PHY Receive Clock Delay for Accurate MAC Data Sampling
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Solution Overview
Problem
In high-speed Ethernet controllers, precise timing alignment of clock and data between Physical Layer Devices (PHY) and Media Access Controller (MAC) is challenging due to independent clocks, requiring separate delays for each data line, which increases circuitry complexity and timing variations.
Innovation Solution
A programmable receive clock delay is introduced, synchronizing data transitions with the rising edge of the delayed receive clock, reducing the need for individual data path delays and simplifying circuitry by controlling a single clock delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate delay circuits are provided for each data line to ensure proper timing alignment, then data sampling accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple separate delay circuits into a single shared delay circuit that serves all data lines. The delay control unit generates a single delay control signal that is applied to the shared delay circuit, which then delays all data lines uniformly. This consolidation reduces the number of components while maintaining timing alignment accuracy across all data lines.
Solution Approach 2:
The shared delay circuit is designed to serve multiple data lines simultaneously with a single delay control signal. This universal delay mechanism provides the same timing adjustment function to all data lines without requiring individual delay circuits for each line, thereby reducing overall device complexity while maintaining sampling accuracy.
2Manufacturing precision
If fixed delay is applied to position data relative to clock edge, then timing alignment is achieved, but adaptability to different timing requirements is reduced
Solution Approach 1:
The patent replaces fixed delay circuits with a programmable delay control mechanism. The delay control unit can dynamically adjust the delay amount based on different timing requirements through a delay control signal. This allows the system to adapt to various timing scenarios while maintaining precise alignment, transforming a static timing solution into a dynamic one.
Solution Approach 2:
The invention changes the delay parameter dynamically by adjusting the delay control signal rather than using fixed physical delay circuits. This allows the delay amount to be modified based on different operating conditions and timing requirements, providing both precision and adaptability in the timing alignment process.
3Measurement precision
If delay is tightly controlled for accurate sampling, then sampling accuracy is improved, but ease of operation deteriorates
Solution Approach 1:
The delay control unit automatically generates and adjusts the delay control signal based on the received clock signal and timing requirements. This self-adjusting mechanism eliminates the need for manual calibration and complex external control, making the system easier to operate while maintaining tight delay control for accurate sampling.
Data Source
AI summary
Output clock adjustment for a digital I/O between physical layer devices and media access controller. A method is disclosed for transferring data received on the input of a physical layer device from a transmission medium to an output associated with the physical layer device and to a media independent layer, the transferred data associated with transferred timing information from the physical layer device to the media independent layer. A receive clock is generated and then the data transitions in the received data are synchronized to at least one edge of the receive clock to provide synchronized receive data. The synchronized received data is then transmitted to the media independent layer. The generated receive clock is delayed by a predetermined clock delay to provide a delayed receive clock, and wherein the data transitions in the synchronized receive data is positioned relative to the rising edge of the delayed receive clock at a predetermined position therein following the rising edge thereof. The delayed receive clock transmitting with the transmitted synchronized receive data.