Duty Margin Monitoring Circuit for Aging-Induced Clock Degradation

The patent applies preliminary action by performing duty cycle monitoring and error detection before the duty cycle degradation causes circuit failure. The system continuously monitors the duty cycle of clock signals and detects errors in advance, allowing corrective actions to be taken before reliability is compromised. This proactive approach prevents rather than reacts to duty cycle issues.

The patent implements feedback through a closed-loop duty cycle monitoring system that detects duty cycle deviations and provides information for corrective actions. The error detection circuit generates error detection results that feed back to indicate when duty cycle adjustment is needed, enabling the system to maintain reliability by continuously adapting to aging and process variations.

The patent uses copying by creating a replica circuit that duplicates the functional circuit's structure and behavior. This replica circuit receives the same clock signal and produces a corresponding output that can be compared with the functional circuit's output. The copying approach allows duty cycle monitoring without requiring entirely new monitoring infrastructure, as the replica serves both as a functional element and a monitoring reference.

The patent introduces an intermediary error detection circuit that compares the outputs of the functional circuit and replica circuit. This intermediary element mediates between the two circuits and detects duty cycle degradation by identifying discrepancies in their outputs. The error detection circuit serves as a bridge that translates physical duty cycle variations into detectable error signals without requiring direct measurement of the clock signal itself.

The patent maintains continuity of useful action by implementing continuous duty cycle monitoring through the replica circuit and error detection circuit. Rather than periodic checks, the system continuously compares the functional circuit output with the replica circuit output, ensuring that duty cycle degradation is detected immediately when it occurs. This continuous monitoring allows for real-time detection without interrupting the primary circuit operation.

The patent applies self-service by designing the monitoring system to operate autonomously using the existing circuit resources. The replica circuit is driven by the same clock signal that drives the functional circuit, and both circuits process the same input data, allowing the monitoring function to serve itself without requiring separate test signals or external monitoring equipment. The system monitors its own duty cycle performance using its operational outputs.