Ethernet PHY Phase Search Using Closed-Loop MSE Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional optimum phase searching methods in Ethernet physical layers lack accuracy and reliability due to the absence of a feedback mechanism, often resulting in misjudgment of the optimum phase, especially when clock signals jitter, and are prone to interference between time recovery circuits and equalizers.
Innovation Solution
The proposed system includes a time recovery circuit with a loop filter and time error detector, and an equalizer with feed forward and feed backward equalizers, utilizing a closed-loop approach to determine optimum phases by analyzing Mean Squared Error (MSE) values and time error detector outputs, ensuring convergence to a stable state and precise phase determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional optimum phase searching method is used to search all possible phases according to MSE values, then phase searching can be performed, but accuracy and reliability deteriorate due to lack of feedback mechanism and interference between time recovery circuit and equalizer
Solution Approach 1:
The patent implements a feedback mechanism where the time error detector continuously monitors phase errors and feeds back adjustment signals to the voltage-controlled oscillator. This closed-loop feedback system enables real-time correction of phase deviations, significantly improving both the reliability and precision of optimum phase determination compared to conventional open-loop methods that lack such feedback control.
Solution Approach 2:
The patent extracts and separates the time recovery circuit functionality from the equalizer by implementing an independent time error detector and voltage-controlled oscillator dedicated to phase recovery. This separation eliminates the interference between time recovery and equalization functions, allowing each circuit to operate optimally without mutual interference, thereby improving both reliability and measurement precision.
2Object-generated harmful factors
If time recovery circuit is disabled temporarily to prevent interference with equalizer, then interference is reduced, but phase searching accuracy deteriorates when clock signals jitter
Solution Approach 1:
The patent extracts the time recovery function into a separate, dedicated circuit module with its own time error detector and voltage-controlled oscillator. This physical and functional separation allows the time recovery circuit to operate independently without interfering with the equalizer, while still providing accurate phase detection even when clock signals jitter, thus resolving the contradiction between reducing interference and maintaining detection precision.
3Device complexity
If open loop phase searching is used for simpler layout, then device complexity is reduced, but accuracy and reliability deteriorate due to absence of feedback mechanism
Solution Approach 1:
The patent implements a closed-loop feedback system where the time error detector continuously monitors phase synchronization status and feeds back control signals to the voltage-controlled oscillator. This feedback mechanism automatically corrects phase deviations in real-time, significantly improving reliability compared to open-loop methods, while the modular architecture keeps device complexity manageable through standardized circuit blocks.
Data Source
AI summary
A system for optimum phase searching in an Ethernet physical layer includes a time recovering circuit and an equalizer. The time recovering circuit includes a loop filter and a time error detector, and the equalizer includes a feed forward equalizer, a slicer and a feed backward equalizer. An optimum phase searching method includes obtaining optimum phases when mean squared errors calculated by the slicer are less than a first threshold, absolute values of mean values of outputs calculated by a time error detector are less than a second threshold, and the outputs are monotonic.