EDRAM Capacitance Variation for Physically Unclonable Function
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current technologies lack an efficient mechanism for implementing Physically Unclonable Functions (PUF) that leverage embedded dynamic random access memory (EDRAM) capacitance variation, which is essential for creating unique and un duplicable hardware functions.
Innovation Solution
A method and circuit utilizing embedded dynamic random access memory (EDRAM) memory cell capacitance variation, where a pair of EDRAM memory cells with true and complement storage capacitors, connected to differential inputs of a sense amplifier, exploit capacitance variations due to manufacturing and process variations to consistently read random data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EDRAM memory cell capacitance variation is utilized for PUF implementation, then unique and unclonable hardware function is achieved, but manufacturing and process variations cause capacitance inconsistency
Solution Approach 1:
The patent changes the operational parameters of the EDRAM cells by controlling the write and read timing sequences. Specifically, it exploits the transient capacitance variation that occurs during the write operation and reads the cells at a specific time window when the capacitance difference is maximized. This parameter change approach converts the harmful manufacturing variations into a useful timing-dependent signal for PUF generation.
Solution Approach 2:
The patent introduces dynamic timing control where the read operation is performed at a specific time after the write operation. The capacitance variation is not static but evolves over time following the write pulse, and the system dynamically captures this variation at the optimal moment. This dynamic approach allows the system to exploit the transient state of the EDRAM cells for generating unique PUF responses.
2Reliability
If timing-dependent capacitance variation is exploited for PUF, then consistent random data reading is achieved, but precise timing control increases circuit complexity
Solution Approach 1:
The patent merges the PUF functionality with the existing EDRAM structure and its built-in write and read control logic. Instead of adding a completely separate timing control mechanism, it utilizes the existing EDRAM control signals (write enable, read enable) and their inherent timing relationships. The PUF read operation is integrated into the normal EDRAM access sequence, leveraging the existing timing infrastructure to reduce overall circuit complexity.
Solution Approach 2:
The EDRAM cells themselves provide the timing reference for the PUF operation through their intrinsic charge discharge characteristics. The capacitance variation occurs naturally following the write pulse without requiring external timing references or additional control circuits. The system essentially uses the physical behavior of the EDRAM cells to self-generate the timing signal needed for consistent PUF reads.
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 effectively implements a Physically Unclonable Function (PUF) by harnessing the timing-dependent capacitance variation of EDRAM cells, ensuring consistent and unique data reading, thus overcoming the limitations of prior art arrangements.
Implementation Method 1
A random variation of memory cell capacitance is used to implement the physically unclonable function. The capacitance variation generally due to manufacturing and process variations in the EDRAM memory cell storage capacitors
Implementation Method 2
there is a timing dependence based upon the EDRAM trench capacitor in which its capacitance increases after it is written and also there is increased variation in this capacitance until it reaches its DC or steady state capacitance
Data Source
AI summary
A method and embedded dynamic random access memory (EDRAM) circuit for implementing a physically unclonable function (PUF), and a design structure on which the subject circuit resides are provided. An embedded dynamic random access memory (EDRAM) circuit includes a first EDRAM memory cell including a memory cell true storage capacitor and a second EDRAM memory cell including a memory cell complement storage capacitor. The memory cell true storage capacitor and the memory cell complement storage capacitor include, for example, trench capacitors or metal insulator metal capacitors (MIM caps). A random variation of memory cell capacitance is used to implement the physically unclonable function. Each memory cell is connected to differential inputs to a sense amplifier. The first and second EDRAM memory cells are written to zero and then the first and second EDRAM memory cells are differentially sensed and the difference is amplified to consistently read the same random data.