FRAM Random Number Generation via Virgin Cell Read
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing systems lack a reliable method to generate unique and random numbers for cryptographic and identification purposes in low-cost devices, such as sensors and RFID tags, without compromising the integrity of ferroelectric random access memory (FRAM) cells, which are prone to data destruction during reading operations.
Innovation Solution
A method to self-generate a random number by reading virgin FRAM bitcells before any data is written, capturing inherent spontaneous polarization and process variations, and storing this randomness for later use, ensuring the integrity of the memory cells and providing sufficient entropy for security applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If FRAM memory cells are read to generate random numbers, then unique and secure random numbers can be obtained, but the integrity of FRAM cells is compromised due to data destruction during reading operations
Solution Approach 1:
The patent applies preliminary action by capturing and storing the random values from virgin FRAM cells before any write operations are performed. The system reads the spontaneous polarization states of uninitialized memory cells, saves these values, and then initializes the cells to a known state. This ensures the random values are obtained before the cells are modified, resolving the contradiction between generating random numbers and preserving cell integrity.
2Manufacturing precision
If virgin FRAM bitcells are read to capture spontaneous polarization, then sufficient entropy for cryptographic purposes is obtained, but the initial state of memory cells is altered
Solution Approach 1:
The system performs the read operation on virgin cells before any initialization or write operations. By capturing the spontaneous polarization values at the very beginning, before the cells are programmed to a known state, the system obtains high-quality entropy while managing the state change. The random values are stored externally, and the cells are then initialized, ensuring the random generation occurs at the optimal moment when maximum entropy is available.
Solution Approach 2:
The patent discards the initial random state of the FRAM cells after capturing their values, and recovers the cells by initializing them to a known state. The random values are extracted from the virgin cells, stored for use, and then the cells are discarded in their original state and recovered through initialization. This allows the system to obtain the entropy benefit while restoring the cells to a usable, predictable state for subsequent operations.
3Stability of the object's composition
If FRAM cells are initialized before random number generation, then memory integrity is maintained, but spontaneous polarization and process variations are lost
Solution Approach 1:
The patent reverses the conventional sequence by performing the random number generation action before initialization. Instead of initializing first and then generating random numbers, the system reads the virgin cells to capture their spontaneous polarization states, stores these values, and then performs initialization. This preliminary capture of random values before any state-changing operations resolves the contradiction by obtaining the entropy when it naturally exists in the uninitialized cells.
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 allows for the generation of unique and secure random numbers without altering the initial state of the FRAM cells, ensuring the security and uniqueness required for cryptographic and identification purposes, while maintaining the non-volatile nature of the memory.
Implementation Method 1
Each individual bit can be accessed... Each ferroelectric memory cell contains one or more ferroelectric capacitors (FeCap)... spontaneous randomly polarized memory cells
Implementation Method 2
A static identity is required by many applications... A unique and random number may be self-generated by a virgin ferroelectric random access memory (FRAM) array... spontaneous randomly polarized memory cells plus some technology randomness caused by process variations
Data Source
AI summary
A system on chip (SoC) may include a nonvolatile ferroelectric random access memory (FRAM). A random number may be created by applying operating power to the ferroelectric random access memory (FRAM) device and reading a sequence of virgin memory locations within the FRAM device to produce the random number sequence. The sequence of virgin memory locations had previously never been written. The random number may be produced during an initial boot of the SoC, for example. Alternatively, the random number may be saved by a test station during testing of the FRAM device after fabrication of the FRAM device. A memory test of the FRAM may then be performed, after which the random number may be stored in a defined location in the FRAM.