Asynchronous SRAM Circuit Using C-Elements for SEE Fault Tolerance
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Solution Overview
Problem
Asynchronous electronic circuits are vulnerable to transient faults, particularly single-event effects (SEEs) and single-event upsets (SEUs), which can cause functionality issues and deadlocks due to the absence of a clock signal for filtering glitches, and existing fault-tolerant solutions are not applicable to asynchronous circuits.
Innovation Solution
The development of a fault-tolerant SRAM circuit design that replicates signals and uses C-elements and staticizer circuits to prevent single-event effects from changing the overall state of the circuit during transient faults, employing series transistors and cross-coupled C-elements to ensure independent operation of replica nodes and correct error propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If asynchronous circuits are used to eliminate clock signal and reduce power consumption, then energy efficiency is improved, but the circuits become vulnerable to transient faults and single-event effects
Solution Approach 1:
The circuit is divided into multiple independent signal paths (original path and inverted path) that process the same information independently. Each path is evaluated separately by C-elements, allowing the system to segment the computation and compare results to detect faults without requiring a clock signal.
Solution Approach 2:
The patent creates redundant copies of the circuit logic by generating inverted signals through separate paths. These copied paths process the same input data independently, and their outputs are compared using C-elements to detect single-event upsets. This copying approach enables fault detection in asynchronous circuits without increasing power consumption significantly.
2Reliability
If radiation hardening techniques are applied to protect against single-event effects, then reliability is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
Instead of using complex radiation hardening techniques, the patent employs a simpler approach by creating redundant inverted signal paths and using C-elements for comparison. This copying method achieves single-event effect immunity with minimal additional circuit complexity, avoiding the need for specialized manufacturing processes.
Solution Approach 2:
The circuit performs self-diagnosis by comparing results from independent inverted paths. The C-elements automatically detect discrepancies caused by single-event upsets without external intervention, enabling the circuit to self-correct or self-flag errors without complex external monitoring systems.
3Reliability
If redundant signal paths are added to detect single-event upsets, then fault detection capability is improved, but circuit area and power consumption increase
Solution Approach 1:
The patent merges the fault detection function with the existing computation logic by using the same inverted signal paths for both data processing and fault detection. The C-elements serve dual purposes: they evaluate the inverted paths for computation and simultaneously compare results for fault detection, eliminating the need for separate detection circuitry and reducing overall circuit area.
Data Source
AI summary
New and improved methods and circuit designs for asynchronous circuits that are tolerant to transient faults, for example of the type introduced through radiation or, more broadly, single-event effects. SEE-tolerant configurations are shown and described for combinational logic circuits, state-holding logic circuits and SRAM memory circuits.