Metastable Flash Memory PUF Circuit for Enhanced Randomness
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Solution Overview
Problem
Existing physical unclonable function (PUF) circuits in semiconductor devices face reduced data security due to reduced randomness of generated random data when the read current level is not centered, affecting the uniqueness and security of the digital fingerprint.
Innovation Solution
A PUF circuit design that includes a flash memory, a current comparator, and a controller, where memory cells are set to a metastable state between the initial and adjacent data states, allowing the current comparator to read currents from memory cells in different sections and generate random bits based on these currents, independent of the read current level, thereby enhancing randomness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the read current level is set to a marginal range near the read current level, then the PUF circuit can generate random data, but the randomness is reduced when the read current level is not in the center of the marginal range
Solution Approach 1:
The patent changes the operating parameter from using a fixed read current level to using a metastable state between 0 and 1 states. This parameter change eliminates the dependency on read current level positioning and ensures high randomness regardless of the read current level, thereby resolving the contradiction between reliability and manufacturing precision
Solution Approach 2:
The patent introduces a metastable state as an intermediary between the initial data state (0 state) and adjacent data state (1 state). This intermediary state serves as a new operating point that is independent of read current level variations, resolving the contradiction by providing a stable basis for random data generation
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 increases the randomness and uniqueness of the random bits generated, improving data security by ensuring equal probabilities for the logical values, thus enhancing the digital fingerprint's uniqueness and security.
Implementation Method 1
sets the plurality of memory cells to a state between the initial data state and an adjacent data state of the initial data state
Implementation Method 2
The flash memory includes a plurality of memory cells... setting the plurality of memory cells to an initial data state, setting the plurality of memory cells to a state between the initial data state and an adjacent data state
Data Source
AI summary
A physically unclonable function includes a flash memory, a current comparator and a controller. The flash memory includes a plurality of memory cells. A method of operating the physically unclonable function circuit includes the controller setting the plurality of memory cells to an initial data state, the controller setting the plurality of memory cells between the initial data state and an adjacent data state of the initial data state, the current comparator reading a first current from a memory cell in a first section of the plurality of the memory cells, the current comparator reading a second current from a memory cell in a second section of the plurality of the memory cells, and the current comparator outputting a random bit according to the first current and the second current.