PHY Time Synchronization Timestamp Storage Jitter Reduction
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Solution Overview
Problem
Existing communication systems, particularly those using Ethernet, face challenges in achieving sub-microsecond timing accuracy due to jitter in clock synchronization, especially when implementing IEEE 1588 Precision Time Protocol.
Innovation Solution
A Physical Layer Transceiver (PHY) with integrated time synchronization, including analog and digital circuitry, storage, and timing circuitry, which generates and stores timestamps for frames, allowing for precise clock synchronization according to the IEEE 1588 Standard, and communicates these timestamps to external devices, thereby improving synchronization accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If Ethernet and local area network technologies are used for clock synchronization, then system adaptability and ease of operation are improved, but timing precision and synchronization accuracy deteriorate due to jitter
Solution Approach 1:
The patent segments the timestamping function into separate hardware components within the PHY device, with independent timestamp generators for transmit and receive paths. This segmentation isolates the precision-critical timestamping operations from the jitter-prone Ethernet communication layer, allowing each segment to operate with deterministic timing while maintaining overall system adaptability to various network technologies.
Solution Approach 2:
The patent introduces an intermediary hardware-assist circuit with frequency-compensated clocks that mediates between the Ethernet communication layer and the timestamping function. This intermediary layer provides a stable timing reference that buffers against jitter from the network medium, translating variable Ethernet timing into precise, compensated timestamps without sacrificing network compatibility.
2Measurement precision
If hardware-assist circuits with frequency compensated clocks are used, then timing precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the timestamping functionality directly into the PHY device structure, combining the hardware-assist circuit, frequency-compensated clocks, and timestamp storage into an integrated unit. This consolidation achieves precise timestamping without the complexity of separate external synchronization devices, as the timestamping functions are unified with the existing PHY communication hardware.
Solution Approach 2:
The PHY device structure is designed with multi-functionality, where the same hardware components serve both Ethernet communication and precision timestamping functions. The analog and digital circuitry handle both data transmission and timing operations, eliminating the need for dedicated separate circuits and reducing overall device complexity while maintaining timestamp accuracy.
3Measurement precision
If timestamps are stored for each frame, then synchronization precision is improved, but loss of time increases due to storage and retrieval operations
Solution Approach 1:
The patent implements preliminary action by generating and storing timestamps at the exact moment each frame is transmitted or received, using hardware-triggered operations. The timestamp is captured immediately when the frame edge is detected, eliminating any delay between the actual transmission/reception event and the timestamp creation. This preliminary capture ensures synchronization precision without adding processing overhead.
Solution Approach 2:
The timestamp storage system operates autonomously through hardware-triggered operations that automatically capture and store timestamps without requiring software intervention or complex processing. The hardware-assist circuit self-manages the timestamp generation and storage, reducing the time loss associated with software-based timestamping while maintaining high synchronization precision.
Data Source
AI summary
Disclosed, inter alia, is a Physical Layer Transceiver (PHY) with integrated time synchronization, such as, but not limited to, IEEE 1588 Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems. The PHY includes circuitry to maintain a current time, and to trigger the storage of timestamps corresponding to received frames. Typically, in response to a request from an external device, the timestamps are retrieved from storage and are communicated to the external device. By moving the triggering of the storage of the timestamps by the PHY itself, rather than by a monitoring of the traffic between the PHY and the Media Access Controller (MAC), higher accuracy can typically be achieved.