ensure reliability through stable and instable cell differentiation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If SRAM PUF uses cross-coupled inverters to generate PUF responses, then unique identity tags can be obtained, but noise amplification occurs resulting in low reliability

Engineering Contradiction:

ImprovePUF response reliabilityVSAvoidnoise amplification

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent implements dynamic mode switching capability that allows the PUF circuit to transition between SRAM mode and inverter mode based on operating conditions. This dynamic adaptation enables the system to select the most reliable operating mode under different environmental conditions, thereby resolving the reliability issue caused by noise amplification in fixed-mode SRAM PUFs.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the operational parameters of the PUF circuit by introducing configurable modes (SRAM mode and inverter mode) with different electrical characteristics. By adjusting the operating mode parameter, the system can optimize the balance between noise amplification and process variation exploitation, improving overall response reliability without sacrificing uniqueness.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If inverter mode PUF amplifies process variation through high-gain characteristic, then PUF responses can be generated, but temperature and voltage changes cause threshold shifts resulting in response flipping

Engineering Contradiction:

ImprovePUF response stabilityVSAvoidtemperature and voltage sensitivity

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent implements dynamic mode switching capability that allows the PUF circuit to transition between SRAM mode and inverter mode based on operating conditions. This dynamic adaptation enables the system to select the most reliable operating mode under different environmental conditions, thereby resolving the reliability issue caused by noise amplification in fixed-mode SRAM PUFs.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent introduces a mode selection mechanism that effectively implements feedback control by monitoring operating conditions and selecting the appropriate PUF mode. This feedback approach compensates for environmental variations by adapting the circuit's operational state, preventing response flipping caused by threshold shifts due to temperature and voltage changes.

Inventive Principle:

Principle #23Feedback

3Reliability

If PUF circuit uses fixed operating mode, then circuit design is simplified, but reliability decreases under varying environmental conditions

Engineering Contradiction:

Improveenvironmental adaptabilityVSAvoidcircuit configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent makes the PUF circuit universal by enabling it to function in multiple modes (SRAM mode and inverter mode). This multi-functionality allows the same circuit structure to adapt to different environmental conditions and application requirements, improving environmental adaptability without requiring multiple separate PUF circuits.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent implements dynamic mode switching capability that allows the PUF circuit to transition between SRAM mode and inverter mode based on operating conditions. This dynamic adaptation enables the system to select the most reliable operating mode under different environmental conditions, thereby resolving the reliability issue caused by noise amplification in fixed-mode SRAM PUFs.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12437119B2Reconfigurable PUF with two PUF functions

Publication Date: 2025.10.07 WENZHOU UNIV

AI summary

A reconfigurable PUF with two PUF functions comprises 2m×n PUF cells, a sequential control module, a row selection module, n amplification modules, n first bit lines, and n second bit lines. Each of the 2m×n PUF cells comprises a first PMOS transistor, a second PMOS transistor, a first NMOS transistor, a second NMOS transistor, a third NMOS transistor, a fourth NMOS transistor, a fifth NMOS transistor, a sixth NMOS transistor and a seventh NMOS transistor. The PUF cells can provide two independent responses, and can operate in a SRAM mode and an inverter mode. Therefore, the reconfigurable PUF with two PUF functions can operate both in the SRAM mode and the inverter mode, and a PUF operating mode with higher reliability is selected for generating final responses.