Multi-Level Phase Detector Filtering Major Crossings
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Solution Overview
Problem
Current phase detectors in high-speed communication systems experience jitter in the recovered clock signal due to tracking both minor and major crossings, leading to increased bit error rates, especially in protocols like PAM3 where major crossings can be out-of-phase with minor crossings.
Innovation Solution
Employing multiple phase circuits to track transitions for different data eyes while statistically filtering the phase information associated with major crossings, combining the resultant phase information to generate early and late signals for clock recovery, thereby reducing jitter in the recovered clock signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single phase detector tracks both minor and major crossings, then clock recovery is achieved, but jitter increases due to out-of-phase crossings
Solution Approach 1:
The phase detector is divided into multiple independent phase detectors, each dedicated to tracking a specific data eye (minor crossing or major crossing). This segmentation allows each detector to focus on a single crossing type without interference from out-of-phase crossings, thereby reducing jitter in the recovered clock signal while maintaining reliable data recovery.
2Stability of the object's composition
If multiple phase detectors are used to track different data eyes, then jitter is reduced, but device complexity increases
Solution Approach 1:
Multiple phase detectors operate in parallel and their outputs are combined through a logical OR operation to generate the final early and late signals. This merging approach allows the system to benefit from multiple specialized detectors while maintaining a relatively simple overall structure, avoiding the need for complex coordination mechanisms between detectors.
3Reliability
If statistical filtering is applied to phase information, then major crossing interference is removed, but processing complexity increases
Solution Approach 1:
The system extracts only the phase information from detectors tracking minor crossings (or major crossings, depending on configuration) and uses this extracted information for clock recovery. By taking out and using only the relevant phase information while discarding information from detectors tracking the other crossing type, the system achieves filtering without requiring complex processing of all available data.
Data Source
AI summary
A phase detector circuit for use with a multi-level signaling communication protocol on a serial communication link is disclosed. The phase detector circuit employs multiple phase and logic circuits to detect data state changes between adjacent ones of voltage levels corresponding to different data states in the communication protocol, and generates early/late signals using the detected data state changes. The phase detector circuit statistically filters data state transitions between non-adjacent voltage levels to improve phase locking and reduce recovered clock jitter.