RAM Null-Read TRNG Using Sense Amplifier Offset Randomness
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Solution Overview
Problem
Current random number generators, particularly pseudorandom number generators, are not suitable for critical applications requiring true randomness, as they can be predictable and reproducible, whereas true random number generators based on physical environments are needed for security and other critical uses.
Innovation Solution
A true random number generator system utilizing a RAM array with a null-read controller and a hash generator, where the null-read controller includes a differential voltage conditioner and a word line overrider to minimize sense amplifier offset voltage, enabling the generation of true random numbers through null-read operations in SRAM or DRAM arrays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pseudorandom number generators are used, then device complexity is reduced and ease of operation is improved, but reliability deteriorates because the numbers are predictable and reproducible
Solution Approach 1:
The patent reuses existing RAM array infrastructure (memory cells, bit lines, sense amplifiers) for dual purposes: normal data storage operations and true random number generation. The same hardware components serve both conventional memory functions and TRNG functions, eliminating the need for separate dedicated random number generation hardware.
Solution Approach 2:
The system uses the inherent physical characteristics of existing RAM components (sense amplifier offset voltages, thermal noise, timing variations) to generate random numbers. The RAM array's own operational variations and physical environment naturally provide the randomness source, requiring minimal additional components.
2Measurement precision
If null-read operations are performed on connected word lines, then more random bits are obtained, but measurement precision deteriorates due to sense amplifier offset voltage
Solution Approach 1:
The patent divides the RAM array into two functional segments: connected word lines for normal data operations and unconnected word lines for random number generation. By selecting unconnected word lines, the system accesses sense amplifiers that are not influenced by data storage operations, isolating the randomness generation process from data interference.
Solution Approach 2:
The system extracts random numbers from the inherent physical variations of unconnected sense amplifiers, separating this randomness extraction function from the main data storage and retrieval operations. This extraction occurs in isolation using dedicated unconnected word lines, preventing interference with normal memory operations.
3Productivity
If multiple null-read operations are performed, then productivity of random number generation is improved, but device complexity increases due to additional control circuits
Solution Approach 1:
The null-read controller is integrated with the existing RAM control logic, merging the random number generation control functions with the memory control infrastructure. The controller uses the same control signals and timing mechanisms already present in the RAM system, avoiding the need for entirely separate control circuits.
Solution Approach 2:
The system pre-charges bit lines and prepares sense amplifiers in advance of the actual null-read operation. By performing preliminary setup actions, the system enables rapid sequential null-read operations without requiring complex real-time control logic for each individual read cycle.
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
The system effectively generates true random numbers by leveraging the spatial and temporal randomness of sense amplifier offset voltages, ensuring unpredictability and integrity, suitable for secure applications.
Implementation Method 1
The sense amplifier senses a differential input signal on pairs of bit lines when they are connected to the sense amplifier, or a pair of local data lines when they are connected to the sense amplifier
Implementation Method 2
The DVC minimizes the sense amplifier offset voltage in the sense amplifier during the a null-read operation
Data Source
AI summary
A system to generate true random numbers includes a RAM array, a null-read controller and a hash generator. The RAM array has memory cells and a sense amplifier. The memory cells store data therein, the cells are connected in rows to word lines and in columns to pairs of bit lines, and the sense amplifier senses a differential input signal. The null-read controller implements a null-read operation by the sense amplifier of a portion of the RAM array. The hash generator receives a null-read result from the null-read operation and outputs a partial true random number based on the null read result