Asynchronous State Machine Stability Detection for Reliable Transitions
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Solution Overview
Problem
Asynchronous finite state machines face challenges in detecting state stability, leading to potential incorrect operations due to premature transitions, which can result in hazards and inefficiencies compared to synchronous systems.
Innovation Solution
An asynchronous finite state machine circuit is designed to detect stability in the current state before transitioning, utilizing state indicators and a control circuit to ensure stable state transitions, incorporating quasi delay-insensitive (QDI) logic and sanitization layers to manage non-persistent signals, and employing dual rail and onehot0 encoding for robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If asynchronous finite state machine transitions occur without stability detection, then operation speed is improved, but reliability deteriorates due to premature transitions and hazards
Solution Approach 1:
The patent implements stability detection mechanisms (such as wait states, handshaking protocols, or timing circuits) that verify the current state is stable before allowing a transition to occur. This preliminary verification action prevents premature transitions and ensures reliable state changes while maintaining asynchronous operation speed.
2Reliability
If synchronous systems are used for state transitions, then reliability is improved through clock synchronization, but speed deteriorates due to clock cycle constraints
Solution Approach 1:
The patent extracts and removes the global clock synchronization mechanism from the state transition process, replacing it with asynchronous stability detection. This allows each state transition to be independently controlled based on actual signal stability rather than being constrained by a universal clock cycle, thereby achieving both reliability and high speed operation.
3Reliability
If stability detection mechanisms are added to asynchronous finite state machines, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent implements self-service stability detection where the finite state machine monitors its own internal signals and automatically determines when a state is stable. The circuit uses its existing state bits and transition logic to generate stability indicators, eliminating the need for external complex control mechanisms while ensuring reliable transitions.
Data Source
AI summary
An asynchronous finite state machine circuit comprising state circuitry configured to be in one of a plurality of states, and transition between states, wherein the asynchronous finite state machine is configured to detect that a current state is stable before the state circuitry can transition to a next state.