Loss-of-Signal Detection Circuit With Positive Feedback

The patent applies positive feedback through cross-coupled inverters that create a regenerative effect. When the differential comparator detects a signal level change, the feedback mechanism rapidly amplifies this change through the inverter loop, enabling the circuit to achieve stable state within 2 UI without requiring traditional filtering. This feedback-based approach resolves the contradiction by providing both fast response and false trigger prevention through regenerative signal amplification rather than filtering.

The patent implements local quality by creating asymmetric detection thresholds through the differential comparator configuration. The comparator compares differential signal levels against reference voltages that are locally optimized to distinguish between genuine LOS conditions and normal signal transitions. This localized threshold optimization at the comparator stage enables fast response while maintaining high reliability by preventing false triggers during normal operations.

The patent merges the filtering function into the core detection circuitry by using the differential comparator and cross-coupled inverter feedback loop as an integrated detection and filtering system. Instead of adding separate filtering components, the design combines signal comparison, threshold detection, and false trigger suppression into a unified circuit structure. This merging approach achieves detection accuracy equivalent to filtered systems while maintaining compact circuit size and low power consumption.