Asynchronous Circuit Voting Logic for Single-Event Fault Immunity
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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) caused by radiation, which existing technologies have not adequately addressed due to their lack of clock-based filtering mechanisms and the complexity of adapting synchronous circuit solutions to asynchronous circuits.
Innovation Solution
The design of fault-tolerant asynchronous circuits using replicated logic circuits, staticizer circuits with C-elements, and cross-coupled inverters to ensure independence of signal nodes and prevent error propagation, combined with a novel staticizer circuit structure that enhances SEE immunity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If asynchronous circuits are used without clock-based filtering, then circuit speed and flexibility are improved, but vulnerability to transient faults and radiation effects increases
Solution Approach 1:
The patent implements fault tolerance by creating multiple replicated copies of the same logic circuit. Each copy processes the same input signals independently, and the outputs are combined using voting logic. This allows the system to tolerate transient faults and radiation effects in individual copies while maintaining correct operation through majority voting among the replicated circuits.
Solution Approach 2:
The patent introduces intermediary voting logic circuits that act as mediators between the replicated logic circuits and the final output. These voting circuits combine the outputs from multiple replicated circuits, resolve discrepancies caused by transient faults, and produce a reliable final output. The voting logic serves as an intermediary layer that filters out errors without requiring clock-based filtering.
2Reliability
If replicated logic circuits with voting logic are implemented, then fault tolerance against SEEs and SEUs is improved, but device complexity increases
Solution Approach 1:
The patent segments the fault tolerance function into distinct modular components: replicated logic circuit blocks and separate voting logic blocks. Each replicated circuit is an independent module that can be designed and verified separately, and the voting logic is segmented into individual voting circuits for each output. This modular segmentation manages complexity by allowing independent design, testing, and replacement of individual segments without affecting the entire system.
Data Source
AI summary
New and improved methods and circuit designs for asynchronous circuits that are tolerant to transient faults, such as the type introduced through radiation or, more broadly, single-event effects (SEEs). SEE-tolerant configurations are shown and described for combinational logic circuits, state-holding logic circuits and SRAM memory circuits, among others.