SRAM Cell Radiation Hardening via Series Delay Elements
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Static Random Access Memory (SRAM) cells in radiation environments are vulnerable to multiple node state changes caused by events like proton strikes, leading to soft errors and Single Event Upsets (SEUs), which current active delay schemes may not adequately address.
Innovation Solution
A radiation hardened SRAM cell design incorporating dual active delays coupled in series, with critical areas positioned to avoid common trajectory zones, ensuring that if one delay is disabled, the other maintains radiation hardness and prevents multiple node state changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single active delay is used in the SRAM cell, then the device complexity is reduced, but the reliability against multiple node state changes from radiation events deteriorates
Solution Approach 1:
The single active delay is segmented into two separate active delays (first active delay and second active delay) that are coupled in series. This segmentation ensures that if one delay is disabled by radiation, the other can still provide protection against multiple node state changes, thereby improving reliability without requiring a completely new delay mechanism.
Solution Approach 2:
The dual active delay configuration provides beforehand cushioning by ensuring that even if one delay element is disabled by radiation events, the other delay element remains operational to continue protecting the SRAM cell. This redundant cushioning approach anticipates potential failures and maintains protection capability.
2Reliability
If critical areas are positioned to avoid common trajectory zones, then the reliability against multiple node state changes is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The design considers the three-dimensional trajectory of radiation particles through the SRAM cell structure. By positioning critical areas in specific spatial dimensions and orientations, the design avoids common trajectory zones where particles are most likely to cause multiple node state changes. This dimensional approach to positioning provides radiation hardness while remaining manufacturable.
Data Source
AI summary
A radiation hardened memory element includes at least two delay elements for maintaining radiation hardness. In an example, the memory element is an SRAM cell. Both delays are coupled together in series so that if either one of the delays fails, a delay will still be maintained within the SRAM cell. The critical areas of the delays may be positioned so that a common line of sight cannot be made between each delay and a circuit node.